Pros and cons of the 40C&D Tohatsu

I'm looking for a higher Hp replacement for the '92 Merc 25 on my '56 FeatherCraft, a 12' aluminum speedboat. From what I've learned on this forum, my Merc weighs 98 lbs. My boat is rated for a 35Hp but thats a "50's era 35". A 40C weighs 136 lbs and a 40D weighs 176 lbs. Naturally, I'd prefer the 2 cyl model but I see the 3 cyl as the way to go if its superior. So, the reason for my post is, I'd like the opinions of the people in the know, you guys, what motor I should go with.
I guess thats about it.
Thanks alot, in advance, for your opinions and information.
Wet Willie
PS
I'd also like to have power trim/tilt on whatever motor I end up with and forgot to ask if those weights incl the trim unit.

The horsepower rating is mostly related to the thrust, not the weight. Put too much thrust on and damage the boat; in a severe case, rip the transom off. You can offset extra weight by putting the battery and fuel forward. The 40C was a great motor in its day, probably better than the D, but that day is past, and parts will become hard to come by. BTW, 1950's era OB's were not necessarily lighter than the C or D, as they used less aluminum and more ferrous parts.

The tilt and trim add a lot of weight in any motor. In fact, even the newer 20 4-stroke goes away from hand-tightened transom clamping to hex-head (wrench-tightened) clamps when you add the power tilt option. The MFS30B, for example (3-cyl EFI 4-stroke), goes 161 pounds in remote model, and is a very torquey rig. The MD40B2 (TLDI), weighs in at 208 pounds in similar configuration, but it might just be more motor than you need.

Considering that all the smaller 2-strokes are becoming dated, and unavailable new in North America, if you plan on running this rig for a long time, the MFS30B may be the setup for you. Many 40D motors are still running, but in salt, corrosion will be taking its toll on many of them.

Thanks for your input. I didn't mean to imply I felt the 50's era OB's were lighter. On the contrary, my rationale behind thinking I could go with a higher Hp with a newer motor was I thought the newer, higher Hps models were lighter. Your suggestion of putting an MFS30 on didn't cross my mind because of my belief that a 4 stroke would be too heavy. However, it sounds mighty tempting if that 161 wt you mentioned includes t/t. But, would I be gaining much in the way of performance with an increase of only 5hp?*
Thanks again for taking the time to opine and I really look forward to your next response.
Wet Willie

In many cases " older " motors were indeed lighter.--------------In fact the 53 ---25 HP Evinrude / Johnson was marketed at 85 LBS ---------Of course that was not propshaft power.

Racer is quite correct when he mentions that the older hp ratings were typically at the powerhead. That could easily translate into 10% loss at the prop shaft. Today though, the numbers are measured at the prop. So... a new 30 (for example), rated at the prop, would be a significant increase from, say, a 25 that was rated at the powerhead -- about 25-30% more power. I can't say whether that merc was rated at the powerhead or at the prop, though The torque curves are a bit different, if switching from a 2-stroke to a 4-stroke as well.

The 2-strokers used to run the best at about 3/4 throttle and up, but we see that the 4-strokes extend that down to running very well at 1/2 throttle or even less, especially the EFI models. So, offsetting the weight penalty of the 4-stroke valves is a longer, flatter torque curve, better economy, and quieter operation.

For insurance purposes, it would be best to stay at or below the hp rating placard, if the boat has one. Those placards were not mandatory in that vintage of boat, so you may not have one. I normally spec a motor that is at least 80% of the placard rating, unless the owner just wants to putt along.

Matching up all these factors, if I had the job of rigging a new motor on your boat, I would try the MFS30B, because it fits all the criteria, without exceeding any of the parameters.

pvanv said:

Matching up all these factors, if I had the job of rigging a new motor on your boat, I would try the MFS30B, because it fits all the criteria, without exceeding any of the parameters.

Click to expand...

I appreciate both of you responding with so much useful information. Now, I'd like to take it one step further. I expect and accept if there's some bias in your response to my next question. Which motor would you prefer if you were in my boat, pun intended, the excellent running '92 Merc 25 that I now have or an MFS30B?
Thanks again.
Wet Willie

If you don't need any new motor at all, stick with what you have. OTOH, if buying a new one, the MFS30 is the best bang for the buck in your size category.

Thanks Paul. I guess that pretty much settles it. I'll stick with what I've got and prop it right unless I find a deal on an MFS30 thats too good to pass on. Could you tell me what yrs the MFS30 was made?
Wet Willie

The original/early MFS30 (the A model) had 3 carbs, and was soon replaced by the EFI (B model), which is still in production.

Was power t/t available, or standard, on any, or all, of them? My biggest complaint with my Merc 25 is the lack of power t/t. Something I must have on my next motor.
Wet Willie

The MFS30 does have TT available.

This belongs in a new thread. Your bold and caps lock make this question seem like you are yelling, BTW.

The 40D was made in the mid 90's. Year is unimportant for servicing and value, since the 40D (and later the D2) were made for several years; exact model/serial and condition is everything. Tohatsu America may be able to give you a year at http://www.tohatsu.com/contact.html

You can get a Factory service manual with all the specs and procedures you need from any dealer, including me.

You probably have a warped head.

sorry for shouting,but at my age i don`t realise,plus the bold capitals save me squinting,with my spectacles on,however being a retired motor mechanic,it made sense to get the head skimmed,when i replaced the gasket.i checked the head when i got it back,and the bow had been removed, it was perfect.the number three pot was letting in water,and had no compression,before,but today i got it running,it only has 50 lbs compression,but at least it runs,and it is dry,thanks for the reply,george