As asked, what is the piston TDC clearance to block deck on sbc 400? I'm trying to figure out what cc dish piston I will need.

 

It's .020 - .025 typically. It's not a dumb question. Do a search and you'll find getting your quench area around .040" is the smartest thing you can do to help prevent detonation in a high compression engine. Having too much area on top of the piston actually promotes detonation instead of preventing it.

If you don't find much here look at the performance section of www.chevytalk.com. Last year it was discussed thoroughly.

 

Depends. The stock deck height of a factory 400 block is
supposed to be 9.025" but rarely is.
The compression height on 400 pistons for 5.7" rod is supposed to be 1.45" but may not be. Advertized cr's are based on different
deck clearanced for different manufactiurers.
eg: keith bloack are rated for a 9.00" block or "0 deck height"
Federal Mogul is different.

COunt on your pistons being .025" to .045" down in the bore on a factory block that has not been decked.

http://www.kb-silvolite.com/

http://www.federal-mogul.com/

 

thanks guys. I was told to aim for the .040" quench area by some others before. I am going to have the block decked to 9.010 and run a .030 gasket. but with the pistons it will only be a .039 quench. ok by me.

 

When using some of the online compression ratio calculators don't forget that the deck height, ie. .025" - .040" from the top of the piston to the top of the block is a negative number.

 

With a total net quench clearance of .040" and 64 cc
heads you'd want a piston with a dish volume of 18 to 21 cc's
to get 9.8/10.0:1 cr for a pump gas motor.

Check out Keith Blacks KB-168 or KB147

http://www.kb-silvolite.com/

 

I'll state the obvious and say, be sure to at least check deck height in cylinders #1,7,2,& 8...
(Using the SAME rod & piston)

They will be different...

I haven't seen one yet that wasn't...

I've seen some at .017 in #2, .019 in #8
.037 in #1, and .039 in #7....

Scenarios like this, is when you should "square-deck" the block...

Sometimes you'll find one that's "close enough" not to square deck....

...Just my 2 cents...