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Re: Cams and Distributors

To: "Christopher M. Delling" <cdelling@srv1.ic.net>
Subject: Re: Cams and Distributors
From: Robert Allen <boballen@sky.net>
Date: Mon, 10 Feb 1997 12:57:57 +0000
Christopher M. Delling wrote:
> 
> Stock engine from a 79B, with an early (pre-smog head)
> Weber DGV Carb
> Early cast-iron manifold into a "standard" exhaust - no cat.
> Stock Distributor fitted with Crane/Allison ignition, stock coil.

Be very sure that the secondary is going fully open on that DGV by the
time you get to 3,000 revs and full throttle is applied.
 
> Now the questions.  I want a little more pep.  It's not bad down low,
> but still peters out above 4000 r.p.m or so.  I have been advised that
> the way to acheive my ends is to swap the cam, and the distributor.
> Since the engine is coming out for a tranny swap, I thought that this is
> the time to consider this.

> I have been told (?) that the stock cam in post '72 cars is suspect, due
> to "soft metal" which results in premature wear.  Anyone out there
> support this?  Is there a way to determine cam wear w/o removing the
> cam?

"Petering Out" could merely be valve float. There are tools to measure
valve spring pressure and dial gauages to determine exactly how much
lift you are getting. If you do go to a new cam, be sure to replace
valve springs with the exact ones recommended by the Cam company.
 
> Will a high performance distributor help by itself, or is it a
> negligable gain w/o a cam swap?

I don't know what a "high performance" distributor is. What is the total
advance you are getting out of your current distributor? Is the vaccum
source manifold vaccum or ported vaccum? You can buy a timing light with
adjustable advance so that you can graph the actual advance curve. You
can get a small amount more power if you can determine exactly how much
advance yur cam/carb combination wants.
 
> Just how much difficulty is there is swapping the cam with the engine in
> the car (should my funds be too limited to do everything at this time, I
> may consider it later - but I really don't want to pull the engine
> again!)
> 
> Any and all opinions are welcomed!
> 
> Best Regards
> 
> Chris Delling

Do a compression check to determine health of the rings/valves. You also
may not be able to pump enough air through the engine at high RPM.
Restircations? Air intake, exhaust. Muffler? ID of tailpipe? Tailpipe
not crimped anywhere? I hear the stock MG header is actually pretty good
so be sure downstream is okay, too.

Bob Allen, Kansas City, '69CGT, '75TR6

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