Racing Fuel Systems

OK... my first post here. Thanks to Mark for the efforts he puts in keeping things going here.

Now to the questions... everything here applies to a 388" Mopar dirt track engine. W-2 heads, 3.79 crank., .040 overbore, choice of two SFT cams from Howards and Jones, M-1 intake. Long tube headers with 3 1/2" outlets. MSD 9T ignition. 1/2 mile paper clip track. Methanol fuel. 7200-7500 rpm max. About 4000 rpm off the corners.

I rebuilt a 4779 Holley 750 for this engine last winter. Bought good stuff to do the rebuild but I traded for an 850 Holley just because. The old carb worked good for the new owner on his open motor modified.

My "new" carb has a welded baseplate that was warped and, while I have it flat as I can get, I'd feel better with a new throttle plate.

On a good recommendation I have been looking at an 850 plate from APD. I like it because it's simple... no extra vacuum fittings. Any other suggestions? I will stay away from cheap imitations like Speedmaster, etc.

How about billet metering blocks? My carb is the old style where the extra fuel supply holes were drilled above the jets. 2 circuit... 3 circuit? Honestly that alone confuses me. I 'm not sure how to tell the difference and what difference that would make.

Last years carb was an early BG... I had to drill out the main feeds since they were pretty small for methanol. This carb is a Braswell of a similar vintage. I haven't really looked it over to see what mods were made to do the conversion.

So how good are QF blocks? Holley? Others?

I have not raced this car yet. Three years of accumulation of parts then old age begins to set in and I get a new knee (to match the other) then I'm hit with two heart attacks just one week apart. I'm feeling pretty good again so I hope to spend more shop time getting busy with engine assembly then on to the chassis.

Thanks for your help...

have you checked into Braswell for the alky blocks? If not, do it early and often.

Also, BLP or Bo Laws is good with alcohol carbs. Mike Laws posts on here, you might contact him.

Been looking at BLP... I can get a recommendation from a couple builders then make a decision..

Shorty with methanol I would go to BLP, order a billet base with welded nickel plated shafts. They will not rust on you and the bases are what I use. For metering blocks it depends on the jet thread size you want to use. They have a methanol 5135 2 circuit with an R thread 1/4-32, H thread 5/16-32, and their custom L thread .350-32. Let me know what size, I may have some use ones here.

Okay... just looking at the air bleeds today. Got my number drill kit out. Looks like the two air bleeds nearest the middle of the carb on each side seem to be blocked, plugged or so small my smallest drill won't pass thru the orifice. Normal?

Also any idea what number squirter is a good place to start? How about main jets.

This is an older 850 with the drilled hole above the main jets.

I ordered a new base plate from BLP. I'm going to use the original throttle shaft as the primary shaft is real tight in the original bas plate and the secondary is within normal tolerance

Also how do I ID this main body? All I can find is a "P-32" cast into one side of the body. No air horn.

BTW...1.74 body.

The inner bleeds are the main system [ main jets ] air bleeds & are sometimes quite small, under 0.030".

My number drills only go to .040... I'll have to find a smaller tool. Just seems that either it's plugged or never was drilled. Can't seem to blow air thru it.

Okay.... here's an update.

I bought a billet base plate from BLP. Bare... I will reuse my seconday shaft and some hard ware.

Also ordered a pair of circle track floats, a couple different power valves (4.5 and 6.5), a pair of Ti needle and seat assy. and a few misc, small parts. getting closer.

Now I need to make a decision on what metering blocks to use...stock alky or BLP.