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So far we've checked these things
Fuel- never leans or goes rich throughout the pull.
Airflow- manifold pressure is good and the hose isn't sucking to.
Cam- number matches the card so it's correct.
Timing chain- dot to dot.
Converter- locked or unlocked issue is still there.
Replaced spings with new BTR 660 and no change.
Plugs are AC Delco iridium gapped on .040
The car doesn't miss or trip any code throughout the pull. It just isn't making power past 5200rpm.
Is this a low compression build by chance, that you were planning on boosting later?
As others have said, a data log of a WOT pull would be very helpful.
To me, it does look like it’s hitting a wall at about 5k RPM, but even before then, the power and torque are already really low for a 408ci LS. I’ve seen similar problems caused by valvetrain problems (excess coilbind clearance, not enough preload, etc.) and excess reluctor runout. There may even be a dead cylinder or two.
I had a slipping transmission cause those little spikes and valleys. Dyno operator thought is was a miss fire but wasn’t showing that on afr and was not audible so he was unsure. Didn’t realize the transmission was slipping until a couple hundred miles later when it was noticeable while driving. What transmission are you using?
Last edited by jasons69chevelle; 08-19-2022 at 08:40 PM.
08-18-2022 | 09:07 PM
