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Old 10-20-2020, 03:48 PM   #26
HO455
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Re: Hard Starting Hot

Ok let's not worry about the timing. It is a mechanical setting that isn't going to change if the truck is hot. It might be able to mask the symptom but it isn't the solution to the problem. And a quick check of spark quality when the engine has hot soaked should reveal weakness in the ignition system.

Your initial post indicates a flooding situation. There are several common causes for that.

The choke being closed. Your pictures show the choke being completely open.

The float may be set on the edge of being too high. The fuel level in the bowl is okay when the fuel is cool, but after the engine has stopped there no longer is cool fuel entering the carburetor. The fuel that is in the bowl will heat up and expand until it flows over into the intake manifold. The cure would be to lower the float a small amount.

And the well plug(s) could be leaking. To determine if this is in fact happening you can check the fuel level in the bowl when the carburetor is cold and then again after it has set for 20 minutes when hot. I will say that if this is happening you would also experience the need to crank the starter a bunch to start a cold engine, as there would be no fuel in the bowl and the fuel pump would have to refill the bowl so the accelerator pump would work. It has been my experience that well plugs generally leak when the carb is cold and seal when hot. That being said I have run across carburetor bodies that have cracked and when cold they don't leak, but leak when hot. Hard to check for other than pull the carburetor off when hot and put a clean cloth underneath it and set back on the intake to hot soak. When it has set for 20 minutes check the cloth for signs of fuel.

I hope I have helped with solving your problem. All of this is my opinion so Good Luck!
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Old 10-20-2020, 05:35 PM   #27
Rich72C10
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Re: Hard Starting Hot

Thank you HO455 for you reply.

Okay, we turned off the engine and I hopped up on the engine real fast and looked down into the primaries. We are seeing fuel still flow in... I'd think that would be bad?

Also, when we were giving it WOT real fast the back larger butterflies are not opening, not even trying (no idea what is happen under them). This leads me to share a observation when driving it and where I would give it a good pedal for max power. I get nothing or at least I don't "hear a thing". About 20 years ago I had a big block 78 Suburban and you went for max power, not other did you feel it you heard it kick in (like a big vacuum sound). I justed assumed that was a big block thing but now reading / looking at a YouTube or to my C10 350 should too. My bad for ignoring that observation until now.

Seem I keep digging myself a hole here on this $400 QJet.
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Old 10-20-2020, 05:51 PM   #28
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Re: Hard Starting Hot

Float level too high or crap in the needle/seat.

The secondary air door won’t move just on a free rev.
I noticed in your picture that the choke stove cover is close to the secondary lock out lever and tang. That might cause the no feel/sound of those big secondaries opening.
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Old 10-20-2020, 07:31 PM   #29
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Re: Hard Starting Hot

Geezer's right the secondary butterfly will not open on a free rev. If you looked into the venturi after shutting off the engine and fuel is running out of the discharge nozzle then I would start with excessive float level, bad float, or too much fuel pressue. Even after shutting off the engine it takes a moment for the pressure to drop. If the fuel bowl level is to high it will leak fuel out the discharge nozzle until the level is more normal. These issues will cause hard starts on quick trips to the store but will go unnoticed overnight.
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Old 10-20-2020, 07:42 PM   #30
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Re: Hard Starting Hot

I just checked the choke stove, it’s tight but no touching - complete free movement.

One thing my brother thought was happing before replacing the carter was pressure was building up and I needed a vented cap. But my 72 has that emissions canister by/under the battery - which we unhooked at the canister because it seemed it was clogged.
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Old 10-20-2020, 07:50 PM   #31
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Re: Hard Starting Hot

How do you mean clogged? I know that this is taking away from the main thrust of the thread, but there is a filter on the bottom of that canister. This will not be something that causes fuel to drip into the primaries, whether it is clogged or not. You can find a complete downloadable service manual for your truck here:

http://67-72chevytrucks.com/vboard/showthread.php?t=558016&highlight=hatzie"]http://67-72chevytrucks.com/vboard/showthread.php?t=558016&highlight=hatzie

Just copy and paste that in a new tab.
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Old 10-20-2020, 08:44 PM   #32
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Re: Hard Starting Hot

hi Steeveedee - I hear what you are saying, thank you for then link.

He blew air from the line at the fuel tank vent and nothing went through until he disconnected it from the canister...... this "seemed" to pressurize the tank or that was my brother's thought process. But this was over a month ago with the Carter QJet.

I actually just tried to take it out but got stopped by needing to take the battery tray out, which has cooling lines mounts under it and a bolt blocked by the radiator. So it was a bigger job than I thought it would be. I was running out of sunlight and mosquitoes were eating me alive - so I couldn't think about trying a different removal method

I want to see what was causing the clog myself (I have the service, overhaul, and assembly original non-reprint manuals). But it surely is not causing a problem now as it is disconnected and there is a clear path from the EEC Tank connection to the engine bay for venting.

Edit: forgot about bad luck. when putting the negative back on, it seems to be stripped/won't tighten. Fun times!
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Old 10-21-2020, 09:04 AM   #33
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Re: Hard Starting Hot

Had a good chat with US Carb and we are going to send it back. It was great they offered a voice call.

One thing I learned from my brother is the Carter 17058213 QJet did not have any problems starting cold or hot- the hot starting started with the US Carb 7042208. She always started fine, its main issue was idle was crap. It is also the one that dumped enough fuel into the engine when stopped that the oil had to be changed (which really kicked off getting the proper matching C10 72 7042208 from US Carb Ebay). Though the fuel dumping we feel was some kind of a EEC Vent line issue.
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Old 10-21-2020, 11:24 AM   #34
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Re: Hard Starting Hot

another oddity after looking at my 72 Chevy Service Manager, section 8 pg 9 is the hard line. It looks like the line are supposed to hug the frame, which makes total sense once I look at the manaual. My lines have popped away from the frame right where the ram horns bolt up to the exhaust. One line was about 1/2 ~ 1 inch from the exhaust and the over right behind it.

I'd image that there is a bit of radiated heat getting to the line(s) from the exhaust and the lines are not getting any cooling effect from the frame. Again, I am just assuming the frame would act like a temperature stabilizer.

From the manual there should be some clips to keep the lines to the frame, guess I need to look for some but for now I used some tie wraps to two holes in the frame. The lines are not much further away but not completely tucked into the frame (but are now touching it pretty good).
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Old 10-21-2020, 11:47 AM   #35
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Re: Hard Starting Hot

New update, the Carter after popping up off the top, first reaction "wow look at all that crap in there". Brother saids it looks like someone dumped cinnamon in the bowl.

Removing tank and having it lined (brother has a shop for that, will be less and faster than new tank) and adding a inline filter is now a high priority. I guess the QJet filter in the carb sucks....
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Old 10-21-2020, 02:03 PM   #36
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Re: Hard Starting Hot

Test drive update:

Hot Starting: Corrected even with A/C left on (though it was a wee bit harder to start)
Intermittent missing / hesitation: Also appears solved
Testing WOT at idle: Back butterflies just a bit engage and open and suck in air. I would not say I hear or feel them kick in when driving. But going up a very nice long upwards grade I can go from 60 to 80.

I think our reasoning for replacing the Carter (other than I really wanted the proper numbered Rochester and not Carter) was due to trash and I am guessing my brother was mistaken about the EEC Canister too (that's my gut telling me that).
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Old 10-21-2020, 03:13 PM   #37
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Cool Re: Hard Starting Hot

Oh and I am buying a replacement for one of these from Ecklers Automotive for my driver's side visor :-D

That takes the guesswork out of pedal pushing LOL


Full Size Chevy Engine Starting Procedure Decal, 1972 40-164566-1
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Old 10-21-2020, 04:02 PM   #38
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Re: Hard Starting Hot

You do know that whether it says carter, Rochester, Weber or Edelbrock on it the carb is exactly the same.
So when you break down in Resume Speed Texas the nearest parts place will know it’s just a quadrajet.
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Old 10-21-2020, 04:25 PM   #39
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Re: Hard Starting Hot

They *both* have Quadrajet stamped on them. But the the one that came on the car came from AutoZone/O'Riley's (don't recall the store) was manufactured by Carter in 1978 (17058213) - previous owner did that - not me. He was rather proud of letting me know it had a new carb on it ;-)

The one that is called out for my 72 C10 350 that came from US Carb has Rochester stamped on it (7042208).


Please see Lars Grimard Tech Bulletin on these two Carbs.
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Old 10-21-2020, 04:28 PM   #40
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Re: Hard Starting Hot

Oh, I think I miss read what you what you were saying, that they are the same. quadrajet is a quadrajet ... I thought you were asking if I was sure a Carter was really a quadrajet.
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Old 10-21-2020, 05:33 PM   #41
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Re: Hard Starting Hot

There are 2 sizes of paper gas filters for quadrajets. A long and a short. If you have the short one where a long one goes trash can go around the filter into the bowl. And there should be a spring behind the filter to keep it seated against the inlet line.
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Old 10-21-2020, 05:43 PM   #42
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Re: Hard Starting Hot

interesting, thank you. How does one tell if you need the long or short? It is possible the replacement for the Carter got a short instead of a long when my brother and shop guy rebuilt it a few months back (but they replaced very little since it was basically new).

But I am sure he has the spring in it...
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Old 10-21-2020, 05:47 PM   #43
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Re: Hard Starting Hot

nm, looks like I get a short on from quadrajetparts.com. I also saw it seems 72 and up get the shorty.

So, that means I cannot go wrong or things would not fit - YAY!
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Old 10-21-2020, 07:08 PM   #44
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Re: Hard Starting Hot

Quote:
Originally Posted by Rich72C10 View Post
New update, the Carter after popping up off the top, first reaction "wow look at all that crap in there". Brother saids it looks like someone dumped cinnamon in the bowl.

Removing tank and having it lined (brother has a shop for that, will be less and faster than new tank) and adding a inline filter is now a high priority. I guess the QJet filter in the carb sucks....
It looks like you found the problem. A bunch of rust traveling from your tank to the filter, clogging it. After it's clogged, it is pushed out of the way due to fuel pressure against the spring. Then a particle of it can get stuck in the needle and seat, flooding. If you don't have rust in the fuel, the Quadrajet inlet fuel filter is all you need. That's the only fuel filter I use.
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Old 10-21-2020, 10:16 PM   #45
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Re: Hard Starting Hot

Quote:
Originally Posted by Rich72C10 View Post
New update, the Carter after popping up off the top, first reaction "wow look at all that crap in there". Brother saids it looks like someone dumped cinnamon in the bowl.

Removing tank and having it lined (brother has a shop for that, will be less and faster than new tank) and adding a inline filter is now a high priority. I guess the QJet filter in the carb sucks....
That "cinnamon" is dried flakes of gasoline. The filter in the carburetor sometimes has a spring to allow fuel to bypass the filter if it is too clogged. Cleaning the tank will go a long way towards reducing this problem. Once you do that, frequent driving reduces but does not eliminate the problem. If you put on an inline fuel filter, I'd recommend a steel can version between the pump and the carb. Plastic and glass filters can have leakage issues. Plastic gets hard and can crack, and the glass ones (if they screw together) can unscrew, with unfavorable results when fuel gets on a hot engine.
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Old 10-22-2020, 12:57 PM   #46
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Re: Hard Starting Hot

Hey sorry, it looks like you have solved this. Haven't checked this post for a while.

So needle and seat I take it? I skimmed the through all the replies.

One other oddity that is worth noting is that incorrect timing can cause this as well as misadjusted float level and nonfunctioning needle and seat.

If the the timing is set with the vacuum canister plugged in for instance, the timing at idle is retarded and will idle very low. To "correct" this people crank the idle speed screw in opening the butterflies too much. Then too much vacuum is pulled through the venturi's at idle and fuel is pushed out of the primary booster venturi essentially flooding the engine or making it run rough.

Same thing can happen when you have a big cam. The fix for this is adjusting the secondary butterflies to be open more at idle and closing the primary butterflies some.
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Old 10-22-2020, 01:33 PM   #47
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Re: Hard Starting Hot

We are sending the US carb back to be checked out, fixed or replaced. The problems all went away when we put back on the carb that came with the truck.

While there was a timing issue at the very beginning - that was not the issue after that. Matter of fact after the other carb was put on and running extremely well we put the timing back to 12 (from 16).

Yes, we always did the timing with the distributor Vacuum disconnected :-)
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Old 10-29-2020, 01:59 PM   #48
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Re: Hard Starting Hot

Heard back from US Carb - it has test bad, as in they are going to throw it away. Something about it having a "hole" it in somewhere that was missed. They apologized that was missed in their QA.

Since I want the proper 72 Carb, I requested a replacement and they assured me it would be pre-tested thoroughly before sending it out to me. I figure, crap happens (always to me) and they have been great through this process. At least I now know my Carter QJet will make a good backup

So much fun fighting multiple issues with the fuel system! Speaking of which, the tank/nozzle was finished today. So she should be up and running later today or tomorrow. Then off to the muffler shop to have all the mounting bits checked and replaced as needed.

New GMCPaul's blank tailgate and hardware ordered, which that work will be done in Ft. Worth at Anderton Paint & Body Shop. Which Insurance paid, minus my deductible.

Oh, any my visor instructions arrived too - it's straight up just like OEM and the material its made out of (like some kind of fiber)
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Old 10-29-2020, 03:21 PM   #49
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Re: Hard Starting Hot

Great to hear you found the problem. Thanks for keeping us posted on the progress.
I suggest you flush the fuel lines and tank. It may cure your cinnamon outbreak.
On your secondary throttle bore operation the lower butterfly's are mechanically operated but the upper ones are vacuum operated. The upper ones have adjustments to them that determine how soon they open. Engine displacement will make them open sooner (and faster) due to the physics of the volume of air flowing through the carburetor. The average 350 won't open them in the way a 454 will. Get your 350 to flow as much air as a stock 454 (not terribly difficult) and it too will sound like a demon from hell Hoovering up sinners.
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Old 10-29-2020, 03:31 PM   #50
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Re: Hard Starting Hot

Thanks for that information - it makes sense about the difference between 350/454!

The tank just came back from the radiator shop completely flushed & sealed. My brother has already "flushed" the lines with his shop's air compressor. So I should have a clean fuel system now
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