Dan-a-rama

I have a '76 L48 that does not have the original engine. A few days ago, a piston broke between the rings. I am wanting to locate a new piston, but not for sure which engine I have. The last owner told me it was a 1969 327. The engine was bored .030 over.

Dan-a-rama

Thanks in advance for any response.

lbzraptor

Take the piston to a place like Napa Auto Parts or a machine shop and they should be able to help you. A lot of Napa stores have machine shops in the back of them.

TimAT

Where are you located? There are members all over the country (and the world) that may know of a good machine shop in your own backyard.

HeadsU.P.

OP is not looking for a machine shop. He wants somebody to read the block code numbers for identification. You will need the numbers off of the front pad also. If somebody finds your ID, you should also check the dia of the piston with a Mic.

Then go to Summit Racing > Engine & componets > Pistons, enter yr, make, model, 30 over.

TimAT

I got that. Unless he's planning on removing the rod from that broken piston with a hammer and punch, he's going to need a competent machine shop.

If that casting number is 3914678, that block is 1968 model year casting, and could be a 302, 327, or 350. The stamp pad on the right front will define that.

Duane4238

Therefore, you need to go to a NAPA store where they will fix you up with a piston pressed on your rod and also the rings on the piston. I went through this a few years back and NAPA supplied everything I needed at an unbelievably affordable price. Give them a try. Don't order what you need for one piston replacement online. If something's not right, you'll have to wait for delivery and return to correct it. Good luck.
Duane

calwldlife

wow.
defective part or what?
I think I would find the numbers and maker of the piston, located somewhere on it and get at least hyperutetic ones that match the broken one. change the all.

lars

Block casting number 3914678 was used on the following engines only in 1968:

1968 302 290hp
1968 327 210hp
1968 350 295hp

All three engines had the same 4" bore, so the only way to tell them apart is to check the stroke:

302: 3" stroke
327: 3.25" stroke
350: 3.48" stroke

If you check the ID pad on the forward passenger side of the engine and post the numbers, I can tell you exactly what the engine is.

Lars

Big2Bird

You sure caught that quick.

lars

Hey, Jeff - I'm just all over it, man...!

Big2Bird

I meant the piston.

Most piston breaks look like grenades. That one looks like he broke it off in the box.

lars

It was probably broken upon engine assembly: The ring compressor was not correctly installed, and the ring broke the ring lands when the piston was pounded into the hole. That piston looks like it has less than 1000 miles on it, so it was broken at assembly.

Lars

427Hotrod

I think you need to look for more problems other which piston to buy. That looks like some detonation issues maybe (is it a hypereutectic?) Have you checked all the others??

JIM

calwldlife

good call

Big2Bird

Gotta be.

CanadaGrant

I can't believe there isn't some damage to the cylinder wall after that...

derekderek

Find a piston that is all the way down. Stick a ruler in it and see if it's three in three and a quarter or three and a half inch down. I'll tell you whether it's a 302, 327, or 350. Post a picture of the top of the piston. Or the top of an intact one and post a picture of the bore this piston came out of several pictures of the bore.

derekderek

You must be sure one piston or actually two Pistons are all the way up flush with the deck. And then two will be all the way down and four will be at the halfway point. Minus of course the one that is not installed.

derekderek

Also possible but unlikely it's a 383. And which case the bottom piston will be 3 and 3/4 inches down.