Backfire

[Todd Burkard]

I have a slight popping or backfire when I downshift and sometimes let up on the throttle. I got the BLM's to all come within + - 4 of 128 from idle to 5500 RPM. This problem wasn't there when I had the, dare I say it, Carb on it, once I put the TPI on I started to get it. The car runs great, pulls hard through all the gears plugs look good but I can only get rid of the Popping or backfire if I crank up the initial timing even then I still get a little.

Is this because of the inertial supercharging effect of the TPI and I am getting a lean pop because of all the air blowing through when the throttle is closed and the motor is still revving at a higher RPM and not as much if any fuel is being delivered?

Specs on the application are

68 - Camaro 327 Stock
87 TPI from a Camaro running stock F-body Code except for the modifications to get the BLM's correct
Screens removed from Mass air
K&N Air filter
50 PSI Fuel pressure on 19Lbs injectors
Headers
Dual Exhaust with glass packs (soon to be removed) no cross over
Converted over O2 Sensor to 3 wire heated design

Thanks in advance

Todd

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