Carb tuning for ET and consistancy...

[The Dartman]

Guys:

I think I'm finally ready to start tuning my combo to get a little more ET and consistancy. My car is currently (over)carbuerated with a Holley 4779C 750 Mechanical Double Pumper. The motor is a 12.5:1 318, with a Racer Brown .510/.292 cam, a Edlebrock Victor Intake, unported 2.02 "J" Heads, MSD 6AL, 3800 Stall converter, and a set of 3.91 gears round out the combo. It ran a 12.87@103 last weekend, which ties the fastest the drivetrain has ever run.

The over carbueration problem causes the car to start a little hard for an MSD, and it will flood very easily. Not only that, I believe the over carberation is also the culprit that makes my car pick up as much as three tenths from daytime time trials, to nighttime eliminations. Hard to win races that way!!

I would like to jet the 750 down, but I don't know where I should start, including what jets are currently shipped in this "off the shelf" unit.

I will be adding a four Phenolic spacer for this weekend, to get a little bottom end back since my 60 foots are still a little slow in the 1.83 range (my best ever with this combo was 1.67).
I also have a problem with my advance springs causing full advance at idle, undoubtedly a major contributor to the hard starting/flooding situation. I will address this problem and throw a fresh set of plugs at it as well.

I really want to explore the lean=power theory, and see if I can get this bad boy to drop down into the 12.60-12.70 range.

Thanks!
The Dartman

[cuda66273]

Too much to type why don't you call me sometime, worth way morw than the 10 cents a minute.

[The Dartman]

Don:

Thanks!! I'll do that on my lunch hour today or tommorrow.

I figured the combination of tuning and distributor curves would "spark" your interest!! (LARGE PUN INTENDED) But I actually didn't want to trouble you (too much) with a Holley question, since you are the BG Demon man.

I have never pulled a plug after a run, so I don't really know how they look after a run. After a street run, the plugs look like a medium golden brown, what I would consider being perfect.

I think I will just test and tune this weekend, rather than worry about the eliminator. Usually I would only get a couple time trials, so tuning is almost out of the question normally.

Thanks!
Dartman

[The Dartman]

Well, I'm all geared up for the track this weekend.

I contacted Don and had a very enlightening conversation about carberation, timing, and ignition systems. I've since hit the net and this forum gathering all the info I can find for tweaking the most from these areas. I picked up a vacuum gauge, an doctor's ear viewing "thingy", a new set of autolites, and a vast assortment of jets.

I will be readjusting the idle mixture first since the transitional and main flow all depend and build upon it. I think I may also pick up another power valve, one that is truly 2 numbers below what my vacuum reading is in gear idling. I think it has a 8.5 in it now, and this motor has never ever made much vacuum. I think it may be possible that this could be contributing to my flooding/rich conditions. Once this is figured out, I will tackle the main jetting based upon the condition of my plugs after a run.

Hopefully, with a new four hole spacer, carb tweaking, ignition tweaking, and a little luck I will hit some solid 12.5's and 12.6's. It's supposed to be in the 40's this weekend, which my car loves anyway!!

Dartman