Hot Rods blown french flathead for my roadster

Dear hambers

Long time I haven't post here, and after building a few other hot-rods I m back at work on my roadster 1932, rolling bones styled.
I just purchase a scot blower, I installed it, and would like your feedback on my installation
For the moment I can t install more than one belt, it is a pity but i will have to make another lower pulley. my lower pulley is 4.5 and upper is 3 1/8.
For your information my engine is a full ported 255ci french flathead, with literio l100 cam and milodon valves.
dual holley 94 with 4.5PV and 48 jets.
Pertronix distributor
Running 5° advance at idle and 25 at 2400rpm.

Without the blower I dynoed the car and get 125hp to the wheels


First run yesterday with the blower, and engine runs good and cool, but no boost can be read or felt. and when I hit the gas to the floor at 2000rpm, the engine felt like less power and slowly increase rpm and it get better, but WOT no boost till 4000rpm... didn t go more because of the result.

here is a movie of the first start

<iframe width="560" height="315" src="https://www.youtube.com/embed/cNwod1ZahQY" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>

 

Any idea ?
Belt is tighten pretty hard I can t imagine it slips...
Advance?
to lean?

I have built a blown flathead with a 4/71 in the past and never experienced this problem

 

I would think that one belt is not enough to spin the supercharger without slipping at any speed, except idle. There has to be a reason why they run more then one in the first place. Even a lot of high amp alternators run two belts and they can't pull as hard as a supercharger.

 

I only run one V-belt, no room for more, and get 5lbs. boost with no slip that I'm aware of, it has almost 180 degrees of wrap. How fresh is the blower?

 

the blower is new from H and H

 

and I have more than 180° wrap

 

Well you already know that with a V belt drive you are going to need more than one belt. A single may be OK on a short drive but when you get it into the Alps and drive it hard it is going to get hot and slip.

The carb jetting is something that you will have to figure out on your own. But you can do that by reading your spark plugs. As for spark advance if you are running much more than about 5 pounds you are going to want to retard it a little bit, less than 5 pounds you should be fine where you are at.

 

I agree I don't think slip is your problem, and since it had 125hp unblown it's not a stuffed up exhaust or something that existed before. Are your carbs now fully opening from the gas pedal?

 

Is the blower input shaft bolted to the impellers? Worded differently, do the blades spin in the blower when you turn the pulley?

 

^^^That may sound stupid but I bought my 471 from H and H and noticed during installation that the blades were not spinning. I removed the front input shaft housing to find all of the bolts were missing, probably removed during dis***embly for polishing. I noticed yours is polished and from H and H so....

 

btt

 

Yes the blade spin, you can clearly ear it...

 

Can't help you, but you have a cool roadster!

 

The carbs able to supply enough gas?

 

What do the plugs look like?

 

bad gasket seal under the blower?

 

I have recheck for any leak.. all good. carbs are good holley 94s , plugs looks a bit black, AFR tell 12.7 at idle and 13 wot.

my last guess, is belt slippage....

 

driving to work this morning, and with the belt super wrapped, I can now see 2 to 3 psi coming around 3500/4000rpm... not much yet, AFR gauge show that I m very lean at 2000rpm, and i feel it under the gas pedal that the engine hesitate, if I slowly push on the gas pedal, it then getting better and better and power is coming.

Should I change my PV's and jets? you advice are welcome