Carb or ignition? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Marty68 · 03-22-2020, 01:44 PM

I have an "early 283" still has cartridge filter and points ignition . It idles really good but smells rich. It cruises fine BUT. at mostly wide open throttle and over 2600? Rpm. It burbles like is fuel starving..
Or ignition.
I bought vacuume guage but I see only idle speed adjustment on carb

Ziegelsteinfaust · 03-22-2020, 08:29 PM

At that cars age it could be the power to the dizzy is not enough, and that can cause you to chase issues.

Run a 12V wire from the battery to the distributor, and try it. Then you can try other coils, and points. If it not apparent if the carb is the suspect

garyd1961 · 03-23-2020, 12:54 AM

I don't think you are suppose to have a full 12 volts with a points distributor.

Marty68 · 03-23-2020, 06:53 AM

Quote:

Originally Posted by garyd1961

I don't think you are suppose to have a full 12 volts with a points distributor.

That I believe is true. Some have internal ballast resistor. That takes the incoming 12 volts and drops it down to 6

geezer#99 · 03-23-2020, 08:57 AM

Running full time 12v is just a test to see if you have a bad coil or points.
Get your motor warmed up to normal temp, hook up the 12v wire to your coil + and test drive it.
If it acts the same then it’s your coil or points.
If it acts up then it’s your carb.
JFYI you can run 12v to the coil for a 100 miles if you need to.

Usually rich smelling is float level a touch high.
Stumbling at wot and cruise is bad fuel pump.

Marty68 · 03-23-2020, 03:11 PM

Quote:

Originally Posted by geezer#99

Running full time 12v is just a test to see if you have a bad coil or points.
Get your motor warmed up to normal temp, hook up the 12v wire to your coil + and test drive it.
If it acts the same then it’s your coil or points.
If it acts up then it’s your carb.
JFYI you can run 12v to the coil for a 100 miles if you need to.

Usually rich smelling is float level a touch high.
Stumbling at wot and cruise is bad fuel pump.

Thank you I will run jumper wire tonight and test drive..

geezer#99 · 03-23-2020, 03:56 PM

Just remember that you’ll need to disconnect the jumper to shut it off.

Marty68 · 03-24-2020, 10:42 AM

the state just ordered a STAY HOME order. so depending if they mean their own employees or just others I may have a lot of time to figure this thing out. I will be checking to see if the coil itself drops voltage to 6r or if there is a resister wire.
I will remove carb top to check and set float level.
then reassemble put jumper wire on and test.
then brew a batch of beer.
maybe it is a good idea to convert to hei.. would like to keep the original (to the 66 engine) small cap distributor..
any input on that?

cadillac_al · 03-24-2020, 11:15 AM

Are these new points or are we crutching along old points and condenser? HEI is hard to beat. I put an HEI on my 70 Impala because I wanted the reliability over the original look. I don't think anybody has ever called me on it unless they all keep it to themselves lol.

rpmerf · 03-24-2020, 11:58 AM

Stay home is mostly just to get people to stop coming in contact with other people. Taking it out for a cruise should be fine. Might be nice, as there are fewer people on the road.

HEI is a nice upgrade. Points are fine as long as you don't mind checking them and setting the dwell every once in a while.

One change at a time! Harder to troubleshoot if you make multiple changes.

I think I would start with as many driveway checks / adjustments as you can first. Set the dwell. Make sure the timing is set correctly. Mostly concerned with the all in timing. When and how much. Vacuum looks good, so I am assuming no leaks. Might look over the cap and rotor to see if it looks like there is a bunch of corrosion. Check the vacuum advance to make sure it is advancing and returning correctly.

If you have the top off the carb, make sure everything moves as it should, and there isn't any gunk. Clean up anything you can with some carb cleaner.

**WorkinLonghorn** · 03-24-2020, 01:03 PM

Fuel-starving at WOT over 2600 RPM? First thing to check is the fuel FILTER !!

Marty68 · 03-24-2020, 02:43 PM

Quote:

Originally Posted by cadillac_al

Are these new points or are we crutching along old points and condenser? HEI is hard to beat. I put an HEI on my 70 Impala because I wanted the reliability over the original look. I don't think anybody has ever called me on it unless they all keep it to themselves lol.

they should keep it to themselves. lol
I bought new points and condenser... they may be going in... float level first...

**tdangle** · 03-24-2020, 04:31 PM

Quote:

Originally Posted by WorkinLonghorn

Fuel-starving at WOT over 2600 RPM? First thing to check is the fuel FILTER !!

I tend to agree, check fuel filter and float in carb to make sure it didn't spring a leak and fill with gas. If it isn't one of the brass floats, then just replace it. Cheap insurance.

Since you mentioned you had new points and condenser, I would just do a full tune up, new points, plugs (?) check all the wires and carb checks or maybe a full rebuild on it. Be aware full voltage to the coil will really shorten life of points.

Marty68 · 03-25-2020, 10:46 AM

i have been busy.. not much time to work on truck.
however i did measure voltage at coil. it is 12 volts. i bought a new coil last hear after screwing up threads on old one.
does the coil internally drop voltage?
should i put ballast resister ahead of coil then replace points and condenser?
driving it last night is seems clear to me it is ignition, under load and a rpm above 2500 is sounds like a random miss. if i keep it under 2500 it is fine and feels responsive
i AM convinced it is ignition.. but i also am convinced of... nevermind lol

geezer#99 · 03-25-2020, 11:08 AM

12 volts.
Idling or shut off with key off?

**paul mora** · 03-25-2020, 11:47 AM

Not sure if you checked or covered it in other post but her sure you vacuum advance system is working properly There could be a leak that prevents it from advancing as you raise the rpms. Or the advance itself is not working. If it is running smooth at idle and does not rev up like normal this could be the problem. Of course you should do a complete review of your ignition system. Verify you have the spark plug wires in correct order pushed in all the way at the plugs and cap. Rotor points and cap are clean and gapped properly. These all give you a good advancing spark.

Marty68 · 03-25-2020, 12:53 PM

Quote:

Originally Posted by geezer#99

12 volts.
Idling or shut off with key off?

key on not running and idling
key off no voltage

geezer#99 · 03-25-2020, 01:51 PM

I guess that means your resistor wire is bypassed.
Full time 12v is burning up your coil and points.

Marty68 · 03-25-2020, 02:55 PM

[QUOTE=geezer#99;8701807]I guess that means your resistor wire is bypassed.
Full time 12v is burning up your coil and points.[

what if my "new" coil has internal resistor? how do i tell can i ohm out coil? what resistance should i see?

REDROCKER652002 · 03-25-2020, 03:12 PM

You can always put in a Pertronix module in the distributor. I had one in my old camaro. Then you can keep the look, but lose the points and condensor.. Just a suggestion.

geezer#99 · 03-25-2020, 03:29 PM

Is your wiring original?
Post a pic of the coil and it’s wiring.

vince1 · 03-25-2020, 05:28 PM

I changed an engine once and left the coil on it that wanted a resistor. It didn't take too long to burn out that coil. If you lift the hood at night and see a blue glow around the top of the coil it is probably getting too many volts.

I have found that if a vehicle sits for a number of years there is a good possibility that the condenser will go bad and the car won't run very good at all. Internal corrosion?

franken · 03-25-2020, 06:09 PM

Key on engine not running...
Both of these are "I think" statements based on my mental picture of the circuit. Be afraid

If the points are open, you'll see 12V since you see source voltage on an open circuit.
If the points are closed, you'll see nothing (or close to it) since the points are grounded.

BTW, new condensers have a reputation for being bad

goatless · 03-25-2020, 08:12 PM

Quote:

Originally Posted by WorkinLonghorn

Fuel-starving at WOT over 2600 RPM? First thing to check is the fuel FILTER !!

Isn't there a spring pushing the filter in, that, in case it gets clogged, fuel pressure from the fuel pump pushes it, allowing unfiltered fuel to bypass the filter?

Thought I noticed it once when rebuilding a 2BL carb.

AcampoDave · 03-25-2020, 10:28 PM

I've seen plenty of old distributors with the mechanical advace all frozen up. You should be able to twist the rotor and have it snap right back. If it doesn't, you can usually remove the whole distributor from the vehicle and spray some WD40 or whatever into the shaft where the advance connects to it and slowly free it up by hand.

03-22-2020, 01:44 PM	#1
Marty68 Registered User Join Date: Nov 2014 Location: west coast, Wi Posts: 534	Carb or ignition? I have an "early 283" still has cartridge filter and points ignition . It idles really good but smells rich. It cruises fine BUT. at mostly wide open throttle and over 2600? Rpm. It burbles like is fuel starving.. Or ignition. I bought vacuume guage but I see only idle speed adjustment on carb Attached Images

03-22-2020, 08:29 PM	#2
Ziegelsteinfaust Registered User Join Date: Dec 2012 Location: Temple City Posts: 3,560	Re: Carb or ignition? At that cars age it could be the power to the dizzy is not enough, and that can cause you to chase issues. Run a 12V wire from the battery to the distributor, and try it. Then you can try other coils, and points. If it not apparent if the carb is the suspect

03-23-2020, 12:54 AM	#3
garyd1961 Registered User Join Date: May 2016 Location: Henderson NC Posts: 975	Re: Carb or ignition? I don't think you are suppose to have a full 12 volts with a points distributor.

03-23-2020, 08:57 AM	#5
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,512	Re: Carb or ignition? Running full time 12v is just a test to see if you have a bad coil or points. Get your motor warmed up to normal temp, hook up the 12v wire to your coil + and test drive it. If it acts the same then it’s your coil or points. If it acts up then it’s your carb. JFYI you can run 12v to the coil for a 100 miles if you need to. Usually rich smelling is float level a touch high. Stumbling at wot and cruise is bad fuel pump.

03-23-2020, 03:56 PM	#7
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,512	Re: Carb or ignition? Just remember that you’ll need to disconnect the jumper to shut it off.

03-24-2020, 10:42 AM	#8
Marty68 Registered User Join Date: Nov 2014 Location: west coast, Wi Posts: 534	Re: Carb or ignition? the state just ordered a STAY HOME order. so depending if they mean their own employees or just others I may have a lot of time to figure this thing out. I will be checking to see if the coil itself drops voltage to 6r or if there is a resister wire. I will remove carb top to check and set float level. then reassemble put jumper wire on and test. then brew a batch of beer. maybe it is a good idea to convert to hei.. would like to keep the original (to the 66 engine) small cap distributor.. any input on that?

03-24-2020, 11:15 AM	#9
cadillac_al Registered User Join Date: Oct 2013 Location: Maine Posts: 2,334	Re: Carb or ignition? Are these new points or are we crutching along old points and condenser? HEI is hard to beat. I put an HEI on my 70 Impala because I wanted the reliability over the original look. I don't think anybody has ever called me on it unless they all keep it to themselves lol. __________________ 76 Chevy K20 76 GMC K15 77 Chevy C10 77 Chevy K10

03-24-2020, 11:58 AM	#10
rpmerf Registered User Join Date: Feb 2011 Location: Parkville, MD Posts: 1,024	Re: Carb or ignition? Stay home is mostly just to get people to stop coming in contact with other people. Taking it out for a cruise should be fine. Might be nice, as there are fewer people on the road. HEI is a nice upgrade. Points are fine as long as you don't mind checking them and setting the dwell every once in a while. One change at a time! Harder to troubleshoot if you make multiple changes. I think I would start with as many driveway checks / adjustments as you can first. Set the dwell. Make sure the timing is set correctly. Mostly concerned with the all in timing. When and how much. Vacuum looks good, so I am assuming no leaks. Might look over the cap and rotor to see if it looks like there is a bunch of corrosion. Check the vacuum advance to make sure it is advancing and returning correctly. If you have the top off the carb, make sure everything moves as it should, and there isn't any gunk. Clean up anything you can with some carb cleaner. __________________ 1970 C20 Custom Camper - 350, TH350 1997 GMC Suburban 1994 Acura Integra GSR 1987 Dodge Daytona Shelby Z

03-24-2020, 01:03 PM	#11
WorkinLonghorn Senior Member Join Date: Dec 2006 Location: Studio City, Calif. Posts: 2,855	Re: Carb or ignition? Fuel-starving at WOT over 2600 RPM? First thing to check is the fuel FILTER !! __________________ '69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, 2nd owner, Work-Truck supreme. Best $300 I ever spent.

03-25-2020, 10:46 AM	#14
Marty68 Registered User Join Date: Nov 2014 Location: west coast, Wi Posts: 534	Re: Carb or ignition? i have been busy.. not much time to work on truck. however i did measure voltage at coil. it is 12 volts. i bought a new coil last hear after screwing up threads on old one. does the coil internally drop voltage? should i put ballast resister ahead of coil then replace points and condenser? driving it last night is seems clear to me it is ignition, under load and a rpm above 2500 is sounds like a random miss. if i keep it under 2500 it is fine and feels responsive i AM convinced it is ignition.. but i also am convinced of... nevermind lol

03-25-2020, 11:08 AM	#15
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,512	Re: Carb or ignition? 12 volts. Idling or shut off with key off? Last edited by geezer#99; 03-25-2020 at 12:32 PM.

03-25-2020, 11:47 AM	#16
paul mora Senior Member Join Date: Jan 2009 Location: huntington beach california Posts: 975	Re: Carb or ignition? Not sure if you checked or covered it in other post but her sure you vacuum advance system is working properly There could be a leak that prevents it from advancing as you raise the rpms. Or the advance itself is not working. If it is running smooth at idle and does not rev up like normal this could be the problem. Of course you should do a complete review of your ignition system. Verify you have the spark plug wires in correct order pushed in all the way at the plugs and cap. Rotor points and cap are clean and gapped properly. These all give you a good advancing spark. __________________ Pulatoy

03-25-2020, 01:51 PM	#18
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,512	Re: Carb or ignition? I guess that means your resistor wire is bypassed. Full time 12v is burning up your coil and points.

03-25-2020, 02:55 PM	#19
Marty68 Registered User Join Date: Nov 2014 Location: west coast, Wi Posts: 534	Re: Carb or ignition? [QUOTE=geezer#99;8701807]I guess that means your resistor wire is bypassed. Full time 12v is burning up your coil and points.[ what if my "new" coil has internal resistor? how do i tell can i ohm out coil? what resistance should i see?

03-25-2020, 03:12 PM	#20
REDROCKER652002 Registered User Join Date: Nov 2018 Location: South San Francisco CA, Posts: 434	Re: Carb or ignition? You can always put in a Pertronix module in the distributor. I had one in my old camaro. Then you can keep the look, but lose the points and condensor.. Just a suggestion.



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03-25-2020, 03:29 PM	#21
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,512	Re: Carb or ignition? Is your wiring original? Post a pic of the coil and it’s wiring.

03-25-2020, 05:28 PM	#22
vince1 Registered User Join Date: Jan 2013 Location: Calgary Alberta Posts: 1,164	Re: Carb or ignition? I changed an engine once and left the coil on it that wanted a resistor. It didn't take too long to burn out that coil. If you lift the hood at night and see a blue glow around the top of the coil it is probably getting too many volts. I have found that if a vehicle sits for a number of years there is a good possibility that the condenser will go bad and the car won't run very good at all. Internal corrosion?

03-25-2020, 06:09 PM	#23
franken Registered User Join Date: Jun 2013 Location: Somewhere Posts: 3,052	Re: Carb or ignition? Key on engine not running... Both of these are "I think" statements based on my mental picture of the circuit. Be afraid If the points are open, you'll see 12V since you see source voltage on an open circuit. If the points are closed, you'll see nothing (or close to it) since the points are grounded. BTW, new condensers have a reputation for being bad

03-25-2020, 10:28 PM	#25
AcampoDave Registered User Join Date: Feb 2013 Location: central California Posts: 2,726	Re: Carb or ignition? I've seen plenty of old distributors with the mechanical advace all frozen up. You should be able to twist the rotor and have it snap right back. If it doesn't, you can usually remove the whole distributor from the vehicle and spray some WD40 or whatever into the shaft where the advance connects to it and slowly free it up by hand.

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