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-   -   Improve mileage 350 with Quadrajet (https://67-72chevytrucks.com/vboard/showthread.php?t=429908)

kikkegek 11-27-2010 05:47 PM

Re: Improve mileage 350 with Quadrajet
 
alrightytighty!

today picked up our ride again. It has been treated with Fluid Film for anti coroosion and is ready for winter. Snow has started coming down this weekend, so we are just in time.

Calculated the mileage from the last ....

*drums mode ON*
.
..
...
....
.....
drove 120 miles (193,08 km)
got gas (LPG in my case)
payd for 51,97 liters (13,729 gallons)

that makes for: 120/13,729 = 8,74 MPG
or
193,08/51,95 = 3,715 km/l

this means improvement. But only for highway...like 99% of this was done driving 90 km/h which is about 55-60 mph.

So mileage is still poor as far as I can judge.

the search continuous...please advise.

tucsonjwt 11-27-2010 08:13 PM

Re: Improve mileage 350 with Quadrajet
 
I read that LPG gets 10% less fuel economy when compared to gasoline. So, 8.74 mpg LPG = 9.6 gasoline equivalent MPG. The 3 squares I have owned were all 3/4 ton (2 -454, 1-350) and ranged between 10-12 mpg. In ideal conditions I could get 14 mpg with my 73 C20 454 all highway, but 12-13 was more likely. Cold weather consumes more gas due to choke being on longer. I have known people with 1/2 ton 350s that got 10 mpg. I have also read that tuning a vehicle to run on LPG is different than one running on gasoline. I suspect that most people driving old V8 pickups don't get more than 10 MPG most of the time, unless they keep their trucks in top shape. Just some random thoughts.

geezer#99 11-27-2010 10:10 PM

Re: Improve mileage 350 with Quadrajet
 
Are you still using that open element air cleaner. Cold air is a fuel hog. Good for HP but bad for mileage.
Pm the op in this link. He's taking his off.
http://67-72chevytrucks.com/vboard/s...d.php?t=432749

kikkegek 11-28-2010 05:42 PM

Re: Improve mileage 350 with Quadrajet
 
Quote:

Originally Posted by geezer#99 (Post 4317245)
Are you still using that open element air cleaner. Cold air is a fuel hog. Good for HP but bad for mileage.
Pm the op in this link. He's taking his off.
http://67-72chevytrucks.com/vboard/s...d.php?t=432749

I am using a filterhouse with a pipe to the grill. See picture:
http://lh5.ggpht.com/_i4YwYZutwgk/TL...0/P1150700.JPG
http://lh4.ggpht.com/_i4YwYZutwgk/TL...0/P1150696.JPG

The second picture is what it looks like behind the grill.

There are different opinions on cold or hot air being better for mileage.

Some say cold air holds more oxygen, so you get more power from heach stroke of the engine. Some say warm air performs less, so you have less power, so you get better mileage. Personally I think the first sounds more reasonable.

This is what Wikipedia says about a Cold Air Intake:
http://en.wikipedia.org/wiki/Cold_air_intake

This is what Wikipedia says about Warm Air Intake:
http://en.wikipedia.org/wiki/Warm_air_intake

Especially the second piece of text mentions a ECU reacting to the warm air, etc. Since my car has no ECU, a WAI will be of no use, I assume.

Anybody got an opinion on this? or field-experience?

motornut 11-29-2010 09:39 AM

Re: Improve mileage 350 with Quadrajet
 
3 Attachment(s)
mine was all bypassed,this was summer,flipped top norm for winter
with a winter grill cover i found i got it warmed up real quick (choke of quicker)inside heat and got better gas mileage
my idea being the all the air around the block is warmer, quicker to help vaporise gas then ice cold from the front
in the winter if it's from the piped front (ideal for summer tho)it may clog up quickly depends tho on road spray
but dosn't it have stock, some kinda plastic cover go around to keep stuff out

Cue-Ball 11-29-2010 08:20 PM

Re: Improve mileage 350 with Quadrajet
 
Quote:

Originally Posted by kikkegek (Post 4318607)
Some say cold air holds more oxygen, so you get more power from each stroke of the engine.

That is true.

Quote:

Some say warm air performs less, so you have less power, so you get better mileage.
Not really true, but could be viewed that way.

Colder air does hold more oxygen, so it has the potential to create more power. But to make that extra power you have to use extra fuel. Hot air, on the other hand, uses less fuel (at a given throttle opening) and therefore makes less power, but you have to open the throttle further and use more air/fuel mix to make the same power. Quite the conundrum.

The ecomodding communities have been going back and forth over this topic for years now. Hotter air gives fewer pumping losses, but colder air is more efficient. Computer retarded timing removes any benefit of a hotter mixture, but computer controlled injectors can create an always-stoich mixture. Cold air holds more oxygen, but hot air atomizes fuel better. Back and forth, on and on. Unfortunately, there are a LOT of factors at work here, beyond just the temperature of the air.

Cold air generally makes more power at WOT because it allows/requires more fuel and because the carb/throttle body butterflies are no longer the primary restriction on the engine. At anything less than WOT the jury is still out. You may see an increase in mileage using cold air, but you may not. It depends on tons of factors like fuel vaporization, length and restriction of intake tract, engine operating temperature, etc. But something to keep in mind is that air that's too cold doesn't atomize fuel well, so cold intake air can often lose power over warm air.

There just simply isn't a "cold air is more fuel efficient" or "warm air is more fuel efficient" statement that can be made. If you're looking for fuel efficiency you should first look at timing, gear ratios, lubricants, exhaust efficiency, etc. before you worry about intake air temp being any sort of a factor at all.

Cue-Ball 11-29-2010 08:49 PM

Re: Improve mileage 350 with Quadrajet
 
Quote:

Originally Posted by camshaftgsxr (Post 4303032)
wow this is as wrong as it gets... ditching the egr will improve gas mileage, but it will also make it non emissions compliant

the egr is an Exhaust Gas Recirculation valve, it pumps exhaust into your engine to keep the airfuel mixture from burning too hot while cruising down the highway, exhaust into an engine hurts the hell out of performance btw...

Exhaust into the intake tract would hurt performance, yes... but when the EGR is running you're not shooting for performance anyway since you're at idle/cruise!

Removing the EGR won't increase fuel mileage, it will make it worse since more fuel will be used at idle and cruise. The hotter air being introduced needs less fuel to burn at stoich. Less fuel = better mileage. When you push on the go pedal and are trying to squeeze power out of the engine the EGR closes (it's vacuum operated) and you're essentially running a non-EGR system.

The whole EGR system can be a pain in the butt, because they're failure prone... but it's a system that increases mileage (on a properly tuned engine), not decreases it.

WILLD420 11-30-2010 01:50 AM

Re: Improve mileage 350 with Quadrajet
 
What altitude are you at? That will tell you what you can do. Altitude determines allowable compression. At sea level, you will be limited to 8.0-8.5-1 compression with 87 octane unleaded. With propane you can run 9.0-9.5-1 pretty safely.

Assuming I had limited funds, say maybe $800 U.S. Here's what I would do.

Find a set of 305 Small block heads, from the mid 80's. They had smaller chambers that would bump your compression up. Rebuild them using 1.94" intake valves and do a mild cleanup of the port under the valve (Pocket Porting.) Install (Z-28) equivalent valve springs.

Buy a camshaft equivalent to a Comp 260H, or similar with duration at .050 near or under 210 degrees. Stick with a single pattern camshaft, ie. intake and exhaust the same duration.

Buy an adjustable vacuum advance can and install it. The oem can may be adjustable, check before you throw it away. (The oem can is calibrated for gasoline and a functional EGR which allows more timing at light throttle. But can be too much once EGR is no longer introduced.) If you set the timing to specs and you have spark knock at light throttle, an adjustable can will cure this and allow total timing to still be 35-36 degrees.

Throw away the factory high restriction muffler(s) and get a nice quiet free flowing turbo design. (Assuming you have the large truck type that are very quiet but don't flow well at all.)

The cam is optional, but will usually give more power and not hurt mpg at all, especially with a decent exhaust. The increase in compression will really wake your engine up, especially if you are at 3,000 ft elevation or higher. Make sure you have a 195 degree thermostat. As long as you aren't overheating during the warmer times, the hotter an engine runs, the more efficient it will be.

The vacuum advance will allow you to advance your part throttle timing as much as possible while still limiting overall timing to a safe point.

In your picture, it looks as though you have the free flowing stainless exhaust manifolds. Those are just as good as headers for general driving and mpg, don't waste your time or money on tube headers if that is the case.

Tall skinny all terrain or highway tread tires will get better mpg than fat tires, or aggressive mud tires.

Adding compression, free flowing exhaust and timing should net you 2-3 mpg minimum gain assuming nothing else changes. Especially with propane. At 8.0-1 compression, propane isn't going to be nearly as efficient.

kikkegek 11-30-2010 06:51 AM

Re: Improve mileage 350 with Quadrajet
 
guys!

thanks for the really extensive (is that corrdect?) answers. appreciate it.

I am at sea level, 15 minutes from the coast in the Netherlands (Europe) freezing my ass of at the moment.

The label is no longer on the car that reads the eact timing settings for my engine at idle and 2500 or 3000 rpms. Can somebody help me, how I should time it?

lindstromjd 11-30-2010 07:35 AM

Re: Improve mileage 350 with Quadrajet
 
Quote:

Originally Posted by kikkegek (Post 4322104)
The label is no longer on the car that reads the eact timing settings for my engine at idle and 2500 or 3000 rpms. Can somebody help me, how I should time it?

I don't think there's a good answer to that question unless someone here is actually running LPG like you are. It's not a set-in-stone sort of thing. My 75 pickup calls for 4 degrees BTDC, and my 78 corvette with the exact same engine calls for 12 degrees BTDC. It's safe to say that my 350 runs a LOT better at 12 degrees.

I would say just play it by ear, but you probably want more specific than that.

kikkegek 11-30-2010 10:13 AM

Re: Improve mileage 350 with Quadrajet
 
oke, lindstromjd, but what you are talking about is initial timing. I am talking about total timing at about 2500-3000 rpm. Because that is the rpms I usually cruise at.

in a youtube vid I saw they said that 32-36 total timing at about 3500 is OK.

WILLD420 12-01-2010 01:35 AM

Re: Improve mileage 350 with Quadrajet
 
Gasoline you can run 32-36 degrees total at 3K rpm pretty safe. It all depends on the engine. Some like more, some less. Two identically built engines can desire 2 different total timing depending on load, carbon buildup, casting flash in the combustion chambers etc.

I would start with factory spec on initial timing and go from there. You may have to adjust the advance mechanism under the rotor for total advance. Sometimes you can tolerate a lot of intial advance, but the total advance allowed by the distributor will put you in excess of 40 degrees total timing. To correct this you have to limit the amount of total timing by either making a stop for the weights or brazing the holes in the advance mechanism then opening them up to the point where you get the desired timing.

You want to run on the ragged edge of detonation for maximum power and efficiency. Advance it till it pings, then back off 2 degrees. Take it for a spin, listen if you think you hear pinging/detonation, back off another 2 degrees. Repeat until you find the sweet spot.

I wouldn't get too upset if you can get up to 10 mpg on propane. I drive a 99 lincoln navigator for work and it's averaging 12 around town and 14 on long trips. That's with a 5.4 liter engine and all the modern fuel injection and better engine design.

Psycho71 12-01-2010 03:49 PM

Re: Improve mileage 350 with Quadrajet
 
Not much on LP engines. But I can offer up another vote for getting rid of that flex fan, in favor of a clutched fan or an electric fan. Seems like every older vehicle i get has one of those flex fans on it when I get them. And almost every time I pull them off and put a clutched or electric fan on, I can literally feel the difference. And I've never noticed one to cool any better than a good operating clutch fan. The only cool thing I've seen from flex fans are the dents in hoods (from inside out) and other damage they do when a blade decides to depart from the rest of the assembly. Usually at higher RPMs which makes things even worse.

kikkegek 12-02-2010 03:57 PM

Re: Improve mileage 350 with Quadrajet
 
ok, when the temperature goes up, I wanna look into total timing.

Right now I wanna focus on earning up the engine more quickly in this freezing weather using some stuff that is still on the engine.

I got the Heat Riser valve in the exhaust.
http://lh5.ggpht.com/_i4YwYZutwgk/TP...0/P1160164.JPG

I have it currently hooked up to a constant vacuum to make sure it is always open. But could hook it up to the vacuum switch on the thermostat housing? So it stays closed untill the engine is warm enough?
But how to hook it up?
http://lh6.ggpht.com/_i4YwYZutwgk/TP...0/P1160293.JPG


then I could hook up the EGR Valve. Does this work together with the heat riser valve?
http://lh6.ggpht.com/_i4YwYZutwgk/TP...0/P1160285.JPG

or does this EGR valve operate on its own?
how should I hook this up?
can I use this small vacuum switch?
http://lh6.ggpht.com/_i4YwYZutwgk/TP...0/P1160291.JPG

WILLD420 12-03-2010 03:05 AM

Re: Improve mileage 350 with Quadrajet
 
The vacuum fitting on your thermostat will work on temperature. That is the fitting you need for the thermostatic valve unless I am mistaken. You need to have it apply vacuum once the engine is warmed up.

The EGR, if I remember, works on ported vacuum with some one-way valves or regulators of some sort. Not sure, since we always disconnected them for more power. Shouldn't be too hard to figure out.

If you can't get it to warm up, make sure you have a 195 degree (Celsius 90?ish) thermostat. If you have one for a lower temp, you may never get any heat once the temps go below freezing. You can also cut a piece of cardboard or thin stiff plastic to cover a portion of the radiator during the winter. There are fancy vinyl radiator covers sold here in the states for the colder climates, similar to what the big rig trucks use in the winter to block most of the airflow through the radiator to keep the engines warm.

Don't be afraid to look on other brand vehicle information. EGR and the heat riser stuff are pretty similar from one manufacturer to another, just have to make sure you get the right side of the vacuum valves for your particular application.

kikkegek 12-03-2010 03:11 AM

Re: Improve mileage 350 with Quadrajet
 
Quote:

Originally Posted by WILLD420 (Post 4328202)
The vacuum fitting on your thermostat will work on temperature. That is the fitting you need for the thermostatic valve unless I am mistaken. Not sure how it works, as we live in the desert and usually cut those valves off for better flow when they quit working like they should.

okay, thanks, can you help me with the two way and the four wayt switch. Do they operate differently? Is the twoway normally closed and the fourway normally open?

and can you help me with the other questions?

foamypirate 12-03-2010 03:11 AM

Re: Improve mileage 350 with Quadrajet
 
Quote:

Originally Posted by camshaftgsxr (Post 4303032)
wow this is as wrong as it gets... ditching the egr will improve gas mileage, but it will also make it non emissions compliant

the egr is an Exhaust Gas Recirculation valve, it pumps exhaust into your engine to keep the airfuel mixture from burning too hot while cruising down the highway, exhaust into an engine hurts the hell out of performance btw...

Actually, you are as wrong as it gets. Recirculating exhaust gas back into the combustion chamber cools the chamber (odd, I know, but it does) and leans the mixture, resulting in IMPROVED fuel mileage. WOT throttle performance and cruising are completely different beasts.

WILLD420 12-03-2010 03:26 AM

Re: Improve mileage 350 with Quadrajet
 
Easiest way to tell how those valves work is a piece of vacuum line. Get a piece long enough you can suck on one end and put the other end on the vacuum port. Then get busy figuring out which way the valves work. If you cant' get any air to go through the valve, it's probably stuck 1/2 way between positions.

The EGR and the Heat Valve work independently of each other. One is strictly for emissions, the other for quicker warmups which lead to lower emissions. The purpose of the EGR valve is to dilute the incoming mixture with air that has already been burned, leading to cooler combustion temperatures and a reduction in NOX emissions. Since you are running propane and I don't think you have to worry about the emissions part, the EGR is up to you, whether you run one or not.

If you hook it up and your MPG improves, then it's a good thing. If you hook it up and nothing changes, but you lose power, then it's a bad thing.

Also, since propane burns with less energy than gasoline, it will take a little longer to warm the engine up to operating temp unless you are making power by loading the engine.

Also, the EGR is more of a load sensitive thing, than a temp related mechanism. It should only be working at part throttle with high vacuum. At higher throttle and reduced vacuum the EGR should become inoperative, allowing more power from the engine.

I'm not a lot of help with the EGR part, as we usually don't run them on the engines I've built in the past.

kikkegek 12-03-2010 03:47 AM

Re: Improve mileage 350 with Quadrajet
 
Quote:

Originally Posted by WILLD420 (Post 4328214)
Easiest way to tell how those valves work is a piece of vacuum line. Get a piece long enough you can suck on one end and put the other end on the vacuum port. Then get busy figuring out which way the valves work. If you cant' get any air to go through the valve, it's probably stuck 1/2 way between positions.

The EGR and the Heat Valve work independently of each other. One is strictly for emissions, the other for quicker warmups which lead to lower emissions. The purpose of the EGR valve is to dilute the incoming mixture with air that has already been burned, leading to cooler combustion temperatures and a reduction in NOX emissions. Since you are running propane and I don't think you have to worry about the emissions part, the EGR is up to you, whether you run one or not.

If you hook it up and your MPG improves, then it's a good thing. If you hook it up and nothing changes, but you lose power, then it's a bad thing.

Also, since propane burns with less energy than gasoline, it will take a little longer to warm the engine up to operating temp unless you are making power by loading the engine.

Also, the EGR is more of a load sensitive thing, than a temp related mechanism. It should only be working at part throttle with high vacuum. At higher throttle and reduced vacuum the EGR should become inoperative, allowing more power from the engine.

I'm not a lot of help with the EGR part, as we usually don't run them on the engines I've built in the past.

thanks, thats some great advise and simpel method for figuring out how the switches work (why didnt I think of that?:banghead:)!!!

I think I'll hook up the Heat riser valve then, to heat up the engine more quickly and see how the vacuum switches work.

I might testrun the EGR to see if it improves mileage. We cruise all the time and allmost never stress the engine, so we are all about mileage and not very hot on power...so the EGR might even help with that!

thanks man!

kikkegek 12-12-2010 04:13 PM

Re: Improve mileage 350 with Quadrajet
 
ok,
made a mistake!
When I adjusted the timing I also connected the Heat Riser Valve in the exhuast to the SMOG port. Thereby closing half of my exhausts as asoon as I started the engine.

Still got low 8 mpg...I changed it. plugged the SMOG port and disconnected the Valve so all my exhausts are open all the time.

lets see what this does? right?

kikkegek 12-21-2010 02:51 PM

Re: Improve mileage 350 with Quadrajet
 
OK,
did some more research.

It seems my car stays cold?
it alwasys stays at the temperature shown in the picture. Just underneath 155F?

I already checked the thermostat. When the engine is cold, it is closed. I have no clue though at which temperature it opens. But after a little drive the coolent flows through the radiator, so the thermostat has opened.

I used a IR thermometer to check temperatures.

I measured 167F at the thermostat housing where the big hose connects.
and I measured about the same 165F at the top of the radiator where the big hose connects.

isnt 165F a bit cool for an engine to run and shouldnt the thermostat be closed?

http://lh5.ggpht.com/_i4YwYZutwgk/TH...0/P1140134.JPG

Somebody I know is shipping me a fanclutch and cooling fan. I am gonna take the flexfan off and install a regular fan again. Because we drive our car all year, the flexfan is unnecessarily cooling the engine at low rpm during winter (cool) times.

rayfinseats 12-22-2010 04:22 AM

Re: Improve mileage 350 with Quadrajet
 
Put your thermostat in a pan full of water with a thermometer and bring to a boil. Then you can see exactly when it opens. Maybe your radiator is just too big. I have made that mistake before.

Cue-Ball 12-22-2010 12:50 PM

Re: Improve mileage 350 with Quadrajet
 
Quote:

Originally Posted by rayfinseats (Post 4364307)
Maybe your radiator is just too big. I have made that mistake before.

That is just patently false information. There's no such thing as a radiator that is too big.

The radiator's job is to dissipate the heat from the engine into the outside air. It's impossible for this job to be made too quick or too efficient, since even 100% efficiency would be sending air-temperature water back into the engine. At that point the engine would cool off to the point that the thermostat closed, the water would start to heat up again, the thermostat would open, and the whole cycle would start over again.

I'd be willing to bet the OP's problem is caused by the thermostat either opening too early or staying open all the time. 80's engines generally use a 195* thermostat. If you're only reading 165* at the housing and radiator, it seems like it's opening too fast (Though, having never used a laser thermostat on my own truck, I'm not sure how much heat loss is normal between the water temperature and the temp of the housing. I'd guess both would be about the same temp). Another clue would be watching the temp of the housing/radiator hose as the truck warms up. If they slowly get hotter, the thermostat is stuck open. If they stay cold, then suddenly get hot, then the thermostat is opening correctly, but might still be opening too early.

kikkegek 12-22-2010 02:18 PM

Re: Improve mileage 350 with Quadrajet
 
thanks cue-bal, I am gonna change the thermostat to a 195F model, just to make sure!

I'll keep you guys updated on the result.

billnorman 12-22-2010 04:40 PM

Re: Improve mileage 350 with Quadrajet
 
I saw in your earliest photographs that the vacuum hose to your EGR valve is not connected. This engine runs poorly with it not connected and operational. You can't run decent timing without EGR or it will ping. Initial timing on this engine is recommended at about 8 degrees BTDC if I'm not mistaken, but you need to set it at total advance to do it right and for this you need a degree wheel and timing light. I'd run the total at 34 degrees unless it pings at partial load. If you don't have EGR all bets are off. Also, the flex fan is dangerous I had a friend that (literally) lost his head when one disintegrated. Any Mercedes mechanics that work on older ones will know how to set the timing at total. Also, I put a 210 degree thermostat in my '85 and have had no problems. Find a thermo clutch fan.

kikkegek 12-22-2010 04:52 PM

Re: Improve mileage 350 with Quadrajet
 
Quote:

Originally Posted by billnorman (Post 4364827)
I saw in your earliest photographs that the vacuum hose to your EGR valve is not connected. This engine runs poorly with it not connected and operational. You can't run decent timing without EGR or it will ping. Initial timing on this engine is recommended at about 8 degrees BTDC if I'm not mistaken, but you need to set it at total advance to do it right and for this you need a degree wheel and timing light. I'd run the total at 34 degrees unless it pings at partial load. If you don't have EGR all bets are off. Also, the flex fan is dangerous I had a friend that (literally) lost his head when one disintegrated. Any Mercedes mechanics that work on older ones will know how to set the timing at total. Also, I put a 210 degree thermostat in my '85 and have had no problems. Find a thermo clutch fan.

he thanks man! but can you explain to me how the EGR would influence the timing?

As far as I am informed this valve only recirculates Exhause Gas when activated. And should do this only to reduce emissions.

please explain to me what you mean?

billnorman 12-23-2010 05:30 AM

Re: Improve mileage 350 with Quadrajet
 
It doesn't influence the timing. It warms and helps disperse the incoming air/fuel charge. Believe me I had to find out the hard way, these motors like warm air inserted into the manifold. I chased a ping for a long time until I found out my EGR valve was defective. Cleaned valve, no more ping. It's a cheap fix, if you don't like the outcome, just leave it disconnected. There should be a map of vacuum lines on a decal under your hood to show you which carburetor port to hook it to. Also, if it's dirty or clogged, it won't function. It's relatively easy to remove, clean and reinstall. I used spray carburetor cleaner. Let me know if it helps. Also, it can be tested when off the vehicle with vacuum.

kikkegek 12-23-2010 06:49 AM

Re: Improve mileage 350 with Quadrajet
 
Quote:

Originally Posted by billnorman (Post 4365989)
It doesn't influence the timing. It warms and helps disperse the incoming air/fuel charge. Believe me I had to find out the hard way, these motors like warm air inserted into the manifold. I chased a ping for a long time until I found out my EGR valve was defective. Cleaned valve, no more ping. It's a cheap fix, if you don't like the outcome, just leave it disconnected. There should be a map of vacuum lines on a decal under your hood to show you which carburetor port to hook it to. Also, if it's dirty or clogged, it won't function. It's relatively easy to remove, clean and reinstall. I used spray carburetor cleaner. Let me know if it helps. Also, it can be tested when off the vehicle with vacuum.

He Bill, thanks man!
what do you mean by " Also, it can be tested when off the vehicle with vacuum."? (I am Dutch, sorry)

billnorman 12-23-2010 08:40 AM

Re: Improve mileage 350 with Quadrajet
 
Below is a generic EGR test. It tests the mechanical opening and diaphragm of a typical EGR valve. In order to test one for function, it either has to be removed and inspected or the engine running and vacuum applied to the port. If it works, the RPM should change when vacuum is applied, probably drop. It is important to get the vacuum source from the proper carburetor passage so it will activate at the correct time.
......An exhaust gas recirculation valve, or "EGR" valve, is an emissions-control devise which reduces the amount of nitrogen which escapes into the atmosphere. The EGR does this by routing a portion of the exhaust gases back into the intake manifold, where those chemicals are burned for a second time in the combustion chambers. A defective EGR valve commonly results in a rough idle and a decrease in power and fuel efficiency. Chevrolet equipped its 1990 passengers cars with a ported-type EGR valve. Fortunately, this type of EGR valve is the easiest to test.
Difficulty:Moderately EasyInstructions
Things You'll Need:
Hand-vacuum pump


1
Apply the parking brake and shift the transmission into either "Park" or "Neutral."

2
Start the engine and allow it to reach operating temperature.

3
Turn the engine off.

4
Inspect the rubber vacuum hose that attaches to the top of the EGR valve for signs of cracks or kinks. A damaged EGR hose should be replaced.

5
Pull the rubber vacuum hose off of the top of the EGR valve.

6
Press the hose which extends from the bottom of a hand-vacuum pump over the nipple on top of the EGR valve. This is the same nipple from which the rubber vacuum hose was attached to.

7
Apply 10 inches of vacuum to the valve with the hand-pump.

8
Position a mirror underneath the top of the EGR valve to inspect the valve's diaphragm. The diaphragm should remain open under the 10 inches of vacuum for a minimum of 20 seconds. If the diaphragm does not open, of if the needle on the hand-pump gradually drops before 20 seconds have expired, the EGR valve leaks and must be replaced. You can also do this by checking the movement with your finger if the valve has reliefs cut in it. ....



Read more: How to Test the EGR Valve in a 1990 Chevy Car | eHow.com http://www.ehow.com/how_6098936_test...#ixzz18wAvnmkP

kikkegek 12-26-2010 09:57 AM

Re: Improve mileage 350 with Quadrajet
 
I got a fan clutch from a buddy, painted the fan ad wanted to install it today. I noticed the flexfan was cooling the engine unnecaessarily during winter. but when I tried installing it I noticed it turns the wrong way!

damn!

http://lh3.ggpht.com/_i4YwYZutwgk/TR.../IMAGE_154.jpg

motornut 12-26-2010 07:40 PM

Re: Improve mileage 350 with Quadrajet
 
Can't turn the blade around onto the clutch?
Posted via Mobile Device

kikkegek 12-27-2010 09:23 AM

Re: Improve mileage 350 with Quadrajet
 
Quote:

Originally Posted by motornut (Post 4371071)
Can't turn the blade around onto the clutch?
Posted via Mobile Device

no. It will just be on backwars. and the fan clutch has a set direction also. see picture.

take a fan and check for youself. They cant run backwards.

http://lh5.ggpht.com/_i4YwYZutwgk/TR...0/DSC00179.JPG

http://lh3.ggpht.com/_i4YwYZutwgk/TR...0/DSC00178.JPG

guess I'll be looking for a fan and fan clutch!

motornut 12-28-2010 10:41 AM

Re: Improve mileage 350 with Quadrajet
 
ok gotcha
no trucks at the house right now

kikkegek 12-30-2010 02:45 PM

Re: Improve mileage 350 with Quadrajet
 
oke, got the thermostat today and replaced it (195F)

first disconnected the upper hose on the radiator. check out the dirt that came out. If you take into account that I just had the cooling liquid refreshed this summer. Shouldn't it be a lot less dirty?
http://lh3.ggpht.com/_i4YwYZutwgk/TR...0/DSC00180.jpg

http://lh3.ggpht.com/_i4YwYZutwgk/TR...0/DSC00182.jpg

I cleaned the thermostat houding and took a good look. NEver had this piece loose yet.
http://lh4.ggpht.com/_i4YwYZutwgk/TR...0/DSC00186.jpg
http://lh5.ggpht.com/_i4YwYZutwgk/TR...0/DSC00188.jpg

here you can see hoe dirty the cooling liquid is. about a quart came out of it. I tried to catch as much as I could in a little bucket.
http://lh5.ggpht.com/_i4YwYZutwgk/TR...0/DSC00193.jpg

when it gets warmer and the days are longer I am gonna have to rinse my cooling system....damn its dirty....previous owner probably had wather in it for a while I think? or never changed it...

these two bolts??? weer holing the thermostat housing. for now I reused them, but I want to change the housing and bolts this summer sometime.
http://lh6.ggpht.com/_i4YwYZutwgk/TR...0/DSC00195.jpg

anybody ever heard of Restone Thermostats? I got it at a local shop.

http://lh5.ggpht.com/_i4YwYZutwgk/TR...0/DSC00196.jpg

this bucket was clean when I started. Look at the dirt!
http://lh3.ggpht.com/_i4YwYZutwgk/TR...0/DSC00197.jpg
http://lh4.ggpht.com/_i4YwYZutwgk/TR...0/DSC00198.jpg

the old thermostat. Seemed to be a 180F.
http://lh4.ggpht.com/_i4YwYZutwgk/TR...0/DSC00199.jpg
http://lh5.ggpht.com/_i4YwYZutwgk/TR...0/DSC00203.jpg

the new thermostat, 195F
http://lh3.ggpht.com/_i4YwYZutwgk/TR...0/DSC00205.jpg
http://lh4.ggpht.com/_i4YwYZutwgk/TR...0/DSC00206.jpg
http://lh4.ggpht.com/_i4YwYZutwgk/TR...0/DSC00208.jpg

just cane back from a testdrive. Al stays dry. So that makes me happy. Now I a will keep an eye on the temperature the next few days and see if the engine gets warmer!

kikkegek 12-30-2010 03:05 PM

Re: Improve mileage 350 with Quadrajet
 
ow!

I take notes of the gallons I get at every trip to the gasstation and the miles we drove.

I made a graph out of it. It seems my work is payng of, because there is a postive sloped trend visible in the mileage. how cool is that!

http://lh6.ggpht.com/_i4YwYZutwgk/TR.../MPG_graph.jpg

billnorman 12-30-2010 04:14 PM

Re: Improve mileage 350 with Quadrajet
 
I have made some more observations.
1. It looks like you have the dreaded GM no darn good pink coolant, recalled and destroyed. What do the rest of you guys think?
2. There are two timing reference stationary references on your motor. One is way ahead of the other. If LPG uses more timing advance than gasoline, perhaps that's what the bigger one is used for.
3. The vacuum advance IMHO softens the spark curve and allows advance in at high vacuum settings (low throttle positions) for economy. I may be wrong in this hypothesis, but if it's hooked to a below the throttle plate source, it will decrease timing when you step on the throttle, and increase it when you drive gently. If it's hooked to a vacuum port AT the throttle venturi, it will increase timing as the engine increases speed. The timing increase function on a Chevy v-8 is by the centrifugal weights.
4. I am not familiar to the functional envelope of a dual fuel engine. I would recommend you research on line the requirements and limits.
5. Personally, I think you need to operate this engine as warm as possible, and if LPG will tolerate an EGR system, hook it back up,
6. Turning the fan around won't change the way it functions. As you are in a very cool climate, why not do away with it altogether and go with electric? The kits can be ordered by mail, I've used them with no adverse effects and they are easy to install or you can get one off of a wrecked car.
7. Just as an aside, I have used Seafoam oil additive to clean and fix my wife's car. If it is possible to use all the time, I'd check the can to make sure, one can added to the oil will thin it out and clean the internals of your engine. This MAY improve your mileage.
8. Your photographs are exceptional. You are persuing this scenario with scientific analysis; cause and effect. I think if you stick to it you will get the best out of the truck.

kikkegek 12-30-2010 04:49 PM

Re: Improve mileage 350 with Quadrajet
 
He BillNorman, thanks for the extensive reply.

some questions on your points:
1. what do you mean? I am dutch and dont understand this.
2. I dont understand this point either. what I can say is that here in the NL they say you should set basic timing to -12 BTDC and disconnect the vacuum advance on LPG.
3. I have the distributor connected to the ported vacuum port on the right of the carb like on the pictures in this topic. Is that right?
4. what do you mean by functional envelop?
5. I have two EGR things on my engineI believe. The EGR valve (currently disconnected) and the Heat riser valve. the last one is currently set to OPEN all the time. Why would I want to run this engine as warm as possible?
6. oh man! I'd love an electric setup. But they are expensive over here. I'll ask around!
7. I'll look into this.
8. hahaha, thanks man! yeah I wanna help others with the info Igather. So good photos help a lot.

hope you can help me some more!

billnorman 12-30-2010 10:10 PM

Re: Improve mileage 350 with Quadrajet
 
1. General Motors had a pink anti-freeze that they recalled because it tended to sludge up cooling systems. I hope that isn't the type in your engine.
2. The photograph you posted 11-10-2010 at 3:59am show two pointer reference timing markers. The shorter of the two sets occurs in advance of the larger one. It is the one that is all dirty. If you use the one closer to the camera, the timing will be more retarded. Now in a gasoline motor, 12 degrees retarded will just about destroy performance, most like 8 to 10 degrees advance at idle. I will have to read up on LPG conversions, like I said, I don't know anything about them. They might like retarded timing. Which degree mark references do you use when setting the timing? How does this motor run? Is it smooth and powerful? I would estimate that if you use the short dirty timing mark numbers the motor will run about 15-20 degrees retarded compared to the long clean references. The marks nearer the camera look like an add-on set that if used would considerably retard the timing.
3. If it was a gasoline motor, There would be a diagram of vacuum hose routing for proper operation. As I previously said, when you said the motor runs at 12 degrees retarded, I realized I'm lost because this is a complete departure from my experience.
I'll read up and try to learn something and get back to you.

motornut 12-30-2010 10:12 PM

Re: Improve mileage 350 with Quadrajet
 
i duno bout it being the pink rad fluid,
(i wondered a mix of red and green or even a sealer?dribbles on the belt?)
i see rust and crud that will block not only the rad but the heater core too.
If you have it inside warm somewhere be sure to remove the lower rad hose and FLUSH this crud out or what you put back will be a waste.
do the heater core too.
You may wana get new bolts for the stat housing,seen those bolts seize and snap off
around hee we have green and red anti freeze,you can't mix them, i believe it wreaks the fluid .....the red is long life so some people figure i can wait even longer lol then the green,what i understand the red breaksdown and wrecks the gasket in some CARS lol like my Grand Am ,the v6 is known for this prob,thank god i got the 4 it just blows the crank seal(thats what i got for Xmas lol)

cheers

billnorman 12-31-2010 06:35 AM

Re: Improve mileage 350 with Quadrajet
 
O.K. here's what I've determined through research. You are getting 10 MPG plus or minus in a Chevrolet truck with LPG conversion. This is about average. LPG conversions historically get less mileage than a gasoline engine, it's just the nature of the beast. Some LPG conversions eliminate the vacuum advance, some leave it on. I read a report about ignition timing with LPG on a Chevrolet that was turbocharged, which raises the effective compression ratio and packs more air/fuel into the cylinders. The owner experimented with ignition timing and ended with 6 degrees BTDC initial timing. He tried various timing settings and advanced it until he heard pinging, then retarded it until it went away in all load arenas. He was satisfied with the results.
LPG does not require nor respond well with warming of the charge (EGR) but gasoline does.
Anything you can do to remove parasitic drag, such as electro fans, tire inflation, free flowing exhaust should benefit you in the long run.
I'm sure your friends call you if they need anything heavy moved, pulled, or bulky items transported because you have a truck, a REAL truck, a Chevrolet truck. Enjoy it, it's no tinny Eurosled with a 1000cc sewing machine motor. Ride in comfort, and look down at them in their low to the ground econoboxes.
Seafoam says their product improves any engine, especially older ones. I use it in my cars and boats.
Looking at the U.S. gasoline future, I am considering an LPG retrofit on my own 1985 or 1996 Pick-up truck.
In summary, forget the EGR valve, run your engine warm this winter, but in the summer drop the thermostat back to 165 f. If it were me, I'd get a good timing light, decide which set of timing marks is appropriate, and experiment with timing. Disconnect the vacuum advance and see where it's set right now at low idle. Then change it, usually in an advance direction by about 4 degrees. If it pings, go back 2 degrees until it stops. This may change in extremely hot weather, it may ping more if warmer. Each engine is different, each advance system is slightly different due to age and manufacturing tolerances.


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