[Healeys] Carb Adjustment Help Requested - BJ8 MkIII

Bob England engl at accesscomm.ca
Sun Aug 13 15:23:29 MDT 2017

I've had a rough idle in the car since we picked it up in May and it seems
to have gotten worse ever so slightly since then.

I've putzed around trying the easy stuff and finally got the bullet and
pulled the carbs yesterday (that was fun!) as one of the carb pistons was
sticking ever so slightly.  Stripped the carbs except for the throttle shaft
and found the floats were set a bit low.  Put it all back together and still
having an issue as she is running quite rich, hence the call for help.

Car: late '64 build BJ8 MkIII
Carbs : HD8 (I think they were new about 15 years ago - not original to
Cam : Dennis Welch DWR-1 (installed about 15 years ago).
Distributor : stock with Petronix Ignitor (Petronix installed last weekend
in the hopes it would help).  New rotor.
Coil : Lucas Sportcoil
Plugs : new Autolite gapped at 25 (installed a couple of weekends ago)
Timing : 15 degrees with strobe (my attempt at static timing was a dismal

I set the carbs as per the manual - 3.5 turns open on the idle trim screws
and 2.5 turn rich on the jet adjusting screw.  Fast idle adjusting screw
completely off of the cam lobe.

The best I can get it is with the jets totally lean (i.e. not sitting on the
cam lobe) and the fast idle screws setting the idle speed.  Idle trim screws
backed way out with little impact on idle.  Carbs are still running rich.

I think I have memorized the adjustment procedure from the manuals I read
them so many time - (Bentley, BMC, and Haynes), and Norman Nock's wonderful
collection of papers.

Should I be going to a leaner needle in the carbs?  Or am I just screwing up
somewhere?  This is my first attempt at adjusting SU's and I'm not too happy
with what I have done so far.

Any and all suggestions appreciated (except maybe if I have to yank the
carbs again).

Thanks in advance.

Bob England

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