[Mgs] Dashpot Oil

[Max Heim]

I find it hard to believe that light oils contribute to “wear” in the carbs. The oil isn’t there to lubricate the carb — it’s there so that its viscosity acts as a damper to piston movement. Higher viscosity would enhance dampening (and then, consider, how much dampening do you want?), but it wouldn’t have any effect on wear that I could see. I suppose it is conceivable that it would help mitigate the effects of prior wear (presumably there is some on 60-year-old carbs) by filling the gaps and restoring the intended level of dampening, but this would need to be established on a case-by-case basis.

Are you sure he wasn’t merely using the 90W as a cure for this particular application?

--
Max Heim
'66 MGB

> On Jun 15, 2021, at 1:17 PM, Michael MacLean <springer.mike51 at gmail.com> wrote:
> 
> I watched a recent John Twist video today on fitting H type SU carbs to a T type MG.  In the video he says to use 90 wt gear oil in the dashpot.  He also said the lighter oils and ATF that so many people recommend contribute to the early wear and tear on the carb.  Anyone else using this weight oil in the carb?  All my life I have been putting 20 wt oil inthe dashpot.
> Mike MacLean
> 1969 MGB GT
> 1960 Austin Healey Sprite
> 1956 Austin Healey BN2 LeMans
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