Slo 6.0

Hello everyone I am new to this so if I mess something up I’m sorry lol. I have a 2005 GTO that is a 408 Stroker with a F1A-94 blower. I recently switched over to e85 and upped the boost from last year. I got it tuned and everything was looking good until we had a serious lifter failure don’t know if this happened while he was tuning it or just out of the blue. I tore the motor down and put a set of Johnson link bars in it and the same exact cam. I remeasured push rod length and bought the correct push rods for the setup. Now out of no where I have what seems to be a misfire during load and hard acceleration. Happens at idle and in gear. Tranny is a built TH400. Now could this be due to the lifter failing during the tune? I have replaced everything as far as plugs,wires, and coils. Still no change. Any input would be much appreciated

Che70velle

iTrader: (6)

Welcome to LS1Tech! Re-post the question over in our Gen4 Internal section. It likely could belong in External section, but since you’ve had a lifter issue, I’d start in Internal Section and let’s see how it goes.

Double06

iTrader: (1)

Check the valve springs that may have helped the lifter failure in the first place. It was going (so you saw no damage when you took apart) and then it may have broke on the new start up.

99T/ATIME

iTrader: (3)

I agree...and do it quick, because if it is a spring, and it fails completely, it could drop a valve and bye bye motor.

Slo 6.0

Just looked over the valve springs and none of them are cracked or broken. They are BTR .660 dual springs so it’s possible it could be the inner one broken and I just can’t see it.

G Atsma

if it is an inner spring you still need to sort it out. Remove and inspect all springs, CLOSELY.

Slo 6.0

Okay so I pulled all the springs and everything is good as far as inner and outer springs. Put everything back together and tried to start it back up and it took it a few seconds to fire up. One other thing I forgot to mention is when it was tuned on the first time on e85 it was a really bad blend my tester came back at 67% I just recently added 15 gallons of known good e85 don’t know if this would effect the car in this way seeing as how it is setup for flex fuel.

Slo 6.0

I’m taking it back to the tuner tomorrow to get more data than what I am able to see with my scan tool so hopefully something comes back that it was in his tune up. The car made 1082rwhp so I know problems are going to happen at this power level. But everything that I have tested mechanically tests fine so I don’t see it really being anything else. My best bet is the lifter was failing during a pull and he made adjustments for a valve not opening all the way. Judging by how the lifter failed it was a high rpm failure because the roller is almost 100% flat, and so was the cam lobe