235 evinrude idle to high

[bmstang]

I have 78 235 evinrude i changed the fouled plugs and now i can't get the idle to go below 2000rpms. I tried the idle screw, link and sync, followed the shop manual nothing is working. I tried adjusting the throttle cable when i get the throttle arm to move back and get the rpms down to around 1200 the timing goes to tdc. It should be around 6 to 8 degrees according to the book and that's where it was with the fouled plugs idling at 900rpms. If i put it back to the original set up it idles at 2000 rpms any help would be greatly appreciated thanks.

 

[emdsapmgr]

Re: 235 evinrude idle to high

Possible the throttle arm (which connects all 3 carbs) is bent. Pull the airbox cover off and visually check to see if all the carb butterflys are fully closed at idle. Possible one or more of the carbs may have a butterfly slightly open, permitting air to go across the mid jets and pickup extra fuel-causing a high idle..

 

[bmstang]

Re: 235 evinrude idle to high

I pulled off the air cover and did the throttle valve sync didn't work and all the plates are closed. Like i said the problem started when i put the plugs in. Do you think it could be in the carbs i rebuilt them not to long ago and really haven't gotten out on the water much but i am wondering if i should look at them again.

 

[bmstang]

Re: 235 evinrude idle to high

Update rebuilt the carbs didn't really find anything wrong put it all back together and got the same results 2000rpm idle. I am lost about ready to have someone come look at it or take it to a marina. The thing about it is it's running great and i can't use it because of the idle. I am hoping somebody has some ideas for me to try thanks.

 

[emdsapmgr]

Re: 235 evinrude idle to high

Sounds like the carbs are ok-fully closed. How have you been setting the idle? The idle is set on this engine by adjusting the timing-not by adjusting the carbs. You can reduce the idle timing by unscrewing in the idle screw on the spark advance lever...it should bring the timer base arm rearward, reducing the idle timing and thus the idle rpm's. Also, you may have to temporarily disconnect the throttle cable at the engine to set the idle adjustment where you want it. If you have to, disconnect the link arm between the spark advance lever and the timer base, and retard the base arm by hand (with the engine running) and see what happens to the idle. The idle should be 650-750 rpms set when in gear-floating in the lake. Don't worry about what the idle degrees of timing number is, set it for the correct rpm.

 

[bmstang]

Re: 235 evinrude idle to high

I understand what your talking about that is the way i started adjusting the idle with the idle screw on the throttle arm. Your right the throttle arm does move back thus retarding the timing. Mine went from 8 degrees to tdc and the idle came down to 1200 rpm's.The cam and cam follower get thrown off and the marks don't line up when you go to far and there is a big space between them. I also was trying to adjust the throttle cable along with it when i turn the trunnion nut it also moves the throttle arm back but then if i go to far the cable gets to tight and it don't want to shift right. I then have to start adjusting the tension screw for the cable. If the timing isn't set between 6 and 8 degrees at idle won't it hurt performance because i did initially take it out when i retarded it to get it 1200rpm's and the performance seemed to be off. I don't know if that was a coincidence or not because i didn't check the timing until the next day. What about the timing screw itself under the flywheel i never touched that yet i don't see how that screw does anything being it's not connected to anything.

 

[emdsapmgr]

Re: 235 evinrude idle to high

I would not touch the screw just under the flywheel. That is the timing stop for max throttle spark advance. Don't adjust it unless you are able to re-time the engine when under load at 5000 rpm. I'd probably disconnect the throttle cable and do a "sync and link" on the engine according to the factory service manual. You can purchase an original factory manual from Ken Cook Co., in Milwaukee-they are also on the web. The cams and rollers and idle adjustment all have to be done together to come out with the correct results. Once you get everything back to normal, then adjust the throttle cable to meet the cable arm stud. Adjusting the throttle cable should have no effect on shifting (that's another adjustment scenario on the other cable.)

 

[Haffiman]

Re: 235 evinrude idle to high

Which plugs did you install.
NGK "R" by any chance or anything marked "R"??

 

[bmstang]

Re: 235 evinrude idle to high

I only have one throttle cable and it goes to the ignition box when i turn the trunnion nut to make the arm go back it tightens up the cable which makes it tight going into forward. I then have to adjust the tensioner mounted on the ignition box. I do have the manual and that's what i have been following with no luck i did see after my last post that the screw under the flywheel is for max spark advancement I would like to know if you know by retarding the timing to get it to idle will it hurt the performance. Could i damage the engine in anyway if the timing isn't right. The other thing i am going to check is if the pointer is in the correct location i am going to follow the manual for instructions. The plugs i used are the ones the manual recommended champion ul77v #831

 

[bmstang]

Re: 235 evinrude idle to high

Forgot to mention i did do the sync and link following the manuals instructions and it did not mention anything about disconnecting the throttle cable to perform the sync and link.

 

[Haffiman]

Re: 235 evinrude idle to high

As I understand this happened AFTER a plug change without any other 'service'?
Have you checked that no cylinder is double firing?
Mark the flywheel with each cyl at TDC.
Take your timing light and check each and one cylinder that it fires at correct spot and ONLY then.
If you can see two of the marks at the flywheel at the same time, you have a double firing situation and most likely a bad power pack.
Further up in your post you mention 6-8 degrees 'at idle'.
Are you mixing the 'pick-up timing point' (when carbs starts to open) with idle?
Sounds rather high.
Depending on water level on leg and prop (pitch) I would guess your idle timing might be almost 10 degrees lower.

 

[bmstang]

Re: 235 evinrude idle to high

The motor was not running right when i got it. Now that i have it running perfect i think it needs to be adjusted. Like i said nothing is working unless i throw the timing off. the 6-8 degrees of timing is from the shop manual and that is where it was set when i got it at 8 degrees it also says 28 degrees at 4300 -4600rpm's.

 

[Haffiman]

Re: 235 evinrude idle to high

Check your manual again.
Screw #54 on attached pick( from boats.net) is your Idle adjustment.
If not mistaken (I do not have the book), the setting you mention is then the roller on the carb hits the cam (pick up timing) timing should be 8 degrees.
However in order to get correct idle speed, you may have to retard timing quite a bit.
This will give that the first rpm increase is only done by advancing timing, until carbs starts to open at 8 degrees.

 

[bmstang]

Re: 235 evinrude idle to high

So your saying it's ok to throw the timing off to get it to idle. When i do that the cam and roller don't line up and they actually separate pretty far apart and the book says the lower mark on the cam should be in the center of the roller. Your right it has to be retarded alot to get it to idle and so far i have only gotten it to 1200 and again that throws it to tdc mark on the flywheel.

 

[bmstang]

Re: 235 evinrude idle to high

Update i pushed the throttle arm back as far as it will go along with the timer base the timer base actually hits a stop. The idle will not go any lower than 1125-1150 rpm's and the timing is now before the tdc mark on the flywheel. Is it ok to run it like this or can i do damage to the motor. I brought the cold choke lever up to about 2500 rpm's rechecked the timing and it was at the tdc mark.

 

[emdsapmgr]

Re: 235 evinrude idle to high

Retarding the timing at idle is the way to reduce idle rpm's. (once you are sure the carb butterflys are completely closed.) The book may specify a particular timing degrees, like 4 or 6 or 8. That is to start out. Every engine is different. They have different pitch props, they sit lower in the water on some boats, etc. Each of these factors affects the idle rpm. The idle is set in gear, when in the water-so every one is different. Your timing degrees where you wind up at idle make no difference-it is a specific rpm you want to achieve. You will not hurt anything by adjusting the idle timing down, as the engine runs very rich at idle. It is incorrect timing at top rpm, where the engine can lean out if the timing is not exactly spot on. If you don't disconnect the throttle cable, it is possible that the sync and link will be incorrect. You need to set the engine idle without any tension present from the throttle cable-which can affect the spark lever position. I would think that at dead idle that the timing marks should line up with the roller. Also, the roller must not touch the cam-you should be able to slip a pc of paper between the cam and roller at idle. Is your current idle speed while the boat is floating in the water?

 

[Haffiman]

Re: 235 evinrude idle to high

Please do as follows:
Loosen ALL carburator links and disconnect throttle cable from engine.
Turn flywheel to 7 degrees (NOT 8) after you have set the ignition pointer to TDC by using a piston stop)
Move the throttle/ignition arm so the mark at the cam aligns with the roller.
Tighten the roller so it just touches the mark.
Tighten the carburator linkage.
Now all carbs should be completely closed, roller at cam-mark and timing on flywheel at 7 degrees!!!
Start the engine.
Advance throttle until roller aligns with the mark and check the timing. It will now probably be 8, but if not fine-adjust.
Use the idle adjust screw, retard timing until you have the specified idle, about 750, when in gear, boat moving free.
It should be a gap between cam and roller. It might be paper thin -it might be 1/2", DOES NOT MATTER!!!!!!!
If engine is healthy, carbs properly set and clean, thermostats working and waterlevel about 3" below the exhaust relief holes at the leg, that engine should be able to idle down to 650 unloaded!

 

[bmstang]

Re: 235 evinrude idle to high

Yes the boat is floating in the water. I disconnected the throttle cable and pushed the throttle arm and timer base as far back as it would go.There is a stop that the timer base hits that will not let it go back any further. The idle is 1125 - 1150 as low as i can get it. I followed the test in the manual for the timer pointer location if i did it right which i think i did the pointer is off 3 1/4 inches and the tdc mark does not fall between the 2 marks. That was with the throttle arm pushed back as far as it will go. My tach markings are as follows and this is a brand new tach i have 0 l l 1 my rpm in gear is the line before the 1. I took the boat out just to see how it would run and it ran great didn't miss a beat i know i am still high on the idle but it's not clunking going into gear. Haffiman i will try your test tomorrow if it doesn't work i guess i will probably just leave it alone. I seen on tashadaddy's site there is a way to check what the full spark advancement is with out running the motor should i try to check the full spark advance or leave it alone.

 

[Haffiman]

Re: 235 evinrude idle to high

With that high idle, all carbs completely closed, I suspect one or more of the carbs are 'leakig'.
I did not quite get yor timing mark adjustment.
Turn no1 piston to TDC.
It is a description in the book using a piston stop, I normally used a dial indicator, use whatever as long as you find EXACT TDC of no1 piston.
Then adjust the timing pointer at the intake to TDC at the flywheel.
When you are at it, mark the flywheel with TDC for all cylinders and perform the test I described earlier.
If timing light is hooked at cyl 1, engine running, you should NOT be able to see any other marks at the flywheel. Same goes for the rest of the cyl's.
If any other marks are readable, it means the PP fires 2 cylinders at the same time.
If you have a plug fouling problem at idle, you may even try to use the QL16V plugs. A surface gap plug as the UL, but slightly 'hotter'.

 

[bmstang]

Re: 235 evinrude idle to high

I don't have a problem fouling plugs.That was before when the motor wasn't running right basically it was running on 4 cylinders had a bad head gasket which knocked out 2 cylinders. The test i performed for the timing mark came from the shop manual. It said to bring tdc 1 1/2 past the pointer and then rotate the flywheel clockwise until #1 comes up then mark it on the flywheel at the pointer.Then rotate it again until 1 comes up again and mark it at the pointer. Then to measure the gap between the marks. It said that the tdc mark should be between the lines and i am 3 1/4 inches off and there is no way to move the pointer that much so something is wrong like i said i will try your test tomorrow. Thanks