72 Carb Issues?

jethro66 · November 24th, 2006, 07:02 PM

I have a 72 Cutlass Supreme conv. 97k miles. For years, always started even though it may be couple weeks in between starts, no issues. Recently, started, but stalls as I depress accelerator. Not a quick stall. Putters slightly in idle (can go minutes and then stalls in idle as well). If I depress accelerator it is doomed to stall quickly.

Disconnected inlet fuel line at in-line filter to rule out fuel filter, fuel pump, or plugged fuel lines. Fuel flowed fine.

Does anyone think it may just need a clean and rebuild or could it be something else?
Any troubleshooting advice?
Is a special breed of mechanic required to rebuild Q-Jet or can any Dallas mechanic do it?

I dare not take it out of the garage in fear of not getting it back up inclined driveway. No Christmas this year. Car blocks stairs from attic where Christmas decorations are stored.

Thanks,
JC

Specman · November 24th, 2006, 09:07 PM

Did you remove the big fitting that goes into the carb too? There is a mini paper filter inside there that gets plugged pretty easy. Used to happen in my boat all the time.

Other than that, dirt in the carb bowl most obvioius cause. Still gets by because the filter is spring loaded.

Quadrajets aren't too difficult to do. Lot easier than a Holley I think.

Oldsguy · November 25th, 2006, 08:30 AM

Look for a vacumm leak too. With one of those you can be running a lot leaner than you expect, not to mention screwing up your vacumm advance on the timing.

jethro66 · November 26th, 2006, 07:08 PM

Thank you for info.

Yes, removed fitting at carb and filter was clean. Initially, I thought it was filter or pump, but both looked and functioned good.

Vacuum leak may be issue. As I depressed accelerator, I heard a loud vacuum leak but cannot pinpoint origin of leak.

Thanks,
JC

69oldsguy · December 18th, 2006, 10:15 PM

If you check all the externals and don't come up with the answer, start looking at the accelerator pump in the carb. If the accel pump fails you wont get a pump shot when you open the throttle, you'll lean way out and it will stall. Keep looking, you'll find it.
Kevin

texasred · December 19th, 2006, 07:21 AM

Contact...heck, join...the North Texas Oldsmobile Club. http://clubs.hemmings.com/clubsites/ntexasoca/
Plenty of like-minded "Oldsiacs" that can help you with parts and info. Plus there's cruises, shows, and lotsa fun things. They should be able to point you to a good guy up there.

In San Antonio, I use Dan Sarvis Wblue70@aol.com. He's an Olds man, a racer (runs 11s in an iron head, QJet, 70 442), and rebuilds QJets. He took mine, rejetted, drilled the throttle blades, and had it set up so well that all I had to do was drop it on and drive it. We went to adjust it, but it was perfect as is! Reasonable price and he does it by mail, too.

C.J.

jethro66 · January 4th, 2007, 07:43 PM

Thanks guys. I finally figured it out over the holidays and she is purring now.

POINTS!!!!! Only needed new points.

Guess I focused too much on the fuel part of the triangle - fuel, air, fire.
When I saw a spark during spark plug check, I ruled out fire. Also, car would and did start up.

Hope everyone had a good Christmas!!!!!

Eightupman · January 5th, 2007, 03:51 PM

I HATE how those $5 parts cause such a freaking headache....I would have sent you to change the accelerator pump in the carb with the info you gave.

Good fix!

John

jethro66 · January 8th, 2007, 06:04 PM

That's about right! Lots of time troubleshooting for a 1 hr fix (that included the drive to buy points).

My friend told me about a Pertronix electronic ignition. I may have to buy one.

Oldsguy · January 9th, 2007, 05:43 AM

I am glad you found the problem. A Petronix kit would probably be a good investment. I have heard good things about those kind of kits. My son used one on his '64 394 and he actually saw an improvement on cold starts and a slight improvement on gas mileage. Of course, all that is subjective as he dind'nt conduct a true controlled experiment in the lab.

Chumley · January 9th, 2007, 10:33 PM

I put a factory HEI in my 402 in my '72 Chevy truck a few years ago. Made ALL the difference in the world. Probably the single most efficient upgrade you can do ( for simplicity ) on these vintage machines.

Chumley

November 24th, 2006, 07:02 PM	#1 (permalink)
jethro66 Junior Member Join Date: Nov 2006 Location: Dallas, TX Posts: 5	72 Carb Issues? I have a 72 Cutlass Supreme conv. 97k miles. For years, always started even though it may be couple weeks in between starts, no issues. Recently, started, but stalls as I depress accelerator. Not a quick stall. Putters slightly in idle (can go minutes and then stalls in idle as well). If I depress accelerator it is doomed to stall quickly. Disconnected inlet fuel line at in-line filter to rule out fuel filter, fuel pump, or plugged fuel lines. Fuel flowed fine. Does anyone think it may just need a clean and rebuild or could it be something else? Any troubleshooting advice? Is a special breed of mechanic required to rebuild Q-Jet or can any Dallas mechanic do it? I dare not take it out of the garage in fear of not getting it back up inclined driveway. No Christmas this year. Car blocks stairs from attic where Christmas decorations are stored. Thanks, JC

November 24th, 2006, 09:07 PM	#2 (permalink)
Specman Registered User Join Date: Aug 2006 Posts: 46	carb issues Did you remove the big fitting that goes into the carb too? There is a mini paper filter inside there that gets plugged pretty easy. Used to happen in my boat all the time. Other than that, dirt in the carb bowl most obvioius cause. Still gets by because the filter is spring loaded. Quadrajets aren't too difficult to do. Lot easier than a Holley I think.

November 25th, 2006, 08:30 AM	#3 (permalink)
Oldsguy Hot Rodder at heart Administrator Join Date: May 2004 Location: Lees Summit MO Posts: 5,360	Look for a vacumm leak too. With one of those you can be running a lot leaner than you expect, not to mention screwing up your vacumm advance on the timing. __________________ Dan '77 Cutlass Supreme '46 2 door "The rocket 455.....it's a sledgehammer approach to a thumbtack world" LuxBlue of HAMB.

December 18th, 2006, 10:15 PM	#5 (permalink)
69oldsguy Registered User Join Date: Dec 2006 Location: Wyoming Posts: 27	If you check all the externals and don't come up with the answer, start looking at the accelerator pump in the carb. If the accel pump fails you wont get a pump shot when you open the throttle, you'll lean way out and it will stall. Keep looking, you'll find it. Kevin __________________ 69 Cutlass S 350-2 TH350 Buckets - Console 52,000 original mi.

December 19th, 2006, 07:21 AM	#6 (permalink)
texasred Tom Servo's Stunt Double Join Date: Apr 2004 Location: San Antonio, Texas Posts: 824	Contact...heck, join...the North Texas Oldsmobile Club. http://clubs.hemmings.com/clubsites/ntexasoca/ Plenty of like-minded "Oldsiacs" that can help you with parts and info. Plus there's cruises, shows, and lotsa fun things. They should be able to point you to a good guy up there. In San Antonio, I use Dan Sarvis Wblue70@aol.com. He's an Olds man, a racer (runs 11s in an iron head, QJet, 70 442), and rebuilds QJets. He took mine, rejetted, drilled the throttle blades, and had it set up so well that all I had to do was drop it on and drive it. We went to adjust it, but it was perfect as is! Reasonable price and he does it by mail, too. C.J. __________________ Dad said, "Sometimes you read Job...sometimes you ARE Job!"

November 26th, 2006, 07:08 PM	#4 (permalink)
jethro66 Junior Member Join Date: Nov 2006 Location: Dallas, TX Posts: 5	Thank you for info. Yes, removed fitting at carb and filter was clean. Initially, I thought it was filter or pump, but both looked and functioned good. Vacuum leak may be issue. As I depressed accelerator, I heard a loud vacuum leak but cannot pinpoint origin of leak. Thanks, JC

January 4th, 2007, 07:43 PM	#7 (permalink)
jethro66 Junior Member Join Date: Nov 2006 Location: Dallas, TX Posts: 5	Thanks guys. I finally figured it out over the holidays and she is purring now. POINTS!!!!! Only needed new points. Guess I focused too much on the fuel part of the triangle - fuel, air, fire. When I saw a spark during spark plug check, I ruled out fire. Also, car would and did start up. Hope everyone had a good Christmas!!!!!

January 5th, 2007, 03:51 PM	#8 (permalink)
Eightupman Registered User Join Date: Nov 2006 Location: Ladson, SC Posts: 497	I HATE how those $5 parts cause such a freaking headache....I would have sent you to change the accelerator pump in the carb with the info you gave. Good fix! John

January 8th, 2007, 06:04 PM	#9 (permalink)
jethro66 Junior Member Join Date: Nov 2006 Location: Dallas, TX Posts: 5	That's about right! Lots of time troubleshooting for a 1 hr fix (that included the drive to buy points). My friend told me about a Pertronix electronic ignition. I may have to buy one.

January 9th, 2007, 05:43 AM	#10 (permalink)
Oldsguy Hot Rodder at heart Administrator Join Date: May 2004 Location: Lees Summit MO Posts: 5,360	I am glad you found the problem. A Petronix kit would probably be a good investment. I have heard good things about those kind of kits. My son used one on his '64 394 and he actually saw an improvement on cold starts and a slight improvement on gas mileage. Of course, all that is subjective as he dind'nt conduct a true controlled experiment in the lab. __________________ Dan '77 Cutlass Supreme '46 2 door "The rocket 455.....it's a sledgehammer approach to a thumbtack world" LuxBlue of HAMB.

January 9th, 2007, 10:33 PM	#11 (permalink)
Chumley Registered User Join Date: Dec 2005 Posts: 217	I put a factory HEI in my 402 in my '72 Chevy truck a few years ago. Made ALL the difference in the world. Probably the single most efficient upgrade you can do ( for simplicity ) on these vintage machines. Chumley

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