OMC 3.8 Chevy 229 block cracked

omc_parted

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So I destroyed my block on my 1981 (J170STRMC1F) by poor winterizing. Have removed everything except the short block (GM 471594) while in the boat. I literally have nothing left to hold the motor to the bell housing, yet it only moves about 1/8 inch from the intermediate. Do I have to remove the intermediate housing and the stern drive to get it out? I am at a crossroads here of either parting out the beast (1984 Cobia Odyssey 170VBR) or finding a small block that will accept my other parts. Also, heard my control cable might be worth some money as well? I had one mechanic tell me i can just move the engine about 3" forward to clear coupler/spline from motor to intermediate. I have put a lot of time into this old girl, but maybe itys time to cut my losses? My stern drive (983487) and all other parts are in perfect condition.
 

Howard Sterndrive

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I had one mechanic tell me i can just move the engine about 3" forward to clear coupler/spline from motor to intermediate.
yep. It's up to you whether you want to leave the intermediate in or take them both out together. I usually take the intermediate with the engine unless I'm refloating the boat.
I have heard of intermediate shaft splines seizing in the engine coupler but I have never had that.

If that's the case, you can remove the int. shaft out the back of the intermediate using a nice big heel bar to steadily pry. Don't pry between the engine and Int - that's aluminum and you'll break the bellhousing.
 

omc_parted

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Thanks boss. I figured putting a pry bar in the gap between engine and housing was dumb. Only a couple more mounts and a few more bolts to take out the housing. Looks simple enough :)
 

omc_parted

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Ok, looks like intermediate housing removal isn't as easy as originally thought. Engine still moves about 1/8" from bell housing and thats all. Do I have to shift the throttle to forward to release the motor from housing? Read that on some blog somewhere.
 

omc_parted

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Engine is out, got a replacement block from a 83 Malibu :) and am ready to rebuild. I'm thinking replace all bearings, cam, crank, and switching the cam from the old OMC to the new Chevy. Anything else I need to be aware of? Freeze plugs will be changed to brass as well.
 

Howard Sterndrive

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I'd just take a couple main and rod caps off and see what kinda shape it's in. Compression test. and then decide if rebuild necessary.
You definitely want to get the 110HP smog cam out and use the marine one if serviceable, or,
Edelbrock EDL2112 is pretty much identical to the OMC 3.8 grind if you need a new cam.
Pioneer SBC brass plug kit will work in the 3.8 for around $20 for the kit
 

omc_parted

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Update as of Oct 2014: Had crank turned, helicoiled the flywheel side, installed new rings, crank bearings, rod bearings 0 Turns pretty good, good compression.Got a gasket kit for the Malibu version. Head gaskets interchangeable? Don't want to redo this work cause of cheap parts. Brass freeze plugs installed, used the boat cam. Also, anyone know if pushrods go in one way or the other?
 

Howard Sterndrive

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if you didn't keep track of the lifters get new ones ($4 each usually). They have to go back in their original locations if reused. The FelPro or similar composite gasket with stainless fire rings will work great. Pushrods either way.
A book like David Vizard's small block chevy rebuilding good. Your local library might even have it.
 

omc_parted

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Got it all put back together, gonna first run it when the temperature here gets over freezing :) Lost my water temp sending unit, the one that screws into the block. Ordered a new one. The wire for it goes up starboard side under the fuel pump. There are a couple of holes it might go into the block, just not sure which one. Anyone know where this goes?
 

Bondo

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Got it all put back together, gonna first run it when the temperature here gets over freezing :) Lost my water temp sending unit, the one that screws into the block. Ordered a new one. The wire for it goes up starboard side under the fuel pump. There are a couple of holes it might go into the block, just not sure which one. Anyone know where this goes?

Ayuh,.... Welcome Aboard,.... Water temp senders are usually mounted in the T-stat housin',...

Sometimes the Oil Pressure sender is mounted down low, portside, aft corner, by the oil filter boss, on the block's rail,...

The hole will have water behind it, if a water temp sender, 'n Oil behind it, if the oil pressure sender,...

Either way, use pipe dope, not tape,... they ground through the threads,...
 

omc_parted

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Found it. Turns out I painted it when I cleaned up the intake manifold. Directly under the thermostat housing by number 2 cylinder. Thanks guys :)
 

K-2

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I'm curious, why couldn't a guy put in a 4.3L instead of a 3.8L . ?
 

Howard Sterndrive

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In 1986, GM changed the 4.3 crankshaft bolt pattern, so a 1985 1/2 to 1986 1/2 4.3 is all that will work with the stringer coupler. And although not that rare, that specific early 4.3 is really hard to find amongst mountains of incompatible 4.3's that came after that date. Like finding a needle in a stack of needles.
The 229 probably no easier to find, but you spend less time going to look at wrong donors people want to sell you.

The other thing is the 3.8/229 exhaust manifolds won't clear the valve covers on a 4. 3
 
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K-2

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Good to know!
I figured there must be reasons, it seems like such an obvious swap.
 

omc_parted

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Apparently, there was a short run on this particular engine, starting in 1980 and ending in 1984. Also, VIN had to be a "9" or a "K" version so as not to get a Buick motor by mistake. The cost of new exhaust manifolds to use a 4.3 was around 1000$ too. So all I did was find the compatible block from an old Malibu (same block, different cam, freeze plugs, etc... Cost was only 200$, but shipping was 250$ :) Long story short: Engine is now ready for 1st run (when the freezing weather stops). Will post pics, etc...after run. All you posters here really helped me get this put together. Probably gonna replace some stringers, transom as well, due to rotten wood at the mounts, etc.. Want to have a strong frame to handle this massive power :)
 

omc_parted

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Speaking of exhausts, turns out I cracked mine too. Both SB and Port. Gonna get them welded tomorrow cause finding these is dang near impossible, plus finding ones NOT cracked is unlikely. No JB weld here. Gotta get it right cause this is a one shot deal :)
 

Bondo

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Speaking of exhausts, turns out I cracked mine too. Both SB and Port. Gonna get them welded tomorrow cause finding these is dang near impossible, plus finding ones NOT cracked is unlikely. No JB weld here. Gotta get it right cause this is a one shot deal :)

Ayuh,..... Weldin' cast iron, rarely goes well, 'n ya end up epoxyin' over the welds anyways,....
As the iron cools, it cracks again, right next to the welds,...

And,... Are ya SURE they aren't cracked, Internally,..??
 

HT32BSX115

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Speaking of exhausts, turns out I cracked mine too. Both SB and Port. Gonna get them welded tomorrow cause finding these is dang near impossible, plus finding ones NOT cracked is unlikely. No JB weld here. Gotta get it right cause this is a one shot deal :)

Don't get yer hopes up on this set-up surviving........

If you experience a hydrolock after your first "run"............it'll be evidence of internal cracks. The manifolds fill with water up to the risers(the "definition" of a "riser") .

When you shut-down, the water level slowly drops but any internal cracks will allow water to run directly into open exhaust valves that remain open after the engine stops turning. (AND if they're hot, they'll warp when the water hits them!!)

Not only would I NOT waste any time using old cracked manifolds, but I wouldn't even attempt to weld them.

(it's like trying to weld "un-weldable" aluminum alloys......you don't even try!) ............Cast iron can be welded but unless you have a furnace to heat the casting and hold it at the right temp, it ain't gonna work............ (and welding inside a jacketed casting is just about impossible)


Good luck,


Rick
 

omc_parted

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Doesn't look like an internal crack. Ran water thru them attached to heads and no water in exhaust port. Talked to a welder, he said he don't even mess with these cause they crack again. Dammit! Anyone know if the aftermarket manifolds will fit?
 
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