454 Engine problems - The 1947 - Present Chevrolet & GMC Truck Message Board Network

JAYBEE · 08-10-2006, 01:39 PM

I have a 490Hp 454 crate motor in my pickup. It is around 4 years old with 10,000 miles on it. All at once with a steady RPM the motor lost 20% of power. A carburator malfunction thinned down the oil with gas. After oil change, carb rebuild, and plugs, The engine is still running very rough. I did a compresion test and cylinders 2,4,6,8,1,3 red around 195psi , cylinders 5,9 had no compresion at all, the needle did not move at all, I added oil to the cylinders, and there was little or no change. The exhaust is smoking on both sides. Appears to be gray. What is the next test I should do to narrow down the bad news?

08-10-2006, 01:39 PM	#1
JAYBEE Registered User Join Date: Oct 2005 Location: FLORIDA Posts: 7	454 Engine problems I have a 490Hp 454 crate motor in my pickup. It is around 4 years old with 10,000 miles on it. All at once with a steady RPM the motor lost 20% of power. A carburator malfunction thinned down the oil with gas. After oil change, carb rebuild, and plugs, The engine is still running very rough. I did a compresion test and cylinders 2,4,6,8,1,3 red around 195psi , cylinders 5,9 had no compresion at all, the needle did not move at all, I added oil to the cylinders, and there was little or no change. The exhaust is smoking on both sides. Appears to be gray. What is the next test I should do to narrow down the bad news?



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