Piston deck height

[Streamln1]

I pulled my engine apart over the weekend to drop off at machine shop...one thing I noticed is that at top dead center the pistons are slightly higher than the deck. Is this normal or did my machine shop in the past take off too much?

[Alex3000gt]

That doesn't seem right.

[familyMAN]

Normal that they protrude slightly. Can't remember exactly how much off hand but search around its probably posted somewhere. Guessing around 8 thou.

[Alex3000gt]

Normal that they protrude slightly. Can't remember exactly how much off hand but search around its probably posted somewhere. Guessing around 8 thou.

Interesting. I haven't had the heads off of my TT yet, but on my NA I could have swore that they sat below the deck height by a few millimeters.

I'll pay attention to that when I pull the engine next month.

[Streamln1]

Ok thanks for the info. Never know with some machine shops

[J. Fast]

I pulled my engine apart over the weekend to drop off at machine shop...one thing I noticed is that at top dead center the pistons are slightly higher than the deck. Is this normal or did my machine shop in the past take off too much?

There's room in there for compression ratio increase if you're worried. Just use a degree wheel when you put it all back together to make sure you comp for the cutwork. How far are you projecting?

[Streamln1]

It's a few thousandths I don't know for sure but I am running a thicker head gasket. I don't know for sure how much was removed prior. This time around were not taking any more off just installing new forged rods and wrist pins

[sergechronos]

Hm, don't have any pictures of it, but I do have the shortblock on a stand in the shop. Could go look at it, but it's cold and I'm lazy. I don't recall the piston tops projecting at all past the deck, if it did it was very very minor.

[familyMAN]

They protrude. 8 thou if I recall. Compressed composite gasket is about 50 thou. You MLS guys will have to comment on MLS but I bet it's similar. Leaves plenty of room and can deck 8 thou also if needed which will have 16 above deck but still 34 to head if your gasket is 50.

[Streamln1]

My head gasket is 120 to compensate for a bit much being taken off the head

[thor'svr4]

yes the pistons do stick above the deck at TDC on both NA and TT.

[GTwizard]

All info about our motors is in the Manual.
Pistons should be .020 above the deck. If a motor has been built before, be careful with tolerance stack up.
Built a motor 2 years ago and the build went bad. The block had been decked too many times in the past.
Shop did not catch that. So the motor had a knock. Was not lower end knock, but upper end. The Pistons where just kissing the heads.
Not enough to cause damage. But enough you could hear it ever so slightly. Motor had to be torn down and have pistons shaved .003 to stop contact with head.

[Streamln1]

All info about our motors is in the Manual.
Pistons should be .020 above the deck. If a motor has been built before, be careful with tolerance stack up.
Built a motor 2 years ago and the build went bad. The block had been decked too many times in the past.
Shop did not catch that. So the motor had a knock. Was not lower end knock, but upper end. The Pistons where just kissing the heads.
Not enough to cause damage. But enough you could hear it ever so slightly. Motor had to be torn down and have pistons shaved .003 to stop contact with head.

That's exactly why I went with thicker head gaskets, I was worried about the same thing, I knew a lot had been taken off of the heads initially from the first machine shop, close to the limit, it was enough that the lower intake manifold didn't want to drop right in. I think some of the old school domestic machine shops go nuts with taking off a lot of material.