So even though I only had low compression on one cylinder I decided what the hell, rather than just replace one stock piston I'll upgrade to JEs. Took the stock LS pistons out,... every top ring land was broken and on one of the pistons the second ring land was broken as well. All were broken in about a 90 degree arc centered on the intake side.

Running the MAP hack with about 11 psi, 450cc injectors. 10 degrees retarded at the distributor apparently wasn't enough. Maybe it was that @#$%&* deltagate.

PLugs looked fine by the way and I couldn't hear any detonation but then again with a 3" thermal exhaust at WOT you can't hear much else anyway.

 

damn! what engine??? I'm running a similar setup on my LS. SAFC & 440's, BTM
@ .75 and stock distributer timing. I hope that doesn't happen to me!

 

ignorance taking hold here...wat are ringlands?

 

b18a i.e. pr4 pistons

 

hey man, do you mean your timing was 10º BTDC, or 16-10º = 6º BTDC?

I got my BTM installed FINALLY on sunday...I blew the damn coil the fist time. Hopefully my motor still loves me...the vaccum seems a bit low (18 in. as opposed to 22in.)...

 

See those grooves where the rings are installed? The sections of metal just underneath each groove are called ring lands, they're what support the rings.

 

10 degrees retarded i.e. 6 degrees BTDC, not 10 degrees BTDC. Basically I turned the distributor clockwise as much as I could. I must have had some detonation and just couldn't hear it.

 

did you tune the a/f at all with a wideband?

 

File, You need boost depandant retard, not just base timing at 11 psi, you are nuts.

Some detonation? You had alot of detonation.

You could have run fine at 7psi or so, too bad you went for 11.

Time to rebuild bigger and better.

Randy

 

Ive heard this too many times, we did the same thing on our Civic, the cause was a boost spike.