I recently purchased an engine (350) from a private party that was supposed to be a good engine. Well the cam was bad in it. upon tear down the pistons have a slight dome on half of it and are stamped 3927173 there are no other numberson the top, and the number cast on the bottom is 3927172. What are they? I was told that the guy that built the engine worked at a GM dealership so they were probably bought there but I can't find out any info online. I will be sending the block and heads to the machine shop for inspection before I can go forward with this build. Thanks

Scott

Photos?

Those numbers are for DZ 302 pistons.

Those numbers are for DZ 302 pistons.They have about a 1/4 inch thick dome.

Yes the dome is about a quarter inch high. I'll get some pics in the morning. if everything checks out ok with the machine shop what kind of compression would these be with a standard bore and 64cc heads (492 strait plugs)? The engine code shows that it is a 350 ci.

Scott

1/4 inch dome would lead me to believe that they are the 11:1 stock pistons

The higher compression ones have domes closer to 1/2 an inch.

When you say engine code, are you talking casting number or pad stamp? The casting number could be the same for 302, 327, and 350 engines, but the pad stamp will be different.

The only way to get those pistons to work is with a 3" stroke crank, so regardless of what the engine started life as it's a 302 now. This isn't bad, because even if you don't want a 302 you can sell the rotating assembly to someone who does for quite a bit.

With those pistons your motor is not a 350. It is either a 302 with stock 5.7" rods or possibly a 327 with stock 5.565" 400 rods.

ok now i am confused. the block is a standard bore 4.00 350 block. the pistons are 302's and the crank is a 3941174 which I beleave is a 327 crank. would this be a 327? I'm going to have to measure the rods on sunday as i didn't get a chance to go over there today. what would be the cubic inch with 5.7 inch rods? or could you even do that? Anybody have any ideas?

Scott

ok now i am confused. the block is a standard bore 4.00 350 block. the pistons are 302's and the crank is a 3941174 which I beleave is a 327 crank. would this be a 327? I'm going to have to measure the rods on sunday as i didn't get a chance to go over there today. what would be the cubic inch with 5.7 inch rods? or could you even do that? Anybody have any ideas?

Scott

You've got a 327 with rods from a 400. A 5.7" rod won't work with those pistons and a 3.25" stroke crank. The pistons would stick out above the deck of the block by about 1/8" and hit the head.

what would be the cubic inch with 5.7 inch rods?
Scott

Rods do not change the CI of the engine.The crank stroke and bore determine the CI.It would be a 327.

ok now i am confused. the block is a standard bore 4.00 350 block. the pistons are 302's and the crank is a 3941174 which I beleave is a 327 crank. would this be a 327? I'm going to have to measure the rods on sunday as i didn't get a chance to go over there today. what would be the cubic inch with 5.7 inch rods? or could you even do that? Anybody have any ideas?

Scott

that is a 307 crank

you do not have a small journal 327 block, you have a 350 block with the 307 crank, if it is standard bore, it will be a 307 CI engine

that is a 307 crank

you do not have a small journal 327 block, you have a 350 block with the 307 crank, if it is standard bore, it will be a 307 CI engine

A 307 has a bore of 3.875" and a stroke of 3.25".

that is a 307 crank

you do not have a small journal 327 block, you have a 350 block with the 307 crank, if it is standard bore, it will be a 307 CI engine

3941174 crank was used in 68 and 69 327 and 68-73 307 3.25 stroke.

here is the pic of the pistons. If they can not be used because of the block being out of spec, what are they worth?

http://inlinethumb09.webshots.com/7752/2854081690043907989S500x500Q85.jpg

Scott