292 inline 6 with prealpha drive for 19.5 cuddy

[RDTBC]

Well, I’ve been working on this project slowly for some time now. Bought a 19.5 glasply cuddy which needed a new motor. The raw water cooled merc 140 was ready for a rebuild and (IMO) not worth it. I bought a complete 165 L6 with outdrive only to find it had a cracked block due to freeze. So, I bought a 292 L6 with the front mounting holes. I’m in the process of rebuilding and will let you all know how it goes. Any tips are appreciated!!

 

[achris]

Hello and welcome to iboats. Sounds like a fun project.

You might want to read this...

What is a ‘Pre-Alpha’ drive?

What is a ‘Pre-Alpha’ drive? We see this all the time…. I have a ‘pre-Alpha’ drive, can you tell me…..??? What parts do I need for my ‘Pre-Alpha’? And so on…. Before anyone can answer those questions, we need to know, exactly WHICH ‘Pre-Alpha’ drive do you have? Mercury never produced a...

forums.iboats.com

 

[Scott Danforth]

going from a 3.0 liter (181 cubes) to a 292 you will need a different ratio outdrive.

 

[RDTBC]

Hello and welcome to iboats. Sounds like a fun project.

You might want to read this...

What is a ‘Pre-Alpha’ drive?

What is a ‘Pre-Alpha’ drive? We see this all the time…. I have a ‘pre-Alpha’ drive, can you tell me…..??? What parts do I need for my ‘Pre-Alpha’? And so on…. Before anyone can answer those questions, we need to know, exactly WHICH ‘Pre-Alpha’ drive do you have? Mercury never produced a...

forums.iboats.com

Thanks Chris - sorry. If memory serves it’s an MC-1. I’ll need to verify with the serial number.

 

[kenny nunez]

Since the 292 is taller you may have to do some cutting if the transom deck area was close to the 3.0. The pan is also deeper so you may have to do some trial fits for bilge clearance and to locate the front mount support for the alignment. The exhaust hose will have to be lengthened. The fuel line needs to be remade because the fuel pump is further back on the block, the alternator adjusting bracket needs to be lengthend. The carburetor from the 165 will work but if you can obtain the correct Quadrajet that came on the original 292 you will have 200 HP.
As long as the 165 drive is in good condition it will hold up to the 292 since your boat is not very heavy and you will have to try different propellers to get the best performance. Also this engine is heavier so adding a set of trim planes will get the boat to plane off quicker.
You might be able to use the original tachometer if it has a setting for a 6 cylinder engine.
I have performed this conversion many times and this is what I can recall having to do.

 

[RDTBC]

going from a 3.0 liter (181 cubes) to a 292 you will need a different ratio outdrive.

Yes, I have the drive from the 165. I’m going to verify by gear tooth count that it is in fact a 1.65 ratio. My understanding is that the 292 was never shipped with an alpha-style drive, so there’s no chart which sets out a correct gear ratio. I’m hopeful that a 1.65 will provide sufficient water flow to cool the bigger 292. If water flow is sufficient, I can adjust the prop to get the right final drive ratio…

I’ll confirm that my outdrive is an MC-1. I checked about a year ago, but I didn’t write it down, so I’m relying on memory.

 

[RDTBC]

Since the 292 is taller you may have to do some cutting if the transom deck area was close to the 3.0. The pan is also deeper so you may have to do some trial fits for bilge clearance and to locate the front mount support for the alignment. The exhaust hose will have to be lengthened. The fuel line needs to be remade because the fuel pump is further back on the block, the alternator adjusting bracket needs to be lengthend. The carburetor from the 165 will work but if you can obtain the correct Quadrajet that came on the original 292 you will have 200 HP.
As long as the 165 drive is in good condition it will hold up to the 292 since your boat is not very heavy and you will have to try different propellers to get the best performance. Also this engine is heavier so adding a set of trim planes will get the boat to plane off quicker.
You might be able to use the original tachometer if it has a setting for a 6 cylinder engine.
I have performed this conversion many times and this is what I can recall having to do.

Much appreciated. I’ve measured as well as I can by tape/eyeball method and I believe the oil pan has a few inches clearance. I might have to cut a bit of glass at the top though - it will be close. Appreciate all the other input - and glad to hear it’s been done before!!

 

[Scott Danforth]

Yes, I have the drive from the 165. I’m going to verify by gear tooth count that it is in fact a 1.65 ratio. My understanding is that the 292 was never shipped with an alpha-style drive, so there’s no chart which sets out a correct gear ratio. I’m hopeful that a 1.65 will provide sufficient water flow to cool the bigger 292. If water flow is sufficient, I can adjust the prop to get the right final drive ratio…

I’ll confirm that my outdrive is an MC-1. I checked about a year ago, but I didn’t write it down, so I’m relying on memory.

250 and 292 can use same drive. cooling flow will be fine as same cooling flow goes to 350's

you will need to go up in pitch for the longer stroked 292

 

[Scott Danforth]

Appreciate all the other input - and glad to hear it’s been done before!!

there are a few supercharged 292's out there as well. came across a pair back in the mid 80's at a poker run. they were in a boat that originally had twin 470's

I think they were weiand superchargers

 

[kenny nunez]

You will also have to either have a set of studs 1/2” 20 X 7/16” X 20 to mount the flywheel and drive coupling or plan “B” drill out the flywheel and drive coupling for the 1/2” studs that the 292 uses.
Be sure to replace the rear motor mount bushings in the flywheel housing.

 

[RDTBC]

Thanks for the tips. I wasn’t aware of the different stud sizing at the flywheel/coupler. I suspect the custom studs will be hard to find. Does anyone know the grade of stud that’s required here? Or name of a supplier?

 

[kenny nunez]

Jeg’s has Moser engineering 1/2” X 20 studs # 8070 You may have to cut shorter. Be careful not to screw the studs against the rear main bearing.
Also ARP # 300-8336 1/2” -20 nut with 5/8” external 12 point .
3/4”O.D. 1/2” 20 nuts will not allow a wrench to fit in the pocket of the coupler.
With this combination you will have to drill out the flywheel and coupler and use Locktite on the nuts.

 

[RDTBC]

Thanks Kenny! Great tip on the ARP nuts to fit inside the coupler pockets.

 

[RDTBC]

there are a few supercharged 292's out there as well. came across a pair back in the mid 80's at a poker run. they were in a boat that originally had twin 470's

I think they were weiand superchargers

Sounds like a great future upgrade! For now, I’m going to focus on getting this boat on the water. They must be pushing 300+HP from a supercharged 292.

 

[achris]

... They must be pushing 300+HP from a supercharged 292.

And in need of a Bravo drive. Alphas would 'self-disassemble'...

Chris.....

 

[RDTBC]

I’m slowly plugging away at rebuilding the 292 for this conversion. I’m ready to install the harmonic balancer and… I seem to have a problem. The 292 balancer I have is too large and does not fit between within the front engine mount bracket. Has anyone encountered and solved this before? From reading a few forums, it seems a smaller balancer (ie. from a 250) is not recommended for use on the 292.
I’ve contemplated a few options:
1. Install a smaller balancer from a 250 (which I already have)
2. Abandon the front mount and use side engine mounts. I found one mounting assembly online (picture attached) which seems to be available, but I don’t think it would fit inside the doghouse.
3. Buy the smallest balancer available for a 292, then shim out the front engine mount to make space… this seems sketchy

Any other suggestions?

 

[achris]

I've edited your correction in and deleted the correction post... (hope you don't mind).

As far as the balancer is concerned, I'd definitely be heading to the side mounts. As well as having the right balancer for the engine, you'll be able to (easily) do a V-belt change.

Chris.....

 

[achris]

As far as the drive ratio is concerned, the 292s came with a II-Drive with a ratio of 1.78:1, so your 1.65:1 is going to be just fine, especially in a 'small' boat (19.5ft)... I'd be super interested in the outcome. I'd start with a 17" prop. Look for max revs in the 3900-4300 range (aim for the upper end). The 165 I had in my boat when I bought it (1986) had a 17" (maxing at 3950rpm) and it struggled. I changed to a 15" (maxing at 4350rpm) and it was excellent.

A little pet project I have in the back of my mind is to get an old B20 (same as I currently have) with a dead 165. I'd find a dead 3L Gen II set up and do a 292 transplant, with the back end and drive system as Gen II. The benefits of a narrower straight six engine, and the reliability and corrosion resistance of the GenII drive... I think it'd be a winning.

Chris.......

 

[Scott Danforth]

1. Install a smaller balancer from a 250 (which I already have)

this would grenade your motor. there are different balance requirements between the 250 cubic inch and the longer stroked 292

 

[RDTBC]

As far as the drive ratio is concerned, the 292s came with a II-Drive with a ratio of 1.78:1, so your 1.65:1 is going to be just fine, especially in a 'small' boat (19.5ft)... I'd be super interested in the outcome. I'd start with a 17" prop. Look for max revs in the 3900-4300 range (aim for the upper end). The 165 I had in my boat when I bought it (1986) had a 17" (maxing at 3950rpm) and it struggled. I changed to a 15" (maxing at 4350rpm) and it was excellent.

A little pet project I have in the back of my mind is to get an old B20 (same as I currently have) with a dead 165. I'd find a dead 3L Gen II set up and do a 292 transplant, with the back end and drive system as Gen II. The benefits of a narrower straight six engine, and the reliability and corrosion resistance of the GenII drive... I think it'd be a winning.

Chris.......

Thanks for the tips. I’ll keep you posted as the project evolves. At the pace I’m moving, prop pitch feels like a distant concern, but I’ll refer back here when the time comes. I’m no expert and I don’t know what a 3L Gen II is, but now I’m curious so I’ll look it up.