260 HP limit and drive model

[Autotech1]

Ok, this is my first post here, so stay with me please. Ive done some searching and read thru unrelated threads, and you guys are awesome.

My dad bought a boat from a friend, a '79 23' Sleekcraft full day cruiser(?) with a merc 260. I believe this drive is a MC-1, if so is there a more common name for it. Also, he bought this boat for $1000.oo because the motor is no good. Otherwise the boat is in awseome shape and seaworthy.

We have a Chevy 350 in perfect working order out of my bros suburban, its a high performance engine so i ask, what kind of HP have you guys seen go thru this outdrive successfully?

This motor idles down to 600RPM and pulls its hardest at aroun 4400RPM so the powerband is right for the application.

 

[Bondo]

Re: 260 HP limit and drive model

The old Mod. 1s are known as Mod.1s,....... Or Pre-Alphas........

Like the Alphas,.....
They'll start to come Unglued when you start approaching 300hp.......
Especially when you tend to Use All 300 of them.......

 

[Autotech1]

Re: 260 HP limit and drive model

Thank you Bond-o.

so would you guess that this boat does in-fact have the Mod.1?

 

[Bondo]

Re: 260 HP limit and drive model

Ayuh.....

 

[QC]

Re: 260 HP limit and drive model

One of my all time favorite boats Autotech. Here's a pic of a restored one if it is the Executive 23. Which I think is the only 23 footer they made then.

Are you in AZ, NV or CA?

BTW, welcome to iboats . . .

 

[Autotech1]

Re: 260 HP limit and drive model

Thats it, ours is the same wood grain witf a brown and cream color two-tone deal.


Im in Norther California, Fortuna. 25 miles south of Humboldt bay.

Thank you for the welcome QC.

 

[Reel Poor]

Re: 260 HP limit and drive model

Nice lookin boat Autotech1.

 

[MSmith3615]

Re: 260 HP limit and drive model

Thats a neat looking boat.... What a deal for $1000...

 

[Autotech1]

Re: 260 HP limit and drive model

Thank you both, as you can see it needs some interior work. My dad wants to take out the front seats and put in captains chairs, I think hes a outta his mind tho.

Ok outdrive serial is #5402755 can anyone verify this for me please?

# on Gimbal is a 5449117

 

[Bondo]

Re: 260 HP limit and drive model

Beautiful Boat,..............

That's Not the Best Picture,........
But, Under the Magnifying Glass,......
I'd say that's Possibly the Original,or Definitely a period Specfic Outdrive/ Transom Assembley for/ of That Boat.......

Welcome Aboard,...............

That Steal of a Deal is of the Caliber of My acquisition of Mom's Paycheck last summer........

Those Slickcrafts are built Solid,....... That Ain't No Bilgeliner there...........d

 

[Autotech1]

Re: 260 HP limit and drive model

Thanks bond-o.

Ok did some research its definately a Mod-1, aka "R", aka Pre-alpha.

 

[John_S]

Re: 260 HP limit and drive model

Beautiful boat!!! I vote for keeping the interior stock design.

Tells us some more about the suburban engine, as many details as possible, so you can get some help on what mods may have to be done.

You should research if this could become a collectors item. It might be worth keeping in a stock configuration. ie do just a short or longblock swap.

 

[QC]

Re: 260 HP limit and drive model

You should research if this could become a collectors item.

FWIW there are still a lot of them out there . . . There is usually one on eBay every couple of weeks. There was a decent running one up in Tahoe two weeks ago that didn't get $2500. Trailer was newer and the interior was good . . .

That restored red and white one above only went for $9000 and it had a fresh engine and drive too. Volvo I think.

 

[Autotech1]

Re: 260 HP limit and drive model

Well it a 4bolt main truck engiine we rebuilt. Its got hypereutectic pistons on stock rods swinging from a stock cast crank. Not sure what heads are on it, but i beleive there ~9:1-8.5:1 compression. weve made it a habit to install brass freeze plugs in all our engines, but im no ture about this one, as my bro built it. we'll surely replace with brass if theyre not already. Its got a high perf oil pump and double-row roller timing chain. Its a pretty hot motor, but i think the marine q jet will detune it a bit making it milder. This is no (car) engine, we built it with drag racing and dependability in mind. After the thrashing in his 6" lifet suburban running on 35s it still runs strong. We wont be doing any mods, well run the marine alt, carb, distro, and merc manifolds, were just puting the engine in place of the dead one.

Heres a lil tip tho for small block chevys;
drill a 1/16" hole in the center pipe plug over the front of the camshaft (with the plug removed of course). This will lube the timing chain wich has no other oil source otherwise, this will doublr the lifespan of your timing set.

 

[Bondo]

Re: 260 HP limit and drive model

Heres a lil tip tho for small block chevys;
drill a 1/16" hole in the center pipe plug over the front of the camshaft (with the plug removed of course). This will lube the timing chain wich has no other oil source otherwise, this will doublr the lifespan of your timing set.

Pretty Cool Motor Tip,.................
It brings up a Question,........... How Long Is,...... Forever Twice.....??..??.........d

It sounds like you've got a Good Solid Motor,........
A set of Vortec Heads would Really Wake it Up,............

 

[John_S]

Re: 260 HP limit and drive model

You should post the year of your suburban motor. There maybe some issue with coupler, flywheel, etc. Bondo is the expert in that area.

Also, if you have the cam specs, that would be good. Offroad cams are great torque builders, which is great in a boat, but sometimes the valve overlap can get you into a possible reversion (sucking in water) problem.

 

[Autotech1]

Re: 260 HP limit and drive model

Not sure of the year, as its was just a block we rebuilt . weve actually had it in about 3 diff vehicles. It is a two peice rear main seal, thats the only change chevy ever made in the crank flange, even at that they use the same flywheel/flexplate. The heads are ndrilled for accesaries as well. weve been biulding small block chevies forever and in our experience a sm, is a sm, is a sm, excepting obvious stuff. early sixties had road draft and heads were not drilled for accs.. vortrechs are different but parts can be swapped when done correcty: old crank in new block with rear seal adapter. new vortec heads on old block. etc

The only noticeablr difference between this one and the one thats in it is the dipstick is on the other side of the block. The previous owner started to swap another car engine in and never finished, he says the motor they started puttin in went bad on them, probably rain water it really rusted under the valve covers. We dont know the history of this motor, but we know we can rely on ours.

Im not worried about fitment issues but thankyou. I understand bond-o is very knowledgeable here And i respect and appreciate any input here. Just dont need that particular info.

And thank you John S for your concern, we'll be using the coupler and flywheel that came with the boat as well.

 

[Reel Poor]

Re: 260 HP limit and drive model

even at that they use the same flywheel/flexplate.

Not True....Bolt pattern on crankshaft flange is different, 86 up uses a different flywheel/flexplate.

in our experience a sm, is a sm, is a sm

Again not so true. Early 90's intake to head bolt pattern changes as well as valve cover design, then another change to vortec. Also roller cam blocks require a machined surface for the cam retainer plate to bolt onto, as well as machined lifter valley bosses for the lifter saddles. I believe it's 96 and up does not have accommodations for mechanical fuel pumps either.

I'm sure you may be aware of some, if not all of these differences, but, marine fitment issues are not as easy, or cheap, to over come as they are in the auto world. You really need to stay with a pre 1986 GM long block assembly to keep from having to jump these hurdles.

Good luck, and keep us up to date on the project.

 

[Autotech1]

Re: 260 HP limit and drive model

Yeah reel poor, im aware of the fuel pump boss, rollercam, and TBI manifold/centerbolt valve covers. Thats what i ment by vortech but i didnt mention the earlier TBIs.

About the crank bolt pattern, thanks i wasnt aware. Was that at the same time as the TBI motors?

BTW, stear clear of TBI heads, they dont flow as good as the vortechs and they are a much thinner casting than either the older heads or the vortechs,ie rust, and they tend to crack between the valves most times.

I beleave this to be a mid eighties block because the dipstick is on the starboard side and it has the mech. fuelpump boss and a two-piece rear seal.

 

[Reel Poor]

Re: 260 HP limit and drive model

About the crank bolt pattern, thanks i wasnt aware. Was that at the same time as the TBI motors?

Many of the 1/2 ton trucks came out with throttle body but the 3/4 and 1 ton trucks still had 4 barrel carbs. The 1 piece rear seal and flange bolt pattern change started in 86.

The marine engines also came with windage trays to keep the crank shaft from dipping in the oil and aireating it, it is essential. Also the marine dipstick tube reaches all the way to the bottom of the oil pan (marine specific) so you can pump the oil out thru the tube, as access to the drain plug in the pan is virtually impossible.