[rbay]

Hello Everyone,

New to this forum. Posed this question to the Minnesota Glastron Carlson forum, looking for any and all input from all of you:

I recently purchased a 1973 Glastron Carlson CV21 to restore....I think I can keep the interior and exterior pretty close to original. It has a newer Berkeley jet pump, but no engine. Two paths engine replacement could take and stay the same 320 hp range at about the same engine "ready to drop in" cost are:
1.) Build and install an early 70's vintage Olds 455 big block like original. I'm pretty certain I would use a Holly Sniper EFI fuel system and an HEI distributor, but otherwise pretty old school. Would integrate into the boat's electrical system, gauges, etc. like the original. It came with Olds 455 logs/snails, water pump plate, and bellhousing. Servicing it would be a project for the owner/mechanic or hot rod shop.
2.) Install a used early 2000's Mercruiser small block, like the 350 MAG. Would have modern ignition and EFI. It would take about $400 worth of wiring, switches, and alarms to integrate it into the original dash and controls. I don't know how easy it will be to connect the bellhousing engine mounts to the pump. Any Mercruiser service center could service it for me or any new owners.

So when thinking about reliability, driveability, sensory, fun, resale, servicing, what would be your vote? I know fuel economy will favor the newer engine, but Michigan summers are pretty short and I don't get to put that many hours on my boats, so that takes a backseat to the other factors. Or am I missing some things to consider? I know there are higher powered options, but 50-55mph is fast enough for me, wife, and puppy to cruise around the local lake. Key to me is confidence we will get back to the ramp without a tow.

Thanks for you thoughts.....option 1 or 2? I know there are a lot of car guys trying to make this same old vs new motor decision on their classic rides, too.

 

[Mash on It]

SBC
Get front and rear (SBC) motor plates.
Find logs and snails in aluminum.
Vortec (L31) style heads and cam is ~330 HP.
Pto adapter for 1 PC rear main SBC.
Use existing alternator for SBC.
Keep it simple, Eddy intake and 750 Holley 4150/4160. GM HEI. Existing gauges will work just fine on an L31.
Your Berk pump likely has an 'A' impeller. L31 should pull ~4700 rpm
Or pony up for a ZZ5/6 (400/405 HP)

Sell (give) the 455 to an olds car guy.

Dan'l

FYI Olds 455, 1968 to 1978
350 Chevy, 1968 to 2003

 

[rbay]

Thanks, Dan'l. At this point, I'm leaning SBC.

You talk about a scratch build, but there are complete Mercruiser 350 MAG MPI engines on eBay for $5500-7500. Why wouldn't I just drop one of those in? They use isolated front and rear 4-point motor mountings. Can I use those and fab some brackets or rails on the stringers, or would that be too much motion for the u-joints in the driveline over time? I see the adapters you mention on berkeleyjet.com.

Some car guy already got the 455.....the boat had no engine when I bought it.

Roger

 

[Mash on It]

How is the mercruiser 4 point mount? It uses a bell housing, I believe, but I'm not up on mercruiser stuff anymore. (4 point jet stuff makes more sense)

What about the computer for the mfi? (Edelbrock intake and Holley 750 solves this easily)
Remote fuel pump? (Still required on an L31 setup, mfi or carb)
While mercruiser exhaust manifolds will certainly work, although aluminum Hardin logs and snails or the like will be considerably lighter. (Weight is the enemy of jet power)
Is it fly-by-wire throttle, or cable controlled?
Jets have no need for thermostatically controlled cooling system. A single pass system is simple and effective, no need for another horsepower robbing water (circulating) pump.
A pto adapter and jet drive line is still needed.

Just my $0.02

Dan'l

 

[rbay]

Hey Dan'l,

The Mercruiser 4-point mounting does use two rear mounts on the bellhousing, but the bellhousing isn't as long so the mounts end up being too far forward. The mount itself is basically a vertical bolt with some rubber donuts around it. So I think the easiest thing to do would be to fab a tubular crossmember to rest on top of the stringers, with a dip to go under the driveshaft.

The Mercruiser engine packages are complete....ECM, fuel pumps (low and high pressure), fuel rail and injectors. In the 2000's they used cable throttle and shifter, analog gauges, separate audible alarm. You mainly need to buy the boat-side wiring harness, about $250. Would take off the power steering pump, plate the water pump or just pull the impeller.

I know what you mean about the weight, the Mercruiser website shows the package at almost 1000#, but I think that might include an outdrive vs. the inboard bobtail.

rbay

 

[rschap1]

Speaking in generalities, a SBC isn't know to make as much torque as preferred for such an application.
And an Olds is usually more expensive to get same power; that is why I mentioned Big Block Ford or Chevy in your other thread.
Not that either can't be done.
But BBF or BBC enjoy more popularity.
If those are only two choices, good luck with the build and enjoy either.

 

[rbay]

Thanks for that input. My neighbor built a 454 Chevy for an old Biscayne he restored, but ended up putting in a more period-proper 409. So he said he'd give me the 454 (I'd probably give him something for his effort). He said the build is nothing too special, but still crazy HP. I'd have to marinize it, and switch out the Olds pieces (logs/snails, water pump plate, bellhousing?), but maybe that is the way to go?

 

[2sangers]

I have a complete set of mounts, exhaust manifolds, water fittings, pto and drive shaft for that big block chevy. All period correct Nicson. That CV21 would be much happier with a big block. Text me if interested 803-351-0578 I'm in SC

 

[Heatseeker]

As mentioned above, go woth a big block. Jet pumps eat torque. You want as much as you can get, and it isn't coming from a 350 without serious investment. Being that you have access to a bbc, that would be the path I would take. But don't discount an Olds. 455's were installed in thousands upon thousands of jets from the factories for a reason. They run reliably and make mounds of torque out of the box. They just have limitations if you are looking to run your boat really hard.

 

[rbay]

Thanks for that input Heatseeker. I'm looking for a pretty mild engine setup, so I'll go with displacement as king. I've got an 8.1L in my 25' bowrider, and coach everyone about getting the cubic inches whenever possible, need to take my own advice. Plus, the Mercruiser drop-in engines seem very heavy, like 300#. I guess they are looking for durability.

My last decision, then, is whether I take the easy path of the Chevy 454 vs. finding an Olds 455. How much does anyone think I devalue a '73 Glastron Carlson CV21 if I don't go with the original Olds?

 

[Mash on It]

The 455 Olds. Berkeley Jet offered Olds 455 engine and jet pump "Packajets" to the marine industry in two ratings, one [email protected], and another [email protected]

These ratings are easily handled by the run-of-the-mill SBC L31 (330 hp/380 lbft) and this is just a Suburban motor.

With an Olds, to run any significant rpm, will need the oil mods, it's a station wagon engine designed to run 2200 rpm in a Vista Cruiser. Run a stock one at 5K rpm, it will last minutes. (Oil return problems)

While my SBC L31 "parts from here and there" motor doesn't exactly set the water on fire, it turns an "A" impeller @ 4650-4700 rpm, and has been wfo for miles, and just shy of 60 mph. Oh, and it just sips fuel compared to my big block jet boat.

Value wise, (personally) I'd pass on anything Olds powered. I'd think a stout SBC would have a better return, although 454 or 460 power might be better yet.

Again, just my $0.02
Dan'l

 

[N2otoofast4u]

Modern LS with Holley or a carb. All that other shit is antiquated boat anchors unless you spend a bunch of $.

And yes, I have first hand experience of an LS in a jet boat, as well as the big 3 big mfg big blocks also mentioned in this thread.

 

[rbay]

You all are great, way above my pay grade for all the motor talk. Although I've been an automotive engineer for 40 years, it's mostly been body related.

Once we northerners come out of hibernation I'm going to ask my neighbor if he's serious about making a deal on his 454. His son seemed a lot more positive than him. In which case I'll need 2sangers bag-o-BBC parts.

Otherwise, I see a lot of LQ9 LS motors (6.0L, iron block, aluminum head, 345hp) online and I'm sure a lot around my home with still some GM plants in my area. That looks like a fine starting point, unless I should pay the money for an aluminum block (LS1)? How deep would I have to dig into the motor for a marine-build? I know about the bronze freeze plugs, but what about head gaskets and cam? Of course, starter, alternator, flame arrestor. And how to get my hands on manifolds or logs/snails for less than $1500?

 

[Mash on It]

Cam specs are really determined with the type of exhaust you plan on running.
A factory type automotive cam should be alright with mercruiser type manifolds, or logs and snails.
Over transom headers, running wet, is a different set of problems. For your boat, I don't think o/t headers are a solution.
Marine engines like the bearing and valve stem clearances opened up a bit, much like running a used 100K mile motor. (Eg: used LQ9) I run factory rod/main specs with my small and big block builds.
Brass frost plugs are suggested, but I've seen plenty with steel ones.
Water flow should be slowed way down from the pump to prevent over pressurizing the engine. Engine water pump isn't required anymore.

Dan'l

 

[rbay]

Agree with you on the exhausts....I'm learning about redrilling some 351W Ford logs and snails to fit, weld in an O2 bung. So new cam probably not required, and a used engine should be loosened up nicely for running on the water. The lake is fairly small with a 45mph speed limit, so won't be staying in the throttle for long periods of time. This boat will be my Woodward Dream Cruise.

For the cooling system, CP Performance has a thermostat/crossover kit for the LS that looks pretty promising, with or without an additional pressure relief valve.

Really down now to iron block LQ9 vs. aluminum block LS1. Would be cooler to put the Corvette engine in it (especially with the Corvette motor covers) and lighter, or stay with the iron for longevity?

 

[N2otoofast4u]

Stick with the tried and proven 5.3 platform is my recommendation. A 6.0 or the 6.2 would be fine, but more $. We literally stuffed a wrecking yard 5.3 with a carb intake into an old shit box, and it’s the funnest little boat to play with. They weigh nothing, make the same or more HP/TQ than a 70s big block, and parts are CHEAP.

Simple electronics make it easy, but if I was to do it again (which I am) it would get Holley EFI. That will be more difficult on a log style exhaust, but not impossible. You’re on the right track with the Ford logs!

Be different! I’ll dig up some pics of the LS carb boat, it’s nothing special, but definitely different. Here’s the current project, 632 with twin 80s, Holley Dominator EFI. It will get a big inch LS based deal next year.

Where are you from?

View attachment 1046383

 

[rbay]

I live just outside Flint, MI.
This CV21 could be a collector's item when restored, so I'm OK spending a little more if it enhances it's value. I've looked up and down the LS engine spectrum and am thinking LS2. I'm seeing dropouts for $4500. I could save about $1K and still get the aluminum block with the L92, but that's a truck intake....nothing like the LS2 with its Corvette or GTO engine covers in the motor compartment!
Unless someone says the aluminum block isn't a good idea for a boat. It would be freshwater use only, and I'm even considering a closed loop cooling system to not have any corrosion, winterizing, or jet water pressure issues. Iron is stronger, but aluminum expands and contracts with heat about 2x as much as iron, so to have aluminum pistons inside an iron block doesn't sound like a good idea, either.

 

[SPECTRA-SANGER]

In a marine block you typically run larger clearance because you don't get the heat like you do in a car and that block is not expanding an example would be I run .004 in a 496 BBC, this is with a forged Race Tec piston at 10:1. They call for .003 in a car but want the extra clearance for marine

 

[rbay]

Right.
The block runs cold, but the pistons run hot, hotter than in a car since you're going to be burning more fuel at cruise speed in a boat. So extra-hot aluminum pistons in an iron block being chilled with raw, cold lake water will have a large temperature differential and need more clearance.
I'd prefer those same pistons in an aluminum block, better if warmed by a thermostat-controlled closed loop cooling system. I would think an oil cooler would be a good idea too since its more the oil than the water that will be cooling the pistons. I see there are even piston cooling jets for an LS engine to spray oil on the underside of the pistons.....anyone know if you have to tear down the engine for installation or just remove the oil pan on a stand? Maybe I'll look for a YouTube.

 

[2sangers]

Google " How to ls swap a jetboat " by CP Performance on you tube. They made several informative videos about the install. We have been swapping them for years, but with dry headers and motor plates in open boats with rail kits. I've looked for years for those elusive Ford manifolds. We run a Sunkisst tunnel drag boat with a turbo aluminum 5.3, and a Sanger Hydro V Drive with an aftermarket iron block efi turbo on methanol in QE.
The "cheap" big block may be easiest but the LS may be best. If set on going EFI, I vote LS