Molykote 321 is a dry film lubricant but I cannot find any in the UK and wondered if anyone knows of an equivalent product.

It is apparently used by a number of car manufacturers to help seal the throttle plates in carbs & bodies and prevent airflow when they are fully closed.

I need something which I can brush onto the 'nearly touching' surfaces of a butterfly / throttle body, effectively closing a small gap of, say 0.5mm. I have heard of some racer boys using silicone sealer like this thread but I don't think it would look very neat and might flake off so I would be interested in any ideas.

Thanks in advance


[Edited on 6-11-10 by RazMan]

Never used Moly 321 but I do use generic dry film lubes quite regularly, having read the blurb on the Moly website they recomend a coating thickness of not more than 1 thou.

I may have a tin in the garage which I can send you if you want to try it? I've only ever seen it in aerosol form. Let me know and I'll go and have a rumage.

Davie

Do you know if a thickness can be built up by painting it on and allowing to dry?

I've found some dry film lube on ebay which is used mainly for bike chains - would this be similar?

[Edited on 5-11-10 by RazMan]

I'm not sure TBH, it's certainly not a product I would ever have thought of trying for this application.

Davie

I always understood that throttle butterflies were only supposed to close to 98% or so, not fully shut off. Have I got it wrong?

I have used this dry film lube on my dash and internal panels, it give a very good satin black look and seems very durable. It is used alot in the oil industry to protect the tools from rusting offshore. I got mine from a company called FIS Chemicals Ltd in Aberdeen.

ETA Correction........ supplier was FIS Chemical Ltd in Aberdeen.

[Edited on 5/11/10 by Slater]

CBE - I think it really depends on the application. Ideally they should close completely to allow the Idle Control Valve to do it's job but if you are not using one you have to rely on some timing and fuelling jiggery pokery (as well as holding the butterflies open of course) to achieve a stable tickover.
In my case I have 12 butterflies to close (twin port V6) so any small leak will be multiplied by 12 which amounts to a lot of air passing when the throttle is closed.

It has been suggested by Marco (cheers mate ) that I could soft solder the butterflies and then file them back until a good fit is achieved. That might be a last resort to consider if I can't achieve a good seal by quicker means - 12 handworked butterflies! [shudder]

Honda, Suburu and Mitsubishi all appear to use this stuff from what I can see on their respective forums. Some people are 'cleaning' their throttlebodies of what appears to be black carbon around the periphery of the throttle butterflies, only to discover they have high tickover problems.

[Edited on 5-11-10 by RazMan]

The bike throttle bodies I had (CBR600) had a black sealer for that very reason - very thin layer of film (less than 0.5mm definitely), but sealed the butterflies - no idea what product it is certainly wasn't silicone as it was pretty hard, but that's what i'd recommend - Dry lube won't fill the gap.

don't use silicone sealer or any other silicone-based product. It will kill your (expensive wide band?) lambda probe.

Sebastiaan

btw: this new wide text box is great! Thanks Chris!

I use 321 at work to to paint the dovetails on Aero Jet engines. Great stuff and it's prevents fretting at extremely high loads. How much do you want?

Woohoo! I only need a very small amount so anything you can spare really. I will gladly offer some beer tokens if required

Just a word of thanks to Toprivetguns who sent me a nice big bottle of Molykote FOC - top man!

p.s. I tried it on the throttle bodies and it certainly improved the gap situation but I think I still need to rework the butterflies yet again as tickover is a tad too high at 1300rpm. I am presently hand fettling them for an even closer fit and another session with the Molykote. Fingers crossed

[Edited on 29-11-10 by RazMan]