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Thread: Big bore crossflow rebuild
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05-23-2020, 01:49 PM #1
Big bore crossflow rebuild
I am rebuilding a 1990 Evinrude XP175. #3 piston badly scored, and the rest just scuffed. Ended up boring 5 holes at .030, and the #3, at .040 over. The block was already at .020". The pistons that I ordered are cast WSM, with rings, and pin. I haven't found much information on here about the WSM. Any opinions, or set up tips?
This engine came with 638/39 heads, also. Thanks.91 Seaswirl 178 spyder sport. Evinrude XP175. (59 MPH, so far, and so close).
85 Sleekcraft SST , 225 Johnson...(sold)
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05-24-2020, 06:17 AM #2
Wsm is a great product, havent heard of a piston failure yet
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05-24-2020, 10:27 PM #3
Cooling system must be at 110% for this motor!!!! Sleeves way to thin..
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05-24-2020, 11:53 PM #4
Are the ports plunge milled or CNCed? So I guess it has no scallops in the pistons and coinciding relief cuts in the block?
You have the best heads. What carbs?
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05-25-2020, 03:51 PM #5
I am having my OMC guy assemble the block/crank,etc. Here is a picture with the #3 cyl. cover removed. Looks like a hairline crack between ports. Those sleeves will be thin, but whadda gonna do. Just an old Flow, on the stock,(5,800), limiter. The carbs are stock 1-3/8" with 63C jets, (stock is 61C). I have some 65C jets I could use from my GT150, to start with.
Has a Bob's nose cone, low water pickup. I will with start with a fresh impeller, also. Using it on a 91 Seaswirl ski boat, just to buzz around a little.91 Seaswirl 178 spyder sport. Evinrude XP175. (59 MPH, so far, and so close).
85 Sleekcraft SST , 225 Johnson...(sold)
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05-27-2020, 05:21 PM #6
Those are plunge milled. Unless you want to spend sometime on them squaring them off, it will run fine. With that boat, I would bother with it. I usually use larger mains on break in. Just don't put too much timing in and premium fuel only and you'll be good.
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05-31-2020, 01:34 PM #7
What's wrong with my boat? OK, I agree. I'm going to give it a shine this month, though. The WSM pistons came in, but my OMC guy turned up his nose at them. I guess we are supposed to run Wiseco.forged.
I hope the boring guy kept it right at 3.625+.030=3.655" , and #3 cyl.at 3.665". The +.030 pistons measure 3.6486". If the machinst thought it was getting wiseco's, it might be a couple thou big.
Last edited by z1rider; 05-31-2020 at 09:40 PM.
91 Seaswirl 178 spyder sport. Evinrude XP175. (59 MPH, so far, and so close).
85 Sleekcraft SST , 225 Johnson...(sold)
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05-31-2020, 09:05 PM #8
Ummm. If its machined for seizcos then use them , ( I think they alot better now days) if bores r correct and good good break in , but dont knock the wsm. Just sayin
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05-31-2020, 10:01 PM #9
I won't be happy if it was bored for wiseco's. I'll be stuck with $500 worth of WSM ashtrays, and I don't smoke! I am keeping my eye out for another big bore block, or complete 20" 175-235 flow, etc. But first I'll wait and get the results on my piston clearance. I still have a 91 Johnson GT150, with a good powerhead, but the rest got torn up pretty good from a submerged log... . I need to make it complete, as a spare. Why am I spending time, and money on all this old stuff? It's the principle now. Breaking equipment, and not making right again feels like a personal failure, even though it probably doesn't make sense to most people.
91 Seaswirl 178 spyder sport. Evinrude XP175. (59 MPH, so far, and so close).
85 Sleekcraft SST , 225 Johnson...(sold)
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06-01-2020, 10:17 AM #10
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06-02-2020, 07:58 AM #11Scream And Fly VIP
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If he bored it to 3.665 it is way too loose for a .030 over piston no matter what brand. That size needs a .040 over cast.
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06-02-2020, 01:29 PM #12
Number three cylinder, ( the bad one), was bored .040 over, and the rest cleaned up at .030" over. The block was already at .020". The .040 piston measures 3.6587".
I should have mentioned that one .040 piston in my earlier post. I haven't heard anything about how they fit, yet.91 Seaswirl 178 spyder sport. Evinrude XP175. (59 MPH, so far, and so close).
85 Sleekcraft SST , 225 Johnson...(sold)
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