DanielRicany

Hello guys, I have a 1985 Corvette with a Mini Ram, Flat tappet ZZ409 cam, Hedman Longtube 1 5/8" headers, 58 MM throttle body, Cat Delete, AIR Delete, EGR Delete, Dynomax Ultra Flo mufflers, Timing set at 10* BTDC, Descreened MAF sensor, air filter lid cut, K&N Air filter, MSD 8.5mm ignition wires, MSD HEI coil, Heated O2 sensor conversion, AFR Gauge w/ Wideband O2 sensor, 3.75 gears, Speedometer calibrator, Throttle body coolant bypass, G2 adapter and a 27SF512 chip.

When I raise the idle in neutral to 3k - 4k RPMs, if I open the door and stick my head out I can hear little pops in the exhaust. At this moment my AFR gauge is reporting 14.7:1 ish at 3k - 4k RPMs.

Does anyone have any ideas as to what is going on? Thank you!

rad928music

You run a High Zinc Oil supplement, or High Zinc Oil?
Could have a Cam lobe going down or collapsed Lifter or lifters.

DanielRicany

Yes I use a bottle of ZDDP additive.

DanielRicany

There's only like 2k miles on the cam.

nutz4c4

A cam can go flat in 20 minutes...What was your break in procedure?

DanielRicany

I varied The RPMs Between 1500 And 3000 For 20 Minutes Without Letting It Stay At One RPM, Just Like TPIS Said

DanielRicany

They Aren't Like Loud Backfires, I Know What The Actual Backfires Sound Like Because I've Been tuning Them Away. They Are Like rumble Backfires. Its Hard To Explain.

bogus

little puff puffs... could be as simple as an exhaust leak or a bit of uncontrolled turbulence...

DanielRicany

It's not really a puff, it's like a pop. I really don't feel like changing the cam again :/

383vett

What's your timing at those rpms with no load? You could have too much advance. More importantly, how does it run at full throttle?

DanielRicany

I don't hear anything at WOT. And I don't really hear it as much from inside the car.

Here is my timing table. My base timing is set at 10* BTDC, and my Initial Spark Advance in the tune is set at 9.84*.