TOPIC: More Power!!!!

Well, It wasn't exactly what I wanted... but I found an excellent running 1978 Merc 1400... attached to a HydraSport bass boat.
This will be the new powerplant behind the 1969 Fabuglas Cruiser. It should move it pretty well.



See/Hear it at:


Couple questions:
1) What should the compression be? My cheapo Harbor Freight tester doesn't read accurately. It was off 15# from a friends Snap-On.
2) I think I may have too much prop for the 19'Cruiser. It's a SS 3-blade Laser II 13" 23Pitch (#48-72760A4-23P), as the bass boat easily passed 50mph at 4000rpm and 2/3rds throttle. I'm never going to try to get the Cruiser that fast. I'd like to top out at 45mph @ 4500rpm or so. Is there a prop-calculator for that? I'd like alot of torque for pulling skiers/tubes, but I'd like to just lope along with decent fuel economy. Suggestions?
3) Anything I should watch for with this engine? Is it sensitive to 2-cycle oils, gear lubes, etc?
4) Anyone want a bass boat?

I wouldn't rev it like that on the water ears in gear. gnarly motor

I like to see compression in the 125 range or higher within 5 lbs of each cylinder

19 might be OK for your boat. I use a 19 on my 61 20 foot Cruisers Inc 570

Looks like you found a really nice Merc there, my thoughts on your questions:
1 - Since you know your HF comp tester is off by 15lbs, you can still use it to get an idea of what's going on. What were the readings? I think it's just as important that they're even across the board, as Jim stated.

2 - There isn't really a prop-calculator that I know of, www.iBoats.com has some good info on their website when you click the "props" icon in the store section. Since you're going to a much heavier boat and looking to do a good bit of pulling skiers, tubers, etc., a 19P Four Blade may be your best choice. If you can find somebody to loan you one or two to check it out that would be the easiest way to determine what works best on the cruiser. You should have no trouble selling the SS Laser II 23P, quite a desirable prop with the "go fast" guys!

3 - A lot of the Merc "gurus" recommend using nothing but Merc oil and lube in those motors, probably good advise. I would at least say use a quality name brand, and definitely synthetic IMHO.

4 - You can always put the bass boat in the Glassifieds, craigslist, etc.. If you're just looking for someone to come tow it out of your yard let me know.

And get your RPM up!! 4500 RPM for that motor is WAY low. Your RPM reading means that there is either something wrong with the set-up (motor too deep, too much propeller, wrong motor angle, etc.) or there is something wrong with the motor itself not allowing it to reach peak RPM. Ideally, you'd like to see that puppy revving into the 5500-6000 range at wide open with a light load in the boat - no matter what boat it's on. Anything less is lugging it - akin to going uphill in 5th gear while towing a trailer... It'll grenade your motor in short order. Doesn't mean you have to run it that hard, but it just has to be capable of reaching that plateau...

- Scott

I agree with Scott. Best to check with merc, see what the max rpm is recommended, and peg that as your target. My manual says 5200, but I got a prop on it right now that at WOT and a light load will hit 6 grand trimmed out. I need another prop with more pitch to get that number down. It's an old motor, and while I don't want it to lug, I sure don't want it to blow up!

Frank

Chinewalker/PC1000... All

I wasn't real clear in my description of what I want out of a different prop.
There's nothing wrong with the Merc. Compression is 105+ on every cylinder with the HF Tester. I will re-test with a better Compression Tester. 4500 wasn't the max RPM's... just as far as I took it on the Hydrasport during testing. This was achieved at about 2/3rds throttle. The Bass boat has a (very) bad transom- and I didn't want the motor to end up at the bottom of the lake!!! 50MPH was fast enough for me to know the engine is up to snuff. If pulling the boats around is any indication- The Hyrdasports is actually heavier than my Cruiser.

1) I'd like a good torque-prop for pulling (multiple)skiers, kneeboards, and/or a large tube. My Cruiser is a Aquafoil-hull and really jumps up on plane.

2) I'd like to be able to go 40mph at ~4000-4500 rpm. With a top-speed of 50-ish. Anything more is too much for my Cruiser.
I'm not sure where a Merc 1400 "likes" to run... as far as balancing power with fuel economy.
I know my John-Rudes like slightly off full-throttle. Backing off 10% from full- loses only a couple MPH, but saves at least a gallon of gas per tank... for all day cruising.
3) I don't want to constantly "lug" the motor with too much pitch.. but I also don't want to over-rev it while cruising.

Should run between 5500-5800 RPM's at full throttle with a light load. I concur on a 19 pitch as a start. Should do just fine for pulling toys.

""I'd like to be able to go 40mph at ~4000-4500 rpm. With a top-speed of 50-ish. Anything more is too much for my Cruiser. ""

Umm, Not to be a naysayer, but just how fast have you had your Fab going? Your boat was designed to run from 14 to 35 mph tops. At those speeds, it will handle the best & will give the most comfortable ride. 40 - 50 mph? You better keep the merc on that Bass boat if you want to do that. I have no doubt that the mighty tower could push your boat to the 40s, but please be careful. Your boat appears to have very little deadrise & this means that it will probably become unstable at faster speeds. At speeds over 30mph the hull may "hunt" for a course & all of the sudden one of the chines will dig in to a wave & you better be holding on when it does. With this much power, your steering should be upgraded as well. I can completely understand the desire for speed & power, but please be careful in that old girl.

Bruce,
The Johnson 90 would easily push the boat to 42MPH (gps).
It was quite stable even in small chop and residual wakes from other boats. Great in a high-speed turn, and it's easily traverses wake even if not hit "square".

I have way overbuilt the floor, stringers and transom from "stock".

Cool - that must have been a very well designed hull to do that.

Do you have any more picts? I really like the lines of the cabin, but the pic is very small.

Bruce

I'm in the process of making up a photo-gallery of the resto/rebuild.
It'll probably be up in a few days.

The Fabuglas is a VERY light cruiser. Expect better than 40mph with that motor. Mine will fly with 420 POUND jOHNSON 90.

VERY ASTUTE ASSESSMENT. My Fabuglas is comfortable in smooth water, will throw you out of the seat if you hit a wave at an angle at speed. It pounds ina a chop. Great river boat though! And has tons of room and better ventilation compared to my Seafair.Bruce Gerard wrote:

""I'd like to be able to go 40mph at ~4000-4500 rpm. With a top-speed of 50-ish. Anything more is too much for my Cruiser. ""

Umm, Not to be a naysayer, but just how fast have you had your Fab going? Your boat was designed to run from 14 to 35 mph tops. At those speeds, it will handle the best & will give the most comfortable ride. 40 - 50 mph? You better keep the merc on that Bass boat if you want to do that. I have no doubt that the mighty tower could push your boat to the 40s, but please be careful. Your boat appears to have very little deadrise & this means that it will probably become unstable at faster speeds. At speeds over 30mph the hull may "hunt" for a course & all of the sudden one of the chines will dig in to a wave & you better be holding on when it does. With this much power, your steering should be upgraded as well. I can completely understand the desire for speed & power, but please be careful in that old girl.