> I don't know much about the interaction of distributors,
> vacuum advances,
> and engine specs, but I can tell you that my 1973 MGB GT has
> a Marina 18V
> engine, with AUD550 HIF-4 carbs, a 41155 25D4 distributor and
> vacuum advance, and compares very well performance-wise to a
> friend's 73 B
> GT that has the proper engine and distributor system. I
> wouldn't describe
> the performance as wonky.
The 41155 distributor is designed for use with ported vacuum on a
68-70 HS4 carb. The HIF carbs on your vehicle have only a manifold port.
The advance characteristics of that distributor in your car are not correct.
Your car will run, but it will run better with the correct matched
parts. SOP performance comparisons can be very misleading, as the condition
of your friend's engine is unknown. You may have a strong engine with good
ring and valve seal. I can guarantee that a 63-71 engine in good condition
will knock the socks off both engines. The correct distributor in your car
will make a very noticable difference. Areas of concern are knocking under
load and fuel mileage. The low compression 18V motor correctly timed can
run on unleaded regular without knocking. Even the 8.8:1 motor can run
under most circumstances on regular unleaded, this can make a major
difference to running costs.
There is a problem tho' as the correct unit is not available,
something that I am trying to remedy. If it didn't make a difference, I'd
find something more productive to do with my time.
Mark, I am just happy that you are driving your car. I'm looking
forward to getting back to work on my 73 GT. I'm aiming to be able to run
it on regular fuel, as it is to be my daily commuter car.
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