motorcycle carbs on a car engine

[94ToyBear]

I have been building a 57 willys pick up Rat rod for awhile now with a 94 Dodge 10 cylinder. I gutted the wiring to have ignition only and put a 4 barrel carb up top a home made high rise intake. I not like that look very much and I dont see it working correctly being that the carb sits on top of the middle cyl and sits far from the out sides. Walking in the junk yard a few weeks ago I came across a 69 Volvo with side carbs...feel in love with the idea of this look on my Rat rod... looked for Volvo carbs and decided not a good idea to get something Euro... then got a bright idea of having Motorcycle carbs on it then thought hey 6 packs are cool why not have 8.
My plan is to take the 4barrel carb of and stick 2 sets of 4 carbs on each side on the intake. I picked up 2 set of mid 80's Cb750 carbs.
Now that I have the carbs I expect there lots of issues to tune them but plan on having fun doing this. Mounting them wont be an Iissue.

Anyone have any suggestions on what I may expect as far as fuel pressure and tuning and what not

[Patrolman]

This could be a lot of work to tune. I know there was the old 6-pack, the triple set of 2bbl carbs. The Datsun 240z guys also run side draft triple carbs. This seems to be a popular tool to use:
http://www.thezstore.com/page/TZS/PROD/TE/60-9976

[Hypoid]

4 barrel carb up top a home made high rise intake.I demand a picture of said intake!

[94ToyBear]

When builing it.

[94ToyBear]

What it looks like now.

[94ToyBear]

The look I am after hoping for functionality too. I like both looks but staggered seems to be the best for functionality so each cyl runner has a carb near it.

[94ToyBear]

Keep in mind im not trying to achieve the the original Hp or torque from the motor just something that gets me cruzing and looks cool.

[Patrolman]

Yeah, that will get you looks. :)

[Hypoid]

I don't know how those carbs will act with a common plenum, or a pressurized fuel supply.

[zukrider]

my buddy Ken makes GSXR mikuni carb swaps for samurais. he would be a wealth of info with this project. ill see if he would be interested in talking to you about it.

[94ToyBear]

I don't know how those carbs will act with a common plenum, or a pressurized fuel supply.
Same here but will be fun to learn and try it for sure

[94ToyBear]

my buddy Ken makes GSXR mikuni carb swaps for samurais. he would be a wealth of info with this project. ill see if he would be interested in talking to you about it.
I appreciate it ! Thank you.

[94ToyBear]

I was thinking id have to make a small low pressure gravity tank above the carbs to mimick the bike tank and have the big tank supply the small one. But who wants fuel hanging over an engine?? Not if I can help it. Well see. Maybe a can use a larger diameter low pressure fuel rail. Im sure ill have to have some type of regulator and fuel return line as well.

[The StRanger]

Two more carbs and run one per hole !!!

[Jim]

Two more carbs and run one per hole !!!

That's my thought. The plenum, imo, just seems to be in the way.

But my comment is only worth these words as I'm not the one sweating it out to create the project!

I'd also look at the MC motor cylinder volume per carb and how close that would match up to the V10's cylinder volume per carb. In a plenum arrangement, one could add or subtract carb's to more closely match airflow the carbs were designed to handle (realizing the RPM range will differ between the motors).

[Haku]

I had GSXR Mikuni carbs on my Samurai for a while, and when they worked they were 1000 percent better then the stock carbuerator. They were a lot more fiddly and not ideal, but it definitely increase the power and how much the little 1.3l Samurai engine could rev (it could hold 6k all day and struggled to hit 4k with the stocker).

The Samurai had a mechanical fuel pump that only provided a few psi of pressure, but that was too much for the Mikuni carbs and they would just spew fuel everywhere. I started with the crappy "Mr. Gasket" fuel pressure regulator, but it worked for a bit and then would either stop regulating (too much flow) or cut the fuel flow completely. I forgot what brand I ended up with, but I think it was Holley and did a much better job.

I suspect the hardest part for your build will be getting both throttles to sync up, and then having all 8 of those carbs synced too. Making runners to mount them shouldn't be too hard, and K and N makes a filter for them too, so you shouldn't have to fab a intake plenum or anything.

As others have said, the big question is whether you'll get them to provide enough fuel. You can get new jets for them at the Motorcycle shops, so you should be able to increase the flow but at the end of the day these are designed for small fast revving motorcycle engines and not a big lopping v10 that is at least 8 times the volumetric size of the engine those carbs are designed for.

Also, in my experience, these carbs definitely seemed like they were designed to use 1 carb per cylinder and I'm not sure how they would work getting vacuum from multiple cylinders like that. There is a plastic piece inside that opens and closes and seems to be a key part of the function of the carb.

I think this would be sweet to see done, but there are definitely some hurdles. Personally, I would at least go find a set of the Mikuni carbs designed for a bigger Motorcycle engine and start with those. I love the sound of the carbs working and they have sweet throttle response and will make that engine sing if you can get enough fuel in there to keep it from detonating.

[94ToyBear]

Thanks for all the input guys I appreciate it all. I did consider doing. One carb per cylinder but got voted away after the cost wasnt so rat rodish. I pick up all 8 carbs for 100 bucks and to find dule or singe carbs together would take a while. And theres that cost thing ones more. If anything I can allways ad a carb to the of what I got and build a different manifold. To be honest I like the single carb set up better.

I might try and do this this weekend and see how it goes. As far as synching them...... thats gona be fuuuuuuuuun to learn lol. Thank god for youtube. any one have any affordable larger Carbs ? I asked about the 1000 and 1100 cc motor and the guy said they arnt to much different and not as common.

[glacierpaul]

"cost wasn't so rat rodish":lmao: That's funny! That looks to be a sweet ride Adam!

[Jim]

If you end up needing MC carbs... kick me a PM. I have two sets from my old V-4 1100cc motor in the garage...

[Hypoid]

If anything I can allways ad a carb to the of what I got and build a different manifold. To be honest I like the single carb set up better.If it were me, I would have made the plenum wider, and sit lower. Along with having the air flow make some sharp turns, the long runners won't do much to stabilize the top of the block and cylinder heads.

[BLOODBANE]

my buddy Ken makes GSXR mikuni carb swaps for samurais. he would be a wealth of info with this project. ill see if he would be interested in talking to you about it.
Those or Webbers. Webbers are a pain to adjust though. Lots of folks use them (we have one on our CJ7)

[94ToyBear]

If it were me, I would have made the plenum wider, and sit lower. Along with having the air flow make some sharp turns, the long runners won't do much to stabilize the top of the block and cylinder heads.
Ill do some different mods to the intake to to this new idea. It actully its pretty stout. Runners are welded to each other below the plenum then welded to the plenum. I get what your saying tho.