aluminum head changes

[JacksonRacing]

I'm switching to aluminum heads and was wondering if I have to do anything with the carb jetting or are they usually close.



Running the same methanol setup that worked good on my steel heads.

[fast_crew]

May have to make some adjustsments to acount for compression and combustion chamber design changes if they are not the same. But should be very close. Note you may have to change timing aswell depending on chambers. What steel head did you use and what are you switching to?

[JacksonRacing]

Going from some old RHS toplines to the USMTS Brodix Spec head.

Running Autolite 3933 plugs, 34 deg timing. It seems to bog down and then go if I put it to the floor quick. The steel heads didn't do that.

Let it warm up, ran some hot laps, and checked the plugs after. They still looked like new, so that doesn't help.

Maybe more timing?

[fast_crew]

A bog when mashing the throttle quickly, tells me you need more pump shot. (accelerator pump) You most likely need a larger squirter and maybe a different pump cam. If it missed and blubbered you would have to much pump shot. I am not sure of the combustion chamber shape, but if it is like a vortec style fast burn chamber you want less timing (about 32) If it's like a standard D shaped chamber, 36* should be very close.

[washeduptoo]

We didn't have to adjust anything when we went from the steel head engine to al head engine earlier this year but we had ran the al head engine before. They were complete engines except the carb and we run gas, not sure if that makes a difference.