1984 Johnson 9.9 Powerhead

[Lundc12]

Hello. I would like to know if a 1974 powerhead will fit in my 1984 Johnson. I actually think it will fit but not sure if the shifter linkage and other bolt on items will all work with it. Thank you.

 

[racerone]

Yes it will.----Not sure why you would go this route ?----The 84 is a much better motor.

 

[Lundc12]

Thank you. The 84 threw the lower rod through the crankcase so looking for the best way to get things going. I didn't realize that the 84 was better than the 74 as I thought internally they were the same except for the center main bearing. Is that not the case?

 

[raczekp1]

only you need to modify water cover jacket panel. 84' powerhead is designed to mount powerpack, 74 powehead water cover jacket have 2 holes less
also 74 have no pee hole but its esay to add
i think 84 ' cdi ignition is much better than point + condenser low tension ignition,
so cdi flywheel is different than points ignition( need to be moved key notch )

 

[Lundc12]

Thanks for the info! I will wait until a later model powerhead becomes available, I want to use all the external components from the 84, especially the CDI ignition. I had not thought about the different ignition...

 

[raczekp1]

internaly both powerheads are the same.the same pistons, crank shaft, bearings, seals,

good powerhead is when cylinders are not scored and when you put piston ring(new one) into cylinder bore and measure ring end gap should be 0.20-0.25 mm
bad cylinder bore is when ring end gap is 0.35 or more. compression with this gap will reach barely 90 psi or less

 

[racerone]

RACZEKP1-----Please note that the pistons / bearings / wristpin / connecting rod on the early engines is NOT the same as the 84 model !!!!!------The entire 74 motor assembly will fit.----Changing just the block and adding the 84 pieces to the 74 model will get tricky.

 

[Lundc12]

I greatly appreciate all the input. Based on your responses I've abandoned looking at the older powerheads. In looking at the parts listings it appears that only the 83, 84, and 85 crankcases share the same part number so maybe I need to restrict my search to one of those years?

It looks lide a complete powerhead is the way to go. On ebay complete powerheads seem to go for around $200 while bare crankcases seem to fetch around $100 to $150, connecting rods $50 to $80, and rod bearings $15 to $35. At those prices it doesn't seem to make sense to buy the individual pieces. Probably better to buy the complete powerhead to rebuild and have extra parts if needed.

 

[racerone]

Prices vary depending on where / how you shop.-----Last bunch of powerheads I picked up was $50 each for about 10 of them !!

 

[Chinewalker]

More or less any full CDI powerhead will bolt right up, as will all peripherals. So, that means 1977 to about 1988. I think 1989 was first year of CD box under flywheel, and you can retrofit those to externally mounted if needed. Also, 9.9 or 15 powerheads will fit.

 

[Lundc12]

Thank you all for your help. I just ordered a rebuilt 1988 15 horse powerhead so with any luck will be back on the water in a few days. It certainly cost a bit more this way but will be nice to just bolt it in and go.