1973 65 hp triumph vs 1974 70hp johnson???

[busted-bayliner]

i have both of the motors an they look identical even the part numbers for a ton of stuff are the same so my question is what makes the 5hp difference theses look like the same exact engine im askin because im baffled. Bigger carb throats? cus the carbs look the same coil packes are the same everything is the same any help or knowlege is appreciated

sorry the title doesnt say my 65hp is a evinrude

 

[busted-bayliner]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

bump no answer?

 

[Chinewalker]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

Significant differences in cylinder head and exhaust tuner...

 

[tumblweed9999]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

Hey dude, I have almost same two engines. 1972 65hp Evinrude Triumph , and a 1975 70hp Johnson. Right now the obvious external difference is 5mph with a 13.25x17P OMC original designed pointy ear propeller.
Old motor wouldnt spin a 19p fast enough, 4900-5000. the 70hp will spin it up to 5700-5800 RPM's. But it runs the best with a new BRP round ear 13.25 x17.
The differences can be found on some oth$r Foru-ms, explained more in detail. What I've gather so far, is the shape of the combustion chamber, the exhaust tuner is more restrictive on the 65, but it's matched to the carbs, the carbs appear to have the same diameter except inside the venturi appears to be shaped different and narrower on the 65hp. If you have different style teeth on the flywheels you might have a 72 flywheel on the 73. Not sure when exactly the change came but somewhere in between 72/73 they changed to the heavier flywheel. racers seem to seek out the 72 flywheel.

 

[durban]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

there are a number of diferances the just a few i will mention the exhaust houseings are different , the adaptor aswell , the gear boxes are not the same ratios & the houseings are different , the flywheels are the same they changed the fly wheels round about 1971\72 , water pumps differ , stators are both 6amp but a slight change in design although the will fit each motor , the top half of the carbs have differances in them as to fuel configuration as tumblweed 9999 mentioned , the intake mainifold plate has got a few differances on it to,then piston size, cylinder heads look the same but are differant diameters in the dome.

 

[tumblweed9999]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

there are a number of diferances the just a few i will mention the exhaust houseings are different , the adaptor aswell , the gear boxes are not the same ratios & the houseings are different , the flywheels are the same they changed the fly wheels round about 1971\72 , water pumps differ , stators are both 6amp but a slight change in design although the will fit each motor , the top half of the carbs have differances in them as to fuel configuration as tumblweed 9999 mentioned , the intake mainifold plate has got a few differances on it to,then piston size, cylinder heads look the same but are differant diameters in the dome.

Thanks Durban
I'm learning alot on these forums. I was not aware of the different gear ratios between the two, but it makes sense. I've seen people mentioning be careful about buying a used one because the 50-55-60hp mechanical shift lower units are not geared the same as the 70-75.
Hey? Did the drive shaft splines on the electric shift match the splines of the mechanical shift going into the powerhead? Just curious, because I might have been misinformed or only partially un-ignorated (<--new word) about this when I was rebuilding the powerhead on the 72. Somebody at an Evinrude parts dept. told me I could not change my 72 triumph into a mechanical shift, because the splines were different, and something else....Control box wiring.

 

[durban]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

the cranksharfts are the same & so does the drive sharfts fit , i think what they ment is propoaly the differance between short sharft & long , if you have a electro shift you have to change the manifold plate to make it manual & drill a hole in the bottom cowling cover for the gear sharft , depending what exhaust youve got you have to change water pump to accomodate , ive uploaded my 60hp evinrude ive done some major conversions to it , but ive used the original manifold plate
http://forums.iboats.com/showthread.php?t=527612

 

[Faztbullet]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

the gear boxes are not the same ratios & the housings are different

Both are 2.42 ratio and only difference is water pump housings ...other than that they are the same. The carbs have larger venturis to flow more CFM.

the intake mainifold plate has got a few differances on it to,then piston size,

The intake and leaf plate assy are the same between engine and both are 49ci engines. The only difference is the wrist pin size and rod as the 73 had the small 5/8 pin and in 74 they started going to the 3/4 pin so engine could have either size in it. The cylinder head will interchange but the 65 hp has more compression as it has a smaller combustion chamber and casr in eyebrow where 70ho is just a round chamber..

 

[durban]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

there are a few changes in the gear box k , example the shift rod plungers are not the same , error on my part the gears only changed in 1975

 

[tumblweed9999]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

Both are 2.42 ratio and only difference is water pump housings ...other than that they are the same. The carbs have larger venturis to flow more CFM.

The cylinder head will interchange but the 65 hp has more compression as it has a smaller combustion chamber and... 70ho is just a round chamber..

Is it worth the trouble to swap the head from my 72-65hp, to the 75-70hp? It
s not broke ......but thats when I start screwing around, historically. Take a perfectly good 1975 Johnson, and tear into it
and make it run different, then change timing, idle screw, road test. tweak. road test. tweak......Or could just go ride around........Although, I'm not sure why, but i can hear the reed valves on this 75 Johnson. Further inspection revealed the exhaust gaskets and intake gaskets are somewhat recent..( this century)...I'm wondering about the reed valves, because the 65hp, never made a peep in that regard. sounds like a kid riding past with playing cards clothes pinned to his bike spokes. and the Hole shot on the 65Hp was crisp and decisive...where as the 70hp seems to wanna think about what just happened when somebody goes WOT on it....savvy?

 

[Chinewalker]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

there are a few changes in the gear box k , example the shift rod plungers are not the same , error on my part the gears only changed in 1975

Gear ratio on standard length 70-75 models stayed the same through their whole run. Only differences in ratio occurred when you get into the rare short shaft (15") models that used parts of the smaller diameter 2-cylinder gearcase that used a 1.87 ratio.

 

[durban]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

from 1975 to 1978 only as 1979 onwards they are not the same ,as there were also 2 models 75 hp in 1979 & they not the same as the previous years

 

[Chinewalker]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

Yes, they are the same ratios. The 3-cylinder 55, 60, 65, 70 & 75 hp standard (20" shaft) models ALL used the 12:29 gear ratio (2.42), and the 15" short shaft variants used the 15:28 ratio (1.87) in the smaller 2-cylinder 50/55 style gear housing. NONE of the 2-cylinder lower units will interchange with a 3-cylinder lower unit, regardless of the gear ratio.

 

[durban]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

i know all that , iam refering to the actaul fitting of the gear they are differant fitting 1975 to 1978 , dont fit 1979 onwards

 

[Faztbullet]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

iam refering to the actaul fitting of the gear they are differant fitting 1975 to 1978 , dont fit 1979 onwards

Thats because they went away from the hydro-mechanical shift in 1975. The 1975 and earlier ones have a pump driven by forward gear and housing internal dimensions are different between the mechanical and hydroshift.

example the shift rod plungers are not the same

Dont know what your calling plungers but pre 1978 units use all the same parts.....

Is it worth the trouble to swap the head from my 72-65hp, to the 75-70hp?

No as gas is chitty nowdays and you would not see the extra 2-4 hp unless on a real lite boat and turned motor at max rpm....

.Or could just go ride around..

best option!!!!!

 

[oldschooltiller]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

Is it OK to tack on other questions about these 3cyl engines? It's kind of turned into a discussion to include other years


What tilt/trim units will interchange?

Is there any advantage to the newer plastic air box? Less noise, increased air flow, anything?

 

[Faztbullet]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

What tilt/trim units will interchange?

1978-1998 will interchange physically but 1978-81 requires wiring mod's as they went from a 3 wire motor to a 2 wire.

Is there any advantage to the newer plastic air box? Less noise, increased air flow, anything?

Easier to get on/off is about it....

 

[durban]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

i have fitted a plastic air box to my 1970 60hp & found no differance at all

 

[durban]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

from 1975 to 1978 only as 1979 onwards they are not the same ,as there were also 2 models 75 hp in 1979 & they not the same as the previous years

example just the frward gear 1973 -1975 65hp & 70hpmodel B part no , 0385567
1975 -1978 70hp & 75hp part no 0387143
1979 -1985 65hp 70hp & 75hp part no 0389964

so why are the part no,s not the same if they are ment to fit , ......?

 

[Faztbullet]

Re: 1973 65 hp triumph vs 1974 70hp johnson???

The part# 385567 supersedes(updates) to 0397490 . The part numbers 0389964 and 0387143 supersedes (updates) to 0397338 which means 1975-1978 uses same gear as 1979-1985 motors