Quote:
Originally Posted by Ironangel
If it's going rich under load, maybe go down on the PV number to open later. Might try a little more timing as well, like 3+ degrees. Put the Holley back on it with maybe a 6.5 PV. That cam will want a little more timing as long as your running 93 octane...
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It goes lean under load like climbing a hill. Due to my engines set up. I get the choice of lean or rich. Unless I buy a expensive carb, and the items to tune it. I think I need a 7.5 or 8.5 PV to keep it going safer for awhile. The 6.5 is a hair to low for my combo.
Diving deep into the weeds last night I am convinced my air bleeds on both carbs are wrong. With the Holley being less wrong on the freeway atleast. As I don't get any progressive richening I get to much progressive leaning of my afr. So I tuned my afr for 3000 rpm where I my driving rpm is.
My timing is pretty maxed out already for this engine, and 89 octane. I did extensive tuning with 91, and had little in the way of positive results. More hp/tq yes, but only slightly. Better mpg no. I used a 1/4 mile app for testing, and results were margin of error levels. The cam bleeds off enough pressure for 89 octane, and is good even in 105* weather. Hell it will run 87 good to about 75*, and about 85* when part throttle detonation starts its return. I was in Reno area with it picking up a built model B engine for my dad's friend. When the station only had 87, and I was on fumes. When I was forced to test it out. Luckily my afr was 12-13 at that elevation so I had cushion. Till I got to the next town. Further testing was at home where I could drain out the 87 if it didn't work.
The cam doesn't need more timing. It's pretty much where power roles over, and my starter has no issues. I have been tuning the truck bi-weekly for several months. Even if it was only a small very small adjustment.