Johnson 1976 15hp; Exhaust Tuner and Reed Shim Update?

[JohnnyGuy]

Hey all,

I have a 1976 15hp Johnson (15r76a), which I currently have the powerhead off of to replace upper thrust mounts.

I have a '87 15hp parts motor on hand and was wondering if it would be worth it to change out the stock square exhaust tuner for the round one found on my '87 parts motor, along with swapping Reed plates to bring my '76 up to date with the 15hp mods that happened later.

I've never touched the Reed's before, I am assuming it's a simple swap?

If I swap to the round exhaust tuner, do I leave the short copper water tube it has at the back in place? My 76 has no tell-tale just the "blubber"/exhaust relief hole at back center and I am curious if this would alter the way I check to ensure the motor is pumping water...

TIA for your comments.

JG

 

[JohnnyGuy]

I thought I may have gotten some quick input on this.
I think I'll be going ahead with it.

My main question would be with regards to the updated exhaust tuner and how it relates to the additional copper tube at the rear of the tuner.
Do I just leave it as is, will water still come out the exhaust relief hole? Do I just remove the short copper tube? Should I be adding the tell tale?

Thoughts?

 

[flyingscott]

I don't think the reed shims are worth it. You should leave the short tube on and make sure it slides into the exhaust relief passage. You will no longer see any water come out at all. Put the peehole in from the 87 motor. I would also put the head on from the 87 motor if it has the top thermostat.

 

[JohnnyGuy]

I don't think the reed shims are worth it. You should leave the short tube on and make sure it slides into the exhaust relief passage. You will no longer see any water come out at all. Put the peehole in from the 87 motor. I would also put the head on from the 87 motor if it has the top thermostat.

flyingscott, thank you for the informative reply. Much appreciated!