383 stroker longevity
 

Im looking to see if anyone has real world experience with the longevity of a 383 stroker.

The engines ive been running are the 400HP Mercury reman stroker scorpion Bravo and the rev limiter is set at 5950rpm. They have not held up whatsoever. I think a lot of that is due to Merc quality control.

I am having a new 383 short block built. Im using a Dart SHP block, eagle 4340 forged crank, Eagle 5.7 H beam rods, Clevite H series bearings, CP forged -15cc dish pistons, CMI headers, stock cam with 0.575" intake lift and 0.596 exhaust lift, stock RHS 235cc iron heads with 2.08" intake and 1.60 exhaust valve. I am reusing the stock intake.

Seems like a lot of rpms

Stock the motor was 5600-6000rpm

What has been failing on your reman engines?

We have spun main bearings twice, burned a hole thru head once. One block had oiling issues where it was coming out of the dipstick which we never could solve, both of them sounded like desiels and would have way too much slop in the Pistons and rings. It was tone of issues. Also they come with a 100psi oil pump which I wasn't sure why.

That combo sure has a ton of cylinder head and cam lift for only 400hp out of a 383.

Did anyone ever run an oil temp test or gauge on these motors while running ?

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Yeh, 100psi is over kill, but 70-80psi is not.

Let me guess, they had a standard 4-5 quart oil pan on this engine ? LOL.

4qt oil pan. I just bought a canton 8qt for my new motor. The motor ran with a 147 degree thermostat. It has an oil cooler as well.

Sounds like detonation and blow by,

^^^Sure does^^^

And the dam oiling system not up to snuff either. Longer stroke crank. 4 quart pan with 5900-6000rpm limit.. hahahahahahahah. Dumb Merc.
Whipped up oil would love to know the temp it ran at. ...maybe not.

Merc calls for minimum 91 octane. They only sell 90 here. Could that be contributing to the detonation?

247hrs on 383. #14010207 block casting. .040" bore. Eagle forged crank, 6" rods, mahle 4032 flattops. Melling #10555 oil pump. Hamburgers 7qt marine pan. With oil cooler/remote filter setup total oil capacity was 9qts. Block cracked in lifter valley above #3 cyl. Never overheated. Bores. Pistons, bearings looked great upon teardown. Would have ran hundreds more hours.

Rebuilt with a Dart SHP block. Used a Melling #10552 pump as Dart does not want a HV pump on the blocks with the priority main oiling. This engine had breakin time when I sold it.

Interesting about the HV oil pump on a dart block with priority main oiling. I'll look u to that. Do you know the reason?

What was your max RPM on that motor? Most of the time I'm idling around a sandbar but sometimes I would do wot for 10-20 min at a time maybe 2 times a month.

It's right in Dart's tech papers that come with the block. Priority main oiling and HV pump is Not recommended or needed. WOT rpm of that setup was 6000-6200. Rev limiter 6400. With my setup, big pan, 9qts oil, oil cooler, oil temp would pass 230+ after 5 mins WOT. No wonder your burning up bearings running 20min at WOT on a stock setup.

Ouch, those poor bearings. What size cooler and oil lines are you running?

Hi Performance Coolers

I have the 807371T1 MERCRUISER OIL COOLER. It's what came stock. It's 10" long.

Too small for running WOT any length of time. Mine was a 2x18" dual oil/ps cooler and you see my temps after 5 mins. You need a 3x18 at minimum for those WOT runs. Though it may be too big if your just cruising and oil temps may not get hot enough. That's were a tstat controlled cooler is optimum.

Just gave our parts to the engine builder and the 1st thing he noticed was the flywheel was externally balanced which was probably causing some of the premature failure as this flywheel came with the 1st of three 383 strokers Merc sent us. he is going to internally balance it. the 2nd thing was the OEM balancer wasn't any good. we are now switching to a ATI balancer. also he recommended a better oil cooler as some of you had suggested.

Some 383's are external some are internal balance. If the damper was moving around on the hub the timing could have been way off causing the detonation which would take the bearings out along with pistons and rings, which could cause the blow by that was pushing the oil out of the dip stick. Just a thought.

ok, you need to address many issues, oil lines, cooler, filter adapter and oil temp gauge, larger pan as you said you are getting. tune with wideband, from what you were doing amounted to the pull and pray tech. killing mains came from oiling(brakedown, contaimination, etc) or poor engine assembly(clearances, line bore etc, burned piston, way lean or timing issue. Just helped a guy with 454, killed 2 remans in no time, said had noise, asked about timing, said set to specs..8 deg, what he did not know was had 30 deg advance...38 total in heavy boat did not work well.

My timing is not adjustable. My distributor isn't actually a distributor, its a high voltage switch. I have the pcm 555 and timing cannot be changed. However poor engine assembly was definitely an issue. I also found out the externally balanced flywheel was for a BBC, not sbc.

What would you recommend for a oil temp gauge on a sbc?