Is there a single barrel sidedraft carb of pretty modern vintage you can find cheap that is good for putting on inlines, one for each two cylinders? I about freaked when I saw what new SUs bring and the aftermarket ones for Harleys are just as bad. Isn't thare a carb the Harley guys all take off a lot because they don't like the looks or just want an S&S? I've seen pictures of inline Buick straight eights with four of something like a Walbro or Mikuni but never did learn what it was exactly. The caption seemed to imply they were cheap and plentiful. I'm thinking about putting three of something on a Slant 6. But this would be good for anything really of similar displacement per cylinder. Webers and Dellortos are not really great for daily driving and they are expensive. SUs work great, if you keep oil in them but three are way over a grand now.
This is an area where the initial cost may be small compared to the cost of re-calibration parts!!! A long time ago we put 4 Mikuni's on a 4 cylinder 2000 Pinto race engine. I spent more time tuning on that thing than I would care to admit. Yes it ran like a scalded dog, and we won the championship that year. The next year the sanctioning body outlawed multiple carbs, and was I happy. One season and those Mikuni's were worn completely out! Most Walbro carbs are for stationary engines, and while they can be tuned to run a constant speed, finding a continually variable ratio transmission so the engine can run at the constant speed might be difficult. Zenith used to make a sidedraft for American Turbo, but this unit is obsolete, and parts are contructed from verypriceum. Probably your best bet in the long run would be Carter YH's (parts readily available reasonable); S.U.'s (buy new ones, or check the slides for wear, also be careful of models, as parts for some are ridiculous in cost); or Zenith-Stromberg (British...maintenance on these can be often). Jon.
The Harley carbs you were referring to were probably Keihn CV carbs. Most were 40 mm throat size and would run a 88 cubic inch engine (2 cyl). 3 of these ought to run your slant 6, but they are constant velocity design, which means the slide is controlled by a diaphragm attached to the slide. Air flow through the venturi causes a pressure drop across the diaphragm which allows a spring to move the slide. The slide moves a variable jet needle to control main fuel flow. The throttle cable operates a ****erfly on the manifold side of the slide and it conttrols air flow. These are reasonably priced, generally from $50 to 100 for good running carbs. Here is a pic of one missing some parts.
Have you considered fuel injection? It's been a long time since anyone used carburetors but the junkyards are full of side draft fuel injection units. Side draft carbs used to be as common on English cars as cold noses on ****er spaniels. Look under the hood of old Jaguars, Triumphs and MGs. Good luck finding one in a junk yard but they do turn up at swap meets and flea markets. Incidentally if you want performance the old Hyperpack style single 4 barrel manifold is your best bet. I hear someone is reproducing them.
Almost all new motorcycles have gone to electronic fuel injection. Anything under 500CC may still have carbs due to cost involved. My new Sportster runs good but the feel of twisting the throttle seems odd compared to the old cable pulling on slide feel. I used to have an MGB with a modern Weber side draft conversion with electric choke and it was bulletproof, three of those would probably work well on your inline. Also had a slant six Valiant with an aftermarket four barrel that was very streetable and easy to tune. You just need to quit making decisions based just on how cheap and buy the right setup for your intended use. It will cost a lot more if you go through several different versions that don't work.
I build, tune and race SU carbs. You want to get three HD6 or HS6 carbs for that engine. you can find them used for not a lot of dough. S&S onlys sells priced by the pound in gold. Find a British junkyard or go hang out with some guys in the local Austin Healey sports Car club. Most of big Healeys came with HS or HD carbs. Usually guys have a few boxes of them..heck I might even have a few laying around needing to be built. Shoot me a pm maybe I can help.
A carter mod YH side draft is going to be easy to find because I have 2 of them laying under my bench!Google up carter YH carb.
I have to take exception with the thought that Webers are pricy and don't work very well for daily use. At swaps around Phoenix and California I see Weber DCOE side drafts sitting in ? piles and have bought them for as little as 20.00 each. Once you baseline them and tune a bit from there you generally have no other problems. Thye are sensitive to fuel pressure, so a regulator is a standard part of the bargin with these carbs. Oh, did I mention that because of their ball bearing throttle shafts they NEVER really wear out? And because they have replacable venturis they can be tuned to work with damn near any size engine... Nothing but plusses!
Yeah, but they have a reputation of being temperamental , and hard to tune. Probably because people have a tendency to get greedy with venturi sizes , looking for the big horsepower numbers. Killing one of the most attractive features of a good Weber setup, torque from low down in the powerband. ( people tend to do the same thing with their cam selection...) I think that once you have them figured out they are easier to tune ( and more accurately ) than , say, a Holley. But I guess that's the reputation they have, and that's OK. More Webers for me...
I use a Carter-Weber side draft and in triples the two barrel two stage system is impressive. I find the side draft version of this carburetor online and one source is Carburetion.com They are a bit of a h***le to setup and tune but once that is done the running characteristics are very good. Normbc9
I'm going to hijack a little. What webers or delorrotos would work good on a stock 302. I've always loved the look.
Willy, You will need 4, Weber 40 IDA type units for the street, and someone good to tune them...and a lot of money to spend ..a 4 barrel works great.
I'm not sure they made a IDA that small ( maybe they did, and I just haven't seen one ) IDF's are available in the smaller sizes 36, 40, 44 or 45, etc, And those are a better carb for the street anyway. IDA's and IDF's do not fit on the same manifolds ( bore spacing is different). I'm running 4 42mm DCNF's on my 350SBC.
I'll give your $30 for every complete DCOE your can ship me. Where else can you get a 50% return on your money for just addressing a package? jack vines
The British Strombergs have diaphragms that give out and that's why everyone gets rid of them. This web page wants $625 outright for TWO refurbed HS6 carbs which would be the right thing for a Slant Six, but I'd need three. The local britcar places claim to have no cores floating around and say they are quoting $300 per unit to their customers. There is a Hitachi version that is unit interchangeable but uses different needles and all other parts, not any cheaper. Would the Keihin, which is what I was thinking of, be adaptable to a SU manifold? Are tuning parts available? Aussiespeed has a nice 3 SU manifold available. Weber manifolds are available used without a lot of work for less. I'm going to ask some AH and Jag hoarders in St. Louis if they have some (HS6s) that I can get going the next time I'm there. Yeah, I considered fuel injection. GM TBI, K-Jet and Megasquirt have all been done and published widely on the net. I don't like the looks of K-Jet but it works well. It takes a lot of space for the air box. I just want to keep this a carbed vehicle with no electronics beyond the ignition. I can always put on the points distributor and as long as I've got 12 volts it runs. Then again they still offer Vertex mags for these engines too.
I have had a metric **** load of them that I have bought like that. I actually e-bayed an bunch of them a couple years ago, but what I have left I have uses for at this time. When I see some more though I'll grab 'em for sure. The last time I came across them that inexpensive was at the Az Street rod ***ociation's swap in Mesa in October. A guy had a box with about 2 3/4 45 DCOEs that he was asking 50.00 for. I had a friend at the show that had been looking for a pair and came and grabbed me and he ended up with the box for 35.00. The trick is to look at the hot rod swaps and not the sporty car type or VW swaps.... Those boy know what they are worth.
I have found and shipped suitable SUs here in the UK to other HAMBers. Let me know if I can help. 3 x HIF 44 could be re-needled to suit and would be a lot cheaper than HS6s
Are the diaphragms no longer available? I had Triumphs and had to replace the diaphragms on cars that had been sitting long enough for stuff to dry rot but never had day to day issues with the carbs. I always appreciated how simple they are. My biggest issues with my TR6 and GT6 was my lead foot. Tore up transmissions and rear ends.
Heck, for that matter look under the hood of a seventies Volvo and they have a version of the SU as well.
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