Don Terrill’s Speed-Talk

I have to wonder if we could construct a screened blanket that would form fit about 2/3 around the crank Assyrian so as to capture most all the oil flung off this wicking the oil away rather than allowing droplets to ricochet back into the violent air currents. If crankcase space allowed such screen...

Would it be worthwhile to coat the exh valves ?

Tell me more about improving the gm bolts.

The root cause of the low speed issue is the slow air velocity at minimal RPM. Fuel droplets will fall out causing some cyl To go lean and the wet intake floor can cause other cyl to go rich. Try installing metal window screen sandwiched with gaskets under the 4 hole spacer. This will force fuel dro...

iPhone doesn’t like to log in, takes multiple attempts before success.

Once logged in usually drops out with most every page change.

Very frustrating.

This is third attempt to post problem as it drops out again before it makes the post.

I’ve thought long ago but never got around to doing it. An elec pump T’d into the oil filter adapter and a Merphy switch such that the pump comes on with the key near immediately pressurizing the oil system to a minimum psi. Crank and start and as the engine oil pressure rises the Merphy turns off t...

No doubt mic’ing rod bolts should indicate any change in length suggesting eminent failure the same may be true with rod length.

I don’t have the tooling to measure accurate rod length but I’ sure someone does. The cost could be well worth the peace of mind.

In the marine world a general rule of thumb is fuel required equals 10% of HP.

Like fbird said, 420 HP generally requires 42 gph gasoline.

Your mileage may vary.

Would it be advantageous to grind ex valve/seat to maximize low lift flow?

Intake angles for high lift flow?

Is this already a common practice?

WOT of 4700 is way too tight on the pump clearance, over loading the motor causing premature failures.

Loosen pump to get closer to 5500 and it should perform well and last much longer.

I’d liked to have seen the valves from the prior failures, perhaps would know more if it was the valve head or keeper failed.

3800 cruising? What was the WOT rpm set by the pump clearance? To tight on the pump can overload the motor creating excessive exhaust valve heat.

While the intake is off check the gasket surface with a straight edge .

No doubt valve springs are required for rpm but I have a question for the cam guys.

With a lift limit would it make sense to increase cam diameter so as to enable increasing duration in the lobes.

Is there even room in an abc for a larger cam bore?

Can you do a clean shut off then pull the plug and inspect for oil? Compare that to pulling the plug immediately after decelerating and high intake vacuum. High vacuum on deceleration may be pulling oil past intake asker yet not leaking enough at wot to show a problem yet. Have heads/intake surfaces...

OP didn’t mention RPM this BOAT engine is operated. Generally rod stretch becomes a critical factor with increased RPM, however in the marine application and somewhat less rpm extremes a tighter squish may be allowed. I wouldn’t get extreme, but set up far closer to minimum should still be well acce...