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Modern sidedraft carburetors

This post was inspired by a post in the High Performance Forum, concerning the use of sidedraft carburetors for multiple carb applications. I am listing the “modern” (1932-up) American-made sidedrafts for cars/trucks/larger industrial engines of which I am aware. There are also some American-made sidedrafts for small engines (motorcycle, chain saw, lawn mower, etc.) which I will not list, as adapting them for automobile/truck application presents additional issues.

So, in alphabetic order:

Autolite (Motorcraft)

None to my knowledge

Carter

YH series — used on: Corvette 6, some 1950’s Nash, some 1950’s and 1960’s marine, turbo Corvair, Cortez Motor Home. Not especially rare, but certainly not inexpensive

Holley

None to my knowledge

Riley

Very rare, very expensive!

Rochester

R and RC series — used only on the turbo Oldsmobile Jetfire. Rare AND expensive!

Stromberg

None to my knowledge

Zenith

11 series (2 barrel) used on late 1940’s and early 1950’s GMC trucks. Rare and expensive
80 series — some 1930’s and 1940’s trucks and industrial
82 series — some 1930’s and 1940’s trucks and industrial

Nicson used the Zenith 80 and 82 series for their aftermarket manifolds. 60 years ago, there was no demand for these carbs, and a few new old stock were available. Today they are exceptionally rare and expensive, although less expensive than the Rochester R and RC models or the Riley models.

Many will turn to the SU (Skinners Union, yes Virginia, the first SU carbs WERE made from hides) as these were used on many European cars in multiples. For those familiar with the SU, these are a possibility. For those NOT intimately familiar with the SU, best bet would be either find someone who is familiar to do a turn-key setup OR LEAVE THEM ALONE! This advice from someone who has tuned 1000’s of them in the past. Yes, they can be made to work, but most are going to require MAJOR machine work (warped slides) by someone that knows what they are doing. Diaphragms for the HD series are either unobtanium or verypriceum. If you must disregard this advice, pick the H series, not the HD series.

Several earlier sidedrafts were produced in the USA of brass construction; but most (other than the Ford T) are quite rare, and in great demand by those doing vintage racecars; so will not cover them here. If you are doing a vintage racecar, and wish the information, call.

There also many additional non-USA-produced sidedrafts; Dellorto, Hitachi, Mikuni, Solex, Stromberg CD, Weber to name some of which I am familiar. Like the SU's, if you are intimately familiar with any of these; make your own decision. If not, best to leave them alone.

Jon.

Also potentially useful: S.U. "HS" and "HIF".
Motorcycle and common/cheap: Keihin CV for Harley-Davidson.
Been done, but $$$ and ???: Linkert bronze bodied Model "M".

Thanks for reminding me of the HS, and HIF; as I forgot to mention them. Was unaware of the Keihin.

Actually, the HS (short) might be of more use than the H that I suggested due to space considerations. But the comments about familiarity still apply.

Of the available sidedraft units, most would probably have best results with the Carter YH (design is virtually identical to the YF) due to more documentation, knowledge, and parts availability. The major drawbacks to the YH are: (1) initial cost, and (2) the FLAPS kits have incorrect bowl cover gasket for most models (1 size fits a few).

Also, there are a few Riley designs that carry the designation "Flynn". I do not know if Flynn bought the rights to the design from Riley, or if they are a rip-off. From the limited number that I have seen, most parts seem to interchange.

Jon.

Keihin CV for Harley-Davidson adapted to a STovebolt.
Thats an intriguing setup.
I ran one on my 77 HD Super Glide and other than one problem I encountered with it at the beginning, it proved to be a dependable carb for the 18 yrs I ran it.
The problem was that the accelerator actuator rod was a hair too long which would make it spit a batch of fuel at idle causing the engine to burp and sometimes stall from being flooded. After I filed a couple 0.001 off the rod it never did it again.

The engine was a 72 CU V Twin, guess what 3x72 CU = 216 CU

Dave

Dave, I can see one possible problem. Would running those carbs make a stovebolt act like a Harley- - - -try to climb into the back of a pickup truck like a hound dawg?
Jerry

I ran a Keihin on my 79 bagger and it's still running to this day,my son has the bike now.Rebuilt it once about 6 years ago easy carb to work on and it looks good.

Three of them on a Stovebolt would look good.


Pete

Weber makes a side draft carb.

I have to take exception to the comments on the difficulty of working with the SU carbs.
The model H, HS and HIF have to be the easiest to adjust, easiest to balance (sync)and least complicated carbs ever.

The HD created a design problem with the addition of the diaphragm and was discontinued quickly. That's why the replacement diaphragm is hard to find, they didn't want you to use it.

The Stromberg carb based on the same principal that replaced the SU in many cars by 1970, was never as good and had the problem of a roller diaphragm sealing the piston. The diaphragm was disposable and failed frequently. You had to replace the diaphragm every year to keep ahead of the problem. They also complicated the carb by adding things like a "bi-metalic temperature compensator" and other emissions crap.

Jim - either I didn't say what I meant to say, or you misunderstood.

The SU carbs, AS USED ORIGINALLY, AND NOT NEEDING MACHINE WORK, are very easy to tune and adjust, no argument, I totally agree.

However, probably 90 percent were warped to the point of needing machined slides 40 years ago, and I doubt they have repaired themselves. Also, we found many with the bodies warped to the point of needing machining AND sleeving.

Also, FOR THE MOST PART, the SU's were used on engines that produce far more RPM than the stovebolt 6, thus having metering needles that will need replacing as the A/F ratio curve is different. As I mentioned in my first post, I do not know the availability of different needles; and SU made dozens of different profiles.

If an enthusiast was familiar with recalibrating these units AND have their own stock of needles, then go for it.

But for those who do not have a huge stock of metering needles (or a precision miniature lathe with a taper attachment) I don't believe the SU is the answer.

And I completely agree about the Stromberg CD (English Stromberg, NOT Stromberg USA). Most were replaced with SU's from the same car before smog emissions.

I really DO like the SU carb, just not to migrate to a different application. (Note the second line in my signature).

dozens of different profiles

Hundreds!

Sometimes, you luck out. The Harley 45" flathead seems to work fairly well with a stock Volvo H4 (1-1/2") with the original "AN" needle.

We have a dyno and oxygen sensor(s) for setting up fuel/air delivery systems and ones that take the longest to dial in are Webers.

That I can easily believe, my experience also; and parts for the Webers are available.

Jon.

Here's a different view of the Corvette triple side draft.

Another view.

I've located one Carter YH side draft, two to go. I'd appreciate any leads you fellas may have regarding what to look for as in Corvair models, links, etc.

I acquired the dual exhaust years ago by trading a T-5 NWC Camaro/S-10 hybrid with a shortened shifter I had made.

The goal of course is to mate the triple side draft and dual exhaust onto my '62 261, '69 Saginaw\Borg-Warner 3sp+od, '57 3.90 rear end. This combination should pull like a champ.


Here's a side draft application in an AD... truck, (not mine) so it looks like it can be done. That would be quite the surprise when you popped the hood.

Cosmo - it is important to MATCH three identical YH carbs. Mismatching will cause major issues.

The Dearborn Marine 2617s and 2618s are probably the most common, and these two numbers ONLY can be mixed.

As to the Corvair, there are seven different. Of these, the most common is the 4141s (also the most expensive) as it was the last, and sold as service replacement for most of the others.

Jon.

Where is the number location on the carb?

Unfortunately, the only identifying number is on the tag.

Jon.

I'm going to do it.