(Chuck continues) All the engine internals are the best and strongest
available and I have no qualms about holding 7200/7500 rpm for long
periods.
I did have trouble with my new engine at Bonneville in August this year.
The compression ratio is 15 to 1 and at first I was using the ERC 118
'fast-burn' gas, which resulted in detonation kicking out the head
gaskets. Fortunately there was no other damage and since then I changed
to ERC 118 'slow-burn' gas and ran another meet with no more trouble.
B: What are the limitations of these engines?
C: Valve springs are the only problem no-one has been able to solve.
I've used all kinds. The seat pressure is 340 pounds and at full lift
(.867") around 900, and the springs fatigue and lose pressure quickly
sometimes. So I have to check and maybe replace some on the head at a
Bonneville meet, to keep away from valve float. The roller cams and
lifters hold up well, but now and then the high spring pressures will
cause cam bearing failure, or maybe a bent pushrod.
B: Tell me about your intake system.
C: It's a home made plenum single-plane manifold with Enderle
butterflies for a throttle, and Enderle fuel injection nozzles a couple
inches from each intake port.
B: Why do you prefer this to a Hilborn BB Chev with individual throttle
bodies?
C: It's easier to tune. I use a thermocouple in each exhaust header to
monitor the gas temperature. We like them all at 1350/1400 degrees. If
there is any variation we can adjust the nozzle size for more or less
fuel. I have 25, 26 and 27 nozzles in this engine. One thousandth in
the nozzle size makes a big difference in the exhaust gas temperature!
Another thing about this intake is that it's low, and I don't have to
have a bump or scoop on top of the hood.
B: How do you cool this big engine?
C: A 4000 watt immersion heater in the 15 gallon water tank gets it to
140 degrees before we fire the engine. A 38 gpm electric pump
circulates it. At the end of a run down the Long Course the temp is
170/180 depending on the air temperature. I like to run the water cool
as it reduces the expansion of the aluminum block and/or heads to limit
the increase in valve tappet clearance which can be so much it reduces
the cam duration appreciably.
B: How much spark lead do these big motors like?
C: The ignition retards 2 degrees at high revs and then it's only 25
degrees total. With big cylinders and 15 to 1 that's all it wants.
B: What is your driving technique on the car?
C: Just short shifting, not too much throttle to avoid wheel spin, and
we want to get into high gear at 5000, and ease the speed on up from
there. Even at 5000 in high gear you can provoke wheel spin with too
much throttle, and it can only take full power near top speed.
B: What's your approach to cold-starting with your fuel injection?
C: I have an auxiliary electric pump with a hose and check-valve to the
distribution block, and a two-second squirt primes the engine. It will
usually start on the starter then, but sometimes it floods, and we have
to push-start it.
B: Do you have a fuel pressure gauge on your distribution block?
C: Yes, it shows about 10 psi at idle, and 56 at high rpm.
B: What future plans have you for the car?
C: We think it has a lot more speed in it, and we may go to fuel class,
even run a little nitro, to see what we can do with it. A car like this
is a constant learning experience. That's what keeps it interesting.
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