Art:
If I am not mistaken, the dished pistons were used to lower the CR for the
US spec cars. The thickness of the head casting remained the same.
Flat-top pistons are a must if you want to get anything above 9:1 CR.
Here are a couple of good links with useful information:
http://auskellian.com/paul/links_files/performance_enhancements.htm#Port_and
_Polish_and_Flow_the_Head
http://www.teglerizer.com/triumphstuff/spitheads.htm
Use this xl spreadsheet to calculate how much you want/need to take off.
(if anybody else need a copy send me an e-mail and I will shoot you a copy)
I recently built a 1500 for street/autocross use. It worked out so well I
am building it again, but that is another story...
On my head I took off .125 to with an early 1500 block using stock flat top
pistons for a just under 9:1 CR
I also had John at Costa Mesa R&D install modified TR7 valves and beehive
springs to the max allowable diameters as per the SCCA Solo GP specs.
http://www.youtube.com/watch?v=oLlY0sTYYBY (I think John can put these
springs on any other TR engine as well - shameless plug for a good friend)
As for cams; on my auto-X motor I used Ted S's 275-4 cam and it is great.
(Another shameless plug)
Let me know if I can help you in any way.
Robert MacKenzie
President, Hill Country Triumph Club
Austin Texas
'79 1500 (street)
'66 GT6 Mk1 (project)
'62 Spitfire 4 (race)
--------------------------
Message: 8
Date: Thu, 7 Oct 2010 11:05:15 -0500
From: "riverside" <riverside@southslope.net>
Subject: [Fot] spit 1500 heads
To: <fot@autox.team.net>
Message-ID: <005401cb6639$6ea1d620$0301a8c0@your55e5f9e3d2>
Content-Type: text/plain; charset="us-ascii"
I am working on warming up a Spit auto X motor and am trying to get the
compression up to about 9:1 from the current 7.5:1 with my TKC3239 head on
my '75. I understand the head thickness on the US market 9:1 head (TKC2748)
is 3.05" vs. 3.10" on the 7.5:1 head. Was there also a change from dished
pistons to flat tops to get the increase? Was the thinner head just that?
thinner
but otherwise identical? I there a factory prescribed maximum amount that
can
be milled froom either head.
anybody have a favorite cam for a 9:1 autocross spit 1500 they can recommend
Thanks!
art de armond
[demime 1.01d removed an attachment of type application/vnd]
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