The Stovebolt Site Forums The Shop Area The HiPo Shop 261 stroker with 3 Keihin carbs

Jon, this is a little off-topic, but it still deals with multiple carbs. I'm considering using three Keihin side drafts on a 261 stroker (close to 300 cubic inches) so each carb only has to supply one cylinder in the firing order on each intake stroke. The Keihin is a Harley Davidson application with the vacuum-operated variable venturi piston like an old S-U carb. Assuming I get it dialed in properly on mixture, what's your opinion of using a triple side draft setup on an inline six? It seems to make more sense than duals. Obviously, I'll have to fabricate my own manifolds.
Jerry

Jerry - I started a new thread so we don't hijack the other thread.

I like triples on an inline 6. For years I have preached that the number of barrels (or plenums) should an even divisor of the number of cylinders (which is why tripower on a V-8 doesn't work well!).

When you start playing with your manifold, get in touch with panic. Some time ago he posted the following link to his website:

http://victorylibrary.com/mopar/intake-tech-c.htm

This is the very best intake manifold article I have read in 55 years! The man knows his material!

Hope you are not thinking of an IR manifold. My personal belief is that the Chevy 6 doesn't have the RPM capability to really use an IR design; so three plenums, with interconnecting pulse tubes.

As to the Keihin carbs: I detest them! Probably will get other opinions here, but I spent more than 40 hours trying to make a worn-out Keihin on a 1972 Honda Civic (We make it simple? - Yeah, right!) function. A good friend of mine volunteered my services to a little old lady who couldn't afford a flange gasket, let alone a carb rebuild. It was a pro bono job. Take a look at the second line in my signature!

If I were doing it, I would take a page from Chevrolet, and use three Carter YH carbs. The Corvette versions are too expensive to think about; but Dearborn Marine used a similiar carb, and they are fairly reasonable. Of course, Dearborn is allied with that company whose name we cannot mention here, but the same as that singer from our youth Tennessee Ernie

Jon

I seem to remember those carbs, or something similar, on Chris-Craft runabouts with "Thunderbird Special" 292 and 312 V8's in them, two side draft Carters on a low-profile manifold, one facing forward and one aft. It was built that way so the engine cover could be a few inches shorter than it would have had to be with a downdraft carb. The 196 cubic inch Nash OHV 6 cylinder also used a side draft Carter, if memory serves me right. I've got one of them on an old Rambler engine out in the barn if I ever dig down deep enough into the pile of junk it's buried in.

BTW, I'd be using like-new Keihins, not some salvage yard piece of junk!
Jerry

What is your take on Mikuni side draft carbs? They seem to be available in may flow rates and way less expensive than many others.

Evan - before I was bitten by the "buy American" bug, I had a Datsun Fairlady 121 CID with two 500 CFM Mikuni 2-barrel carbs. This was a factory (Datsun) installation. It ran like a scalded dog! How long would they last? Don't know, as other circumstances forced me so sell the car with about 35k miles.

Later, we sponsered a winged 4 cylinder (Pinto 2000 engine) dirt racer. The owner found and acquired an intake with 4 Mikuni side-draft carbs; and AFTER SPENDING MORE TIME ON THE CARBS THAN I SPENT RESTORING MY GTO ENGINE they ran like a scalded dog....for about 1/2 the season. By the end of the season, the inferior zinc alloy metal was totally worn beyond repair!

As one grows older, one realizes that time is one's most important asset. I wouldn't personally do the Mikuni nightmare again. Period.

If you are 18 and have more time than you know what do with; and unlimited resources to spend on additional venturii, main jets, air jets, compensator jets, etc., etc., etc., go for it!

Jon.

Jon,
First I must let you know these questions are from one with a missing control chromosome when it comes to carbs, intakes, and camshafts. Even worse is if I ever bought one I still have it and over 65 years of gathering (wife says hoarding) it gets to be a little much. Predator-have several, Holley 3 bbl-same, 54 Vette induction and exhaust-only one, Autolite inline 4 bbl-just 2, you get the idea. My partner, who has passed, handled the tuning on our roundy cars while I worked the chassis building/setting up. Even after a clean sweep one weekend I couldn't leave the car alone but instead had to try for just one more tenth off lap time for the next and thus all the junk build up. Now to pick your brain; would you have any idea how much angle, tilted to the side, one could run an inline Autolite 4bbl on? Can mill a wedge plate but would rather have a straighter shot to the intake valve. Thank you; Evan
Pics of just a FEW of the intakes headed to new owners, I hope.

http://s32.photobucket.com/user/coilover/media/Intake%20manifolds%20003.jpg.html
http://s32.photobucket.com/user/coilover/media/Intake%20manifolds%20002.jpg.html

Evan - I honestly have no clue; I have never worked with the inline Autolite. Try asking this question on the H.A.M.B. website.

And, of course, if you would like to add other weird carburetors to your collection, call me

Jon.