Karl Butler

I just bought my first c3 at sea level but I live at 5000+ feet I have a big block 454 and two holley 600 double pumpers on a tunnel ram. Do I just need to mess with the just bring them 3 sizes down and mess with the idle mix screws or is there more?

gkull

I live at 5000 also and I had a tunnel rammed street rod. Yes 2 3 jet sizes and bump up the timing the same amount and readjust the idle mixture to get the best vacuum

cv67

If you want to go a step further and can spare 200 bux call Summit and get thier AEM 02 sensor kit you can really tell more via gauge unles you got a good feel for things.

cagotzmann

I live @ 2300ft. The stock holley 770 avenger cam with 72-75 jets. Primary / Secondary. and a 6.5 power valve. 1/4 mile times 14.4 sec. 104 MPH

I have a zeitronix o2 data logger for each bank of cylinders. 2-4-6-8 and 1-3-5-7.

http://www.zeitronix.com/

This recorded afr in the 10 range for WOT.

I ended up at 69-74 with a 8.5 power valve.

AFR now in the 12.5 - 13.3 range with a 13.18 1/4 mile times @ 108.2 MPH

I see you have 2 options.

1. get a AFR tool / kit to get it dialed in correctly
2. go to the track to maximize MPH at the end of 1/4 mile. trail and error method.

but at 5000ft you will need to decrease jets sizes and play with timing.

I also have a programmable MSD unit to make any timing curve, which was very helpful at the track. It takes 2 minutes to make adjustments and take another run.

Here is a example from the data logger.

I am logging AFR / RPM / Vacuum / Sensor voltages etc.