85 timing

[witchcrafter]

im new to rebuilding the boat motors but i do have a question. i blew my 115 and i took the intake and carbs off and put it on my 85 both same year 1977. i also took all the coils from the 115 and the stator and timing thing and put them on there also. NOW for the big question. what steps are there to timing these motors? is there a post on here about this or maybe a website i can read up on? i cant seem to get in to the brp site so maybe another one. ive built plenty of car and truck motors from stock to all out drag motors so i know my way around this stuff but the boat motors are new to me.

thanks
bryan

 

[iwombat]

Re: 85 timing

Well, you'll need a manual for a proper link & sync; it's different for each year and motor. The '77 L&S instructions has you jumping around among a few sections.

As for timing, the only thing you really set there is the max advance. You can do that statically. I think there's procedures on that in the FAQ section.



Edit: Yep - here you go - http://forums.iboats.com/showthread.php?t=228183

 

[witchcrafter]

Re: 85 timing

kewl man thanks i will get the hang of these forums i was looking around but didnt see it. now how do i find out what my motors timing should be at? and in the post he talks about a spark tester whats that? i think i may know is it something to tell if you are getting spark? if so i got on.

 

[iwombat]

Re: 85 timing

My feeble memory says 26-degrees for the 85. I'll have to double check when I have access to the shop manual. If you still have the sticker on top of the air intake it'll say right there.

A spark tester is a little device that has an adjustable air gap. You ground one side and hook the spark plug to the other. Unless you're testing spark, you can just ground out the plug wires to the block using nails/wire/whatever.

 

[witchcrafter]

Re: 85 timing

ok yeah i got one of those that are adjustable i use to check spark when im working on cars. thanks again

 

[iwombat]

Re: 85 timing

Well, my feeble memory wasn't so feeble. Max advance on the 85 is 26-degrees.


Also the jetting:

85hp: hi 0.049 low 0.025
115hp: hi 0.059 low 0.029



Did you check the throat size of the 115 carbs? I'm curious as to what they are.

 

[witchcrafter]

Re: 85 timing

how do i do that?

 

[iwombat]

Re: 85 timing

The throat size is written right on the front of the carb on the bottom right. The carb size in the image is 1" as noted by the 1.

 

[witchcrafter]

Re: 85 timing

ok will check on those for you and get back to ya.

 

[witchcrafter]

Re: 85 timing

ok on both of my /8's they are 1" and on the 115 it is 1 5/16". is this th depth of the carbs?

 

[iwombat]

Re: 85 timing

It's the diameter of the throats.

If you put those on the 85, you're going to have to do some experimenting with jet sizes. But, you'll likely get a bit more power out of it.

 

[witchcrafter]

Re: 85 timing

yeah i figured all that but i will just have to tinker with it till i get it to run correct. now on the back exhaust plate on the 85 it is all flat and on the 115 it has some humps in it. will this make a big differance in performance?

 

[iwombat]

Re: 85 timing

I asked the same question to DHadley, and the answer I got was all about RPM ranges. Bottom line - you won't see a big difference in performance unless you operate in 5.8K and above. There's also some filler blocks inside the exhaust. They are optional - some say it's better w/o them. If you include those you'll need to grind a small piece out of the block and make sure those filler blocks fit flush. If not, you'll need to do some custom gasket cutting.

 

[witchcrafter]

Re: 85 timing

ok kewl. i dont know what a filler block is.is there somewhere on the net i can get an exploede view of these two motors and maybe a list of what is what. i cant get on brp website for some reason i put my email address in like it ask and it keeps going back to the same page..