78 140 johnson rods and pistons

[fishdady]

I have a Johnson 140 ( mod-140tl78c ser-j4990278) I'm doing a rebuild on it, and when I tore it down, the rod part# was 312712 (should be 387831) The piston just had OMC 362969 trw 470-99 (should be 388671 std.). This is my first rebuild, so, I'm confused on these numbers. I hope this isn't a frankenstien engine. Any help would be greatly appreciated. Thanks, Fishdady

 

[slimjohnson]

Re: 78 140 johnson rods and pistons

I would have to get my parts book out but i know that some of the part numbers changed through the years. marineengine.com is a goodplace to check for all the part numbers that are all the same thing. just look up your engine and they will list all the parts and all the superceded part numbers.

 

[fishdady]

Re: 78 140 johnson rods and pistons

I would have to get my parts book out but i know that some of the part numbers changed through the years. marineengine.com is a goodplace to check for all the part numbers that are all the same thing. just look up your engine and they will list all the parts and all the superceded part numbers.

Thanks, I'll try that. I've tried everything, trying to figure this out. I'll let you know. Thanks again, fishdady

 

[fishdady]

Re: 78 140 johnson rods and pistons

Thanks, slimjohnson, but, came up empty again. I'm not sure what I have. Fishdady

 

[fishdady]

Re: 78 140 johnson rods and pistons

Here's another number block # is 388607. Can't find it either. Any help would be appreciated.

 

[slimjohnson]

Re: 78 140 johnson rods and pistons

just another thing to keep in mind is that sometimes the casting numbers and part numbers are not always the same. I dont no if it works that way on the rods and pistons. On my crossflow i didnt check those numbers while i had it apart. You can always have the machine shop just check the measurements and it really doesnt matter on the numbers as long as you get the correct new bearings and parts to fit what you have. All those numbers start to get blurry to me after a while.

 

[slimjohnson]

Re: 78 140 johnson rods and pistons

I will try to check my fsm tomorrow and see what i come up with

 

[daselbee]

Re: 78 140 johnson rods and pistons

The number on the side of the rods is a casting number. Same for most numbers on the carbs and carb bodies.
My 1996 V6 heads have a casting nyumber on them.
On my newer pistons, 1996 up for sure....the part number is etched into the top of the piston.
There doesn't seem to be any rhyme or reason to it....

I really wish I had a casting number to part number reference. don't even know if one exists.

 

[fishdady]

Re: 78 140 johnson rods and pistons

Be nice to have a cross number reference. I've looked everywhere and came up blank. I know it's 8 1/2 inch bore, just confusing for a novice. This may seem crazy, rebuilding an engine that old to some people, but, this has been a good old girl to me, and, I think she's still got some life to her. Thought I could figure it out by the block # today, but, hit another dead end. Anyways, I sure do appreciate the help (daselbee and slimjohnson). Thanks again, fishdady

 

[Haffiman]

Re: 78 140 johnson rods and pistons

You may have an old set of TRW(Now Federal Mogul/Speed Pro) pistons installed. Any signs of previous dismantling and overhaul?

 

[fishdady]

Re: 78 140 johnson rods and pistons

Looks like 3 and 4 have some damage to the crank throws. See dents and dings (nothing major), maybe rod let go some time. 1 and 2 throws are machined smooth. The way things look, the answer would be yes. There is a trw # inside the piston 470-99 also omc 322969. I just noticed on original post I put 362969. Sorry. I'm going to get on the fed-mog(trw) site again and see if I can find this piston again. Once again, I appreciate everyone's help. fishdady

 

[Haffiman]

Re: 78 140 johnson rods and pistons

You will not find them on the Fed-Mog or Speed Pro sites as they are no longer in their 'inventory'. TRW however ha them long time ago.
Whatever you do, see to that all pistons are of same 'brand' to keep the weights under control. Std size or over-size of same brand does not matter as all are compensated/calibrated to same weight.

 

[fishdady]

Re: 78 140 johnson rods and pistons

O.K. will do. Thanks to everyone. fishdady