Stroker? da war doch mal was:
"-------
90632D:
You can dig up some hearsay things about the stroker concept on the web by googling it. I talked to John Kipping
himself about it, as he's the one who first told me of it. But that was some years ago.
The earlier 1300 engines had smaller diameter bores on the big end of the rods. And, correspondingly smaller
sections on the crankshaft. The late 1300 and 1500 engines were made much larger. I've heard various stories about
why this happened, I do not know which stories are true.
In any case, the techique is to get some early 1300 rods and bearings. Take them in hand with the crankshaft and
go to a good machine shop and have the crankshaft turned down to the appropriate size for those bearings. Have it
done offset, so you increase the stroke.
The piston recommendation, as I recall, was GT6. Again, as I recall this works nicely because it is a lower piston
and just so happens to work well with the stroked 1500 crank, not popping out of the block, smashing against the
valves. Again, no experience, and this is just recollection.
I have never run one of those engines. John told me his worked great. I don't dispute his words. I would have
concern about stroking out a 3 bearing crank myself. But, if one were to behave with it, it should be just fine.
-------
tktrain:
I just found the following post on the club triumph forums by a poster that goes by "slimboyfat"(Dave Pearson,
Canley Classics) that was made back in July of this year. He says:
"Bore to standard TR6 piston size (and use standard TR6 pistons!). Offset grind crank to TR6 stroke (using small
bearing rods), and you end up with 1660cc.
You have to compensate for large increase in compression by using one of the low compression California market
heads. We were using the air injection type with the holes blocked off because they used to be cheap, and
plentiful.
The 1660 in our Courier was probably the first ever of the breed as it was the engine we (John Kipping back then)
developed the theory with back in the 80's. It's still going strong nearly 25 years later although it has had a
few lay-ups over the years. We gave it a precautionary strip down a couple of years ago and the bearings
(Vandervell) still had plenty of meat on them.
As an aside when the 1660 first went onto the road it had a Catalytic converter fitted, that used to confuse the
MOT man!
At this point I would like to mention that we had nothing to do with the disastrous 'Sports' 1700's that were sold
to unsuspecting Spitfire 1500 owners in the late 90's, early naughties. By that stage we had come to the
conclusion that the 1660 is a fine old slogger that deserves to be in something that needs torque (that's why they
powered out Couriers!). No way could it be described as 'sporting'. Treat it as such and expect a ventilated
block. This was the experience of a goodly number of those poor unsuspecting Spitfire owners."
----"
mfG
Harry
