[Healeys] Carb Adjustment Help Requested - BJ8 MkIII

[Bob Spidell]

Where did you set the needles in the vacuum pistons?

BOTTOM GROOVE ON NEEDLE JUST ABOVE BOTTOM OF PISTON (SO YOU CAN'T SEE THE
GROOVE).

 >>> I think this may be the problem.  I don't have my SU books handy, 
but IIRC you should set the top of the groove level with the bottom of 
the piston.  I remember doing just this and it made a difference, esp. 
at idle.

ON THE JAGS, I SWITCHED TO A 35 GAP WITH THE SPORTS COIL OVER A 25 GAP AS
THIS SEEMED TO BE THE RECOMMENDED APPROACH.  DO YOU THINK A LARGER GAP WOULD
HELP?

 >>> I'd try a little smaller gap, just to see.  Also, if you have the 
original coil and it was working, I'd slap it back in.

Bob


On 8/13/2017 9:47 PM, Bob England wrote:
> Bob
>
> See notes in CAPS below ....
>
> Thanks.
>
> BobE
>
> -----Original Message-----
> From: Healeys [mailto:healeys-bounces at autox.team.net] On Behalf Of Bob
> Spidell
> Sent: August 13, 2017 6:31 PM
> To: healeys at autox.team.net
> Subject: Re: [Healeys] Carb Adjustment Help Requested - BJ8 MkIII
>
> How do you know you're running rich; is the car blowing black smoke, even
> when warmed-up with the choke off?
> YUP.  IF I SET THE IDLE UP AROUND 1200rpm, BLACK SMOKE STOPS.
>
> Where did you set the needles in the vacuum pistons?
>
> BOTTOM GROOVE ON NEEDLE JUST ABOVE BOTTOM OF PISTON (SO YOU CAN'T SEE THE
> GROOVE).
>
> Sounds to me like your floats are set too high; take the dashpots off and
> see where the top of the jets are relative to the jet bridge, and where the
> fuel level is inside the jet with the pump on (don't leave the key in the
> 'on' position for long when the engine isn't running lest you fry your
> Pertronix).
>
> FLOATS COULD BE HIGH.  I THOUGHT THEY WERE LOW SO I ADJUSTED THEM HIGHER
> (USING 7/16" TEST BAR).
> WHERE SHOULD THE FUEL LEVEL BE INSIDE THE JET WITH THE PUMP ON?
>
> Did you inspect the jet diaphragms when you had the carbs apart?
>
> I DID INDEED.  THEY LOOKED GOOD.
>
> If the car sat for a long time they could have cracked; if so you'll never
> get the mixture set right.
>
> FWIW, I have a BJ8 with DWR-1 cam and Pertronix and the idle--at 750
> give-or-take--is a bit lopey but solid (I gap my plugs at 0.028").
> There were some bad Sports Coils going around, and I'd stick to Champion or
> NGK plugs.
>
> I MAY SWITCH TO THE CHAMPION.  I'VE HEARD THAT FOR SOME REASON CHAMPIONS ARE
> A SWEET SPOT FOR THE CARS.
> ON THE JAGS, I SWITCHED TO A 35 GAP WITH THE SPORTS COIL OVER A 25 GAP AS
> THIS SEEMED TO BE THE RECOMMENDED APPROACH.  DO YOU THINK A LARGER GAP WOULD
> HELP?
>
> I THINK, LOOKING BACK, WHEN I PICKED UP THE CAR IN MAY THE IDLE WAS LOPEY AS
> YOU DESCRIBE.  ON A RECENT 500km ROUND TRIP, BY THE TIME I GOT HOME THE CAR
> WAS MISSING (HENCE THE START OF MY JOURNEY TO ADJUST THINGS).
>
> Timing for a BJ8 is set at 15deg BTDC at 600RPM with vacuum advance pipe
> disconnected and port on carb plugged (doesn't make much difference).
>
> Bob
>
> On 8/13/2017 4:20 PM, David Porter wrote:
>> what are the compression numbers? Timing is set at 750RPM and 6
>> degrees BTDC. Is it better or worse with chokes engaged? DP
>>
>>
>>
>> On 8/13/2017 3:23 PM, Bob England wrote:
>>> 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 car).
>>> 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 failure!).
>>>
>>> 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
>>>
>>>
>>>
>
>