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Search found 10 matches

by nwticerider
Tue Sep 17, 2019 12:24 am
Forum: Engine Tech
Topic: another blown up jetboat motor sbc
Replies: 16
Views: 1039

Re: another blown up jetboat motor sbc

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?
by nwticerider
Tue Sep 17, 2019 12:14 am
Forum: Engine Tech
Topic: another blown up jetboat motor sbc
Replies: 16
Views: 1039

Re: another blown up jetboat motor sbc

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...
by nwticerider
Wed Sep 11, 2019 6:17 pm
Forum: Engine Tech
Topic: another blown up jetboat motor sbc
Replies: 16
Views: 1039

Re: another blown up jetboat motor sbc

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
by nwticerider
Wed Sep 11, 2019 1:49 am
Forum: Engine Tech
Topic: another blown up jetboat motor sbc
Replies: 16
Views: 1039

Re: another blown up jetboat motor sbc

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...
by nwticerider
Tue Sep 10, 2019 4:37 pm
Forum: Engine Tech
Topic: another blown up jetboat motor sbc
Replies: 16
Views: 1039

another blown up jetboat motor sbc

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...
by nwticerider
Sat May 04, 2019 12:48 pm
Forum: Engine Tech
Topic: Anybody try valve spring oilers on a SBC?
Replies: 12
Views: 1135

Re: Anybody try valve spring oilers on a SBC?

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...
by nwticerider
Sat Apr 27, 2019 9:30 pm
Forum: Engine Tech
Topic: Real Compression Ratio Daily driver
Replies: 53
Views: 2454

Real Compression Ratio Daily driver

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...
by nwticerider
Sun Jun 17, 2018 1:18 am
Forum: Engine Tech
Topic: Engine machine shop destroyed my block
Replies: 83
Views: 10876

Re: Engine machine shop destroyed my block

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...
by nwticerider
Sun Mar 18, 2018 1:27 pm
Forum: Engine Tech
Topic: Help with manifold matching
Replies: 21
Views: 2967

Re: Help with manifold matching

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...
by nwticerider
Sun Mar 18, 2018 12:32 am
Forum: Engine Tech
Topic: Help with manifold matching
Replies: 21
Views: 2967

Help with manifold matching

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...