Oh, he also says "if plugs show no detonation, suspect the O2. Careful with ignition timing. Put the carb back to usual, run it, and run it hard, then check plugs." Devon
I’ll have to examine the plugs more, and the ground strap too. Currently it seems like the plugs are quite rich
Wow, lean. Yeah.......sorry you had to see this the hard way........whenever tuning always pull the plugs they tell you alot if you just look. EGT tell you exhaust gas temps, normally lean equals hotter temps. I have 2 on my car.....but they are not cut and dry. Different fuel. Different temp, change timing, different temp, to close or too far from the clyinder head different temp, weather change different temp. Its not uncommon on mine to see 15-30 degrees difference run to run
To be fair, I pulled the #1 plug multiple times, I just wasn't sure how damn rich it was. Think I could unfoul these plugs with some good run time? I think the A/F gauge is accurate at part throttle at least, when the air is moving slower. I think I'll keep my primary jetting of 82 or 84 and then jump the secondaries to 90 or 92
yes twins with a CSU brand modified Holley 750 double pumper. Perfect air fuel ratios at all boost levels right out of the box no tuning needed. I’m switching to E-85 with another custom CSU carb this year. I loaned a friend my E-85 carb and he made 1000 rear wheel HP with a 5.3LS on boost. Pretty amazing, perfect fuel curve.
Well an interesting piece of info. Holley jet drill sizes are different than Proform sizes. So a Proform 87.5/91 primary/secondary is really a 84/90 in Holley jets. So my next step will probably be to enrich the secondary side at the track.
Holley jet sizes don't directly equal a drill size, they sometimes have several jet sizes that use the same hole size but depending on te angles in and out these effect flow rates. This is why its important not to damage the jet and use a jet tool not a screw driver to install and remove them. Holley number are flow rates, actually in cubic centimeters per minute. I think typically going up a jet size is 2% more flow than the next lower number. I added a chart to show that jet size doesn't equal drill size always with holley........but there are some company's that make jets that are drill sized not flow rated. Yes its turned but its easier to read being bigger
That was the exact chart I referenced earlier, so I guess it does have to do with diameter and angling, but a small amount only. Thanks Ben
So when i here someone say I had to go up 10 jet sizes. I see red flags, they just up the fuel flow close to 20%, its very odd if the carb is proper size that it needs that big of adjustment.....normal +/- 5 sizes from build specs is more than enough to tune one in
