Well, late Sunday night, we finally get my gfs engine back together, all spec'd perfectly. It is a low compression(9.5:1) motor, so there really was no need to clay the pistons, etc.
Well, we go to spin it over(no timing belt, valves/cams relaxed), and at TDC, theres a definate interference. You can still turn the motor over by hand, but its definately hitting.
What are my options? Its a GE 85.5mm O-ringed B20 block, B16A head, Endyn RollerWave pistons, Crower Rods, LS Crank.
Im assuming its less than .0001" of "contact" because its relatively easy to spin through it. Should I just clay the engine, find out where its contacting, then compensate w/the dremel?
Im FRESH out of ideas, and quite frankly ready to roll this ******* car off a cliff
Oh, if a thicker headgasket will work and actually SEAL the engine, Im down. Just let me know where to get one. I need an LS/B20 head gasket...
TIA

 

Hmm, weird. I bet you they took way too much off the deck. Have you noticed the piston to deck height? Also since its a big n/a bore have you deshrouded the head to accomodate the bore size?
Or. Assuming its n/a, what compression pistons are they. I guess it could be possible for the sides of the dome to hit the head if it wasnt de-shrouded.
Cometic makes a .043" headgasket. So that gives you another .014" of clearance.


Modified by 93LSivic at 2:19 AM 5/10/2004

 

Well, it was fine before w/85mm pistons. We got the engine in a car from Viren, pulled it apart, and the pistons were grenaded.
Had to go bigger, so 85.5 is the final size. I guess I didnt even think twice about enlarging the combustion chamber of the head to match(because it was fine before). This is definately why. ugh...time to take it back to the machine shop, Im a welder not a engine builder. I can bolt **** together fine, but anything more and its out of my reach.
Thanks for the tip Dan, I will tear-down sometime this week if time permits. Im limited to Sunday evenings for "extra" projects right now.
BTW, a Cometic was on there before, and it blew. I have not heard good things about Cometic anyway, so ya(Im sure it blew from the awesome tuning that was done).

 

People either love or hate the Cometics. I love them and havent had one failure yet on any of my personal engines, or customers. ****, I even re-used one before back when I was build LS and it held up just fine...........how about that for reliability. Couple coats of copper spray is all i do for them.

 

can you point me in a good direction for purchasing one? At this point, it seems easier to me than completely re-machining the head. Email me if you can source one for me please...

 

I may be able to get one for you, but that seems like an odd size. I actually had to call Cometic directly about 3 weeks ago and have them do a run of my headgaskets since I couldnt find any from our distributors. Mine wasnt anything too special, just the 83mm MLS .030" gasket. I guess since they are only designed for sleeved apps then they dont make too many of them at a time.

 

well, GE sent us an 86mm, because it IS an oddball size. Dont know if that helps any

 

Cody, is the head on the car?

Does it only hit when the piston reaches TDC? If the head is off see if the piston is coming out of the hole or not.

It is possible that it could be hitting the combustion chamber but by no means would I recommend opening the head to 85.5mm, not a great idea. You will lose compression and actually chaneg the way the motor responds to igtion timing.

Fix it with a thicker headgasket if the piston is coming out of the hole