1977 johnson 85 and 115

i have a 85 and a 115 both same year. i cracked the block on the 115 and i am in the process on putting the carbs and intake from the 115 to the 85. what makes the differance of these motors (bore stroke) or is it like i have heard and it is just the exhaust and the intake.i also put the lower unit from the 115 on the 85 b/c the unit from the 85 was bad. from what all i see they are the same other than the carbs and the intake. will this intake and carb set up be to much for the 85?

Re: 1977 johnson 85 and 115

I think the displacement is the same between the two blocks, but port timing is definitely different. I believe the throat size of the carbs is different too - you can check the size on the front of the carbs. The 85hp is 1" and the 115 is 1-1/4" (I think). You'll certainly need to rejet. The lower unit should work just fine though.

Re: 1977 johnson 85 and 115

These early crossflow 85 and 100 hp engines used the same block casting, but it was machined with a different bore and used a smaller piston than the larger hp V4's. Crank and rods were the same. They were 92 cubic inches instead of 99.6. In 1979 (and later) all V4 crossflows were changed to use the same block bore and pistons, the 99.6. I'd follow iwombat's suggestion on swapping the carbs. They should make a noticeable difference in your 85. He is correct, in that you may need to rejet the mains down somewhat so that it does not overfuel at top end. If you have the intake manifold off, transferring the 115/140 hp intake filler blocks (322684) to the 85 will also help improve the hp.

Re: 1977 johnson 85 and 115

Thanks em - After posting I kinda remembered it was something odd like that.

Re: 1977 johnson 85 and 115

thanks guys i have installed the 115 intake on the 85 and the lower unit went right up in there like a charm. i will take it out prob this weekend and see if i will need to rejet it.