Hi Olin,
Depending on the state of tune, you regraph the distributor advance curve so
that the engine has total maximum advance of around 34 - 36 degrees at
around 3,500 rpm engine rpm.
If you've got 35 degrees at 2,000 rpm - I'd expect it to be pinging at low
rpm.
What fuel are you using? Higher octane?
Best
Chris
----- Original Message -----
From: <olin.brimberry@talecris.com>
To: <healeys@autox.team.net>
Sent: Wednesday, October 19, 2005 4:37 AM
Subject: Vacuum Advance Units - High Compression
> My problem is that over long runs at 3000+ rpm in OD, I am getting some
> pinging and overheating. Everything below 3000 is great. I want to avoid
> advancing too much, but I am thinking that maybe I need to have my
> distributor set up for hi-compression. I have high compression pistons
> (arias) and my cam was suppose to be ground to BJ8 specs. From memory, my
> timing is advancing to approx 30-35 degrees around 2000 RPM. I still have
> the stock distributor and assume the same advance unit. I am running the
> 3.54 rear end with a 28% OD, so I am sure that it adds to the torque
> requirements.
>
> Per the email from Curt below, I would be interested in knowing the vacuum
> settings (normally 5-12-8 for MKII) for the "High compression special
> orders" vacuum units. IE, the start of advance, max advance, etc. If
> anyone could relay that information I would certainly appreciate it.
> Better yet, if you have a good one lying around for sale, email directly.
>
> What do the racers do when they keep the stock distributor and have high
> performance guts?
>
> Regards,
>
> Olin Brimberry
> Raleigh, NC
> 62 BT7
>
>
>
> Date: Sun, 16 Oct 2005 18:20:31 EDT
> From: CNAArndt@aol.com
> Subject: Re: Distributor Vacuum Units
>
> Josef,
>
> Off the top of my head ;) here is a short list through 1960.
>
> BN1/2
>
> 1953-55 Early distributor 40320A - vacuum 420006
>
> 1955 Early 100M distributor 40422 - vacuum 420755
>
> 1956 Later distributor 40495A - vacuum 54411727
>
> 1956 Later 100M distributor 40520A - vacuum 54411233
>
> BN4/6
>
> 1957 For distributor 40532A - the vacuum control unit is 54412033. I
> believe
> that this the one for the BN4.
>
> 1958-59 For distributor 40581A/B - the vacuum contol unit is 421189, which
> should be for the BN6.
>
>
> 3000 Mk1
>
> 1959-60 distributor 40662A/D - vacuum 421189
>
> AN5
>
> 1958-59 distributor 40561D/H - vacuum 54411100
>
> 1960 distributor 40561J vacuum 54411100
>
> "High compression special orders."
>
> 1958-59 distributor 40656A/B & E - vacuum 425700
>
> 1960 distributor 40656D & F - vacuum 425700
>
> Cheers,
>
> Curt Arndt
> Carlsbad, CA
> '55 BN1, '60 AN5 :{) '72 RWA Midget
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