The OMC Cross Flow Thread

[Forkin' Crazy]

Your right, I'm wrong. Happy now? Oh and I never said that you said anything about a lost locater pin, but that is the only way I can see to hang a ring in a stock port. Or if your rings got caught in the port (could happen on any motor but not as likely on a crossflow), sounds like the machinist didn't champher the port when he bored it. I use to work at an OMC dealership in the early 80's for what that is worth. Well good for your dad working for OMC. How that proves your case is beyond me. I have literally hundreds of hours on OMC Xflows, but that realy doesn't mean **** either I guess. Have a nice day.

I keep looking over my post and I still don't see where I posted locating pin causing any problems. Maybe your seeing something I don't. I personally have seen a couple go down when the ring gets caught on the sharp edge of the port window in the sleeve. As for a known problem. Im just taking the word of a certified omc tech who had a brand new 235 that went down with the same problem after less then ten hours. But I suppose what the f*** would he know. Ill ask him if there was a bulletin sent out by omc on it. I also grew up on cross flows. Literally. My dad worked at OMC.

[Instigator]

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Very cool! For a 30 yr old John Deer motor That's a bit better than when you were down here.

[john j 80 viking]

I agree! I worked at OMC Engineering in the late 60's and 70's when they came out with that d*** ring. Run them high, run them low, they are a port grabber. They will run longer if you raduis the port edges. Just my .03 worth.

I have to agree with Forkin on this, if it was a problem it seems that it was a QC problem.

Also, have you seen the port shape in the 9 pages of performance (modifications to omc 235 - v6 engine)

I tried to search for the 9 pages, no luck. Can someone post a link?

[Forkin' Crazy]

Also, have you seen the port shape in the 9 pages of performance (modifications to omc 235 - v6 engine)

I tried to search for the 9 pages, no luck. Can someone post a link?

Send me your email addy. Have it on a PDF.

[coupe]

Man, I've been waiting on this thread to come around. I got a 79 Viking with a '83 2.6L XP......been GPS 79 MPH with a 26" through hub turbo out of the box. Want to find a suitable SRX to get it well into the 80's. Was told when I bought the boat it had been 90+ with a 30" cleaver, but most dont run a cleaver on a V-pad 'stream.

Anyone got any good info on the 2.6L XP's?

[Riverman]

but most don't run a cleaver on a V-pad 'stream.

30 cleaver is my favourite prop on the Viper.

[john j 80 viking]

I know a bunch of us could ramble on for a while about your motor, but the most important things for keeping it from blowing up are always use fresh high octain fuel, correct timing, and never over prop your motor. Do a cross flow search in the tech forum and feel free to ask if you can't find what you need.

You can do way better than that turbo prop. An SRX, chopper, Mazco, or any other over hub high perf prop in the 27-30" range should easily get you into the 80mph range.

That 2.6 xp will eat up Merc 2.4's all day long.

[97mirage]

Forkin...Check PMs. Thanks.

[Forkin' Crazy]

It was in a gif not a pdf, but sent any way.

but the most important things for keeping it from blowing up are always use fresh high octain fuel, correct timing, and never over prop your motor.

[Instigator]

A 1983 XP 2.6 in 1986 w/a 26" Raker @ 6300 (8% slip) and 77 MPH's (indicated)
<a href="http://s290.photobucket.com/albums/ll255/Instigatorspixs/?action=view&current=conquestatspeed.jpg" target="_blank"><img src="http://i290.photobucket.com/albums/ll255/Instigatorspixs/conquestatspeed.jpg" border="0" alt="Photobucket"></a>

Same boat w/a looper.
<a href="http://s290.photobucket.com/albums/ll255/Instigatorspixs/?action=view&current=conquest.jpg" target="_blank"><img src="http://i290.photobucket.com/albums/ll255/Instigatorspixs/conquest.jpg" border="0" alt="Photobucket"></a>

Not a flow but a cleaver on a Stream.
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[john j 80 viking]

Here are the 9 pages (thanks Forkin). This isn't the first time this has been on S&F. I couldn't find it, probably because of the new format. Some great info!

Credit for this work goes to Alan Stoker.

[biohzrd]

Correct me if I'm wrong (and I probably am), but I was under the impression that when you modify the 235 according to the 9 pages above it basically tuns it into a race only type of engine. Is this correct or if one is built like this it can have good longevity aswell?

[john j 80 viking]

I am no Guru, but IMO other than the added stress from the tighter heads and the actual power increase I don't see anything in the 9 pages that would turn a 235 into a time bomb.

The biggest thing I think you could do for reliability is to use low ring pistons.

They recomend retarding the timing back to 26 or 28*, and recomend 62-6800 rpms which is conservative for a race motor.

[DavidW]

Does cutting the piston skirt cause more piston slap or any longevity problems? I asked one outboard guru about this and he said it causes no problems and offered a pretty good explanation but I still wonder.

[Forkin' Crazy]

Never had any problems. The XP/GT motors came with the piston skirts cut from the factory.