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Could use a little help with new project...

wca_tim

Active member
A long post, but would really appreciate any thoughts you might have...

I picked up a new toy / project yesterday (pics below) and would love some advice / input if you have any. I've never touched an I/O drive boat before, but have built or rebuilt cars, street bikes, and outboards in past lives as well as done some paint and body work and a little glass work. One of the reasons I felt comfortable taking this on was the great information I found while digging around on here - Thanks to lots of you for taking the time to explain things so clearly. There is a lot I wouldn't have had a clue about that now seems pretty clear how to proceed.

Background: It was apparently kept inside for a good bit of it's life excet for sitting outside for the last 8-10 months. The upholstry is in fairly bad shape, but the foam is still firm and complete and although the wood is a bit soft in places. It's a 1988 Diplomat I/O that came from the factory with Chevy 4.3 L v-6. I bought this boat for little more than a new prop would cost, but had to deal with changing tires and redoing a wheel bearing under the watchful eyes of the guy's pit bull - growling at me through an awful thin-looking chain length fence. The original engine is in pieces but, but everything seems to be there. The Alpha one drive turns freely, goes into and out of gear easily by hand, doesn't feel tooo sloppy, and had reasonable looking lube in it (no chunks of scary looking metal, etc...). The boat was run last year and was serviced by a local mechanic at the beginning of the saeason. The owner apparently ran it until it died, tore it all apart and then parked it behind his garadge thinking he was going to put it back together. From what I can tell the floor wood, hull, etc... are all structurally sound. I was looking for something to play with on the weekends and that I could start teaching my 12 year old daughter to slalom behind, maybe take up wake-boarding in the afternoons, etc... Way too much water here to go much longer without another boat...

First priority is power. This is a place I could really use some input. I've had a bunch of outboards, but never in I/O drive before. I'm thinking crate motor from one of the shops that does marine engines. The heads I have were redone last year and look fine, but if I can get a long block without spending too much, I'd rather not mess with a rebuild. Moving things around and going with a 350 is tempting, but it'd be more work than I want to do right now and I gotta be reasonable about the budget (have a daughter that would probably like to be a ble to go college in a few years). Would also like to get it put together and enjoy time on the water this summer. At this point with the looming reality of $4 and higer per gallon for gas, seems to make a lot of sense to go with a consergvative 4.3 and the factory heads, cam, intake, carb, exhaust layout, etc. for starters. Any recommendations on Engine shops to check with? Mods / upgrades I should consider? Anything to watch out for? I'm in Eastern North Carolina.

Biggest worry / question beyond engine is the exhaust manifolds. One of them was cracked on the outside and was brazed (we're talking 5 or 6 inches -maybe owner let it freeze?). From what I'm reading a water leak can be a major problem. Would be easy to imagine that if that bad on outside, might also be cracked on the inside. Given that the engine weas blowing headgaskets and getting water / piston damage to one or two of the cylinders on that side (twice apparently and once even after new head was installed. Owner was told after last time that there was probably a casting flaw in the block that was causing the problem???), seems like it might not be a bad idea to replace the cracked one at a minimum. If I'm gonna do that, I'd also consider making any other modifcations that make sense to exhaust now as well.

I've got a good sense of what do do for the badly oxidized gelcoat from previous posts. Played with it a little last night with some standard rubbing coumpound and then polishing compound. Even though there some significant oxidation, it's probably never been touched before and can still find areas with facotry orange peel - Lots of clear coat left and metalflake looks miles below the surface. Plan to gently wetsand with ca. 1200 grit, then go to Aqua-Buff and once happy that oxidation is all gone I'll try using Starbright w/Teflon marine polish. There are a few dings and scrapes that I'll seal with epoxy for now just to be sure (will have ot reread to see which type is best), and then worry about doing anything more involved on the bottom half of the hull This Winter.

Finally the upholstery: Once I get the power figured out, I'll see what new skins from checkmate would cost (have the phone number from previous posts. based on comments from others, this seems like the best option). If they fit in the budget after ordering an engine, I'll do the wood myself (realy like the idea of coating marine plywood with resin). The foam is in pretty reasonable shape from what I can see so far and should do fine. If the skins don't fit into the budget, I might try my hand at making them myself (yea, I got a sewing machine and ain't afraid to use it...). I haven't found any soft spots in the floor yet and the carpet looks like it'll clean up pretty well so I'll avoid tearing into that this year.

Assuming ya got this far, thanks in advance for any input / direction!!
 

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Welcome to the board. Boat looks to be in good shape. You should have not trouble bring the finish back. As far as the engine goes I can't help much. I'm an O/B guy. I am sure there will be someone along that can help.
 
Anything to watch out for in Eastern North Carolina ?

How about Black Bear & Cotton Mouth's ! :yell:

There are some guy's on this site that have the answers your looking for. I bet it don't take long.

Welcome to the board .
 
If you are using Aqua Buff, then 1000 grit is the finest grit I would bother with. I've seen Aqua Buff, take out 600 grit scratches.

Me, I would wet sand with 400, 600, then 1000. Then Aquabuff.

If you are using the new Hookit Dry sanding disks(for a DA) like I've been using latetly, then hit it with 400, 600, 800, 1000. Then Aquabuff.

I end up using both of these methods any more, the wetsanding for the details, and the DA for places where the speed will really help.

I used to be dead set against using DA, but with new technology in papers and pads, these aren't the grinders that they used to be. AND with the Hookit papers, you can actually stick paper back onto the pad. THAT alone makes the paper worth the SMALL extra cost over the stick on stuff.
 
I think I'd be scared to go with da.... I'm already a little leary of taking too much off - don't have a feel for it at this point. Did a little more today with 800, then 1200 then polishing compound at high rpm with good 3m wool bonnet... (what I had on hand) and the part I did looks GREAT!!! Also did a good job scrubbing everything out and organizing the pile of parts in the engine compartment and on the floor. Once I got all the oil and crap out of the carpet, etc... It is already starting to look a lot nicer than I thought it was! and loks pretty clearly based on mercruiser manual that all the parts are there... heads and manifods don't look bad at all on a closer look, valves even in decent shape. Think I'll run the heads and block by the machine shop this week and see what they think. Who knows, may just do shortblock with good crank and pistons and think about mods or even different engine this winter... Would easily be on the water in a couple weeks... Anyhow, Thanks for the heads up, if I get in a little bit of a hurry I'll try the da...

I may post the power question on the engine board later... would be interested if anyone has experience with rebuilt or even new 4.3... Based on searches seems like I could get a long block for under 1500... if decide to go that route.

Cheers!!!

ps. black bears I kin deal with - they tend ta run when ya walk up on em in the pocossan... If ya get close enough to see em at all... cottonmouth is a whole different story!!
 
Throw both manifolds and risers in the trash. glm aluminum are lighter and reasonable at about 600.00
sometimes less on e-bay
the "headgaskets" probably were manifold leaks all along.
I love the 350 in my diplomat, but we started from a 4 cly and had to build allthe stringers from scratch to mount it.
 
I caught the message on the manifolds loud and clear - both above and on a number of other posts. Although, exhaust interiors look carboned, not rusted, and valves on the heads look fine.... I also measured and looks like shoe-horning a healthy 350 in wouldn't be too tough a proposition, but would reqiure major investments in exhaust, etc. in addition to the engine. The math on weight for smallblock with a different exhaust, aluminum intake, etc... was pretty clear also.

I'm thinking that for this year i'll probably go with new reman v-6 4bl and new stock exhaust manifolds. should keep my total investment under $2k and from what i'm reading maybe put me somewhere in the 50's with the 23 pitch ss prop that's on it. plenty for skiing, boarding and playing on the river for the time being.

The gelcoat is coming along. I've not had a lot of time to work on it right now, but hitting it a little here and there. beautiful deep black with silver metalflake. It's a cryin shame when someone let something like that go so far.... must have been a work of art when it was new.

Any advice / experience on where to order engine from?
 
exhaust will cost the same for v6 or v8
make sure engine builder really builds marine engines...ie stainless flame rings on head gaskets, brass expansion plugs, forged internals, marine grind cam
is yours a 4bbl now or 2bbl?
 
btw we are getting 69mph on gps with a 4 blade 22p ski prop with the 350 in our diplomat. My son bought the short block on e-bay for 169.00 and we spent 300.00 on a set of rebuilt heads. my manifolds were not cracked so we had all of the gasket surfaces milled flat at our local machine shop to cure all of the leaks we had.(local mech told us we were blowing head gaskets but it was the manifolds leaking inside. shortblock is forged 350 with 4 valve relief flat top pistons. the only thing the seller did not know what the spec's were on the cam. It sounds like a dragster with the thru hull exhaust( I love It).
 
currently has 2bbl config.

Definately will be sure on marine config!

On manifolds / exhaust, assumed that if I just replace the stock v-6 manifolds with new, I can get both for about 250. to go to v-8 or even magor ,mods to v6 wouldn't I have to upgrade the entire exhaust
? Was thinging that if swapped to v-8 longer term would want to go with through hull exhaust set-up to get reasonable backpressure and would want some kind of noise control... (love the sound of an uncorked v-8 with a good lope to it - one of my favorite sounds... but not really sure i want to have to talk over that all the time when we're playing on the water... or attract that much attention... although with the Fountain guys always out playing, anything I migh do would be quiet in compariso!).

I spose on the cheap, I could go with shortblock or lower end rebuild, new exhaust manifolds, and use the heads that I've got (haven't had em to machine shop yet, but they look really good overall - the valves aren't burned or warped and the seats / surfaces look good to me. the more i read and thin about it, the more convinced i am that the problems the previuos owner had were mainly from leaks in exhaust manifold(s). Oh, and would need a cam too... he left that laying on the seat to rust(?!).
 
Head Pictures...

Here's what the combustion chambers look like...
 

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Risers are the same, but if you do not replace them take them to a machine shop and have them true up the gasket surface on a belt table sander or something. Intake and exh manifolds cost roughly the same for v6 or v8
you would need a v8 distributor and wires. the mounts should work, might have to look into that. I had a local exh shop bend two peices of 3 inch pipe into s-bends to match cardboard templates and used a 3 1/4 hole saw. beveled outer edge, sealed transom with 2part epoxy and used flax packing with 3m 5200 sealer and trim rings to finnish exhaust. put rubber flappers on pipes to help with water reversion. I have thought about making some homemade silencers with vegetable cans but I love the sound.
 
pistons and cams are available for the 4.3, just make sure the cam has min 110 lobe seperation and pref. 112 to 114.
go with forged flat top 4 valve relief pistons, 460 480 lift cam, alum. intake, 600 holley v6 should make lots of powr
On the holley 750 double pumper we are running, the powervalves have been removed and blocked off, and primary jets went up to 76's(4 sizes)-choke airhorn had been removed previously-dont know what diff. has made, but the boat starts with about 3/4 turn of the starter every time. Idles all day pulling skiers pulls like a freight train. will put your back into the seat from almost any speed.
 
Only reason I suggested the GLM brand aluminum manifolds and risers is for the weight reduction over the cast iron manifolds that are on it now.
I will probably have to replace mine next year and will go with a set of them myself.
 
sorry, one more thing. when we put the v8 in it, I did not have a y-pipe so we made a block off plate out of 1/4 in aluminm plate and bolted it on to the transom unit.
88 should have 4 inch outlet risers, and the rubber couplers reduce that to 3 inch to the y-pipe.
88 v-6 cam lift was only 3.95 int. 4.04 exh wold not take much to improve on that.
 
4.3 v6

i saw a complet 4.3 mercruiser on ebay last week complete engine and alpha drive. was in michigan but was only 1200.00
 
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