I can categorically say that if you use an unaltered 1500 head on a 1300
engine, you will not be very satisfied with the performance. The reason is
that the 1500 heads are about a quarter inch thicker than the 1300 heads and
unless you cut it way down, the compression ratio will be so low that it
will suffer.
I have a large valve 1500 head on the Mk3 (1300) engine in my red Mk1 Spit,
Huxley. In order to achieve the desired compression ratio, I had to have
about a quarter inch of metal shaved off the bottom.
All you have to do to verify this is compare a stock 1500 head with any head
off a 1300 engine.
Regarding Unleaded heads, I doubt that Triumph did those prior to 1975 since
that was the first year Unleaded fuel was universally offered in the US and
the first year the government mandated new cars use it.
Joe
-----Original Message-----
From: triumphs-bounces@autox.team.net
[mailto:triumphs-bounces@autox.team.net] On Behalf Of jimmuller@rcn.com
Sent: Friday, April 23, 2010 8:49 AM
To: Triumphs@autox.team.net
Subject: Re: [TR] Identifying Spitfire Cylinder head # TKC 2748( Now another
Head and Block)
> Wayne, that block would be a circa 1972 Spitfire MkIV
> "Federal" (hence the "U" in the suffix) engine, low
> compression and recessed bores.
I've rarely had occasion to think about such things (if it runs, you just
run it) and I haven't followed this thread too closely (too much going on
lately). But I recall being told that the 7.5:1 vs. 9.0:1 difference was
strictly in the head.
Yes, no?
--
Jim Muller
Or maybe they really said "No, it's all in your head."
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