Projects Building My 34 B'Ville Coupe With a Potvin

I spoke to Chico about it and I think he said it was Fred Larsen that used a planetary OD from an old GM truck or something.

 

I've seen this done a few times.

https://www.jalopyjournal.com/forum/threads/chevy-alternator-backwards.358507/

 

Now THATS outside the box. Cool, I’ve seen the cable drive used before. Speed Demon uses a cable drive fuel pump. As I only have the front of the blower to drive it space may become an issue.

 

I figured if you could pull off the Potvin conversion (as you have), the cable driven alternator would be a cakewalk.
The first similar one I ever saw was on a flattie powered car, though if I remember correctly it was a generator.
I've looked for it before because I was curious what was used for the drive and connection components.

 

Damn very very nice work.....................and thought going into this

 

I was thinking about making replacement flexplate adapter (Wilcap GM adapter) for my blown Hemi, that includes a v-belt groove to drive the alternator. My transmission situation is a little busy, so I am not sure that it could get crammed in, but it might work with a more conventional setup.

 

Now I've seen it all, dude is building his own harmonic balancer? That custom manifold is trick too. I'm subscribed, no doubt I'll be learning something here.

 

Yup, the engine in Chico's Modified Roadster was one of Fred's old spares, which used said overdrive setup on the blower.

Driving the alternator off the blower would result in the alternator spinning at half engine speed. Most alternators are driven at twice engine speed. If we call idle speed 800rpms, that puts the alternator spinning at 1600 (2x engine speed). With the alternator driven at half speed, engine rpm would have to be over 4,000rpm before the alternator is putting out it's max amperage and at idle, would be putting out a very negligible amount (similar to a driveshaft mounted setup).

The setup posted above works by using an idler pulley off the main v-belt to drive the alternator cable, so the right ratio can be achieved. With the Potvin setup, there's no pulleys to run an idler off.

 

Cripes!
Not being Potvin-centric that completely escaped me.
Man, Fred Larsen must have been the coolest guy, I had the pleasure of talking with him by phone some years back when I called Mooneyes inquiring about their Grand Sport style sbc crossram intake manifold, office guy patched me directly to the shop and Fred picked up, it had to have been a fifteen minute discussion, he seemed willing to just chat as long as I wanted to.

 

Thank you, the payoff is when it all works

 

What am I missing? The blower turns at engine speed and if you pulley it up you can get 2:1

 

He was definitely the real deal. I had the chance to work with him for a few years before both he and Bill Jenks passed. Wouldn't trade it for the world.

You're not missing anything, I had a brainfart! I was discussing driving the alternator off a Hilborn distributor drive with someone last week, which would limit it to 1/2 speed and for some reason had that in my mind when I replied.

 

Google <NASCAR cable driven fuel pump> and fall down into that rabbit hole. Lots of ways to consider driving the alternator.


Vic

PS: I'm the guy that built/prepared the 1429 C/D/E/Rear--engine modified roadster

 

Great to meet ya. mine is car 1149 , North of 49 Racing ,AA/BFRMR It sure would be nice to go racing but we can't get there.

Ted

 

No Problem. I'm glad I'm not the only one that happens to.
ted

 

Just found this thread, I definitely gottta subscribe!!

 

I received my side plates for my Halibrand quick change from Bruce at QuickChange Exchange. These things are works of art. Thank you Bruce for taking up the challenge of producing them. They are going to look mighty fine under the 34.

 

This is some inspirational work. I wish my three window had the space for a Potvin.

 

If i was a smart man, I think i would have started with a new pair of rails but now that I have so much effort into them I ain't goin back. The rails are now raised 1.5 inches in the front and lengthened 3 inches. Pinched 10 inches at the front of the rails by taking the curve out of them from the front body mount hole forward. This will allow me to get rid of the inner fender panels and run a flat side hood. Repairs mostly done (still some holes to fill. The rear of the frame is kicked up 3 inches to get it to sit low like a b'ville car should. The top and bottom flanges have been ground to 1 3/4 inches in prep for the boxing plates. The front and rear will be bobbed with a "A" rear crossmember in the rear and a custom cross member in front to go with the torsion bar suspension.

 

Got the body set on the chassis for some mods. On a open wheel 34 I don't care for the inner fender panel. AT Bonneville it was sometimes eliminated and I like the look. This is not an easy mod, i needed to replace the rockers anyway. So the mods are to soften the bend in the bottom of the frame rail. If you look close you can see the marker line that will be the new bottom of the frame.
To make things look symmetrical I'm lowering the rockers at the front to make the gap at the bottom of the body and bottom of the frame a little closer to the same all the way along. This will flow into the bottom of the new hood side panel. You can now see the gap at the bottom of the door where the front bottom of the door will be extended down to meet up with the new rockers. The sub rail also needed to be lowered accordingly. This mad is made a little harder in that any of the replacement pieces you can buy do not fit so I've decided just to make them.

 

So cool. I had no idea you were building this. Damm Covid bullshit.

 

Hey Buddy, yes this will be the last one. The T is getting harder to get into so I thought something with more room

 

Would love to see this

 

It is currently stuck in supply chain prison, in the back of the shop.

 

Bin a long time getting work done on this thing. I did get some done. I managed to straighten out the lower body line. That is a lot more work than I thought.

 

Here's some pics of the lower body line. Enough of teaching myself sheet metal work, back to chassis and drive train

 

Looking good! Nice frame table to work on.

 

Thanks. I put it together from some tubing I had. It’s supposed to be a single use unit.

 

next up is the chassis. this thing is going to cause all kinds of issues. Front suspension will be torsion bar (i think) With the 3 " stretch in the frame, I only need to put it back 4 inches into the firewall.

 

In these pics you can see I've got the intake tubes added to the intake. Once the engine is finished I'll add the top, bottom, front and back to complete the intake. You can't see them but the injector bungs are under the manifold in the runners, It will be very difficult to see them when done. I'll still have all the mechanical injection nozzles and hoses in place to make it look authentic. I don't like the pulley on the front but it's the only place to run a belt. I thought about other options but thought this with a generator would look right.