Supercharging a Model A

[GeneBob]

Originally Posted by jeepguy1948

I notice that on the turbo charged twin engine dragster they used a constant velocity SU carburetor, I doubt that was for no reason. I would think that almost any motor would benefit from a constant velocity carburetor, after all countless millions of motorcycles can’t be wrong.

The first the Harley riders do is take off the CV carb and put on a Mikuni. The CV may work for some engines but the throttle response is terrible on a Harley.

[GeneBob]

Originally Posted by jeepguy1948

I have been looking into using a Holley Sniper EFI on my banger. I wonder how that blower and the Sniper would work together? Pretty good I expect.

Funny that you mention that combo, I really wanted to try it but couldn't justify the cost. I ended up buying the air/fuel ratio meter and tuning the Stromberg in with it.

[GeneBob]

Here are a couple pictures
Sorry, the picture on the left is right side up in my file and I don't know how to rotate it for the Barn.

[Bruce of MN]

[Bruce of MN]

Originally Posted by jeepguy1948

I notice that on the turbo charged twin engine dragster they used a constant velocity SU carburetor, I doubt that was for no reason. I would think that almost any motor would benefit from a constant velocity carburetor, after all countless millions of motorcycles can’t be wrong.

SU and Stromberg carbs were used on millions of British cars, too.

[GeneBob]

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Thanks Bruce.

[Jim Brierley]

Originally Posted by jeepguy1948

I notice that on the turbo charged twin engine dragster they used a constant velocity SU carburetor, I doubt that was for no reason. I would think that almost any motor would benefit from a constant velocity carburetor, after all countless millions of motorcycles can’t be wrong.

You're probably right, and I don't know the reason but Eddy still uses that type of carb.

[johnneilson]

Jim,

Eddie was testing with 4BBl Holley this year, at the time of popping head gaskets.

That shortly before block decided to let loose.

A new motor is going together, 5 main, girdle and bigger turbo.

John

[Smokedtires]

With stock cranks breaking, I would be wary of adding the additional strain associated with driving a supercharger.

I love boost, but have been contemplating a high compression head for my Model A since from what I've read really helps with hill climbs. In most race engines, head flow is crucial for adding power. The flathead 4 seems very restricted in air flow by the nature of its design.

[GeneBob]

Smokedtires,
I have not broken a crank if you were referring to my post. The pulley on the front keeps coming loose and breaking. The last one basically left the car completely on a local highway.
I would like to find a great deal on a Burlington or SCAT crankshaft but they both are pretty precious. In the mean time, I have ordered serpentine pulleys for the car and will do some planning on re-installing the supercharger; that is if I don't give up and start down the path of a V8 swap.

[Smokedtires]

I didn't think your crank broke, I was referring to the cranks as being inferior. Why not consider a modern 4 cyl to supercharge? If not concerned with stock appearance, it could be an easier route.

[GeneBob]

A modern 4 is not as cool as a supercharged original.
I have looked at optional engines and have not found anything worth the hassle unless I go all the way with a V8.
Ford's V6's are a pretty pathetic series, their 4's are worse. The most interesting V6 is the old GMC big block V6 but it weighs like 800 lbs. The Chevy V6's are not very interesting. I am not interested in the Japanese engines.
So, either I supercharge the original because that is fun and cool or I go all the way.

[Smokedtires]

I like your way of thinking. Your problem solving efforts are great.

This is an interesting guy you might enjoy if you haven't seen him. https://youtu.be/DqopaEr4Er4

[GeneBob]

I just watched the video. Amazing thinking and ability to create solutions.
I am still trying to figure out why my front pulleys don't last and they are going 240 mph.

[Smokedtires]

I had a problem once with the power steering pulley on my Corvette coming off. The bore on the pulley was torn up and replacements weren't available. I turned the bore to press a new bushing in then heated the bushing to get it on the pump shaft. Hasn't come back off since.

[4bangerbob]

Some random thoughts.

Typically superchargers run a belt with "teeth" as shown in one of the attached photos.

There was a gentleman that pats on the HAMB that is running a supercharged model A. I reading through the thread he went from a tooth belt, then considered chain drive and then switched to dual V belts. See attached pictures.

I did not see mentioned what material your crankshaft pulley was made from. (maybe I missed this) cast iron, steel. I think steel would be preferred in this application, as I have had failures with cast pulleys. Also one other thing to consider is belt tension. Original model A ran generators and belt load required to run a generator and water pump was low and belt tension is also low. When one considers changing to an alternator the force required to spin the generator is higher and subsequent belt tension must be higher. The higher belt tension does increase side load on the bearings. I would believe this thinking would also apply to the installation of the belt driven supercharger.

Here is the link the the thread on HAMB where most of the photos came from.

https://www.jalopyjournal.com/forum/...enade.1220215/

[jeepguy1948]

I was really surprised that you had better success with the Stromberg pre blower. I would have bet money that the webber would be the better carb. Makes me re think my Webber install.

[GeneBob]

4bangerbob, I have 100% success at destroying front pulleys. Before I put the blower on, I loosened a 1 piece cast pulley, after installing the blower, I broke that same pulley. I then got a steel pulley from SOS and put that on with a locking tab on the retaining bolt. That pulley split from the keyway outward. Charley Yapp blamed me for the split pulley with some BS about the key not being fit properly. He could have said he doesn't replace his parts that break but instead tried to BS his way through it. Then, I happened to have an old 2 piece cast pulley that I added a second 1/4" keyway to. That one grenaded driving down the highway. Amazingly, the one piece of pulley that landed in the front crossmember showed the same driving direction hammering.
The pulleys always show wear like hammering on the driving side of the key. This makes me think it is a torsional load. I am now collecting parts to put a serpentine belt on and trying to figure out if I am overpressuring the engine block.
I appreciate the link and will spend more time looking at it when I am not half asleep.

Jeepguy1948, I was disappointed in the Weber performance and started trying to tune it. I may not know what I am doing but followed the recommendations in the Weber tuners book and what I could find online. My engine ran better with the Stromberg from day one of installing it. When I put the supercharger on, I re-tried the Weber and was disappointed again. The Stromberg worked better again.

[jeepguy1948]

Maybe I’ll sell my Webber carb and intake (not yet installed) and buy a Stromberg and intake instead. That would certain be easier to deal with, Webbers are somewhat intimidating anyway. I have been investigating the possibilities of a Holley Sniper EFI recently and may give that a try. As far as I can find nobody has yet done it on the Model A engine that was running a flathead on it. I do know of a guy that has installed the Sniper on a 4banger flathead Jeep motor with excellent results and that is a 134CI flathead motor rated motor 60 hp stock. As Jim Brierley points out in his book the A motor is a big motor at 200CI so it can benefit from more volume on the intake. The Sniper model I am looking at is their smallest one that Holley has made so far it was designed for the 200CI 6 Ford rated 140 hp it replaces the Autolite 1100 one barrel carb. And is plug and play with the cpu in the Sniper itself, the only external component required is an air/fuel sensor in the exhaust (within 18” of the manifold).

[jeepguy1948]

I would add that I would try a Marvel if I could find one that I felt was reasonably priced.