Got my block back from the machine shop, assembled the rotataing assembly. I was about to clay the motor when i realized, the flat sides of the pistons also stick out above the block. I measured about 0.007" above the block deck. To my knowledge block was decked 0.010" What would have caused the pistons to be so far out besides the block being decked more than i thought? Im also running oem LS Crank and rods, USDM ITR pistons, in a gsr block. I got a cometic 0.036" headgasket, should i go with the 0.051" or should i try grinding off some of the piston material?.

 

i would just check piston to head clearance.. if you have enough clearance dont worry about it.. chances are that you will have enough clearance with a .036 gasket and its only .007 out of the hole.. if im correct the flat part of the combustion chamber is .040-.042 deep so that will give you .69 piston to head clearance.. the next thing you should check is your piston to vavle.. hope this helps

 

you have to put your dial indicator on the edge of the pistion and measure how much it rocks back and forth in the bore. since you are running and oem style piston it will probably only be a few thousands in which case i would run the .036 gasket. if you have .003 rock + .007 out, that gives you .026 piston to cyl head which should get your quench pretty tight at RPM if you are running a gsr head. if you are running a B16 head i would definetly run the thinner gasket. even an OEM gasket in that case.

 

I got a gsr head and gsr block, i spoke to the machininst this morning, block was milled 0.01" and head milled .015" So should i be okay w/ the 0.036" headgasket?

 

where did you get the info that the gsr head is 0.04" above the block deck? I would like to read more on that. thanks

 

are you running the stock rod bolts and what RPM are you planning on turning this thing??

if you arent planning on going over 9000rpm i would probably go with the .036 gasket with .026 piston to head.
perhaps DonF or Mike Belben have built some simular combo's with the oem rods with the quench that tight.

if you are worried about it you will be fine for sure if you run the .051 gasket. you might be leaving some power on the table though.

 

GSR block and head, stock ls crank and rods, arp rod bolts. Redline set to 8500 rpm. I read on the endyn site that the minumum is 0.045" P2H clearance for stock rods and 0.035" for Eagle steel rods. Is that the absolute min.?

 

i have a similar problem only my pistons stick out 3.8 mm out of the block. Its a B16A with 82mm ctr pistons. What do you guys think is the problem?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B16A CRX &raquo;</TD></TR><TR><TD CLASS="quote">i have a similar problem only my pistons stick out 3.8 mm out of the block. Its a B16A with 82mm ctr pistons. What do you guys think is the problem?</TD></TR></TABLE> That you do not have a 77.2 mm crank or your rod is 4mm too long.

 

I'm just thinking that the pistons i got weren't cast perfectly, therefor the top of the pistons come out too much. Your case is way worse then mines. 3.8mm is like what 0.15"?

 

ok. i think its my crank then. sorry if i thread jacked i just had a question and needed an answer.

 

yeah, different crank or rod setup will be your problem, unless the block was decked like .2"

 

i have no idea. ive been callin the machine shop to find out the deck height and the stroke and all that but he is taking his sweet time.

 

I just checked on c-speedracing.com estimated 12.2:1 comp. How safe will the setup be till i get it tuned. Only have access to 91 octane

 

if you want to you can make a milling machine fixture and make a setup to skim each pistons dome sides .007" all depends on how hardcore you are on this....

 

i think im just gonna get a 0.055" cometic h.g. and pull some timing out to prevent detonation.

 

with a .055" gasket ur gonna take away a decent amount of compression. if its truely 12.2:1 than with that gasket ull probably be at a solid 12. itll run on 91 but ur gonna have to pull some timing out of it.

 

yeah, Don F told me to pull 2 degrees. So did b19coupe. Also, head has been milled 0.015" and the block decked 0.006" So im thinking CR will be around 12:1. I can live w/ that since its a d.d. and i only have access to 91 octane.


Modified by all-mtr-teg at 4:34 PM 8/29/2007