About 1,200 miles ago I did all the mods in my sig. I was noticing a lack of power at high rpm's. I was told that I should readjust the rocker arms as I had them adjusted according to my factory service manual(1 full turn past zero lash). I changed that to 1/4 turn on many other peoples recommendations. I took it for a ride and babied it for a few miles(until it was warmed up). It ran nice and smooth, so I think that solved the power problem because it wasn't smooth before. I turned around to bring it home and took it up to 6,500 rpm in 2nd gear. As it was climbing I heard a backfire and some stumbling. I let off and could here a lot of clattering coming from the left side of the motor. I coasted most of the way home and pulled the vlave cover. I found the exhaust rocker nut loose on the #1, but the pushrod still in place, and the intake pushrod bent really bad and wedged down under the intake manifoldon the #1. The rocker not was still tight. I'm wondering why this happened. Also i heard that early LT1's came with hardened pushrods. Could I use one of my stock pushrods in place of this one? There was no problem with them when I replaced them with the Combination Motorsports set up. Sorry for the long post. Any help would be greatly appreciated. I just want to break into the 12's! Anyone in Rochester want to take a look?

Andy

 

Hey Andy, it sounds like there was some kind of problem with how the rocker arms were set. You are correct, 1 turn past zero lash is too much. I usually do the hyd rollers about 1/4 turn, then bump the whole nut/lock a little more....ends up being about 1/3 turn total.

That is interesting how it only happened on cylinder #1, but intake and exhaust. Your heads are totally stock (aside from valvesprings)? Could be the install height on those two were slightly off, lock nuts may have not been tightened enough, or the valvetrain geometry was off somehow. You had the Combination pushrods too? Pushrods could have been the wrong length, but I doubt that.

I will be in Rochester on Wednesday, and I may have a little extra time to take a look at it. Where do you live?

Jason

 

I live in Greece near Dewey and Stone, if you know where that is. I work 2pm-10pm. I don't know what your schedule looks like. Let me know. I'd really appreciate someone with experience giving me a hand.

Thanks,

Andy