Sputtering Cleveland

351carlo · Apr 13, 2004

Ok guys, it's running strong...but not at low RPM's. It seems to sputter and die out, often time giving me a backfire/sputter type sound. Idle is pretty rough, yet once it gains in RPM it feels fine. Power wise, when I first hit it I'm completely dead, then it jumps up tremendously. For example, tonight in the rain, from a dead stop I couldn't power brake the wheels, yet if I stopped it and floored it forward, once it gained RPM I would break the rear loose. I've replaced cap and rotor. Tomorrow will be wires, plugs, points, condensor and hopefully I'll time the motor.

Thanks guys,
Carlo

BTW 351 Cleveland 2v.

Fifth_Beatle · Apr 13, 2004

Sounds a lot like what I'm going through. I have a 302-2V that has always been a strong runner, but I drove it sparingly. Now that I use it as my daily driver, I have had to tune and retune it regularly. I replaced spark plugs, wires, rotor, points, cap, coil, alternator, voltage meter, even the distributor vacuum. Still, it hesitates at low RPMs, and only runs nice when I hit 60 or 70mph.

Ronstang · Apr 13, 2004

Have you guys checked for vacuum leaks? If you have power brakes disconnect and plug the booster hose and see if idle improves. While idling spray WD-40 around the carb base and intake manifold....if speed increases or idle improves you found a leak. If you don't have any vacuum leaks it sounds like you are having carb problems and an adjstment/rebuild is in order.

Fomocohipo · Apr 13, 2004

My 289 had some what the same problem, A Tech at the shop I work at said to spray propane around through a hose with a 50 thou orfice and if it stutters you found a vacume leak. I didnt find any so I messed with my carb a little and found riching up the secondary circut almost solved the problem. I suppose it wasnt dumping enough fuel in so I opened up the secondary jets and put in stiffer springs on my metering rods so they pop up quicker.

351carlo · Apr 13, 2004

Well...

I have checked for vacuum leaks. The idle became very nice when I would spray carb cleaner down the carburetor.

Any clues?

dodgestang · Apr 13, 2004

351carlo said:
I have checked for vacuum leaks. The idle became very nice when I would spray carb cleaner down the carburetor.

Any clues?

YOu don't spray carb cleaner down the carb to check for leaks.

You spray it around the base where it bolts onto the intake. If the idle speeds up then you know you have a vacuum leak.

Cantedvalve · Apr 13, 2004

351carlo said:
Ok guys, it's running strong...but not at low RPM's. It seems to sputter and die out, often time giving me a backfire/sputter type sound. Idle is pretty rough, yet once it gains in RPM it feels fine. Power wise, when I first hit it I'm completely dead, then it jumps up tremendously. For example, tonight in the rain, from a dead stop I couldn't power brake the wheels, yet if I stopped it and floored it forward, once it gained RPM I would break the rear loose. I've replaced cap and rotor. Tomorrow will be wires, plugs, points, condensor and hopefully I'll time the motor.

Thanks guys,
Carlo

BTW 351 Cleveland 2v.

Sputtering accompanied with backfiring is a sign of an extreme lean condition. This could be a carb adjustment or a bad vacuum leak. Try tuning it out at the idle screws and/or getting a new carb gasket. Also might want to replace your fuel filter.

351carlo · Apr 13, 2004

dodgestang said:
YOu don't spray carb cleaner down the carb to check for leaks.

You spray it around the base where it bolts onto the intake. If the idle speeds up then you know you have a vacuum leak.

Haha, my apologies for my poor wording. I meant when I sprayed carb cleaner down the barrels, it would greatly improve my idle. I was wondering if this could be because of a 'lean' A/F situation. And as far as checking vacuum, I've sprayed every location I could find, and replaced old lines which I thought may have been the culprits as well as replacing any vacuum caps which were old.

Thanks so much, I'm gonna bring it up to my store (Pep Boys) and have a technician hook it up to the engine diag machine. What takes him 45 mins would take me 3 hours. It's worth it. Plus I want him to tell me the condition of the valvetrain. Thanks again guys.

Carlo-You all should have warned me of how difficult the plugs are on these 351 Clevelands in the mustang...haha.

Max Power · Apr 13, 2004

Sounds like the carb may need a rebuild. Perhaps your accelerator pump is failing.

Also, ditch the points and put in a Pertronix system. They are really easy to install, about $75 and you never need points again.

351carlo · Apr 13, 2004

Thanks guys...

Thanks guys, it ended up being a bad intake manifold gasket. Hey I'm just surprised it held up for 34 years. Ordered my new Edelbrock 4 barrel intake for the 351-2v heads tonight. Now it's off to picking out the carburetor. I'm gonna start a new thread for that, just because I leave for Atlanta in the morning and need to order my carb pronto.

THANKS AGAIN

'69Mach1Chick · Apr 13, 2004

Fifth_Beatle said:
Sounds a lot like what I'm going through. I have a 302-2V that has always been a strong runner, but I drove it sparingly. Now that I use it as my daily driver, I have had to tune and retune it regularly. I replaced spark plugs, wires, rotor, points, cap, coil, alternator, voltage meter, even the distributor vacuum. Still, it hesitates at low RPMs, and only runs nice when I hit 60 or 70mph.

I have the same exact thing....mine used to never rev down and idle like crazy...i replaced all that stuff and adjusted the idle. It was fine for awhile but now i have an exhaust leak and it is running like that. I really have to pump the gas to get it started.

Fifth_Beatle · Apr 14, 2004

It's pretty much a learning process. I've owned my car for 15 years, and during that time, have learned a new skill every year, from bodywork to brake overhaul to ignition timing. Love old cars...

Sputtering Cleveland

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