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Engine ID 1984 251hp

D

Dave P

New member
I have a 1984 251 chris craft and I'm trying to id the engine. There's no tag on the back of the block, the decal on the valve covers is unreadable. The GM ID is GM3970010. When I look this up it it tells me it could be a 350, 307, or 327. I would like to know what I have. I know it's not a 327 cuz they weren't put in that year. Could anyone tell me what I have or how I can tell. I'm sure it was repowered before I got it, but there's no history on it. Thanks guys:confused:
 
Re: Engine ID

The only real way to ID a Chev engine is going to be to physically measure the Bore and Stroke.

These engines have the same physical external markings, contours and everything else, etc, etc.

It was about this time that GM changed to the single rear Crankshaft seal, and rocker covers using the centre lining of the hold-down bolts.

Bruce.
 
Thanks for the reply. Is there any other numbers anywhere on the block or a certin way to tell if it's a 350?? Thanks
 
1986 was the start year(I think) for the one piece rear main. In 1986 you could get a one piece rear main with perimeter bolted valve covers.

You will probably have to measure the stroke.
 
Another way of measuring the capacity is to go to your local Race Track and see if any of the officials (Scrutineers) have a basic Capacity Checker.

Down here, the Sprint Car guys have a simple machine that screws into the Spark Plug, and measures the number of revolutions, and the amount of air that is displaced, and this gives the cylinder capacity, and then after a simple multiplication, the total engine capacity.

This way the engine can be quickly checked for size without stripping it down. Which is sometimes required between rounds on a race day.

Bruce.
 
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