Carb Spacer?

[Guest]

Will a $50 carb spacer provide a $50 increase in performance on a 45? It's bored +.060, oversized valves, #6 aluminum heads, M88, WR exhaust.

[T. Cotten]

Will a $50 carb spacer provide a $50 increase in performance on a 45? It's bored +.060, oversized valves, #6 aluminum heads, M88, WR exhaust.

Golly Rex,..

If your machine was produced with the 1109-41 spacer, and you have the 'short' manifold to go with it, then its what the MOCO decided was best.

(I've got a cigar box full of them, priced each at half that!)

You can get better performance at modern highway speeds with a larger venturi.

....Cotten

[kitabel]

I agree, the original M-88 venturi is too small @ 15/16". Either the 1-1/16" (std. WL) or 1-1/8" (M-41/51L) is a nice increase. A spacer in theory is a tiny step forward (if it doesn't bite your leg) but minor compared to more venturi area.
However, since the M-88 (and M-54B, 84, 90, 97 and most Indian models) does not have an external air correction opening, your internal air compensating notch (in the venturi's leading edge) should be present or applied (hacksaw & file) to the new venturi; I'm not sure you can easily find a big internal venturi.

[Rubone]

The spacer was to move the carb out when equipped with the short manifold to make the oil bath air cleaner fit better and get the carb further out from the heat, not for performance (a longer manifold on a stock 45 is like 50% of nothing) . As stated, a bigger venturi (and a switch to an adjustable high speed needle) will make much better sense.

[kitabel]

An extra 2 feet or so of manifold length would be even better, but where to put it?
By comparison, a similar low peak RPM engine (1960-61 Chrysler 413 as installed in the 300F & G) used 28" runners for greatly improved mid range torque.

[T. Cotten]

.. I'm not sure you can easily find a big internal venturi.

Indian suppliers have them, Kitabel!

#102455 for the 1 1/16", and #102456 for the 1 1/8".

Unfortunately they are not readily available in over-size O.D.s for borewear repair, but they can be swaged.

....Cotten

[Guest]

Thanks for all the direction!

This build was a piece by piece process starting with the original carb having @ 3/4" venturi possibly from a G engine. After a few years of searching I found an M-88 & replaced everything in it and added the high speed needle. I'll pursue an 1 1/8" unit and mill the slot. I've never had spacer, but learned of them on a WR parts website. If you think my project would benefit from one I'll buy one of yours and give it a good home, Tom.

I was achieving acceptable highway speeds after the engine upgrades and increasing the engine sprocket size. Can't remember the new tooth count, will get back with that tomorrow.

Would that venturi be specific to Indian applications? I've been told a more than one show that my bike is actually an Indian and the military never used any HD models. I was also informed that my 1976 Electraglide was actually a 1955 Hydraglide after I put on dual fishtails and light visors.

[kitabel]

W/r/t "the military never used any HD models": IIRC total 42WLA volume 88,000.

The 1-1/16" may be easier to find. The 1-1/8" may be worth a tiny bit of top speed, but also require slightly richer low speed for good response. No free lunch!

Except in hill country, most solo owners prefer the largest engine sprocket they can find to quiet the engine down: 34 tooth.

[T. Cotten]

You may find an Indian venturi is five bucks cheaper, Rex!

Both sizes are available from http://www.jerrygreersengineering.com/catalog.php;
If you have a heavy payload, and tall sprockets, I would go with the 1 1/16" (102455).

Or you could just bore out your 15/16" to whatever you please. You can form the airfoil "digitally" (emery on your index digit).
Don't mess with the 3/4", because it is extremely rare.

I have used several of the spacers... for tools! Unless your manifold looks like the one on the right in the attachment, I doubt you need it.

.....Cotten
PS: Ya gotta love 'sidewalk commandos' that know more about your machine than you do. I've been told more than once that Harley made Indians.
I just looked surprised, and said, "Wow! I didn't know that!", and went back to the bar.

Chevy valves in a Panhead was another good one.

[RichO]

Cotton, Do you use a stock gasket on both sides of the spacer or just the spacer? You normally use just a gasket between carb body and manifold.

[T. Cotten]

Dr. Sprocket!

I believe the parts books show a heavy gasket against the manifold, and a thin one against the carb flange.

The thick asbestos gaskets are getting scarce.

....Cotten
PS: Beware of some poorly-cut modern gaskets, as shown by the arrow in the attachment.