Technical Two carbs, each sitting on own maniford....equalizer knowledge/help Q.

Studied situation. Differing opinions about needed, why and how to, as you would expect.
Q: Is an equalizer tube needed ?
Q: If best to use carb balance/equalizer tube, does the size of the tube/equalizer matter ?
Q: If used, what material should I use for construction, i.e.- copper, rubber hose, etc....?
Q: As long as tube is on intake(s), is there best place for install...closest to block ?

 

OK, I'll bite with my opinions. A tube is advisable. Diameter should be somewhere between the size of a brake line and a sewer pipe, Material should be heat-, fire- and fuel-proof. Don't understand your last question. Jack E/NJ

 

What engine,carbs,manifold?

 

Last question: The equalizer tube should be as close to the carbs as possible.

 

How many cylinders?
How many ports does each manifold runner service?
What is the firing order?

An equalizer tube is often a good thing, but it is not as important as good manifold design, in the first place.

Intake pulse management needs to be taken into account when designing a manifold, or manifold set.

For example, in inline-6, with one manifold servicing 1-2-3, and another servicing 4-5-6, is not always functionally incorrect.

 

>>>in inline-6, with one manifold servicing 1-2-3, and another servicing 2-3-4, is functionally incorrect.>>>

Yeah, not to mention 5 & 6 would be starving for fuel and air. 8^) Jack E/NJ

 

Indeed.

 

Just noticed that this last sentence was missing from gimpys last post but not in my in mailbox?

gimpyshotrods>>>Also, an inline-4, with one manifold servicing 1-2, and another servicing 3-4, is functionally incorrect. >>>

Was this edited out of the post?

Jack E/NJ

 

OK, I missed it. Thanks. Jack E/NJ

 

Thanks to you guys. I think that I got my questions answered, i.e.- Brake line size and up would suffice.
This is a '32 four cylinder engine. Two intake valves are served by one port(flathead configuration), that is reason that I've made two 'manifolds'. Side draft Riley carbs (circa '35) mounted to side of (7:1)flathead equipped B block of maybe 220 cubes and warmed up ! This is experiment to see if I can make it run and how good or bad with this setup. If good, will put on four port Riley OHV head , for which the carbs were made. I can ad a pic if anyone wants. Firing order is 1243

 

DEFINITELY post pictures!

I would not run an equalizer that is less than half the area of one throttle blade.

Fuel resistant rubber hose is fine.

 

Yes, we need pictures

 

With absolutely NO experience with the set-up you are doing.......

It is my opinion that the connection tube should be significantly larger than a piece of brake line. Take a look at the connection tube used on various import 4-cylinder engines ( MG, Volvo, Austin Healey, etc.) with dual carbs. I no longer have one of the import manifolds to look at, but if I were doing this, I would compare the cross-sectional area of the connection tube in the import manifold to the cross-sectional area of the port; and then make my connection tube the same (or close) ratio.

The engineers that designed these systems really did have a reason for their design.

Just out of curiosity, are your Rileys the 1 1/2 inch or the 2 inch versions?

Jon.

 

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Hey Jon,
Well, pictures are easier to work ideas with, so here's pictures to evaluate situation.
I'm thinking maybe 3/8" or 1/2" copper with brass elbows(right angle, on top of intakes where I've put marks.
I'd like to put between, but again with linkage, stuff maybe not doable, so top seems like best candidate location, eh ?
Riley made these 'types' of carbs , primarily for racing. Although he made several (5/6 iterations?). For the Riley 4 port, he made different 1 1/2" variety. That is what is pictured. Now these were made for his 4 port, so people must have run them on the street. Hard to find anyone who has ever run them...at all. His 2" were wildly successful for racers , I learned. Maybe tooo much for street use though ?? I'd love to talk to old timer who has actually used these...but maybe have to wait till I can see them in afterlife..lol

 

Explain? In my Ford 6 cyl it always worked out..

 

What is the firing order? That is the deciding factor.

Works, and works at peak efficiency are not the same thing.

Unless the intake pulses are balanced, you may have uneven performance across cylinders.

Without knowing what engine, and the firing order, I cannot say. Some are fine, others, not so much.

 

Hardtimes - you probably already know this, but calibration parts for the Rileys are readily available (combination of Stromberg and Holley).

If your 4-port is running as individual runner (IR) rather than plenum, 4 carbs probably will work pretty well. Remember the equation CFM = RPM x CID / 3456 is for a 4-stroke multiple cylinder engine of at least 4 cylinders. With fewer cylinders (and using an IR design means as far as the carburetion is concerned, you have four 1-cylinder engines) the CFM in the equation is adjusted by 4/number of cylinders.

Jon.

 

i don't know anything about equalizer tubes but thought i would add this photo of a 702 cu in gmc engine. common block separate intakes and carbs joined by what appears to be a 1" pipe. don't know if this helps the discussion or if it is not relevant. experts chime in.

 

I think this illustrates the theory nicely.

 

I have a A H Sprite, 1098 4 banger, it has 2 SU carbs. They each feed two cylinders through a common port. The manifold they sit on is a Cooper Works unit for a mini. The chambers below the carb base are connected by a cast in balance tube of about 1 1/4 inch od. Good enough for John Cooper, good enough for me.

 

Thanks to you all for your input. Jon, I have a clue with info that you are helping with here. I know an old racer who has four Winfields (set up as sidedrafts) on four intake manifolds similar to mine shown. They run a Ford B engine with rare OHV head. He raced this engine during his time.
And, IMO, Riley was pretty smart guy to utilize readily available carb parts from Stromberg/ Chandler Groves.
Regarding the Riley 4-Port Head usage, before head/carbs can be matted up, I'm going to have to fabricate /duplicate the special aluminum manifold that he made for use of his carbs on his heads.

 

Thanks, good info !
My 'experiment' will work with a smaller tube, say 1/2" (better than none, my guess), but for the real deal, I'll have to make or locate a Riley intake with proper engineered mixing plenum/tube built in.

 

Wonder what this one looks like, inside?

 

Hey Jim,
Well, that center,between the two carb mounts is a fancy looking hollow equalizer connecting 'tube'. Kinda like this one pictured

 

I figured that....I was just hinting that you might want to be copying the design. although in a side draft configuration.

 

From the internet but very similar. The ends of the balance tube are sealed with Welsh Plugs.
http://www.sportsandclassics.com/wp-content/uploads/2017/01/2017-01-20-19.44.20.jpg

 

Balance tube..If it is large [as in same as carb to port like the riley; i.e. intake runners] then both carbs will supply both ports at all times..The smaller the tube the less it can transfer so works in the mostly idle speed area; to tune carbs for idle speed/mixture balance..at higher rpm then the carbs will "single out" and each carb will only be suppying one port with the balance tube being too small to add much from one runner to the other..

 

equal size makes sense. but on the 702 it is not as big as just one runner. but then again that motor is made for low end torque.
it would be neat to put a valve in the balance tube, run up the rpm's and shut it off to see what would happen.

 

This set up held a few records at Bonneville in both my 40 Chev coupe and roadster.