>On Saturday, November 02, 1996 Phil Bates wrote:
>>I recently bought an MGA.
>
Congrats ... excellent purchase ;^)
>>I knew that it had an MGB block because I checked this before
>>buying, but everything else looked pretty much stock MGA. I
>>have since realized I have an MGA 1500 head on the engine.
>
... got a "15" in the casting number on the rear of the head eh?
If you have a "16" in the casting number then the head is from
a 1622 engine ... the valves, porting, combustion chamber are
the same as the early 'B' heads.
>>I am not sure if MGB valves are in it or not, or how to tell.
>
You will have to pull the head to determine valve size. I would
ass*u*me that it has stock 1500 valves.
>>Also, I don't know what this will do to my performance, or engine
>>longevity.
It will impact performance ... can't think of reason why it would
have any impact on longevity.
>>It seems like the compression ration would be very high.
Yep ... the combustion chamber on the 1500/1600 cylinder
head is 38.7 cc versus 43 cc for the 1622/1798 cylinder head ...
my guess, fitting the 1500 cylinder head would increase the
compression ratio to about 9.5:1.
>>I seem to be getting a lot of upper rpm power, but I haven't
>>checked the carb tuning or timing yet. Any thoughts on this
>>configuration??
Assuming a stock 1500 head ... the valves and ports are smaller
... you have increased the compression ratio, but you have
decreased the flow of intake/exhaust gases. My guess is
that overall performance has been decreased. The upper rpm
power could be the result of the 1500 head, a 'tweaked' cam,
or both.
>>I know it is common to put an early B head on a MGA block, but
>>an A head on a B block, I just don't know much about this.
>
I guess that if its what you got its what you use ... IMHO, for the
reasons stated above, I would be looking for 'big valve' head from
a 'B' 18V engine ... the little purist voice in me says find a 1500
engine ;^)
If you stay with the 1798 engine ... don't use the stock 'A' exhaust
header (it's way to restrictive) ... the stock 'A' water pump may
cause overheating (it has less flow than the 'B' pump) ... your 'A'
will be referred to, by others on this list, as a 'Bastard', but it will
kick Truimph a$$ 8^)
'I ain't no stinkin xpert' ...YMMV
Safety Fast ... larry.g.unger@lmco.com
'62 MGA 1600 MkII
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