Inliners International Forums General Discussion Hi Performance Newbie with a carburetor question

Hi everyone, I am a newbie to the straight six world (not motors and cars in general). I recently picked up a very well built chevy 292 for my 61' c-10. I am in the process of fabricating a custom intake/exhaust manifold. My question is this; has anyone out there used mulitple big twin harley davidson carbs instead of webers? I figured 3-4 would be sufficient to feed the motor. Here's a few details on the motor: Bored .040, flat top alum. pistons, fully ported and polished head including oversized valves and roller rockers. Thanks for any help in this area. I'm glad I found this place

I'm no expert on Harley carbs but from my experience with British and Jap bikes I know they don't have an accelerator pump in them. If the Harley carbs don't use an accelerator pump then I think their use on a car or truck wouldn't be very compatable. If they do have accelerator pumps then I'd try to find out how much air they flow and if the floats & needles can withstand the pressure of being supplied by a fuel pump. Motorcycle carbs are generally gravity fed from the tank being above the carbs.

Ages ago the old sprint cars that ran Ford Model A or Model B 4 cylinder engines ran dual carbs and did not use the accelerator pumps but with the rpm of the engine at racing speeds and the relatively light weight of the little race cars the accelerator pumps weren't really needed.

Just a few things to ponder if you don't get a specific answer. It does sound like a great low cost option to Weber side drafts if it can be made to work.

Hi Guys,
Yes, Harley carbs do have accelerator pumps. Some of the Bonneville inliners have run S&S carbs and I believe I have seen Harley carbs on a inline engine in the 12 Port News.

Jim R

Thanks for the info Jim. Another option to think about whenever I get around to doing a Chevy 153 based 4 banger.

Thanks for the input, I'm going to try and figure out if they can be used with a fuel pump. I'll try anything to avoid paying $1500 for three little carbs!

Mike, the S&S carbs have indeed been used on inlines, with great success. They are available either with or without accelerator pumps. The photos shows a 261 motor tuned by Armond Orr, using 3 S&S carbs. It ran 150 MPH - in a pickup truck! Armond doesn't frequent this board, but perhaps we can talk him into a guest appearance.



We also have a club member here in Florida who is a longtime Harley rider/builder and we've talked at length about sidedraft bike carbs and how they would work on an Inline engine. S&S can be a little pricey, this guy recommends either the OEM Harley carbs or even SU's from a 4.2 Jaguar. I'm sure there are many more possiblities including Mikuni, Amal and Dell'Orto. It just depends on what you can turn up at bike swap meets. But the Harley carbs would seem to be a natural as the V-twins airflow requirements are about the same as a big inline motor would need.

Jack,
Thanks a lot for the input, a close friend of mine is a service manager at a local HD dealer. He told me he can get used OEM carbs all day long due to people upgrading. I know for sure the stock carbs for the 88 inch motors have accelerator pumps and plenty of options for jet sizes. I just can't see paying $450+ for one weber. The photo you posted is EXACTLY what I pictured for a set-up(less the air box). Thanks again Jack.

Dear L S Mike;

Are these HD carbs a 'bolt on' item (like the photo indicates) or is/are there adapters involved??

Thanks John M.....

Look close John. The picture Jack posted has short adaptors. These should be fairly easy to make or have made.

Jim

Mikuni flat slide carburetors are the E ticket on a Harley. Easy to tune and they come in a lot of different bores. Dellortos are cool but not that much fun to deal with. Parts are not easy to come by either. Having owned a number of motorcycles that use them I'm not really crazy about them at all.
(Unfortunately)I have small fortune worth in Dellorto SS1's sitting on a display shelf in my garage. These are "new" having been completely restored and rebuilt by the Dellorto specialists in the UK. They are gold to the vintage motorcycle racing crowd and they are a bear to get parts for and when you do be ready for a shock. I recently heard of 1 carb body, 1 complete carb and a parts carb going for $600 at a swap meet and the buyer was very happy to pay.

Here's the Mikuni link:

http://www.mikuni.com/fs-products_guides.html

wowsa! what a hott lookin' piece that is. i can't decide which is more nostalgic, 3 down drafts, or 3 side drafts..i have to admit, that is a pretty wicked thing. i'd love to try something like that on mine...how much are 3 side drafts goin for these days? with a few adapters...yeah, it'd be slick. i'd love to hear how the project goes mike.

Sam