FL Intake Manifold

[otis71]

I recently removed the manifold on a 74” knuckle to fix loose, leaking nipples only to find it was the shorter EL manifold. Fixed the nipples and reinstalled the manifold with the existing peek packing seals with no leaks during the bubble test. My question is can I expect them to stay sealed with less nipple for the seals to hold to? Before I initially removed it only the nipples leaked and manifold held upon preliminary testing. Either way I want to find a correct one but it may take time since most everything on the market is someone else garbage and run this manifold for the time being.

[Jerry Wieland]

I recently removed the manifold on a 74” knuckle to fix loose, leaking nipples only to find it was the shorter EL manifold. Fixed the nipples and reinstalled the manifold with the existing peek packing seals with no leaks during the bubble test. My question is can I expect them to stay sealed with less nipple for the seals to hold to? Before I initially removed it only the nipples leaked and manifold held upon preliminary testing. Either way I want to find a correct one but it may take time since most everything on the market is someone else garbage and run this manifold for the time being.

This has been an ongoing argument for decades. The parts book shows no differentiation between an EL and a FL manifold by part number. I have looked for the 'elusive' wide FL manifold for almost 50 years and have generally failed. The very vast majority of manifolds seem to be of the so-called EL variety so I assume that the same manifoold was used on both EL and FL applications. That being said - on occasion a manifold in the wide confiduration can be found so who knows. I have assumed for years that one of the reasons that FL barrels exploded was due to an air leak and lean mixture caused by too narrow of an intake manifold.

If in fact they made an FL manifold how come so few show up in the fossil record. It doesn't make sense.

On a bike to see some miles I always try to find an aftermarket Colony manifold and size it to fit. Sadly Colony is no longer making the manifold but Tedds is and I have not used his.

Jerry

[T. Cotten]

It has been suggested, Jerry,

That oversized replacements were meant to be cut to length, but they didn't seem to exist until the Pan era, if then.
(Knucks usually measured ~3.410")

The Tedd offerings that crossed my benches were obvious Colony "seconds", and required a lot of work.
TDD2NDS.jpg
(Note wavy-gravy spigots, and the flange was too!)
TDDGRND.jpg

I have been successfully outfitting Pan EL manifolds for FLs, but only by scrupulous reconditioning of the spigots, accurately fitting seals to the nut bevel as well as the spigot diameter, and by the grace of the PEEK material itself.

...Cotten

[otis71]

A friend has 2 of the longer FL manifolds that unfortunately have been polished and chrome plated so evidently some exist. According to Palmer the factory castings were the same for both and were machined to length but the dealers were supplied with only the longer version and the buyer needed to machine it to his engine. Seems strange the dealers weren’t supplied both lengths with separate part numbers.
So back to the original question; will the short one be adequate if it passes the bubble test?

[T. Cotten]

Well, Otis,...

If I serviced it, the answer is yes, with the usual caveat of dutiful maintenance, and all other things being in order.

If its someone else's product, ask them!

(Obviously, I can only record others' failures, as successes would never cross my benches.)

...Cotten

[MMasa]

I agree wholeheartedly with Jerry.
While I do have two of the longer manifolds (one is NOS) far to few exist for it to have been a production part during all of 74” knuck/pan era.
Probably a later parts counter part.
JMO

[T. Cotten]

Here's a previous discussion, Folks,..

https://forum.antiquemotorcycle.org/...take-manifolds

..Cotten

[knucklehead 61]

I have machined a tube & welded it to one side of an EL manifold to fit a FL knuckle for a chopper I built recently. worked out well.