Carby mounts

[Brett C]

My carby mounts are looking pretty sad. My question is: should I just fit new rubber ones, or are the solid aluminium ones worth the extra expense - if so which ones?

Brett

[branko.gt]

Short answer is rubber,

The long answer is that rubber provides best support for the operation of the carburettors. Solid mounts can be troublesome and although the UK vendors claim perfect operation I have heard a lot of horror stories about carburettors shaking to pieces.
Well, I made that last part about falling to pieces up but the vibration does cause troublesome operation of the carbies and will make otherwise perfectly good engine and carbie setup start behaving erratically and most likely loose power.

Maybe those people who had problems did not know how to fit them properly but if that is the case than again it is not worth while the risk. Some of the people trying and abandoning solid mounts have been working with Alfa engines a long time and have been winning races with them.
I am not the one to teach the gospel of "if alfa did it originally, it must be right", but, the fact is though that there is little on the 105 series that is not well thought our or put there as a saving measure.
Solid mounts are not bad as a concept but they are just not right for the Alfa twin cam four.

[vin sharp]

Solid mounts do cause issues with needle/seat and consequent float level, as well as aerating the fuel. Quite a few people have had problems  with rich running other issues and several have reverted back the the rubber isolators; hence all the used solid mounts on ebay in the last year....the top NSW engine builder who most recently started the solid trend here, has replaced all his customers' & now uses rubbers & spacers exclusivly.
No surprises really, all this was tried way back in the 70; and 80's by all us smarties who knew better: after all, Lotus twincams and Hemi Sixes didn't have the big thick rubber isolators on their Webers and they worked OK. But the long-stroke, all alloy, tall and wide Alfa engine transmitted a few natural frequency vibrations that the others didn't have, and the Alfa engineers had been there and done that long before we ever did, and they worked out that they really did need to spend money on a rather awkward and probably expensive to produce isolator for a very good reason.
Now history will repeat itself no doubt, and Weber agents will delight in all the needles & seats, floats and pins, and all the jetting parts people purchase to try to fix their carb running problems.......and yes, I've sold several sets Weber parts to people after explaining what their real problem is; then later they also finally purchased rubber mounts when they couldn't seem to fix it!
Vin

[Brett C]

Thanks Guys, I'll stick with rubber then!

What you say makes good sense; modifiying highly engineered machines usually has unexpected side effects.

Are there any hidden traps in changing the mounts?

Cheers

Brett

[Rosso2300S]

Solid mounts are fine if you are racing and constantly working on the engine, etc. but not for a road car, as everyone has already said. Use the original AR type or to add a bit more stability the siamese type is excellent. You use a siamese mount between 2 and 3 port and a single on 1 and 4 port. This adds to the stability provided by the support strut mounting on the air intake body without compromising the N & S and float pin integrity or shortening time between tuneups etc. GBC  

[djm411]

I'm coming to the same point where the rubber mounts need replacing and though about the solid mounts. I was wondering if the following would be a posibility/could work

Due to the complexity/pain in the proverbial nature of replacing these rubber mounts, is it worth converting to the solid initial mounts as previously suggested and using a rubber dampener between it and the carburettor. For example creating a short extensions out of rubber with the ability to then make the extensions bolt up to this with a tongue as such inside the rubber to ensure a nice even flow?

Thanks

[festy]

I'd be concerned about heat soak as much as vibration with solid mounts.
The inlet manifold runs at the same temperture as your coolant - and without an insulator between the manifold and the carbs, you could end up with mixtures going way out or even boiling your fuel.
If you're going to try the solid mounts, put an insulating spacer (bakelite or similar) between the mounts and the carbs to stop the heat transfer - just like what Alfa did to stop heat soak in the fuel pump.
Or if you're making your own solid mounts, you could make them like the EFI spiders' inlet which has a short length of rubber hose joining the two halves.
That would act as both an insulator and a vibration dampener, but you might have to do something to secure the carbs better...

[djm411]

Thanks Festy,
I am also intending to run extention that have been made from an industrial Nylon, which should aid in the insulation process.

Happy to hears others opinions on these ideas.

[werdna]

I'm about to purchase a set of aluminium mounts, would be interested in purchasing the rubbers if you are making them. Quite a few people seem to be having issues with the remanufactured mounts cracking after a short amount of time. Apparrently the rubber used can't handle the conditions/the new rubber isnt up to scratch. Not too sure what to do at this stage with replacing the mounts - can anyone offer any other suggestions or point me in the direction of some higher quality mounts?
THanks,
Andrew

[dfrye]

I have a set of Alfaholics Aluminium mounts I'd be happy to part with for all the reasons stated above. Contact me if you want them.

//dean

[branko.gt]

I'm about to purchase a set of aluminium mounts, would be interested in purchasing the rubbers if you are making them. Quite a few people seem to be having issues with the remanufactured mounts cracking after a short amount of time. Apparrently the rubber used can't handle the conditions/the new rubber isnt up to scratch. Not too sure what to do at this stage with replacing the mounts - can anyone offer any other suggestions or point me in the direction of some higher quality mounts?
THanks,
Andrew

there are some original pirelli mounts around but at a premium price. AKRON is what is nowadays sold as pirelli as they may be a part of a company.  Well installed an with proper length support rod (with a new bush) they should be fine. 
Regarding the aluminium mounts, i have heard only bad stories, i am not sure if they were incorrectly installed or they are indeed not suited for alfa engines. The people that i heard this from seem to know what they are talking about but it is still a second hand advice. I, for one, am convinced enough not to contemplate the idea of the solid carby mounts.  YMMV

unless you are doing a lot of custom development on your engine, the factory set-up of carby support and air box is as good as it gets ...

[werdna]

Thanks for the info guy, really appreciated. I ended up purchasing the rubber mounts. There is some discussion of the aluminium mounts elsewhere, but not quite as in depth as what has been posted above (or as objective). Hopefully i'll be able to get a couple of years out of them. Any suggestions on a gasket sealant to use? and/or any tricks I should know before installation/removal?
Andrew

[ItalCarGuy]

I have heard many recent horror stories of the repro rubber carb mounts failing in the first few weeks of fitment so I was going to try the Alfaholics solid mount option with a bit of trepidation. This thread has helped scare me away from them so I sold my new AH mounts! Anyway, there is good news for all as OKP in Germany have a fresh batch of carb mounts made by the original manufacturer - Pirelli!

Here's hoping they are as good as the originals!

http://www.okp.de/t3/index.php?id=9&L=1&tx_ttnews%5Btt_news%5D=976&tx_ttnews%5BbackPid%5D=8&cHash=3e17839b839a535e7eb59f6aa43e0a15

[festy]

there are some original pirelli mounts around but at a premium price.

That's an understatement!
I have a NOS set of carb mounts tucked away on a shelf for a rainy day -  but I haven't been able to bring myself to fit them because they're worth more than my alfetta