chevy 350 ? about year of motor.

[fishon101674]

I have what was told to me when I boat my airboat a few years ago, That its a stock 1992 chevy 350 vortec motor. That was converted from fuel injected to carb. It has an edelbrock aluminum intake and holley 2 barrel carb. The # that i found are on the drivers side back of the head on the lip where the trans would bolt to. 10054727 5.7 lg. Is that all the numbers that I need to see if its truly a 1992. I'll tell you why I'm trying to find out the year. My airboat has been loosing rpm. I use to spin 2950 rpm and now I spin 2300 rpm. So I just took a compression check. Its not good. Im no machanic. This was my readings standing at back of motor ( were prop is). on the left side from front of motor back 80psi 94psi 85psi 140psi. now right side of motor from front to back. 138psi 100psi 150psi 135psi. I'm not sure if it rings, valaves, or head gasket. When I first start it up, it does puff out some little light blue smoke then clears up. Any help would be good.

 

[hurst01]

OK, from what I see with the numbers you gave, it is a 5.7L 350 block and can be from 1986-1999 (early), and can be either a 2 or 4 bolt main with a one piece rear main seal.

The numbers you gave for the compression are all over the place. Pull the spark plugs and give it a couple squirts of motor oil and check the compression again. If the compression jumps up considerably, it indicates loss of compression at the rings. If it doesn't change noticeably then it could be assumed that it is leaking through the valves. This could be because the valves are adjusted too tight or they are burned.

Could be that you could get by with performing a valve job. Since the engine has a bit of a smoke at start-up, it would be safe to say that the valve stem seals are leaking. The nice thing about this is that since it is in an air boat, you have easy access to the engine and it should be an easy matter to pull the heads. Once the heads are pulled you can see from deposits and dampness on the top of the piston whether it needs rings or not.

Perform another compression test (wet) and get back to us with the numbers and I can give you some suggestions on where to go :twisted: . Just joking :lol: You should be able to get some good suggestions on here. I eat, drink and sleep small block Chevy engines.

Out of curiosity, what size blade (length and pitch) are you swinging? Does the engine have a governor to keep the RPM down to 2900? Is that the recommended RPM for the prop, if not, what is the recommended RPM? If you can answer these and more questions to come, we can help you get fixed up.