3 cyl OMC ???

[David_L6]

What are the reasons for the different pistons and rods in the Mod 50 as compared to the regular service engine?

How does switching from the fishing motor piston/rod combo to the Mod 50 piston/rod combo affect port timing?

[crankbearing]

I have a question about the three cylinders OMC's as well. I have heard mixed comments about using a stinger powerhead in comparison to say a 70 3 cylinder and issues that the stinger is not as strong for formula "E" as a base powerhead.

Is there any truth to this? If so what are the actual differences in the two and why would you or would you not use the stinger powerhead?

Regards,

[modifiedoutboard]

Does any one have a old spec sheet from the mod 50?
APBA has specs on all the FE engines helps to Design.

[pro350hydro]

Originally posted by modifiedoutboard
Does any one have a old spec sheet from the mod 50?
APBA has specs on all the FE engines helps to Design.

You are the tech guru, don't you have a spec sheet?

[modifiedoutboard]

Never asked for the old tech sheets.

[ER 7J]

There are only several things different between a 75 hp stinger and a 70 hp...

A- The 75 had larger bore carbs.
B- The 75 has a chamfered exhaust port, the chamfer is cast into the sleeve but can be easily duplicated.
C- Different exhaust tuner.
D-Different decals and paint

Ed Runne

[Travis Fulton]

Originally posted by crankbearing
I have a question about the three cylinders OMC's as well. I have heard mixed comments about using a stinger powerhead in comparison to say a 70 3 cylinder and issues that the stinger is not as strong for formula "E" as a base powerhead.

Is there any truth to this? If so what are the actual differences in the two and why would you or would you not use the stinger powerhead?

Regards,


the stinger is 49 ci the current 70 hp is 56 ci

the stinger did have a larger bore carb but the newer carbs can be modified to out preform the old stinger pices, sst 60 carb are superior.

i would like to see some specs on the tuner if anyone would have any?? never seen one,

[ER 7J]

OMC built a 55 hp 60hp 65hp 70hp and a 75hp based on the 49cu in powerhead. The first year the powerhead was used in production was in 1968
The 56 cu in powerhead was introduced in 1986 that was also the last year of production for the 49 cu in engine, it was built as a 65hp that year.
Any of the aluminum single venturi carbs are (probably) legal on the FE engines, but the later style carbs with the plastic low speed covers are not legal.
Ed Runne

[crankbearing]

So, are guys building the stinger powerhead as a fe motor or opting for the later 65, 70's etc...

Is there a difference in the pistons as well between the stinger and the others.

Regards,

[Travis Fulton]

arent the 49 cube slugs are smaller (bore)???????

[ER 7J]

The Only differance in the block is the chamfered exhaust port! takes about 10 min. with a die grinder to turn a 70hp block into a 75 hp block.
all the flat top pistons are the same (early had small w pin bores later had large .625 w pin bores).....early pistons had high rings the factory went to lower rings in the late 70's to help engines live with lower octane fuel.
Early 55 hp and 60 hp pistons were domed
Ed Runne

[pro350hydro]

Ed,

Thanks for sharing your "wealth" of knowledge to those on this board who truly want to learn more about the FE motors. It is nice to see peoples questions getting answered with "actual" answers rather than just b*&^%$#t. I'm sure there are several FE's drivers here that appreciate what you are doing.

Mike
R-15

[hydroman6]

" later style carbs w/ the plastic low speed covers"

Can you elaborate on this a little? Do you mean any of the ones with the little removable plastic piece with a hole in it in front of the low speed jet? Don't the Mod 60 carbs have this? Would they be legal?

[form-e one]

i guess my 55hp block isint the one to have or modify...hehehe???,,,it went over 100mph....cheyney

[Ron Hill]

This class isn't something I'm "INTO" but I was wondering if powerheads are hard to find? Or are there millions out there?

Is there one that people USUALLY USE?


The reason I'm asking, I know of several dealers, out here, that seem to have many "CLEAN" looking OMC 3 Holers without gearcases...

If anyone needs these....give me serial number you'd like and what you want or would like to pay. Maybe, I can do something..

Last year I found one brand new OMC "A" Short block and one complete OMC "A" Fishing motor, both were cheap...

If power heads aren't a problem, I won't waste my time looking for them...