I don't know which cars had flat-topped pistons and which had dished-tops, but I
do know that to convert the 1300 engine into the 1500, Triumph increased the
stroke, and not the bore.
Logic tells me that if you increase the stroke, and leave all other factors the
same, then a) then engine size will increase, and b) the compression will
increase. This would seem to confirm Craig's thoughts that simply putting a
head from a high-comp 1500 onto a 1300, without changing the pistons or milling
the head, will not affect the compression. If you want to increase compression,
you either have to replace dished pistons with flat-top pistons, or mill the
head.
All this is theory, because I've never done anything like this in practice, so
don't be surprised if someone comes forward to say this is wrong!
Dean
----------------
Date: Tue, 7 Sep 1999 16:39:57 -0500
From: "Mostrom, Paul" <Mostrom.Paul@principal.com>
Subject: RE: Cylinder head interchangeability
Someone correct me, but I'm pretty sure that the flat top pistons from the '76
1500 engine are what make the difference. Vicki Brit lists the '76 pistons as
'flat top' with a 9:1 ratio. The '73-'75 and '77-'80 1500 pistons are dished
with a 7.5:1 ratio.
Now can anyone out there tell me. Can the '76 flat top pistons be put into a
'79 1500 engine? I have a spare engine that I plan on rebuilding for my '77
and I don't intend to build it stock.
Thanks,
Paul Mostrom
'77 Spitfire 1500
> '80 Ford F-100 (Triumph Support Vehicle)
>
>
'Black holes, where God divided by zero......'
- -----Original Message-----
From: Craig Smith [mailto:CraigS@iewc.com]
Sent: Tuesday, September 07, 1999 3:07 PM
To: 'Douglas Braun & Nadia Papakonstantinou'; spitfires@autox.team.net
Subject: RE: Cylinder head interchangeability
My understanding is the high comp. comes from a longer stoke.
Bore size on a 1296 is 2.90"
Bore size on a 1493 is 2.90"
You might change the heads and not get anything.
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