6-71 super charger questions........Performance guys!

[FRITZ]

Ok i have a 6-71 on a 327 chevy. I got 2 edelbrock (carter afb type) carbs .... now when i set this thing up do i use the chokes in the carbs,... take them out, as i remember, you leave the choke in the rear carb and take the front choke out. am i rite? its been a verry long time for me, just want to be sure
Thanks again guys
FRITZ

[QQMOON]

Im no expert but I would take them out
JR

[FWilliams]

rear carb only is the way i set them up with edelbrocks, i am assuming you are running a pair of 500's. they also tend to be a little on the lean side for superchargers right out of the box.

[FRITZ]

Thank God fer "Racefab"
yup a pair of 500's, underdriven, not to rad of a cam.
You were spot on with my piston question a few weeks ago also. thanks much! Can you recomend wnat kind of valve spring to run in thoses 76cc heads. I assume i should be running a heavy sping to keep the valves closed. Im also deciding on a distributer also, hows the Accel breakerless unit?
out of princapel i want the Roswell Rod to run and drive and not be just a static show car......Im just a prick that way ,LOL....thanks
FRITZ

[FWilliams]

i would have to see the cam specs to figure out a spring.,you want to keep the intake valve on its seat because there is added pressure behind it from the blower. although it is not a real big problem on street driven superchargers, running small boost

which 76 cc head casting do you have?

[FRITZ]

Racefab,...I have yet to buy a set. Local speed shop here "S&K Speed" said they have 76 (or was it 75) cc heads built and on the shelf. is there a type i should look for/
FRITZ

[AHotRod]

Be sure and run the carbs at the same time, NOT progressive.

AHotRod

[FRITZ]

BTTT

[Scotch]

I'd highly recommend you use o2 sensor to jet correctly. Lean out will kill ya.

The 76cc heads will provide lower static compression (shoot for 8:1) so with blower boost you should be okay on pump gas- 92 or 93 minimum.

You didn't mention if the huffer being over or underdriven. This is important, but for a street car I'd usggest underdriving about 20 percent.

Agree with choking one carb only.

With regard to valvesprings- these are relevant to the cam design and specs. Hyd. flat tappet requires a mild spring, solid flat tappet a bit more, and rollers even more. They have some great cams designed for blowers (with more exhaust duration to help all that boost leave), and I'd highly recommend one of these too.

A quicker ignition curve usually works well - many run locked-out distributors on blower motors with no advance at all.

Blowers tend to hide bad engineering with boost, so make sure the motor runs bitchin' without the huffer, too. If you can, plumb a breather through a check valve to the exhaust to help draw crankcase pressure out. I've seen too many boosted engines push oil pan gaskets out from excessive crankcase pressures, so either vent it through the exhaust or plumb in a vacuum pump (Moroso makes a nice one w/brakcets for SBC).


Scotch~!

[Paul]

dammit, now I gotta have a blower too http://www.jalopyjournal.com/ubbthreads/images/graemlins/mad.gif

Paul

[porknbeaner]

Well everyone has addessed everything but the accel distributer.
Now someone is going to get their panties in a wad for sure but the Accel distributer is a bad choice.
I would probably look toward a mallory magnetic if I wanted to go breakerless. I would also think about a control box MSD or something so I could control my spark. MSD makes a unit (as I'm sure most do) that is boost sensative.

[Bugman]

I wouldn't run a blowe without an MSD box, even in it's just the standard non boost sensitive type. My blower motor started hard and popped on accleration till I put a 6A-L box on. Night and day difference.

-Jeff