The OMC Cross Flow Thread

[john j 80 viking]

Ok my White Motor Brothers, I want to discuss anything Cross Flow related.
Such as

.Top speeds
.Set ups
.Tuning
.Trouble shooting
.Performance tips
.Parts finding, sharing or trading
.Experiments whether successful or not
.Racing history
.Post pictures

I'll start with a question and a secret.
Question.
How fast would a modern high performance hull like an Allison or an STV go with a relatively stock 235 (just the usual bolt-ons)?

Now the secret.
This is my second year running my 235 with no top ring in a piston. The lip above the top ring broke off of a high ring piston and the ring broke off when it went by the port, so I moved the piston so the ring was in the exhaust port and fished the rest of it out. Now I only have a bottom ring on that piston. The good part is I still have 110lbs compression in that hole and I still see upper 80's w/ my Viking!

This is not the first motor I have done this with and I plan on fixing it this winter with a low ring piston.

[Da Bull]

I always wanted to take one of those second effort mod-vp stage 1 2 3 or something like that and resleeve it to the same size as a 3 liter looper OMC. Pistons would have to be made but i can`t help but wonder how it would perform. I drove an Allison XR2002 around 1987 or so with one of these motors at 2.6 liters (stock) and it was very impressive for the day.

DB

[john j 80 viking]

I couldn't remember if Land and Sea offered a big bore conversion for cross flows. This is from the 1995 Land & Sea catalog. Some usefull information, hope nobody minds.

[terry taylor]

Please tell us your prop pitch and rpm. to reach upper 80, s thanks.

[john j 80 viking]

Please tell us your prop pitch and rpm. to reach upper 80, s thanks.

Top speed so far is 87.6mph/gps @ 6500rpms. Thats with a 30p inline chopper that I recently aquired. My old top speed with another 30p inline chopper that I got with my boat in 1997 was 85.7mph/gps @ 62-6300rpms and that was in optimum conditions. I ran 87.6 in poor conditions, warm temps, sticky water, and 30-40lbs of gear in my boat, so I think 90mph may be within reach .

I took a close look at both props, they both have the same part numbers. My old one has the line cutters, and the cup runs from the trailing edge of the blades, all the way around the tip, almost to the leading edge of the blade. My new prop has much thinner blades and the cup is only on the trailing edge of the blade, it stops right where the blade starts to turn round.

One thing I noticed while driving the boat whith the old prop is when at or near top speed the boat would continuously climb then touch down, like a very slow porposing
motion. The new prop seems to carry the boat well and is more predictable.

[Forkin' Crazy]

1990 XB 2002 CompPro (cut down lip), 10" set back, 2.6 GT bone stock less Boyesen reeds, solid mounts, Bob's cone and torque tab (even still has the complete air box) with a unworked 29" SRX. 94.9 GPS at 6800.

2001 SS 2000 Excell (cut lip), 10" set back, 80 235 light porting, V stacks, gold fly wheel, Boyesen reeds, solid mounts, ??? cone, weld on tab unworked SRX 94.2 GPS at 6800.

[Bartyparty69]

The cross flows are known for snagging rings on the port windows. As a mater of fact I am fixing a 90hp for a friend of mine that snagged a ring last week. The key is to bevel the port windows when you rebuild it. They last a lot longer.

[Forkin' Crazy]

The cross flows are known for snagging rings on the port windows. As a mater of fact I am fixing a 90hp for a friend of mine that snagged a ring last week. The key is to bevel the port windows when you rebuild it. They last a lot longer.

Really? I say bull****. Never happened to me and I have run Xflows since I crawled in a boat… Had a few blow… never a locating pin that would cause a loose ring.

[Forkin' Crazy]

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[Forkin' Crazy]

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Any one?

[john j 80 viking]

1990 XB 2002 CompPro (cut down lip), 10" set back, 2.6 GT bone stock less Boyesen reeds, solid mounts, Bob's cone and torque tab (even still has the complete air box) with a unworked 29" SRX. 94.9 GPS at 6800.

2001 SS 2000 Excell (cut lip), 10" set back, 80 235 light porting, V stacks, gold fly wheel, Boyesen reeds, solid mounts, ??? cone, weld on tab unworked SRX 94.2 GPS at 6800.

Thanks Forkin, been wondering that for a long time.

[john j 80 viking]

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Any one?

The coolest sound in the world!

[john j 80 viking]

From this morning.



I want to be in the 90mph club really bad.

[Bartyparty69]

Really? I say bull****. Never happened to me and I have run Xflows since I crawled in a boat… Had a few blow… never a locating pin that would cause a loose ring.

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.

[194268]

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.

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.