1977 rude w/ 1988 parts?

hi and merry christmas to everyone.<br /> here's what i got, i have a 1977 evinrude 115hp engine that i put parts(stator, rectifier, timer base, flywheel, powerpack,bubble back) from a 1988 110hp evinrude. i know, i know it's not kosher but i got everything to work as far as the ignition system to work. my problem is i cranked her up and the idle is way to high and i can't seem to get it down. the carbs were rebuilt and cleaned before install and they are the originals from the 1977, 1 5/16. what do you guys think? is my problem in the ignition system or is it in my carbs? any thoughts thanks chaz

Re: 1977 rude w/ 1988 parts?

I would start at ignition timing, Chaz. <br /><br />I assume that you did the link 'n' synch according to the book for the '77, including verifying that all butterflies are completely closed with throttle off, but with the '88 ignition system it may be too far advanced. <br /><br />If that is the case it would melt a piston pretty quickly if opened up.<br /><br />You need to find a way to verify that the starting timing is exactly as specified for the '77 engine.

Re: 1977 rude w/ 1988 parts?

yes did a link n synch by the book and all butterflies are closed. it must be too far advanced cus i can completely disconnect the linkage to the timing base and still high idle. well i thought i could make this work, but looks like it not gonna work. thanks chaz

Re: 1977 rude w/ 1988 parts?

I think the update to 1988 ignition (SPARK) is a good idea.Doing the sync/linc includes basic timing ? No ?<br /><br />Also "bubble-back" is not an ignition part.(grin).<br /><br />My guess is those 1 5/16 carbs are very mismatched to the exhaust .They cannot pump enough air to fill it,and back pressure is lacking.Running lean can increase idle RPM's.Try putting the "flat" exhaust plate back on,and let us know how it works.<br /><br />DHP

Re: 1977 rude w/ 1988 parts?

Those carbs should (and will) work on either the flat or bubbled exhaust. Disconnect ALL the linkage, even the link between the 2 carbs. Loosen the screw on the cam follower too.<br /><br />BTW -- how high is it idling? What rpm?

Re: 1977 rude w/ 1988 parts?

Dhadley,I thought the throttle bore was different,and reduced air flow would upset the balance.<br /><br />DHP

Re: 1977 rude w/ 1988 parts?

The 1-5/16 carbs are the same as up to 1998 115's.(crossflows)<br />It should be real close to what a 1977 140 was with the Bubbleback and systems you have listed.<br /><br />DHPMARINE, on this engine, the smaller venturi carbs give better hole-shot...the larger venturies are a bit slower on the low-end, but increase the top-end flow...I "think" it will work fine. I don't think it would be an issue unless he had 1-3/8 carbs, then it would take a few mods to get it to run at it's best.<br />I ran 1-5/16 carbs on my bubbleback 115, and it was the best running V4 I ever owned...wish I would have never sold it, in fact.<br /><br />EDIT: I believe there were some early 115's with 1-1/4" carbs, but the 1-5/16 should suit him well.

Re: 1977 rude w/ 1988 parts?

We used to run the small carbs on the race boats for better acceleration, like Kenny mentioned. On real long courses we ran the larger carbs. There is a balance that at some point the stock ports wont flow any more but they all should idle fine. Even if you run V6 carbs on a V4. The old 2 & 3 cylinder race motors used to run those carbs too.