Halloran

iTrader: (7)

I'll post pics on this later if needed. I need to know just how much the forged diamond flat top pistons should come out of the hole on an LS1 without the head gasket. I have eagle 6.125 rods and 3.622 stroke. Mine noticeably come out of the hole that's why I'm asking.

Thanks

Randy WS6

iTrader: (69)

Is your pistons made for the 6.125" rod ? (347 stroker pistons) , You will need to contact Diamond on piston height out of the hole.. You will haft to measure the height to tell Diamond the piston to deck height before any body can help you. Around .005" is normal.

WeberRacingEquipment

iTrader: (4)

The piston, rod, crank and deck height all play into how much a piston should come out of the hole. If you list some more specs on the pistons and block I am sure we can figure something out for ya.

Sales2@Texas-speed

iTrader: (5)

Weber is right. We need a bit more info (particularly piston part number which will be stamped into the bottom of the piston on the skirt) to know for sure what you've got. Average for Diamond on the LSx pistons will be .005" out, but that isn't a constant! How are you measuring it? Many people freak out when they see a piston rocking in the hole, and one side is a bit farther out than the other. That's normal as well

Sigforty

I know the diamonds in my engine sit about .010 above the deck.

Halloran

iTrader: (7)

Ok so here are some pics. It's tough to measure with a feeler guage but my closest estimate is that the piston comes out about .080" that's to the very top and not taking into account the valve reliefs. With the head gasket on the piston sits nearly flush. To get you some more specs from the box the pistons came in I have a bore of 3.905", comp height of 1.315, effective volume of -1.6cc wrist pin of .927 x 2.500, rod length is 6.125. Not sure what else information I can provide but let me know if I'm ok...otherwise I'll need some more technical information as to what is going on.

Mssingkid

iTrader: (7)

You should get a caliper and measure it correctly.



Not to expensive, and it can help prevent some Piston to valve luvin.

rons 00z

iTrader: (10)

whats the part number for the pistons? i'm going to go out there and say that sits too high which tells me your piston is probably for a shorter rod and not the 6.125 you have.

Sigforty

You really should use a dial indicator to measure how much they come out. I am pretty sure they should be close to mine. Diamond likes to have their stuff about .01 out.

Halloran

iTrader: (7)

The part number is 11502

Sales2@Texas-speed

iTrader: (5)

By the math they are .011" out of the hole. A dial caliper is NOT the right way to measure how far a piston is out of the hole, BTW.

3.622/2+6.125+1.315 = 9.251
Standard deck on Gen3/4 blocks is 9.24 (not always exact, but close enough for this calculation).

9.251-9.24 = .011 out of the hole

You're fine. That's a VERY common piston for 347ci LSx motors!

brad8266

iTrader: (23)

Just going by eye that looks too high out but if you got the 6.125 rods and 6.125 pistons then you should be fine and I wouldnt be sure of why they are out so much.

Verify exact amount its sticking out and post those results.

Could just be my eyes though, I suck at visualizing distances.

1989GTA

I agree. Maybe you can lay something along side the pistons for reference and take a picture. Maybe a feeler gauge of a certain thickness. Things do get packaged wrong.

They do appear to stick up further than they should. The gap between the piston and the bore should only be say .005" or less so you should not be able to see down the bore all that much.

Halloran

iTrader: (7)

Ok, I pulled apart my feeler gauge set and started to stack them ontop of eachother until they were even with the top of the piston. The piston comes up .070" above the deck of the block. I'm not sure about the piston to wall clearance since it's almost impossible to get a correct feeler gauge measurement in a round area. Another thing I notice is that when I put the gaskets and heads on and rotate the motor by the pulley bolt I can actually feel the pistons come up and touch the head just slightly before going back down into the block. I shouldn't have any resistance cranking the motor with the gaskets and heads just resting there right? Maybe I'm just paranoid and the car will run fine once it's warmed up but I'm pretty **** about this stuff and want to make sure everything is as it should be before I start it up. I definitely DON'T want to damage my heads and pistons if I can avoid it.

BIG BAD BLACKSS

iTrader: (4)

If you can feel the piston touching the head when you rotate an unbolted head, then you have a pretty serious problem! You sure its contacting the head just laying on top of the uncompressed gasket?Can you get some play doh in there to see just how thin its getting for sure?

Halloran

iTrader: (7)

I will do that first thing in the morning...

Randy WS6

iTrader: (69)

The pistons can not be higher than the head gaskets ,it will hit the head ,.070" or even near it i way to high. You haft to give enough room for stretch at high rev for the crank ,rods, pistons. Your pistons look to be for stock rod length, But that's just my opinion

NEMESISVETTE

iTrader: (2)

That looks scary. I had TSP build me a 347 shortblock with diamond pistons and I noticed they came out a bit (not that much) but it is normal to have the mole pop out the hole.

Sales2@Texas-speed

iTrader: (5)

The only way to be sure is to measure from the center of the piston. The piston rocks in the bore, so it's not uncommon for one side to be out of the hole further than the opposite side. Can you still get to the rods to see what they say? On the side, they'll normally be stamped or engraved with a length. If you, for instance have a 6.200" rod in there instead of the 6.125", your pistons would be out of the hole .086"!

Sigforty

So what do you use?