Calling all engine folks

[Callyb]

I recently purchased a mid and lower unit to convert my '84 Merc Black Max from a 20" to a 25". It came with the t&t, transmitters and swivel (which are all in better shape than what I currently have). So the plan is to swap my powerhead over to this new mid and lower.

Here is where the question is. Has anyone ever put a newer style lower cowl and hood on a Black Max, or at least have some info as to what is involved with doing it? The leg looks to be the same well into the 2000's which makes me think it is a plausible mod, I just can't seem to find anyone that has documented it.

EDIT:

This style cowl and hood


All help and/or info is appreciated (as always)!

Thanks in advance.

[fitz73222]

Let me ponder this!

[fitz73222]

Hi Carl,

Is the mid section you purchased the same vintage as yours? You have the old split cowl design which was a mechanics dream. You could have access to every nut, bolt and component in 30 seconds. The downside was that they were incredibly noisy with little or no insulation or sound deadening. Your engine is a 2.4 liter block and with it, some early design factors to consider. The major difference in cowling designs was that yours was mounted basically on a rear hinge that encompassed the support of the upper cowlings and small lower side covers the hid the powerhead bolts. Newer style engines had a two piece lower engine pan that basically sandwiched on to a large foam  o-ring, supported by the exhaust adapter plate between the powerhead mating surface and the actual lower midsection. The lower engine pan did not have any permanent rigid fasteners bolting it to the midsection. 4 screws that held the the two halves together just squeezed against the big o-ring and held everything in alignment. I guess the rigidity became none essential because the engines were no longer tilted up and down manually but instead used power trim.  Your midsection will not work with lower cowling on the engine you portrayed. The above water exhaust ports were redesigned and relocated to be higher up and narrower than the location on your 80's midsection. That said, I would look at any of the 1990's bucket cowl designs that still utilized your above water exhaust port locations and should be an easy adaptation. Plus you get a one piece cowl, better insulated, nice looking and MUCH quieter. I know Capt'n John has researched adapting the Alien cowl design on your style midsection so I invite him to advise further on whether or not it is feasible. Additionally, you could spend some serious coin for the parts to do this unless you can find some used cowlings and engine pans in decent shape. You may also have to change your exhaust adapter to get the o-ring mount where you need it for the upgrade. The good news is that in the early  to mid 90's, Mercury was still making 2.4 and 2.5 models during the same years so the adapter plate should be available for your engine with the o-ring feature.

[Callyb]

Fitz, Thank you for a very fast and very informative response.

Is the mid section you purchased the same vintage as yours?

Yes. Well, it is an '85...same thing though.

I would look at any of the 1990's bucket cowl designs

I have seen quite a few of those for a very reasonable price. I very well may go that route. I'm really just trying to avoid having a nice rebuilt boat with an 80's vintage Black Max hanging off of the back for a few years until I can hang a nice new one on her.

Thanks again for the input :!:  

[GoneFission]

2.4 and 2.5 engines can interchange cowls, but you need uppers and lowers.  You will need to remove the powerhead and fit the lower pan in place.  It may require one or two (depending on type) new gaskets on the pan.  Here's one way to check it out - check the gasket part number for the pan to midsection gasket for your engine and the year/model you want to use the cowl from.  You can bet the cowls are interchangeable if they use the same gasket.  

[200CCPMerc200]

The pic you show is a 3 liter and nothing on a 3 fits a 2.4 or 2.5, in 1988 the 2.4 went to the bucket cowl and the clam shell was canned. Any 2.4 or 2.5 parts will fit each other , but you will have to modify the mid a bit to fit the later style 2 pc adapter /tuner plate. You have the old style sgl. Ram mid. I would get a new style 88-91 2.4 150/175/200 3 ram mid, then everything bolts up fine. Make sure you have a 2.4 tuner as a 2.5 isn't enough back pressure for a stock 2.4 200hp motor.

[200CCPMerc200]

I have about 10-12 sets of 2.4 buckets and pans around, but they are expensive to ship, i custom machine mids for perf. Apps, so, i have none of them to spare. They are cheap to buy , but again expensive to ship, best to find a local blown mota'

[Aswaff400]

The pic you show is a 3 liter and nothing on a 3 fits a 2.4 or 2.5, in 1988 the 2.4 went to the bucket cowl and the clam shell was canned..

the 135-150-175 optimax's are 2.5 liters

[GoneFission]

The pic you show is a 3 liter and nothing on a 3 fits a 2.4 or 2.5, in 1988 the 2.4 went to the bucket cowl and the clam shell was canned..

the 135-150-175 optimax's are 2.5 liters

Optis are completely different motors - very little changeover from early models.  I would not count on a Opti cowl fitting 80s/90s vintage 2.4/2.5.  

Ship by Greyhound - cowls are really expensive by UPS or FedEx due to size, but Greyhound charges by weight only.  But you gotta go to the bus station to pick it up...

[Callyb]

Sorry I have been absent, it's been a very busy week. As soon as I get my paypal account squared away I am going to purchase a cowl that Farley believes is a 1996. I guess we will all find out in a few weeks what the compatibility is for sure. Either way, I'm not above some fabrication work if need be...

I'll post the progress in my build thread, unless you guys prefer I put it in this section.

Thanks again for the input.

[fitz73222]

Sorry I have been absent, it's been a very busy week. As soon as I get my paypal account squared away I am going to purchase a cowl that Farley believes is a 1996. I guess we will all find out in a few weeks what the compatibility is for sure. Either way, I'm not above some fabrication work if need be...

I'll post the progress in my build thread, unless you guys prefer I put it in this section.

Thanks again for the input.

I just worked on a 1995 2.5 last night and made some observations about the lower cowling configuration, most notibly the bottom bumper extensions and retainers that hold the lower cowling in place. Search the needed parts carefully from a schematic for that year and make sure you have everything you need. This engine happened to be taking its last breath without major surgery with number 3 full of water and a gearcase full of water so it may be available at some point.

[Capt. Bob]

I'll post the progress in my build thread, unless you guys prefer I put it in this section.

Carl,
Keep it here since we've had the input from the piston heads and members are following. This is a little different from just painting a cowling and should make for an interesting thread. You can link back here from your rebuild when you reinstall.  

Good luck and a lot of pics.

[Callyb]

Keep it here since we've had the input from the piston heads and members are following. This is a little different from just painting a cowling and should make for an interesting thread. You can link back here from your rebuild when you reinstall.

Good luck and a lot of pics.

Will do, Thanks! :)

[Callyb]

Well, here is the style I bought, but I can't get the pic to link from ebay. Trim switch and all...

We'll see how it goes...

[wingtime]

I think that should fit good with the right exhaust plate or whatever you call that section.  

BTW I swapped out mid sections to convert my early 90's 200HP 2.5 from a 20" shaft to a 25" shaft.  I think I ended up with a 2001 or so mid with a factory new to me 97 power head with 94 or so model year carbs and electrics.  A true Franken-Merc!  She ran like a scalded ape too boy!