Evinrude 9.9/15 throttle blocked from full opening.

[oldboat1]

still think that adj screw is adjusted in too far, with binding a secondary result. Main result would be that the adjustment at the the idle mark would be way off. (with proper adjustment [the link and sync at idle], I'm pretty sure there would be no binding with throttle advance either.) That's if the older carb otherwise fits OK.

Having said that, I bought that washer earlier this year when I had lost one during a repair. It does have the effect of moving the cam away from the body, whether or not that is the main purpose -- also facilitates smooth movement of the cam.

curious about the fit of that replacement carb -- guess you might be trying to use the '89 silencer assembly on it (sounds like you took it off for the pic -- fits without binding anywhere?)

 

[driver0606]

The bolt has a screwdriver slot and the head is visible in my first photo. I do not want to take it out until I have the old carb back and may need to swop some parts. I will also find out what parts have been already swopped from one carb to the other. Does anybody know the exact thickness of the spacer?

 

[Chinewalker]

My '76 has no spacer and does not use the adjustable roller assy. On my '76 the cam itself is adjustable for pickup point with no adjustment for full throttle plate opening. Your motor uses the adjustable roller assy for pickup point with a jack screw on the cam for throttle plate max opening adjustment. My '76 has the larger roller instead of the small one so I had to make that cut corner on the choke spring plate for clearance. You have an early model carb body with no shoulder bolt spacer. Just use a Bic to heat the area of interference on the air box. When plastic is hot use something other than your finger to push in the affected area for clearance. Than set the pickup point and max throttle opening. Just a note...on mine if the plate over rotates and drops past the main nozzle just a little it runs real rich at that point.

Your cam follower's shoulder bolt SHOULD have the washer in there. Affects synchronization of spark and throttle. Absolutely no reason to be melting any plastic to make it work.

 

[Chinewalker]

still think that adj screw is adjusted in too far, with binding a secondary result. Main result would be that the adjustment at the the idle mark would be way off. (with proper adjustment [the link and sync at idle], I'm pretty sure there would be no binding with throttle advance either.) That's if the older carb otherwise fits OK.

Having said that, I bought that washer earlier this year when I had lost one during a repair. It does have the effect of moving the cam away from the body, whether or not that is the main purpose -- also facilitates smooth movement of the cam.

curious about the fit of that replacement carb -- guess you might be trying to use the '89 silencer assembly on it (sounds like you took it off for the pic -- fits without binding anywhere?)

The carb silencer is the same from 1977 on up to the early 1990s, so that is not the issue. The all metal vs. plastic capped carbs are interchangeable. All hook-ups and alignments are the same - cover, choke, cam follower, etc. As stated previously, I am 99.9% sure that if the OP simply adds the washer to the cam follower assembly, all will be well. I am guessing because I don't have one in front of me, but the washer is close to 1/16" thick. If you don't have a dealer nearby to get an OEM washer, then a doubled up pair of standard hardware store SST washers of the right ID should work. Pop the recoil off, put a 3/8" coarse thread nut on the bottom of it to hold it together, and remove the cam follower. install the washers, and reassemble.

 

[thumbnut]

Hmm..My 76 has a .030in or so washer. I just checked part #s and they are the same. Can't imagine .030 or so sideways will make a difference. Even 1/16th..Mine is a mix and match motor and I have had to make adjustments for fit. Just check the interference and see if a sideways move is the cure.

My 76 has 2 base air box numbers listed..old as 0319289....later is 0322120. All later years use the 0322120 base. Maybe cosmetic..dunno.

 

[oldboat1]

driver -- has that cam roller been adjusted ("synced") at the low speed mark? continue to think the jamming issue would go away (me too -- with a pic of the cam adjusted at that idle setting). :joyous:

 

[Chinewalker]

Hmm..My 76 has a .030in or so washer. I just checked part #s and they are the same. Can't imagine .030 or so sideways will make a difference. Even 1/16th..Mine is a mix and match motor and I have had to make adjustments for fit. Just check the interference and see if a sideways move is the cure.

My 76 has 2 base air box numbers listed..old as 0319289....later is 0322120. All later years use the 0322120 base. Maybe cosmetic..dunno.

First years used a white cover, later ones were a black cover. Not sure why the change - cost to manufacture? Brittleness with fuel exposure?

 

[thumbnut]

Well, I see the issue is with the carb body, not the air box. I will start over in preK and learn to read better..I consider myself balled out.

 

[driver0606]

I have put washers (a little over one sixteenth inch) behind the pivot bolt and it allows the screw to clear the carb body. Synced on mark as described, which was made easier by painting it white. Throttle now appears to open to max. Will report after sea trial soon.

 

[driver0606]

It was the washer (or rather, the lack of it!). The boat will now do over 20 knots solo, although will not get on the plane with two people. Very many thanks to all of you who took so much trouble to comment on the situation.
If there is anybody out there who is not completely bored with my questions, the larger photo shows the roller position at full throttle, with the cam at the bottom of the photo. Is that about right, please?
The smaller photo shows the trim adjustment. I would like to try the engine with the trim at maximum "in", but the holes for this position seem to be blocked with rusty steel plugs, leaving only the upper four open. Any reason not to drill them out? They will not tap out.

 

[AlTn]

can you adjust your roller so the center point will be inline with the highest point on the timing cam? < it's not quite there yet > at this point make sure the carb butterfly is perfectly horizontal in the carb throat and not under or over rotated...no reason not to make that lower hole usable and try that position out...weight distribution becomes a big factor when trying to plane ...the second person may have to sit in the very most forward position as well as having to move other gear around

 

[oldboat1]

I would drill out that fifth hole, nearest the transom -- looks to me like somebody was using a bolt as a tilt pin, and it rusted. If you place the tilt pin in that lowest hole, you will push the bow down a bit more, possibly helping with planing. 20 knots is pretty quick, though.

that cam roller adjustment still looks suspicious to me (just looks like the adj screw is in further than usual -- know the throttle is open in the pic.... The relevant roller adjustment is on the other end of that cam (where I think you highlighted the mark). If you set the roller to hit the idle mark just as the carb is opening, you've got it, or most of it. That black plastic cam has some adjustment too (hex bolt in the pic, I think). It does look like the throttle is not quite wide open -- would look for the roller to end up at the high point of the plastic cam (carb fully open when the throttle is fully open) -- like AITn sees it, above. If you adj the cam, you will need to go back and check the idle setting sync, and probably tweak it a little.

 

[Chinewalker]

The cam on these motors is not adjustable. It is sandwiched between the armature plate and the retainer plate. Adjustments should be made on the follower.

 

[Vic.S]

The cam on these motors is not adjustable. It is sandwiched between the armature plate and the retainer plate. Adjustments should be made on the follower.

Is that not the cam adjusting screw near the bottom RH corner of the OP's larger picture:

 

[oldboat1]

reference is to the plastic "throttle cam and screw assembly", as the '89 part is listed/described (secured as Chinewalker indicates). The screw adjusts the contact point of the cam at the open throttle mark. Earlier metal cams had no adjustment screw (and also were not prone to breaking).

 

[driver0606]

Thanks. I am pretty sure the throttle is fully open at the position shown in the photo. Also, the external pin on the throttle butterfly shaft is vertical at what seems to be fully open, is that a reliable indication?. I guess I could back off the roller arm screw to allow the cam to move up to the highest point, but that would throw out the sync at idle. Or I could try the adjusting screw in the cam. I will check that next time I go to the boat.

 

[oldboat1]

my opinion? You likely need to back off both the cam screw and the roller adj screw. (Use a little wd-40 if you adjust the cam screw -- plastic cam plate can break.) Actually, if both adjustments are out of spec, you could probably get decent operation. Think you might have effectively adjusted the roller to compensate on both the low and the high end for placement of the throttle cam. Not sure if that works, but think offhand it could.

Think you would also find that the clearance between the carb body and the roller adjustment screw would increase (arm will tip forward and up with adjustment, incidentally moving the screw head away for the carb.) [dead horse I've been flogging....]

(btw, I broke the plastic cam on a similar motor by just dropping it on the shop floor, not adjusting it!)

 

[Vic.S]

my opinion? You likely need to back off both the cam screw and the roller adj screw. (Use a little wd-40 if you adjust the cam screw -- plastic cam plate can break.) Actually, if both adjustments are out of spec, you could probably get decent operation. Think you might have effectively adjusted the roller to compensate on both the low and the high end for placement of the throttle cam. Not sure if that works, but think offhand it could.

Think you would also find that the clearance between the carb body and the roller adjustment screw would increase (arm will tip forward and up with adjustment, incidentally moving the screw head away for the carb.) [dead horse I've been flogging....]

(btw, I broke the plastic cam on a similar motor by just dropping it on the shop floor, not adjusting it!)

Surely the screw on the cam follower has to be adjusted so that the cam just touches the roller and starts to open the carb butterfly valve when the mark on the cam lines up with the roller.

Then at the full throttle position the screw on the cam is adjusted so that the carb butterfly is in its fully open position.

The procedure is described in LeeRoy's Ramblings

LeeRoy also warns of some of the complications that changing the carb may introduce. The OP has of course done that but has hopefully read the relevant parts of LeeRoy's webpages and is aware of any problems that may have caused.

I too feel that the position of the roller looks wrong. I suspect because the carb to manifold spacing is too small.

However if the above two settings can be made within the range of the adjustment screws there should be no need for any remedial action

 

[oldboat1]

^^^agree.

In thinking about it a little more, not sure whether cam adj would be clockwise or counterclockwise (object as I see it would be to bump the cam in toward the manifold/flywheel -- whichever direction that adjustment would be for the hex bolt). If the idle/low speed sync has been set, it might then need to be readjusted -- would want to look at it again, anyway. But will add, if currently comfortable with the low speed sync, and the throttle and carb are fully open when they should be -- and nothing else binding -- may be good to go. Would like to hear about operation when you get to that.

 

[driver0606]

The sync on the cam mark is spot on. In the photo the cam plate is fully forward against the stop . There is about 1/4 inch after the roller to the highest point. The throttle is already fully open, although I can adjust that on the cam plate. The engine is about 1988 and the carb is 1981 to 85, but they use the same cam arm and roller. The only way I can move the roller up the ramp is by removing the washers on the shoulder bolt and reducing the diameter of the roller arm adjustment screw head so it does not bind. This would move the roller up about 3/32 inch. Is it worth it?. After that, it would be cutting the cam arm and/ or the carb body. Seems rather extreme. Does the roller always go up to the top of the cam?
I will certainly report on the result of future tests, its the least I can do after all this help!.