[Healeys] HD8 Su's

[Bob Spidell]

I've had my HD8 carbs out/apart a few times for rebuilds or for head 
work, etc., and I've not seen any evidence that--for my carbs, 
anyway--the oil is lost by any means other than exiting the vent in the 
cap (two oily splotches on the underside of the bonnet). The vacuum seal 
around the piston in the vacuum chamber has to be all but airtight, and 
I'm told they are custom machined and fitted to each other (i.e. you 
don't want to swap parts in SUs).


On 6/18/2021 6:58 AM, i erbs via Healeys wrote:
> Seems oil could leave arournd threads of dashpots or out vent holes in 
> dashpots
>
> Ira Erbs
> 1959 AH 100-6
> 1967 MGB
> Milwaukie, OR
>
> On Fri, Jun 18, 2021, 6:46 AM healeyguy--- via Healeys 
> <healeys at autox.team.net <mailto:healeys at autox.team.net>> wrote:
>
>     Bob etal
>     Contemplating the damper oil loss.  What is the path of the engine
>     vacuum that allows/causes the oil to disappear.
>     If the engine is not running there is no vacuum, therefore no way
>     for oil loss in an SU carb.
>     Engine running, engine vacuum could potentially pull at carb parts
>     interface that control the oil reservoir at two locations,
>     That being the fit of the damper plunger tip to the tube in the
>     piston or the fit of the outside of the piston tube to the chamber.
>     Suspect that oil loss is a result of a poor fit at these locations.
>     P
>
>     -----Original Message-----
>     From: Bob Spidell <bspidell at comcast.net <mailto:bspidell at comcast.net>>
>     To: Michael Salter <michaelsalter at gmail.com
>     <mailto:michaelsalter at gmail.com>>
>     Cc: healeys at autox.team.net <mailto:healeys at autox.team.net>
>     <healeys at autox.team.net <mailto:healeys at autox.team.net>>
>     Sent: Thu, Jun 17, 2021 11:16 pm
>     Subject: Re: [Healeys] HD8 Su's
>
>     Yeah ... I overfill a little and let them find their level.
>
>     On 6/17/2021 9:34 AM, Michael Salter wrote:
>     Actually Bob even that is too much ... resistance just before the
>     cap reaches the threads is sufficient.  At that level I find that
>     the oil never goes away.
>
>
>
>     On Thu., Jun. 17, 2021, 10:34 a.m. Bob Spidell,
>     <bspidell at comcast.net <mailto:bspidell at comcast.net>> wrote:
>
>         My observation as well. I fill them until you feel resistance
>         when the cap is about a half inch from the top of the carb.
>
>
>         On 6/16/2021 10:47 PM, Alan Seigrist via Healeys wrote:
>>         Roger -
>>
>>         you don't need that much oil in the HD8 pistons for this to
>>         work correctly.  HD8s throw all excess oil out the vent... so
>>         if you are overfilling it will all go out anyway.
>>
>>         The main thing to check is to take the dampers out and slide
>>         them back in with the shaft straight up, and if you feel
>>         resistance toward the bottom.... you don't need to refill.  I
>>         suspect you are overthinking it. I used to think HD8s use too
>>         much oil until I realised they don't need all that much to
>>         work correctly.
>>
>>         Cheers,
>>
>>         Alan
>>
>>         On Thu, Jun 17, 2021 at 12:59 AM Roger Grace via Healeys
>>         <healeys at autox.team.net <mailto:healeys at autox.team.net>> wrote:
>>
>>             Ok have spoken to Joe who was most helpful.
>>             We did some measurements together over the phone and
>>             established that my dampers are correct.
>>             He says that he has encountered this before but not sure
>>             of the reason.
>>             Suggests that I run the dashpots dry then start again.
>>             In meantime he will do more research.
>>             rg
>>
>>
>

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