1972 Cobalt Ski Boat

[Andy3]

Re: 1972 Cobalt Ski Boat

Going to pop the intake manifold off tonight and see what surprises await me under there. I'm dreading having to pull the engine out, but it's becoming very clear that the inside of this engine is pretty nasty. I've attached a few pics.

 

[Bondo]

Re: 1972 Cobalt Ski Boat

Going to pop the intake manifold off tonight and see what surprises await me under there. I'm dreading having to pull the engine out, but it's becoming very clear that the inside of this engine is pretty nasty. I've attached a few pics.View attachment 116045View attachment 116046View attachment 116047View attachment 116048

Ayuh,.... Ya might as well yank the whole motor out,...
It's easier to work on, on a stand...

That motor needs Serious help...

 

[Andy3]

Re: 1972 Cobalt Ski Boat

Well, after removing the intake and searching diligently for a crack and not finding one, I started getting excited. Removing the heads and finding problems with the head gasket on the starboard side, which had given me the low compression readings, I was sure I wouldn't have to pull the engine. However, drained the crankcase oil/water this morning and everything but the kitchen sink came out with it. Lots of thick sludge. I can only imagine how clogged the oil pick up is. Also, while trying to locate the petcocks on the block, I found one missing petcock with a very rusted hole, one missing freeze plug with a VERY rusted hole, and one loose freeze plug, as if someone had attempted to remove it. All in all, I think someone's trying to tell me something. I'm planning on planting a couple of posts on each side of the boat with a beam across them to attach a hoist to. Any good sources for an economical rebuilt for this thing?

 

[Bondo]

Re: 1972 Cobalt Ski Boat

Well, after removing the intake and searching diligently for a crack and not finding one, I started getting excited. Removing the heads and finding problems with the head gasket on the starboard side, which had given me the low compression readings, I was sure I wouldn't have to pull the engine. However, drained the crankcase oil/water this morning and everything but the kitchen sink came out with it. Lots of thick sludge. I can only imagine how clogged the oil pick up is. Also, while trying to locate the petcocks on the block, I found one missing petcock with a very rusted hole, one missing freeze plug with a VERY rusted hole, and one loose freeze plug, as if someone had attempted to remove it. All in all, I think someone's trying to tell me something. I'm planning on planting a couple of posts on each side of the boat with a beam across them to attach a hoist to. Any good sources for an economical rebuilt for this thing?

Ayuh,.... That someone was most probably Ice...

Ya need another motor, not a cheap rebuild kit....

 

[Riegfrghtl]

Re: 1972 Cobalt Ski Boat

Best bet would be to try to find a long block of same year or close to so that you can reuse many of the parts such as fuel pump, valve covers, oil pan, intake manifold, etc.

 

[Riegfrghtl]

Re: 1972 Cobalt Ski Boat

Rapido marine has 302 long blocks for around $1350.00

 

[Andy3]

Re: 1972 Cobalt Ski Boat

The intake will have to be replaced as well. The edges of the water passages where it mates to the heads is corroded and chipped off. As well as the thermostat housing and cover. My economical project isn't going to be so economical.

 

[Bondo]

Re: 1972 Cobalt Ski Boat

My economical project isn't going to be so economical.

Ayuh,... yer learnin',..... Cheap boats are NEVER Cheap....

 

[Andy3]

Re: 1972 Cobalt Ski Boat

So far, I've only spent the $500 for the boat and trailer and maybe $28 for the manual. At this point I can either sell it to get my money back and look for something else or proceed with replacing the engine. Any advice?

 

[Bondo]

Re: 1972 Cobalt Ski Boat

So far, I've only spent the $500 for the boat and trailer and maybe $28 for the manual. At this point I can either sell it to get my money back and look for something else or proceed with replacing the engine. Any advice?

Ayuh,.... Generally speakin',...
Fords cost a 'ell of alot more to work on, 'n Stuff is harder to find....
Finding a project powered by a Chevy, 'n an Alpha 1 or newer is easier, 'n cheaper in the long run....

Not that boatin', 'n fixin' boats is Ever cheap....

 

[haulnazz15]

Re: 1972 Cobalt Ski Boat

Ayuh,.... Generally speakin',...
Fords cost a 'ell of alot more to work on, 'n Stuff is harder to find....
Finding a project powered by a Chevy, 'n an Alpha 1 or newer is easier, 'n cheaper in the long run....

Not that boatin', 'n fixin' boats is Ever cheap....

Will have to disagree on the Ford vs Chevy argument. The Rapido (or any other company) marinized long block can be found for $1200-1400, just the same as an SBC. The carb is the same assuming 4bbl (600cfm) for either Ford or Chevy, the intake is roughly the same cost if going with an aftermarket unit like an Edelbrock. Really, the only thing that can be more expensive for a Ford powerplant is the exhaust manifolds, and if you get center-risers, they aren't significantly more expensive than the GM counterparts. He can be back up and running for somewhere in the ballpark of $2200-2500, just the same as if he had a cracked Chevy block. The difference will be that he wouldn't have to find a worthy outdrive/alpha I setup and go through the hassle of installing a new transom assembly.

Not that there isn't probably a lot of maintenance needed on that boat as-is, but I don't think it would be any cheaper to go GM than to stay with the Ford. I've never heard of a Ford being more expensive to work on from a mechanic's stand point. Heck it should be cheaper since that dizzy and all of the major components are accessible from the front!

 

[Andy3]

Re: 1972 Cobalt Ski Boat

I'm leaning towards replacing this engine and putting new exhaust manifolds on. At least this way, I will know exactly what I have. While I have the engine out, and have good access to the transom, is there anything I need to do while it's easily accessible? I'm thinking replace the sump pump since I have no idea how much life is left in this one, and they're inexpensive. Other than a good cleaning, what should I look for? Is there a seal/gasket that seals the exterior transom plate (not sure if I'm using the correct terminology) to the transom? Is this an item that usually fails, leaks, etc?

 

[haulnazz15]

Re: 1972 Cobalt Ski Boat

Well, if the sump pump works, I'd leave it. They're not difficult to change out in most boats, even when underneathe the oil pan. I wold strongly suggest that you replace manifolds AND risers. Risers are more prone to failure, and it would give you a chance to move up to the center-riser conversions which is much more economical in the long run. I wouldn't worry about the transom seal (outside the boat in between the the transom and outer housing. It's likely a cork gasket and if it isn't broke, don't fix it. However, I would take the opportunity to replace the lower anode bolts if needed, and check the transom for overall rigidity before you start investing money in a new engine. No use putting in a new engine when the transom is toast.

 

[Andy3]

Re: 1972 Cobalt Ski Boat

I'm not sure that I have enough room for the center risers. The engine cover kind of slopes (higher in back than in front), so not sure if there's enough clearance. Would the center risers still connect to the y-pipe ok?

 

[haulnazz15]

Re: 1972 Cobalt Ski Boat

Yes, the kit will come with exhaust tubing and two cast-iron elbows that make the transition from the y-pipe to the center-riser output. The center risers aren't any taller than the aft-risers, it just locates them toward the middle.

 

[Andy3]

Re: 1972 Cobalt Ski Boat

Unless anybody really wants to buy it! Lol $600, as-is, where-is.

 

[Andy3]

Re: 1972 Cobalt Ski Boat

I looked at Rapido Marine and that really looks like the way to go. Just out of curiosity, what is the main differences between a 302 short block for auto vs marine? Going to start construction of a homemade engine hoist frame this evening. Thinking 4x4 wooden posts with a 4x6 beam across the top.

 

[haulnazz15]

Re: 1972 Cobalt Ski Boat

I looked at Rapido Marine and that really looks like the way to go. Just out of curiosity, what is the main differences between a 302 short block for auto vs marine? Going to start construction of a homemade engine hoist frame this evening. Thinking 4x4 wooden posts with a 4x6 beam across the top.

Why not just buy a regular engine hoist? In any case, the main difference in the marine/auto stuff is going to be the freeze plugs being made of brass for marine, and the cam. Most marine cams are designed with low-end torque and are similar to truck/RV cams so that all the power is made at lower RPM's. Remember, your engine won't be going above 4500 rpms, so an aggressive auto cam that makes it's peak power @ 5,500rpms is of no use to you.

 

[Andy3]

Re: 1972 Cobalt Ski Boat

Recently divorced and renting a house. Nowhere to work except a small area in the back yard. Plus, the back of the boat is almost 6 feet high, not to mention the distance required to actually get the engine high enough to clear the boat. A friend is loaning me a chain hoist to attach to the beam, so I'll be out about $50 for the lumber. I had read that about the low end torque. Good info.