[Healeys] Carb Adjustment Help Requested - BJ8 MkIII

[Bob Spidell]

I just tore down a BJ8 engine with about 110K miles since rebuild.  I 
always ran at 15deg per the manual and there was no damage to any of the 
pistons or rings (see attached).  Of course, I always ran 91-octane or 
better gas (except on a couple occasions when it wasn't available).  I 
never heard any knock, but my co-pilot on my long trips said he did when 
I inadvertently lugged the engine a couple times.

Somebody did a 'study' on why the BJ8 engine needed so much initial 
advance, I believe the theory is that the plugs are set further recessed 
in the plug than the earlier engines.

Bob


On 8/14/2017 8:12 AM, David Porter wrote:
>
> yeah.. I get that. It's just that for ANY stock engine to have more 
> than 10 degrees initial is unusual.. sure they seem to run better, but 
> when the total is too high bad things will happen in due course...
>
>
> On 8/14/2017 7:33 AM, BJ8Healeys wrote:
>>
>> 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
>>
>> HBJ8L/36666
>>
>> 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
>>
>>

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