Don Terrill’s Speed-Talk

wiseco has some d cup pistons to get the compression down,
there may be a few other that use the d cup to keep a good quench and lower compression.

Another couple of pictures.

The combustion chambers don't particularly look lean, but the may be getting carboned up from the choke and slow speed idling???

Wouldn't 20 minutes of running lean burn that off?

I had a good look at the plugs from the cylinders that were not damaged and there was definitely lean signs. Since the engine stopped right after running at this point it clearly showed lean. the photo is after I sprayed the oil off with brake clean Previous plug checks were after a cool down or low...

Yep, That cam probably peaks at 37-3800 tq and 5500 hp.

The best fuel efficiency was at 36 to 3800 rpm.

Although a lot of the hamilton 212 pumps max the rpm at 4200 rpm .

After work I will start the teardown.

Regards

Haven't torn the engine down yet this time. Removed it froom the boat this evening and the antifreeze was in the oil pan. not a good sign. last one had detached exhaust valve head. They are the severe duty series not the extreme duty. the rest of the cylinders looked a bit rich if anything. the rest...

Hello everyone, I read an old post about this same dropping valves from the jet boat motor in a 383 sbc and have experienced it twice now. Just ripping along at around 3800rpm for twenty minutes and boom. The old post was from 2011 and never did come up with a solution. Dart SHP with a scat forged c...

That spacer above looks like a great and simple addition. Does anyone have a rule of thumb of when this kind of system should be considered? Is the spring pressure the main reason or the rpm? Custom 390 SBC Comp 986 dual spring Seat load: 132lbs @1.750'' Open load: 293lbs @1.250'' On a river jet boa...

I have been reading this forum and a few others and the 10.5 to 1 compression ratio just keeps getting thrown around all the time. Who is actually driving around with this daily and where do you get the gas. A flat top piston in a sbc at 10.5 to 1 detonates continuously. Are people just not calulati...

I would be more concerned with the taper and out of round than the extra thou or two of clearance. Gap the rings correctly, as stated in an earlier post and get that engine humming. It is unfortunate that somehow they got it that far over but unless the pistons are very short like a dirt bike it wil...

Thanks for the replies. I believe most of the flow is on the bottom of the port and it matches there so I am going to run it. Just a bit of radiusing in the mismatch, clean up the casting slag, and radius the plenum divider. If it was for a high revving all out effort this would be more of a concern...

I am having some problems finding a manifold to get close to the 200cc heads I am using. the airgap rpm that came on the engine is not even close. Checked by scribing a line on the gasket and then removed the manifold. There is enought material to seal, but not enough to hog out and back up into the...