[Mgs] HIF's

[mgbob at juno.com]

   The truly right way to do things at this point would be to follow the book
instructions. Not having it to hand, here is what I would do:
   Turn down the loose idle screw to contact the carb body
   Loosen the throttle shaft link
   Synchronise the two carbs-this is why each has an idle screw
   Snug the throttle shaft link
   Now, with engine off, see that the throttle shaft pins engage the carb jaws
equally, so that when the shaft is turned, both throttle shafts start to turn
at the same instant.
   Engine running, check the sychronisation.
   Drive 200 miles before sunset.
Bob

---------- Original Message ----------
From: Monte Jane Morris <montejane at gmail.com>
To: PaulHunt73 <paulhunt73 at virginmedia.com>
Cc: MG list <mgs at autox.team.net>
Subject: Re: [Mgs] HIF's
Date: Fri, 18 Apr 2014 10:34:40 -0500

I removed the dampers and did get the clunk, although with the dampers in I
didn't. Go figure.

Anyhow, the carbs are back on and the "cruise control" is now fixed.  I
figured I would need to readadjust something besides the idle when the
carbs went back on but I didn't touch anything else and it is running
excellent again.

Evidently the cause was the idle screw clinch nut on the back carb came
loose and under 30 minutes of constant highway speeds the idle screw
rotated downwards about 5 turns causing the butterfly to remain open.

The rear carb idle screw is fairly loose when the clinch nut is loose. Is
this common or should I retap and put a slightly larger screw/bolt in?

As always, many thanks to you list members who helped diagnose the problem.
I don't have to "resemble a mechanic" if I have you guys around:).

Monte
79B owner since 2001. Former 67B and 68B owner starting in 1972.


On Fri, Apr 18, 2014 at 9:14 AM, PaulHunt73
<paulhunt73 at virginmedia.com>wrote:

> The clunk test is done with the engine off.  It won't clunk at idle as the
> idle airflow lifts it off the bottom, and lifting it any more than 1/32"
> will probably stall it.
>
> Strictly speaking the clunk test should be performed with the jet raised
> level with the bridge, i.e. about two full turns from the normal position.
> If it clunks here i.e. the needle doesn't bind then it definitely won't
> bind with the jet in the lower running position.  But with sprung needles
> instead of fixed it's very unlikely to bind anyway, and with HIFs there is
> no provision for centring the jet even if it doesn't clunk.  But it's still
> worth doing to make sure it isn't binding, perhaps due to a bent needle.
>
> The dampers won't make any difference to the clunk test.  They only damp
> the upward movement of the piston, when you have forced them up against the
> damper and then let them go they should drop smartly with said clunk.
>
> PaulH.
>
>
> ----- Original Message -----
>
>> Several of you mentioned that after lifting the pistons you should hear a
>> "clunk" when they drop. Is this when the car is off, idling, or both?
_______________________________________________

Mgs at autox.team.net
Donate: http://www.team.net/donate.html
Suggested annual donation  $12.75
Archive: http://www.team.net/archive
Forums: http://www.team.net/forums
Unsubscribe: http://autox.team.net/mailman/options/mgs/mgbob@juno.com