From: NAME: Mike Jeffreys [DAT31 ]
FUNC: DAT31
TEL: 0473-645609 <JEFFREYS M J AT WEB AT WEBCS>
To: british-cars@hoosier.utah.edu@unet
Lawrance writes:
>While both the TR-7's and the SAABs seem to do OK with their straight
>four's, I have yet to hear of a Stag that hasn't had severe engine
>problems.
The TR7 had a fairly bad name for warped heads due to overheating. I
believe this was due to poor corrosion inhibiters in the antifreeze (or no
antifreeze) allowing the fairly cheap alloy in the head to corrode and pass
into the coolant and then into the radiator, causing the radiator to block
up, causing the overheating. The fitters would then fit a new head (but not
a new radiator) and the cycle would start again (only in days).
Also the angled head studs needed to be tightened frequently and properly.
The Stag (I guess) would also have had the above, in addition to a coolant
plumbing problem (since cured) and an overly long and stretchable camshaft
chain (the 2nd head).
What this means is that a person who uses proper antifreeze, high quality
oil (for the chain) and the updated plumbing should have no problems.
>Does this mean that you can beef up your Stag's performance by
>slapping on a couple of 16 valve Dolomite heads?
No, you will need two types of head, the left and the right, and only one
type was made (the left, looking from the driver's position) unless
somebody knows differently?
To improve performance, use new fast road cams and tubular exhaust
manifolds.
Another method is to look into using TR7 or Sprint pistons (there should be
'meat' enough in the liners, if not use TR7 liners). This will increase the
bore but will need the con rod small ends to be modified (enlarged), and
this maybe a problem. (3.5 litres?).
Note: pistons may need too much machining (other than for valve cut outs).
If you have 1000 pounds to spend, get a crankshaft designed to use the TR7
stroke (and therefore con rods and pistons). A problem may occur with the
rods hitting the side of the block, but otherwise: 4 easy litres.
If you have lots of money get a casting of the other 16valve head made
(50000 pounds?) and make yourself a 32 valve 4 litre Triumph!!! (300 bhp?).
A new inlet manifold would also be necessary (for Weber fuel injection!).
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