advice on 4.3 rebuild

[snowman4evr2012]

Hi, so we just got this 1988 boat, and supposedly it just needed a head gasket but while troubleshooting it after pulling intake we found the block cracked in the lifter valley. Its a solid boat with fiberglass floors and is in what i would consider fairly good shape. Engine is showing 1200 hours. So just acquired a running 1989 tbi 4.3 out of a van. We plan on swapping everything over from the omc to this engine after we freshen it up a bit. Just wanted to see if we could get some advice from an expert, as we are not. Iam an electrician not a boat mechanic! Anyway here's what were thinking, and the many questions I have on this endeavor. We aint got a whole lot of money to invest in this as it was unexpected to say the least.

Have old omc heads rebuilt-- By rebuilt i mean by a professional not myself. Iam thinking new valve stem seals / 3angle valve job? anything else?

Any ideas on the best rebuild kit / gaskets we should use?

Should the pistons / cam be replaced, or swaped over from the omc to the van motor?

New timing chain

I want new lifters

was thinking about swapping out the factory freeze plugs for brass, but is this necessary for freshwater use only?

Of course was gonna give it new cap,rotor, points, plugs, wires, etc..

 

[Scott Danforth]

Strip the van motor down to a long block, because that is all you can use.

Pistons are same in both motors

You will need to install brass core plugs and marine head gaskets

From there, get new marine water pump. Transfer all your marine accessories over.

Get rid of the batwing exhaust manifolds.

I personally would use a 1996 or later motor with vortec heads and a balance shaft

 

[Scott Danforth]

here is some further reading on the 4.3 https://forums.iboats.com/forum/eng...history-of-the-4-3-liter-with-casting-numbers

regarding the heads, both motors would have the same head.

Felpro makes the best gaskets short of cometic head gaskets. however your not working on a high hp big block

not sure why you would spend money on new lifters, generally not needed unless you install a new cam

 

[Lou C]

The 88 came with a roller cam/lifters and the 89 should have them too. When I took my 88 apart to replace the head gaskets and heads the lifters and cam lobes looked like new...
You will need the marine style intake from the old engine as the automotive engine intake is probably different. Compare the 2, hopefully the intake is not cracked as well. If you need another they are not that easy to find but they are out there. I was able to find a 4bbl intake in good shape for my pre-vortec '88 as a spare on ebay.

If you are replacing the OMC batwings, I had them on my engine, had 3 sets (salt water you have to replace every 5-7 seasons) and never had a leakage problem, but some have. If you want to replace what you have not to take a chance, then the Barr OMC/Volvo center riser system will fit, but you need to use the Volvo style 90* adapters (part # 12 above) to adapt the 4" elbow hose to the 3.5" OMC Y pipe. When I did mine last summer I used these 90* adapters and the OE Volvo hose which all fit perfect, no leaks and looks factory.

 

[snowman4evr2012]

Wow. Thank you so much Mr Danforth, and Lou. Sounds like I will be keeping the old lifters and cam out of the omc. Thats good news. Now since this will be a freshwater boat, would you still use the brass core plugs? Would you install new rings while I have it out?

 

[Lou C]

Yes to the core plugs, the steel ones were intended to be used with antifreeze and corrosion inhibitors , I’d stil use marine head gaskets by Fel Pro as well. Rings, that is up to you. See how the cyl walls look. The 89 probably has the roller lifter cam but the cam profile may be different, on the 88 it may be the standard marine cam if that engine is original to the boat. I dont’ know if you could use the OMC cam in the other engine, without changing the cam bearings.

 

[snowman4evr2012]

operation-remove the boat motor

 

[snowman4evr2012]

Any one know what these are? So I tore down the motor today and it was busted on the outside as well. Both exhaust manifolds were also busted on the bottom. (and the guy we got it from said it just needed a head gasket, yeah right) Can those be welded or should they be replaced regardless? Also noticed the engine block out of the boat had a 867 stamped on it? It did have roller lifters for what thats worth. Engine we got to replace it has a 887 stamped on its block.

 

[Lou C]

flappers, see my response on the hull truth

 

[tazzerblue5]

Hows your swap going? I'm looking at doing the same, have a 1996 maxum with cracked block. I bought it that way. I've found MABBCO out of Tyler TX. has a pretty good price on short blocks and LB. Just wondering which way to go.. How did your turn out?

 

[snowman4evr2012]

hi tazzer. sorry but just now seen your post. The local napa machine shop still has my block but iam picking up another today. tired of waiting. ill just have a spare i guess. Imho there are two ways to go, buy a longblock ready to go or tear yours completley down and find a doner block from a scapyard and use everything from yours and rebuild your own. iam peretty particular and want mine done right. you dont know what your getting when you buy a longblock in case you spend mega bucks.

 

[kpg7121]

hi tazzer. sorry but just now seen your post. The local napa machine shop still has my block but iam picking up another today. tired of waiting. ill just have a spare i guess. Imho there are two ways to go, buy a longblock ready to go or tear yours completley down and find a doner block from a scapyard and use everything from yours and rebuild your own. iam peretty particular and want mine done right. you dont know what your getting when you buy a longblock in case you spend mega bucks.

That is one damn nice lookin boat. Best of luck with her.

 

[snowman4evr2012]

thx kpg.

 

[Scott Danforth]

Any one know what these are? So I tore down the motor today and it was busted on the outside as well. Both exhaust manifolds were also busted on the bottom. (and the guy we got it from said it just needed a head gasket, yeah right) Can those be welded or should they be replaced regardless? Also noticed the engine block out of the boat had a 867 stamped on it? It did have roller lifters for what thats worth. Engine we got to replace it has a 887 stamped on its block.

get new manifolds, attempting to weld up cast iron manifolds is a fools folly that will end up with an annoying leak if your lucky or a hydrolocked motor with a busted off starter if your not lucky

manfolds and elbows are cheap, so buy a complete set.