Weak engine? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

woody82 · 07-21-2014, 02:11 PM

I have 72 c10 with a factory 402 big block The engine is supposed to be a factory rebuilt engine,I have no reason to believe otherwise I actually found a certificate under the seat stating that it is.I can tell the engine has been apart by the blue gaskets.It idles really rough like it has a healthy cam in it but it seems gutless.A 4 cylinder would walk all over it.I took the distributor apart and cleaned it and replaced the advance weights and put a new vacuum advance on it didn't help much.Did a compression check all around 150 on a cold engine I no my bad but those manifolds burn the crap out of your fingers.I just can't figure out why this engine has no power.Like I said the engine sounds mean like it has a big cam in it.

Sklptrljay · 07-21-2014, 03:12 PM

Dist. 180 degrees out? I've seen that happen before. Hot manifolds could mean it's way too advanced.

Wrenchbender Ret · 07-21-2014, 03:50 PM

Is the initial timing right. It should be about 12 degrees BTDC. Sometimes the Marks are wrong. Try advanceing it & see what happens. It could be a bad vacuum leak. The carb base may not match the manifold. The secondary throttle valves may not be closeing all the way. Check for a clogged up exhaust system. If everything checks out it may be like Jay says. The timing chain may be off a tooth. If it was more then that it would not run at all.

07-21-2014, 02:11 PM	#1
woody82 Registered User Join Date: Jun 2014 Location: Bllomfield Iowa Posts: 49	Weak engine? I have 72 c10 with a factory 402 big block The engine is supposed to be a factory rebuilt engine,I have no reason to believe otherwise I actually found a certificate under the seat stating that it is.I can tell the engine has been apart by the blue gaskets.It idles really rough like it has a healthy cam in it but it seems gutless.A 4 cylinder would walk all over it.I took the distributor apart and cleaned it and replaced the advance weights and put a new vacuum advance on it didn't help much.Did a compression check all around 150 on a cold engine I no my bad but those manifolds burn the crap out of your fingers.I just can't figure out why this engine has no power.Like I said the engine sounds mean like it has a big cam in it.

07-21-2014, 03:12 PM	#2
Sklptrljay Registered User Join Date: Apr 2012 Location: Stillwater, Oklahoma Posts: 874	Re: Weak engine? Dist. 180 degrees out? I've seen that happen before. Hot manifolds could mean it's way too advanced. __________________ 1971 C/10 SWB, 15x8 Rallys, 4.5" X 7" static drop, C-notched, 350/350, 3.73 Posi. .........A 383 and Gear Vendors are on my bucket list. 1972 GMC 4X4 K1500 Survivor - Sold No matter what problems life throws at you, your time on Earth can be incredibly fulfilling and rewarding.....if you just lower your expectations. -Phil Dunphy Last edited by Sklptrljay; 07-21-2014 at 07:57 PM.

07-21-2014, 03:50 PM	#3
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,229	Re: Weak engine? Is the initial timing right. It should be about 12 degrees BTDC. Sometimes the Marks are wrong. Try advanceing it & see what happens. It could be a bad vacuum leak. The carb base may not match the manifold. The secondary throttle valves may not be closeing all the way. Check for a clogged up exhaust system. If everything checks out it may be like Jay says. The timing chain may be off a tooth. If it was more then that it would not run at all.



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