Do you know the basic specs of the cam? (lift and duration?) how about the
changes in the distributer curve? Was the head modified? What's the diameter
of your header, downpipe and exhaust and how many mufflers? What needles are
in the carbs? What plugs have they suggested to use? These are all questions
that can help get you closer to an answer, your current info isn't adequate
for even long distance guessing imho.
General stuff... Peter Burgess' book on MGB power tuning (Moss has it) is
VERY informative and accurate, gives a lot of dyno numbers on various mods
and important for you shows how cam profiles change when you add the roller
rockers. Jetting is going to be the big deal hear, do NOT assume that the
needles in your 1 3/4 SUs are going to be right, either rich OR lean... If
lots of flow work was done to the head it'll certainly be in danger of too
lean, depending on the advance curve, and if they did no improvements to the
head past bolting it onto the car there's a good chance you're
over-carburatored. Get more info from your shop, and then find someone who
actually knows what they are doing to set it up.. an exhaust gas meter,
scope, and even a dyno are called for to do this right. Someone who races a B
would be a good candidate. If you can't muster all that, find a way to
anyway! If you simply must do it yourself, start conservative, make changes
slowly, and check things like exhaust smell & temp and plug color often.
A friend of mine built a big motor like this, decided after a brief trial to
"call it good" and 100 miles later had melted a piston due to the fact that
he was plenty rich with his foot buried but MUCH too lean at high speed
cruise!
Good luck and happy high performance motoring.
(much of original message deleted for space)
>From: "a.d.zimmerman" <a.d.zimmerman@worldnet.att.net>
>Subject: Experience with custom engine components?
>With tech. assistance from my
l>ocal supplier, I purchased a number of custom components for my B's
>engine as part of a ground-up makeover. I have installed the aluminum
>cross-flow head, 1 3/4" SU's, an Advanced Performance Technology street
>cam, high-lift roller rockers, oversize (.060) pistons, heavy-duty valve
>springs, stainless headers, electronic ignition--Pertronix (and of
>course a re-curved distributor). To go with these upgrades (and to keep
>me from getting killed), I've also upgraded clutch, suspension, and
>brakes. I was wondering if anyone else has had any experience with any or
all >of these components?
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