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MG MGA - 1800 head on 1500 engine

I recently found out that there is a MGB 1800 cylinder head on my 1500 engine (someone showed me). Can anyone tell me how I should tune the carburettors (needles...) to have good results for this combination ? Many thanks for any advice.
gva guido

I don't believe that the fact that it's an 1800 head, will make any difference in turning the carbs....Technique should be exactly the same, as long as the standard SU's are on the engine....
Just follow the tuning procedures in the manual....
As with most of these old British cars, every car is a little different anyway...Tune for best running, based on standard techniques....At least , that's what I have found with the 1800 head on my 1600.
Edward Wesson 60MGA

As Edward says the car is probably fine with the standard needle. Maybe the breathing at higher revs is better and then a needle with a richer profile may be needed, but which one? The only way to really find out is to book a session on a rolling road, with an operator that knows his old cars and SU's.

In Holland BCCP in Gramsbergen is able to put your car on a dyno with the added advantage that they stock SU needles.
Willem van der Veer

Do a compression test first. The 18 head has larger chamber volume. It works well on the 1622cc engine (MGA 1600-MK-II), For 1500/1600 engines it will be lower compression. The 150 with stock 18 head may show only about 135-psig compression at cranking speed (at best). Lower compression reduces power and fuel efficiency. Slightly better breathing increases power, perhaps more than is lost by lower compression, so it may run better at full chat.

Standard compression ratio can be restored by shaving the head about 0.047", from original 3.187" thickness down to final 3.140" height. After shaving that much you should check valve head clearance to block at full lift. With valve lash adjusted to zero (for test only), There should be 0.060" minimum clearance between intake valve head and block, 0.080" clearance between exhaust valve and block, and 0.020" clearance between valve and piston (never a problem in these engines). Valve head clearance at full lift depends somewhat on its rest position, con condition of the valves and seats when worn or after repair can make a difference. You will not know what you have inside until you measure things.
Barney Gaylord

Many thanks for all your comments !
gva guido

This thread was discussed between 26/01/2014 and 27/01/2014

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