Johnson "70mod"

**filthy phill** · 03-01-2017

con rods for sst60 are same as 70hp bridgeport. part number 394462 same length no different.
piston no for sst60 and 70hp bridgeport part no 394461 same pistons.
crankshaft for sst60 is what was used on 65, 70, 75 hp to 1986 (after that fishing motors went to multi spline) part number 328788 same throw 4 splines.

these are all omc specs and part numbers.

so no idea where the myth of the long rods and longer throw cranks come from.
I do know that is what fast fred would use in a special mod 50, but not what omc used for the sst60 motor.

**Hevi Kevi** · 03-01-2017

Yes, they are the same connecting rods and cranks. No, they are not all the same size. Everything has a tolerance. This is why guys pull apart piles of engines to build one.

**filthy phill** · 03-01-2017

not talking about guys trying to re-create a sst60 and building one up, were talking about a genuine OMC sst60 block being different to a fishing motor block.

**Hevi Kevi** · 03-01-2017

Originally Posted by filthy phill

not talking about guys trying to re-create a sst60 and building one up, were talking about a genuine OMC sst60 block being different to a fishing motor block.

ok imagine this scenario
get a good 56 bridgeport fishing motor powerhead with say 130 psi compression. take of normal head and then put on a genuine un-molested sst60 cylinder head.
do you think this motor would even start let alone run good ?

It would start, run very well and likely be around 160psi

Kevin

**filthy phill** · 03-01-2017

would it realy
what about the large gap where the SST60 piston normally goes into the head.
Genuine sst60 head is not flat like the fishing motor head, it has a recess for the piston to enter.

I would of thought compression is going to be pretty low with this head on a fishing block thats NOT been decked to allow piston entry into the head.

.

**LittleCharger** · 03-01-2017

Originally Posted by filthy phill

would it realy
what about the large gap where the SST60 piston normally goes into the head.
Genuine sst60 head is not flat like the fishing motor head, it has a recess for the piston to enter.

I would of thought compression is going to be pretty low with this head on a fishing block thats NOT been decked to allow piston entry into the head.

.

The piston doesn't go into the head on a decked block, it protrudes into the head gasket.

**filthy phill** · 03-01-2017

what ?
you saying that you could put a fishing motor head on a genuine sst60 and the piston would not hit the head ?

**LittleCharger** · 03-01-2017

Originally Posted by filthy phill

what ?
you saying that you could put a fishing motor head on a genuine sst60 and the piston would not hit the head ?

Yup because the piston doesn't stick through the head gasket.

You need to look at the sst60 specs not sure where your getting the idea that the pocket width of the cylinder head is the diameter of the piston

**hupiveneilija** · 03-01-2017

Originally Posted by Hevi Kevi

hupiveneilija,
Did you have any problems with the head warping when you welded up the chambers?

Kevin

I really dont know, havent done myself, sorry.

I was wondering FastFreds "most positive trough" comment while ago, but then it opened to me😂. Toleranses. Thats why you need piles of motors as said.
I have worked with one I got, allthough I got one spare yesterday to play with if Ive done something really wrong, like transfer timing😊.