Alternative Carburetion?

[John Nickell]

I don’t know a lot about this subject and have yet to do much research but I was wondering if the use of side draft motorcycle carburetors on a flat head 6 would be possible. If one could solve the linkage problem I think a setup with a single carb feeding two cylinders would work well. Since these carbs would be connected only to a single intake port and not to each other, what difficulties would one face in synchronizing these carbs? It seems like there are a lot of motorcycle enthusiasts among the group that may be able to help out with this one. Again this is just a thought but I think it would be pretty cool if I could get it to work.

[greg g]

3.7 Liters(displacement of 218/230) divided by 6 is .62 liters the displacement of 1 cylinder. Since most bike are in the neighborhood of 1 litre total displacement, it would seem at even 1 carb per two cylinders, they wouldn't flow enough to be feasable. I posted a pic of a studebaker flathead six running a weber side draft from a Jaguar (3.8/4.0 litre) 6 there is a link to the truck forum in last weeks posts here, that might be a more suitable way to go.

http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=4143

[Brad Lustig]

You could always run 1 carb per cylinder. You want to talk about a syncing nightmare! I wonder if flow would be a problem for the 3 carbs since you're only cranking over a max of 4000rpm vs up to say 10,000rpm for a motorcycle. I'll bet if you compare the CFMs you could probably find something that might work.

[John Nickell]

What range of CFM would be appropriate? Maybe it would make more sense to look into the side draft carbs used in foreign cars rather than motorcycles. I know that the Weber carb shown in the other post can get pretty pricy, but look pretty cool. I have found motorcycle carbs that are made to run 1300 cc engines. 3 of these would put it around 4000 cc which is 4 liters, plenty big for our engines.

[48mirage]

Interesting idea. To cut down on the number of carberators needed take a look at the S&S Super "G". They are used on the current 117 cubic inch Big Dog motorcycles. You could probably get by with just 2 of those and they would be easier to sychronize.

Jim

[claybill]

2 - 44mm mikuni's would do it. just make up a manifold and GO!

one 40 mik pulls a harley 1340 cc

claybill

[John Nickell]

I have also come across SU carburetors used in 60's and 70's european cars that seem like they would work. Like greg had mentioned in his other post Jaguar used them in pairs and triples to power their XK engines. I think it would be fun to play with three of these and see what the results would be.

[james curl]

If you could find three Carter YH series carburetors they would work fine as Cheverolet used them on the 235 I/6 in the 54 Corvette and on the Corvair Spyders with the turbo. If you made three seperate manifolds the engine probably not run correctly ubtil you added a balance tube to the manifolds. If you look at most English cars with multi carburatiors they all have a balanace tube connecting the seperate runners.

[Merle Coggins]

Syncronizing multiple carbs on a motorcycle is a piece of cake. You either need a vaccume gauge for each carb, or a set of carb sticks. (mercury tubes) You need a vaccume tap in the manifold between each carb and the intake port. Then just adjust the idle speed screws to get the vaccume epual for each carb.

That would be an interesting modification. I do have a spare set of carbs for a Honda 650 NIghthawk. Hmm..........

Merle

[Plymouthy Adams]

the Honda CB1000 is a six cylinder bike with the carbs which are also 6 in mumber already mounted and synced on a single manifold with a single center throttle cable pull. Syncing these are not a problem and can be done without even being mounted to an engine...!

[Merle Coggins]

Tim, I think you meant the Honda CBX. It and the Gold Wings are the only 6 cylinder bikes made by Honda. The 1500cc Gold Wings used 2 carburetors, but as I recall they worked as a primary/secondary setup. And the 1800cc version is fuel injected, which is getting off the topic... Or is it? Has anyone made a fuel injection setup for a Mopar Flattie?

Merle

[claybill]

OPEL gt's from 1960-61 used 2 sidedraft webers or solex? you can get them from 'GT' SPEED SHOPS ON LINE,

I STILL THINK 2 MIKUNIS WOULD BE YOUR BEST SHOT..AND CHEAPEST.

......been there.

but in the long run...WHY? 2 or 3 stock carter downdrafts are working fine.

most fun would be routing airleaners, like hudson hornet style..

bill

[Young Ed]

Someone in our 39-47 mopar truck group has a FI flattie. Its a TBI unit off a small v6. I think like 3.1L.

[Jim Shepard]

I've recently been thinking about a similar thing for my B2B. My idea is a 'log'-type manifold with three B&B Carters, each feeding two cylinders. With cast iron headers and dual exhausts, it seems like the 218 should be able to handle this. Seems like someone posted a picture of an early indy-type race car with a flattie running three or four carbs.

[Don Coatney]

Three carb manifolds are not all that uncommon. Here are a few from the George Asche collection.

]

[Jim Shepard]

Wow! What a collection. Are any of the after-market ones still being made?

[Don Coatney]

Give George Asche a call (814) 354-2621

[Jim Shepard]

Thanks...

[kiwi mopar]

this is 48 webbers

i think you can get 30 or 35 the smallest.

[kiwi mopar]

by the way it is a 265ci or 4.3 liters motor.