In message <950912033903_16999486@mail04.mail.aol.com> writes:
> Hi all,
>
> I'm thinking about rebuilding one of my TR-4 engines to a mild competition
> level.
>
> I'm not sure exactly what I'm going to do and that is why I'm writing.
>
> I have some TR friends of course, and there is also British Frame and Engine
> to talk to, but I was hoping to pick some people's brains on the list here.
>
> So howbout it? Anyone knowledgeable in the area of building a hot TR-4
> engine wanna give me their address so I can quiz them about it at length?
>
> Thanks in Advance
> Scott Tilton
> In Richmond Virginia
You REALLY want to get the flyer from British Frame & engine. Its the place for
a lot of parts that you can't get anywhere else and the types of parts/heavy
duty fasteners gives you an idea of what breaks. The TR speed tuning booklet is
helpful but remember the newer cams are better than the old ones mentioned
there.
Basically, the stock engine is stong but harmonics tends to break the carank at
the base of the flywheel flange if you spend much time above 5200 RPM. If you
work around that problem, the ends of the rocker shafts have been known to go at
higher revs, and the transmission housing has been known to break where those
two vertical slots are at the bell housing junction.
Some highlights from my engine:
- drive line balanced
- Crank nitrided, different rear seal fitted, harmonic dampener added to change
harmonic characteristics so the crank wouldn't come appart at 5200 RPM
- 280 degree cam for more power but still have low & mid range
- factory optional finned Al oil pan with oil temp guage & deeper oil pickup
- Aftermarket finned Al valve cover.
- four tube header ceramic coated on inside
- oil pump surfaced for max flow
- External oil cooler
- 87mm pistons
- TR4A head for more intake flow flexability
+ 60 Thousandths taken off head
+ shroud removed from head near intake valve
+ chambers, valve pockets, ports polished
+ Oversize valves
+ Venturi valve seats (make pocket wider, insert hardened seats upside
down, cut new seats for valve. Creates venturi to accelerate air flow
at entrance to chamber)
+ lightened rocker arms
+ solid spacers between arms
+ modified rocker shaft support to better support shaft ends
+ new dual springs & lighter retainer
+ shorter hollow chrome molly push rods (to go with shaved head)
- 45 DCOEs (SUs best for racing in lower classes but I HAD to have DCOEs)
- recurved distributer (DCOEs do not provide proper vacume for advance)
- heavier duty fixings throughout
Additional things you could do:
- lighten flywheel and redrill to accept lighter TR6 clutch
- Use TR6 transmission. It doesn't have the slits and the bellhousing will not
break off under hard use. You will need to make slight modifications to the
transmission mounting cross mamber.
Take care,
TeriAnn
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