49.7 using 4.00" rods

[OUTBOARDER]

Going to go mod a piston for 49.7 ci triple to accept 4.00" rod:confused:
any thoughts out there?

Thanks
Anthony

[Phil McDaniel]

All you have to do is find the right piston/wrist pin hole size,,,wrist pin location,,, skirt porting,,,etc.
Which rod are you planning to use????

You know, several years ago OMC and all it's money and capability invested time in their motors to stay ahead of their competition. They had far more than the average lay outboard person. From their tech. and available parts today which will make the 49.7 an O.K. racer. You are still going to wind up with the same distance from the center of the rod to the top of piston as in all other piston/rods available. My thoughts are"If it ain't broke---don't fix it"
Hope this saves you a lot of time and money. Phil

[Bunker Hill]

What's the objective here, what are you trying to achieve?

[OUTBOARDER]

All you have to do is find the right piston/wrist pin hole size,,,wrist pin location,,, skirt porting,,,etc.
Which rod are you planning to use????

You know, several years ago OMC and all it's money and capability invested time in their motors to stay ahead of their competition. They had far more than the average lay outboard person. From their tech. and available parts today which will make the 49.7 an O.K. racer. You are still going to wind up with the same distance from the center of the rod to the top of piston as in all other piston/rods available. My thoughts are"If it ain't broke---don't fix it"
Hope this saves you a lot of time and money. Phil

want to use improved 56ci rods that are 4" center to center, like a number of others, please dont tell anyone it's a secret;)

thanks Phil

[David Mason]

It has been tried many, many times by many racers. You are wasting time and a customers money.

[F-12]

Good advise , David. There are many more things you can waste time and money on than this.

[OUTBOARDER]

What's the objective here, what are you trying to achieve?

To put the rod to stroke ratio where it needs to be for relibility, saftey as well as performance. FEH is a great class since you have the freedom to do this. Design the engine from the ground up.
Had to make a 45ss from scratch from ground up for FEH and it performed well.

Any way I found a prospective piston available in 76-76.5-77-77.5-78mm
will take a look and see if it will work for my application.

The local outboard junk yard has 4.000" 56ci rods, less expensive , in better condition and more robust than the 3.688" rods that originally came from a
2cyl crossflow making about 10 or 15 hp hp per hole.

Would never use antique parts for a "new" engine not in FEH

Thanks,
Anthony McCulloch

[Bunker Hill]

Answers my curiosity, Thanks

Bunker

[David Mason]

You deliver a reliable product. If you are building for reliablilty why are going through all the trouble to make it for racing ? Is it going to be a front runner or field filler ? A simple stock powerhead put together with stock parts with no porting or special parts will run just fine and offer very little issues. Much cheaper than going through the work you have mentioned. Is this your motor or are you charging someone to build them one ? If so, can you name your customer ?

[OUTBOARDER]

You deliver a reliable product. If you are building for reliablilty why are going through all the trouble to make it for racing ? Is it going to be a front runner or field filler ? A simple stock powerhead put together with stock parts with no porting or special parts will run just fine and offer very little issues. Much cheaper than going through the work you have mentioned. Is this your motor or are you charging someone to build them one ? If so, can you name your customer ?

Already answered Dave, it is less expensive since locally we do not have FEH race ready powerheads lying around. have already discussed the cost effectivene$$ of burning down ten $tocker$ a in one $eason vs say a Runne 49.7 .............

Quote: Much cheaper than going through the work you have mentioned?????
A: I did not mention work???:confused:


Q: Is this your motor or are you charging someone to build them one ? If so, can you name your customer ?
A: talk to me at the races or call 757 338-2008

PS: Let me know how much for one of yours and what it will do:rolleyes:

Have a good one!!!

[David Mason]

Already answered Dave, it is less expensive since locally we do not have FEH race ready powerheads lying around. have already discussed the cost effectivene$$ of burning down ten $tocker$ a in one $eason vs say a Runne 49.7 .............

Quote: Much cheaper than going through the work you have mentioned?????
A: I did not mention work???:confused:


Q: Is this your motor or are you charging someone to build them one ? If so, can you name your customer ?
A: talk to me at the races or call 757 338-2008

PS: Let me know how much for one of yours and what it will do:rolleyes:

Have a good one!!!

I don't have any for sale right now, nor have I ever. Never have sold 850CCM engines. Only one I know of Dad sold, and that was his original one to Harry Brinkman to help the class get going back when they invented it.

If I built a stock engine it would not burn down ten times :confused: If you are having trouble burning up stock engines I would say it is an issue not related to the powerhead.

Sorry, I won't be calling, I had my fill the last go around.

[OUTBOARDER]

I don't have any for sale right now, nor have I ever. Never have sold 850CCM engines. Only one I know of Dad sold, and that was his original one to Harry Brinkman to help the class get going back when they invented it.

If I built a stock engine it would not burn down ten times :confused: If you are having trouble burning up stock engines I would say it is an issue not related to the powerhead.

Sorry, I won't be calling, I had my fill the last go around.

Was FEH a stock class in the beggining? That is interesting how times have changed. That explains a different perspective Stock vs Mod!!!!!!!!!!!!!!!
Back in 1999 APBA listed it as the most open of the mod classes that is what interested me to learn about two stroke outboard engines.

Problem was the FEH engines were not availble in my area!!!

Have to go and put my order in for some pistons:p

Anthony

[Phil McDaniel]

In Cincinnati, Ohio in 1983 the mod commission met with others to structure what is today the FEH, FER. There was a lot of input from mostly "E" Class drivers. Along with Brinkman,Mason,Pigott,Brill,Terrell,Hemp,Robb Sr.&myself as well as a host of others the class took off. The only controversy was the 650XS as to wheather it was a production motor or not. This was where and how it was birthed and you see where it is today. Can't remember who was Mod V.P. at the time. Maybe Engler???

[Powerabout]

How long are the;
a) old 'big twin' rods?
b) how long are the mod 50 rods?

Phil
What rod length are your pistons designed for?

Thanks
Powerabout

[Phil McDaniel]

Rods:
Back in the 70's when OMC was building the Mod.50 they took a rod that they already manufactured to use for this motor. It was in the 2 cyl. motors in the 50's and 60's and early 70's. The casting # on the rod is 308301 and had(from what I've seen)3 diff. versions. One had 3 holes drilled in the cap. Another version had a relief in the wrist pin(both sides) for clips to hold brg. assy. in. And 3rd. was the solid rods. ALL of these rods have a small wrist pin.
OMC used this mold to cast Mod.50 rods. Crank-end the same,but instead of the small wrist pin, they made it a large wrist pin as found in the 3 cyls. of last production.
Their pistons(Mod.50) were unique to the 3cyl. only and were built with the longer rod as an assy. to give the racing version of the 3cyl. longevity. Even though both assys. were the same in length(from split of crank end of rod to top of piston)the longer would prove to be the better in the life of the motors.
The rods are still around today as I bought 5 new ones a couple monthe ago.

Hope this helps in your rod and piston selections. Phil

[Powerabout]

Thanks Phil

What rod length are your pistons for?
Where does the 56 rod length fit into this picture
is it longer or shorter than the mod 50?

Those old big twin rods must still be around as the 40hp they came from was manufactured as a commercial engine for years as I still see army/navy guys using them around the world.

Powerabout

[Phil McDaniel]

As near as I can measure the rods(fish and Mod.50) measure 4.242" +/-. This is from center of crank end to center of wrist pin end.

As for the 56 ci/SST60 rods they are shorter than these above and do not fit into this equasion at all.

When I look for good used ones, I go by the casting # I gave you so as to no confusion. Makes it easier. I like the solid rods of the 3.

Thanks Phil

[Powerabout]

Phil
So your pistons suit the long rod with small wrist pin