Mighty Whitey

what is the general rule as far as optimal quench height for an LT1?

I've heard .040" and then I've heard .030'? which is it?

all motor 355, steel rods, and forged pistons if all that matters?

thanks guys.

ulakovic22

iTrader: (12)

Typically you want to be around .035-.040 on your quench, but you have to make sure the rest of you combo works first. Just like everything else it's just a guideline. Stock quench is like .075.

aboatguy

I'm running 32 thousandths without problem. I've heard of guys running 27 thou, but if your planning on a tight quench you have to ensure everything's right.

CNC Stew

I'm at .034

TravisA

iTrader: (4)

I'm running .041... The Ol' George Carlin look alike wouldn't zero deck mine like I wanted and left them .026 in the hole. I had to modify a gen1 gasket that is .015" to get mine down to .041

TwoFast4Lv

iTrader: (8)

I 'Shoot' for .040 and take any thing from .035-.050

I had one engine I ran .032 on. That was a little close for me

1989GTA

Running .035" quench here. No problems.

96capricemgr

iTrader: (1)

max rpm could be a consideration too.

Mighty Whitey

my setup on the car is pretty much dead at 6500rpm, so there is VERY little need for it to ever be twisted any higher.

I was thinking zero deck with impala gaskets (.029" compressed, correct?) which would give effectively a .029" quench height (duh!)

I can imagine a rod, piston, crank throw, and warm oil clearance being anywhere near .029" but I might be wrong.

is .029" too tight? I wouldn't think so if everything was INDEED "blueprinted" to assure symmetrical crank throw length as well as having a square deck surface, and quality rods and pistons are used (respectively)

what are fel-pro gaskets for aluminum head motors compressed? .043"?

.043" quench height is a hell of a lot better than the stock .060+!

TwoFast4Lv

iTrader: (8)

You guys ever take piston rock or any of that into the equation?

thebufenator

iTrader: (2)

TravisA, how hard was it to modify?

Which gasket did you use?

I think I need to do the same.....

TravisA

iTrader: (4)

I installed mine without rings and took measurements top(valley side) and bottom of the pistons....I measured mine by rocking them up and down and averaged the two numbers.

If thats what your asking....
I used the felpro-1094 gasket....

You have to enlarge the water passages on the top of the gasket. Its the two passages on the top left and right side of the block. I also trimmed where the oil drains back into the valley through the head. I used a dremel with a cut off wheel to enlarge the holes and then sprayed them down with copper spray-a-gasket ....You have to be very careful to not cut into the fire ring and not get to close to the top of the gasket. I also used a very,very small amount of permatex around the water passages.

Mine has held together for 14 miles... There is a couple of guys on cz28.com that have ran these gaskets with no problems. Plus there only $19 to $20 apiece.

bigdan1

is there something i dont get here ?
if you run zero deck height and .029 gasket youll get .029 quench but with a 54cc head your CR will reach something around 11.8:1 aint that way too high?

or like I asked ,is there something i dont understand?
in my case I have .20 deck hieght ,ill put a .026 mr.gasket to obtain around 10.8:1 Cr it looks more then enough to me ...

Dan

thebufenator

iTrader: (2)

static compression ratio is not a big deal, dynamic compression ratio is what matters.

Bigger cams give you a smaller dynamic compression ratio......so running 12:1 with a larger cam is just fine, as long as quench is good

thebufenator

iTrader: (2)

TravisA.....only 14 miles?
How long ago did u do this?

TravisA

iTrader: (4)

Yep only 14 miles on it right now. Its been together and running since the end of Sept.....

-Travis

1989GTA

Mighty Whitey. If you want to use the .029 Impala head gasket why don't you leave the pistons say .006" down the hole instead of a zero deck. That would give you a .035" quench. There is no magic in a zero deck.

bigdan1

I know all that crap about static compression .....
but still 54cc+ zero deck height +.026 gasket makes for too much compression unless you go for at least 245 dur @.050 i dont think that most run these ...ill run aprox 235 dur @ .050 and no way id go less then .040-.045 quench on a DD .....
Dan

96capricemgr

iTrader: (1)

I am running about .052 quench on a genuinely never disassembled stock shortblock .026 measure near center of piston with a straight endge and feeler gauge, and a .026 gasket. 53.1cc chamber, I come up with about 11.2-3 static compression and she pumps just shy of 230psi on a gauge. 8K miles a year on 93 octane.

jasonisdn

iTrader: (1)

.027 cometic
.005 in the hole with custom diamond nitrous pistons.
revving to 7000rpm no issues. the guy/company that set it up is very smart and i would trust him with a WMD.