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Re: was Dizzy help/now Engine ID?

To: "Telewest \(PH\)" <>, <>
Subject: Re: was Dizzy help/now Engine ID?
From: "Bill Mills" <>
Date: Sun, 26 May 2002 20:53:27 -0400
This brings up the problem that I need to solve before I know which dizzy is
correct for this engine.  I don't know which engine I have.  I am running
this engine in a '74 'BGT, but I bought the engine from an individual about
5 years ago with no engine ID plate, he couldn't tell me which model the
engine came from.  The only clue I have is that it has a head with the air
rail ports (plugged off) and it does not have any outlet from the head for a
water choke.  It is a 5-main block.  So I feel like it was some where
between a '69 to a '75.  The main thing I need to determine is whether it is
a HC or a LC so I can determine which distributor and which carbs are
correct for it.  I currently have HIF4's on it with the vacuum from the
manifold to the dizzy (I've got some HS4's that could go on if I rebush the
throttle shafts, and a side draft Weber, but that is another story).  I got
the engine with out carbs and without a distributor so we are shooting in
the dark here.  Any thoughts on how to tell whether the engine is HC or LC
with out pulling the head (don't want to pull the head on a good running
engine just to find out). Can I tell anything from pulling the valve cover
and looking at the valve setup?

'74 'BGT (but engine is ??)

----- Original Message -----
From: "Telewest (PH)" <>
To: "Bill Mills" <>; <>
Sent: Sunday, May 26, 2002 5:43 AM
Subject: Re: Dizzy help

> No idea what application a 41147 is for but the vacuum advance almost
> certainly works the same as any other.  I say 'almost' as some people
> that the vacuum capsule on some dizzies on some engines *retards* the
> whereas all those for the MGB advance it, ported vacuum or manifold.
> However your biggest problem is likely to be the curves on the 41147 will
> different from what your engine requires.  If the two dizzies are both the
> same type i.e. both 25Ds or both 45Ds then just swap the vacuum capsule
> and retain the dizzie body.  That way at least you will keep the
> advance as it was.  The vacuum capsules usually have the advance details
> stamped on them somewhere in the form 5-13-10 which means the vacuum
> starts at 5 in. Hg. and reaches a maximum of 10 dizzie degrees (20
> crankshaft degrees) at 13 in. Hg.
> According to the Leyland Workshop Manual the 41339 is for the 1971 8.8:1
> compression engine, i.e. high compression.
> If you have the 18V 672/673 (CB) engine you should have the 41491.  If you
> have the later 18V 836/837 (RB) engine I cannot find that listed in any of
> my sources so don't know what it should be.  The 41491 has a higher max
> centrifugal advance than the 41339 and requires more vacuum to give the
> amount of vacuum advance.
> ----- Original Message -----
> From: "Bill Mills" <>
> To: <>
> Sent: Sunday, May 26, 2002 3:56 AM
> Subject: Dizzy help
> > I had to pull the dizzy on my '74 BGT with HIF4's because the vaccum
> advance
> > was leaking.  I got a 41147 to put in there.  This number does not match
> > with ones on paul's chart at
> >
> >
> > any ideas what a 41147 was from, would it work with a manifold vaccum
> > source???
> >
> >
> > I've also got a 41339 in the shop that may have a good vaccum advance
> > on it.  It is listed as appropriate for a '71 low compression and
> > vaccum source which is what I have with the HIF4's.

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