Potvin style blower set-up/Flathead

Hi Guys,

I know that Rat******* uses the MSD boost retard control on his 4-71 blown flathead and by all accounts it works really really well.

If you were doing a blow through setup, you could always put in a couple of pressure relief valves set for a certain boost value

Danny

 

Your idea and workmenship is very nice.Are you gonna run flat piston with domed head?What brand heads you useing? Is that cam a roller? I don't think you will have two much boost at 1 to1 .Thanks

 

I'm gonna use stock cast iron 59ab heads. The pistons are flattops. I am using the cast iron heads mostly because the expansion rate is the same as the block, hopefully helping head gasket sealing. I can grind on the combustion chambers without worrying about destroying a set of expensive heads. Plus the aluminum heads are usually designed to raise compression, which I definitely do not want. The cam is not a roller... Too much $$$ and a nightmare from a valvespring standpoint...

 

Flat top pistons with dome head is asking for trouble.If I could run iron heads I would.If you want to talk PM me,I think I could save you some problems.

 

Couple more pics...Pressure side manifold..

 

i saw someone mentioned the 1:1 drive maybe being a bit much, but flatdog thinks you will be ok... would a GMC blower be able to withstand high RPM runs even with the high performance upgrade? what is going to keep the blower from flying apart (***uming it is built correctly) at 5000 rpm?

not trying to be a smart*** by the way... im actually very interested in seeing how this works out.

 

Update:
I decided to go with two S&S Super B carburators. They don't have accelorator pumps, so I decided to steal Holleys design and fab a remote pump. It will be fed from the carb float bowls and feed into the carb air horns via some homemade jets... Hope it works.

Oh Yeah, I got the transfer tubes tacked together, and the throttle linkage is shaping up too.

 

This thing is killer...

So why the S&S and not soem side-draft Webbers?

Danny

 

Mostly because I already had some S&S stuff lying around.

 

Sounds like a pretty good reason to me!!!

Whats the flow like on those S&S carbs?

Danny

 

Very cool. Keep us posted.

 

The Old Man finished my main cap supports today! I thelps that my Dad is a closet machinist....

 

Amazing work. Any updates?

 

The crank is currently having the rod journals cut down to run the h-beam rods (Buick 2" journal)....

 

Hey is the drive cush you have on the end of the crank to the blower a kawasaki jetski cush? If thats the right word for it? What ya got going looks way cool! LTR Dave

 

Yes, It's a Kaw Jet Ski drive coupling.... I used to work on Watercraft in another life.. When I started thinking about the project, I needed a coupler that would dampen vibration, allow for a small amount of mis-alignment, handle the power, and be CHEAP.. I think the coupler was around $20...

 

Got some stuff out of the way, time to revive some projects. I was originally going to use an original Flathead pulley to run the blower. Many folks thought that the stock pulley would not live, so.....

When the crank got back from the grinder (rod journals turned down to 2"), I chucked the crank in the lathe and turned the snout down to SBC dimensions, broached a small O.D. SBC balancer and here it is...

This should give me something sustancial to bolt my drive adapter to, as well as dampen some crank vibrations.

 

Really nice work!

I almost whent for a front mounted setup for my 4-71 myself,
but desided to go for a top mounted with a Hilborn 2-port,
i am a coward
Cant wait to see it finished.
By the way, what crank do you use?
And how mutch lift has the cam?

Br
Kjell

 

How'd this work out??

 

I'd like to know too.

 

Love the project.
However: remember that what comes out of that blow-off valve is flammable mixture under pressure, and if the car is at speed it will wash past the exhaust pipes.
The cush drive is excellent.
I have doubts about the discharge tubes to the engine. They both enter the manifold at an angle, and that's going to do strange things to mixture distribution. If it's going straight in, each tube should be vertical for 2" at least before the manifold. If you need lower height, run a single big diameter tube above the manifold with short runners to the ports and feed the tubes into the end. The big diameter slows the mix as it enters.
I ***ume you're regulating the fuel pressure wayyy down to the S&S - remember they're gravity feed. You could also run them progressive, might make jetting easier.

 

bttt.........

 

Damn, he heasn't been on here in three months, I'd like to see where this went.

 

Ten years later, any news? Looks like a cool build.

 

Well he has not been logged in since August 5, 2016.

You could tag him, although he may not get an email notification.

@stank468