1988 20hp evinrude converting to 35hp & adding electric start

[bowfisher2636]

Alright guys I acquired a 20hp 1988 evinrude this summer and ran her all summer now I have acquired a donor 35hp motor with electric start. I plan on a flywheel swap and adding the starter and also a solenoid. After that I plan on adding the 35hp intake manifold (carb plate) and adding a 35 hp starter I'm going to add a tach in the next week and test the stock motor before I modify and post my results then start the modifications along with pictures and all the steps

 

[boobie]

Why are you doing this ???? Maybe I'm missing something.

 

[scout-j-m]

Good luck. I will be following to see how it goes.

What hull is the motor on?

If you haven't picked a tach yet, I like the Hardline brand ones on Amazon which are about $25.

 

[Guest]

Be advised, that the pistons and con rods may be different between your 20 and the 35.

Years ago, I took a 1973 Johnson "20" and tried to make it a "25" by changing to a 25 carb and 25 flywheel. The motor ran a little faster but after looking at a parts list between the 2 models, the pistons were different and the con rods were too.

You may get improved performance, but you won't hit 35 hp. A good suggestion would be a set of aftermarket CCCM Reeds.

 

[flyingscott]

The 35 cube blocks can be converted from 20 to 35 hp fairly easily. There is usually a timing change involved so make sure you check that. The 22 cube block there were differences between the 20/25 hp models not so much with the 35 cube blocks.

 

[racerone]

Actually 31.8 cubic inch.

 

[flyingscott]

Actually 31.8 cubic inch.

Yup

 

[bowfisher2636]

I have gotten the electric start on today didn't get to video the process but it went fairly smooth. Had to go to the local
Hardware to get another bolt that was longer. I'm going to run a on off on switch and tie in a rod from the internal shift point so it will have a light on so it won't be cranked in gear. I have been doing a lot of looking and I don't think I will run into any problems swapping the carb and intake manifold over. I also purchased a tiny tach today. I noticed a comment about changing the timing. I do not know how to change the timing nor have I ever tinkered with it. Anyone care to put some input on that

 

[bowfisher2636]

Good luck. I will be following to see how it goes.

What hull is the motor on?

If you haven't picked a tach yet, I like the Hardline brand ones on Amazon which are about $25.

I purchased a tiny tach and also it's on a 14/48 hull with a 5 foot aluminum bowfishing deck running 8 high pressure sodiums with rails loaded down by myself the stock motor will run 22mph via gps with a semi worn out prop. I also plan on putting the factory 35 prop on there after I test the modifications with my original prop

 

[jasper60103]

... I noticed a comment about changing the timing. I do not know how to change the timing nor have I ever tinkered with it. Anyone care to put some input on that

Bowfisher,
I've never adjusted timing before either, but
you may want to look at Joe Reeves WOT timing procedure in the stickies...
http://forums.iboats.com/forum/engin...edure?t=228183
This is a non-running method to adjust the timing advance at WOT.

Currently, there is a bolt with a rubber stop (#13) on your port bracket. That stop limits your timing advance at WOT.
You have to make sure that adjustment is correct for your motor on the new starter bracket.

Since I have an '88 30 HP, I can lookup the timing degree setting from my motor
if you like.

jasper

 

[bowfisher2636]

Bowfisher,
I've never adjusted timing before either, but
you may want to look at Joe Reeves WOT timing procedure in the stickies...
http://forums.iboats.com/forum/engin...edure?t=228183
This is a non-running method to adjust the timing advance at WOT.

Currently, there is a bolt with a rubber stop (#13) on your port bracket. That stop limits your timing advance at WOT.
You have to make sure that adjustment is correct for your motor on the new starter bracket.

Since I have an '88 30 HP, I can lookup the timing degree setting from my motor
if you like.

jasper

Jasper,
I seen that bolt with the rubber end and had no clue what it was for I have now gotten everything installed including the manifold plate carb flywheel electric start and a 35hp prop I have not cranked it I only spun it over to make sure everything was ok with the starter when I turned it over I had the kill switch off so it wouldn't crank. And yes please see what your timing degree is for me please I plan on finishing tomorrow

 

[bowfisher2636]

Also the timing bolt with the rubber end was never tampered with it setting the same as it was pulled off from the 35 motor

 

[jasper60103]

Mine is 30 BTC. Keep us posted.

 

[bowfisher2636]

Mine is 30 BTC. Keep us posted.

Jasper,

I will I rekon I have the advance right it was prolly still in spec since it came from the other motor and wasn't tampered with I cranked it and idled it and revved it to about 2700 rpm you can only rev up about 1/3 throttle or a little more in neutral it ran like a sewing machine like that though gonna try to take her out tomorrow or Sunday

 

[jasper60103]

Awesome. Electric start is a nice feature. There's no going back now.

 

[bowfisher2636]

I have some videos and photos but it won't upload them from my iPhone it says they are to larger. Any info on how to post them

 

[hardwater fisherman]

You should be able to upload them by using photo bucket. Also in the forum rules and guidelines at the very top of the forum page there is some info on how to upload photos.

 

[bowfisher2636]

Alright guys I gotta good update! Took it out today cranked and idles like a champ after a minute of getting into the the throttle it would loose power and I would have to stop and take off again(after the test I opened up the motor hood when I got home and found out the reed plate fuel hose was off I forgot to zip tie it) other than that it ran like a scolded dog I only got into wot for about 30 seconds since I'm still in the test phase. It ran hard the motor was really loud but it guess that is to be expected since I went up 15hp. For the short snipit that I went wot I hit 30mph and it was still gaining. I was turning about 5,500 Rpms is that to high? What is max I should run? And also the throttle response now it awesome it's super sensitive

 

[jasper60103]

Alright guys I gotta good update! Took it out today cranked and idles like a champ after a minute of getting into the the throttle it would loose power and I would have to stop and take off again(after the test I opened up the motor hood when I got home and found out the reed plate fuel hose was off I forgot to zip tie it) other than that it ran like a scolded dog I only got into wot for about 30 seconds since I'm still in the test phase. It ran hard the motor was really loud but it guess that is to be expected since I went up 15hp. For the short snipit that I went wot I hit 30mph and it was still gaining. I was turning about 5,500 Rpms is that to high? What is max I should run? And also the throttle response now it awesome it's super sensitive

Good to hear.
For the 1988 30HP the full throttle operating range 5200 to 5800 RPM.
30 HP is rated at 5500 RPM.

Thanks for the update.

 

[bowfisher2636]

Alright so I noticed it was still digging like it could turn more do I need to be cautious about getting into it? Like always keep a check on the Rpms? Also that may have been the max it could go seeing as the boat wasn't loaded down near what it is when we bowfish. Another question for ya jasper should I increase my fuel lines on the motor to the next size up since my motor will demand more fuel? Reason I'm asking is the tits on the carb will only allow one certain size not much I can go up. And also I do have a aftermarket coilpack on there that I'm pretty sure has no rev limiter