_Remi

Hi,

I just had my stock heads replaced by Edelbrock aluminium on my 289. I already had aluminium intake, a 600cfm carb and the car was running great.

Now (that's my first impression), it seems to be pulling really hard when I floor it but I feel a loss of torque in normal driving. Plus (and that is the biggest problem), it is misfiring when I accelerate quickly. For example, it does it when I do a fast double clutch, I am sure that it was not the case before. It also does it if I am driving normally and suddenly decide to floor it.

Can the misfire come from the new heads?

Does a change of heads require a complete tuning? Maybe my carb needs to be adjusted now?

I also had my exhaust replaced by a flowmaster 40series, can it affect it?

Thanks very much!

valley firearms

Check your firing order and valve lash.

Starfury

+1

Also, you probably need to retune the carb. New heads mean more flow, which usually necessitates some carb tuning.

Also, what's your timing like? Static and dynamic.

jonward786

i would bet good money ur running lean with those new heads

_Remi

Thanks!

The problem only happens when I accelerate quickly. Once it stops sputtering it pulls really hard all the way up to 5500 RPM (I don't go further ).

Is it a running lean symptom?

Starfury

Sounds like it. What kind of carb do you have? Could be an excessively lean cruise mix, lean accelerator pump, or improper transition from cruise to power mode.

my77stang

+2 to everything said in this thread.

btw, isn't double clutching for kids who watched the fast and the furious too many times?

urban_cowboy

I totally agree Star. Head change or cam change necessarily facilitates a tune up. Is is a missfire or a stumble? It sounds like you are having a lean bog off idle or light cruise. This is easy to diagnose with a AFR meter, but without it, you are going to have to narrow it down with trial and error. You may try increasing the pump cam to a more aggressive one or richen the idle and light cruise mixture. If WOT is good, you probably have your jets about right and just need to work on the transition.

Gary H

Add some timing too. My AFR's like 17* initial.

urban_cowboy

Wow, 17* initial? What total timing are you running? Do you have problems starting it with that much timing before TDC? I am running like 10-11* initial and though that was a bunch. Stock is like 6*.