Dick T, in response to me querying him on my own race engine wrote,
>2. Use of flat top pistons would be surpassed with a forged domed
piston.
>At Venolia, my die gives a slanted dome roughly the shape of a slightly
>larger combustion chamber. The height of the dome is perhaps 1/4"
sloping
>to about 1/16". While the piston was originally designed for .060 OS
bore,
>it could easily be turned to .037" OS bore. I assume the moly rings
would
>have to be supplied to venolia so they could properly machine the
grooves
>and oil return holes etc. This piston also uses floating Chevy pins
and
My pistons cost $75 each with a jobber discount.
There are quite a few people on this list with similar ambitions,
and venolia pop up pistons could be considered attractive,
but not likely at $200 each.
Care to see if they still have your molds?
>3.Carrilo rods must cost a fortune? Z28 rods with tiny brazed buttons
work
>fine and NEVER have failed below 8100rpm but did let go once when a
>suspected 9000 was touched. The Z28 has a husky bolt size as well.
Carrillos cost $200 each, but clones can be bought for as low
as $100.
They offer the ultimate in protection, and the H beam faces the
correct direction for the heavy reciprocating loads present of
really high RPM engines. Unlike the rootes design.
You will surely brake the crank before the rods in this case.
My rods are for 5 liter formula 5000 motor, that used to make
about 850 BHP.
ever used 6 inch rods?
>8.I would suggest lightening the valve train wherever possible and this
>includes making "swiss cheese" holes in the lifter walls. Even tiny
amounts
>removed can have an affect at extreme rpm's.
Does this have negative effects on the lifters?
>9.Your combustion chamber deshrouding of the valves is of course SOP
and
>will pay off in filling efficiency...and net power gains. The 11.5:1
CR is
>nice but perhaps the domed piston offer would push you over 12:1 .
Not having the domed pistons, I am at the mercy of the amount of
meat taken from the chambers to make the head flow. It is a
compromise, and not by design.
>10. The Weber carbs are a dream come true. Ah! if only my car could
have
>run them. I somehow feel 34mm choke size to be a bit too small for
really
>peak hp and rpm. More like 37-38mm sounds better to me??? The 34mm
would
>however make the engine produce better low and mid range hp.
Having such large chokes works great to reduce restriction, and
the air velocity and really large jets will allow propper operation,
but at lower RPM, the pilot system will have to be have a heavy
and long effect until the chokes have enough air going through them
to pull the fuel from the jets.
I am of the belief that if the engine is to have any lower RPM usage,
the carburettion should not be too reliant upon the pilot system.
This means that I will not make the horsepower that I could have
but also means I dont get a really big flat spot at lower throttle
angles.
Just opinion though.
>12. Will your 10+24 deg. distributor be enough? I know you can set to
36
>deg or whatever the engine likes, but for easier cranking and likely
faster
>starting, it might be better to have say 5 deg BTDC at cranking, as a
basic
>static setting, then let idle (around 1000) be say 10 deg. I advise
this
>because in the event of a spin out where the engine may stall, you have
to
>crank it over and restart. Some guys have the timing set at a fixed
>setting which is quite high and things run great..but restarting is
almost
>chancy with a hot engine.
This is a good idea, starting a hot HC engine can be uhhh- fun.
Thanks for the info.
Jarrid Gross
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