[Healeys] Carb Adjustment Help Requested - BJ8 MkIII

BJ8Healeys sbyers at ec.rr.com
Mon Aug 14 07:33:54 MDT 2017

Dave, I'm not the one having the problem and asking the question; but I was responding to your statement that the timing is set to 6° @ 750 RPM, which does not agree with what is published in the BMC workshop manual for the Mk III engine (see attached).  My Glenn's AUSTIN AUSTIN-HEALEY REPAIR AND TUNEUP GUIDE (copyright 1965, and also says CHILTON 1432 on the spine) gives the same numbers as the BMC manual.  I do understand what you mean about the advance (I have a Mallory Dual-Point distributor with mechanical advance only), but questioned where your numbers came from.  



Steve Byers


BJ8 Registry

AHCA Delegate at Large

Havelock, NC  




-----Original Message-----
From: David Porter [mailto:frogeye at porterscustom.com] 
Sent: Monday, August 14, 2017 8:53 AM
To: BJ8Healeys; healeys at autox.team.net
Subject: Re: [Healeys] Carb Adjustment Help Requested - BJ8 MkIII


Steve, my Glenn's book shows the dist as 40966A/B with centrifugal advance starting at 500RPM with 7.5 degrees, max centrifugal adds 19 more degrees at 3200RPM plus another 8 for the vacuum advance giving a total max of 34.5 degrees. Thus if at 3200RPM your total is more than

34.5 back off the initial. If your strobe light won't allow you to calculate total, get one that will. ;~) Healey engines are very good at not pinging audibly. Can't count the number of engines I've seen with damaged ring lands from too much advance.



On 8/13/2017 6:41 PM, BJ8Healeys wrote:

> Dave, are you sure about those numbers?  I believe the manual 

> specifies 10 BTDC static and 15 BTDC @ 600 RPM.


> Steve Byers

> HBJ8L/36666

> BJ8 Registry

> AHCA Delegate at Large

> Havelock, NC



> -----Original Message-----

> From: Healeys [ <mailto:healeys-bounces at autox.team.net> mailto:healeys-bounces at autox.team.net] On Behalf Of 

> David Porter

> Sent: Sunday, August 13, 2017 7:20 PM

> To: Bob England;  <mailto:healeys at autox.team.net> healeys at autox.team.net

> Subject: Re: [Healeys] Carb Adjustment Help Requested - BJ8 MkIII


> 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


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Dave Porter Porter Custom Bicycles 2909 Arno St. NE Albuquerque, NM

87107 505-352-1378 Go HERE: my world  <http://www.porterbikes.com/> www.porterbikes.com/



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