Centrifugal supercharged Avanti II

[grobb284]

I used the Holley Commander system, with a Paxton. It utilized GM sensors, had a knock sensor and a MAP sensor from a Grand National. Was inexpensive, and I was pleased with it.

[CaffeineRacer]

Grobb, was there any custom tuning required to get the Holley system to cooperate with the supercharger? Is this on the car in your signature? I'd love to see some pictures of this setup. Was this an SN60 paxton unit or one of their newer units.

[Devildog]

Devil Dog, does the distributor on your Avanti have a vacuum advance? If so what is the vacuum source for this advance and will it be effected by the supercharger?

Yes, vacuum advance. Basic old GM HEI distributor with vacuum off intake. If I did a supercharger and loose vacuum, the much bigger concern would losing the vacuum boost on power brakes. Easy way is to go to a hydro-boost brake system and clear that big ugly GM actuator out of engine bay.

As to what to do for vacuum advance, go to a digital control ignition, or just leave the vacuum plugged on the HEI. The vacuum advance only advances the spark at cruise to yield a little better gas mileage. My old 61 Corvette with factory high performance Mallory ignition doesn't even have a vacuum advance, most of the factory performance set-ups did not. With those old 2 x 4 WCFB's, it gets 20 mpg on highway at 70 mph, it has for 47 years that I have driven it.

With having 8 small barrels with progressive linkage, it is sort a poor mans EFI. While at highway cruise only two of the small barrels are open, but since small they are open wider than on single larger 4 bbl carb. Wider open for better A/F mixing than a larger carb with two bbls just cracked at cruise.

Even in the day, the drag racers would remove the really neat Chevy FI system and install the 2 x 4 WCFB's because they could get a little more torque and get hp quicker than with the FI. The FI would make more horsepower (on a road course) but not in the 12-14 sec down the strip.

Joe

[mfg]

A local '63 Avanti owner has a 283 CI Chevy in his car with a sidemount Paxton...He uses the sealed Avanti R2 AFB carb....Clean and reliable setup, at a quick glance one thinks their looking at a Studebaker R2 engine!

[plwindish]

There was an 89 Avanti convertible at Dover that had a crate tunnel port(I think 350) supercharged with a Paxton unit. It also had a Gear Venders overdrive unit as well. There is a ton of room under the 89 hood due to the Caprice frame. It would not be as easy to do on an older II.

[Avanti83]

There was an 89 Avanti convertible at Dover that had a crate tunnel port(I think 350) supercharged with a Paxton unit. It also had a Gear Venders overdrive unit as well. There is a ton of room under the 89 hood due to the Caprice frame. It would not be as easy to do on an older II.

Sounds like the one that Jeff Rice bought/sold in early 2011 if it was red. It was a really nice car. Probably a youtube video or two around also.