Been Lazy

[Elgindave2]

Hi all.
Had to pull the Homelite in June.
Have to replace the cam with the new revised cam with the nylon distributor drive key. Mine had the old style drive key. Hence have to change out cam with new style drive.
Got to check out valve clearances and put the proper spacers in.
Hope to have it up and running before it is time to put the pontoon away for the winter.
If wasn't for Bill R. It wouldn't be possible. Thanks Bill.

[Super Sportster]

Me too!

Still haven't run the Bearcat 85 this year on the boat and it's looking like it won't happen till Sept now. Still have the powerhead for the first Bearcat 55 on the work bench, been done with it for quite some time. Just have to bolt it up to lower leg. The Homelite that I put on the boat last year has been used quite a bit and runs awesome so I've not been in a hurry to remove it.:nono1:

So Dave, am I missing something here, you had it running in May after replacing the cam and you had to pull it again in June for second cam replacement?

[Elgindave2]

Yes my cam drive broke again. Rotor came apart and a peice of it fell down into the dist. and bound it up. That is what snapped the drive key.

[Super Sportster]

Bummer! I hope you do get it fixed before you have to put it away.

[trsexton]

I had a similar problem due to excessive wear in my distributor. I remedied it two ways. First I got a new distributor with petronix ignition from Bill so no more points. Second I made the key out of aluminum, and now i always carry a spare.

Tom

[Tim McCrain]

Tom,
I'm curious, what kind of wear did you find that caused the key to shear?

I had problems with mine shearing brass keys and eventually solved the problem by making them out of HDMPE plastic. I never did figure out exactly what the issue was, I tore the distributor down and everything was fine, no bearing slop or any problem that I could see.

The last time it sheared on me was at Alder Lake, I cut a temporary replacement on the water from the cap of a plastic water bottle and once we limped to shore I whittled one out of wood. That worked well enough to go for a cruise and then get back to the launch.

I'm running the Pertronix ignition too.

Tim

[Helmar]

I don't remember ever shearing one of those?
And, yeah, what is there to bind other than something IN the distributor?..

It would be nice to get a heads up on a possible issue...

Me, I am still using points and condenser from NAPA.

[Skagitguy]

Hey guys, No more problems for you ! I have a nice " Dr Frankenmerc " 85 hp Merc 4 sale. See Chuck's " Winter Lay A Way Program " in Classified Ads. Chuck :BigHappy1:

[Tim McCrain]

I'm with you ...

I don't remember ever shearing one of those?
And, yeah, what is there to bind other than something IN the distributor?..

It would be nice to get a heads up on a possible issue...

Me, I am still using points and condenser from NAPA.

I have no idea what the problem was, I just know that the brass keys kept shearing off and there wasn't anything binding that I could see.

[Helmar]

Hey, I think Chuck has a motor that he is selling. Anyone else notice that

[Tim McCrain]

Hey, I think Chuck has a motor that he is selling. Anyone else notice that

No, really? Megaphone1

[Super Sportster]

I don't remember ever shearing one of those?
And, yeah, what is there to bind other than something IN the distributor?..

It would be nice to get a heads up on a possible issue...

Me, I am still using points and condenser from NAPA.

In the repair manual it talks about a line-up tool for the distributor to use when tightening up the valve cover. Possible problem if not setup correctly?
Thinking about this another thought comes to mind, the depth of contact with the key, wear on the key and distributor slot, correct valve cover and o-ring selection as there are two different valve covers, early and late. Correct shimming of the camshaft end play. I'll have to look at the parts engine as the valve cover is off and see if any of this makes sense.


I've not had a problem with either of the two 55's I've been regularly running, one with points the other with pertronix. Both have running perfectly.

[Tim McCrain]

In the repair manual it talks about a line-up tool for the distributor to use when tightening up the valve cover. Possible problem if not setup correctly?
Thinking about this another thought comes to mind, the depth of contact with the key, wear on the key and distributor slot, correct valve cover and o-ring selection as there are two different valve covers, early and late. Correct shimming of the camshaft end play. I'll have to look at the parts engine as the valve cover is off and see if any of this makes sense.


I've not had a problem with either of the two 55's I've been regularly running, one with points the other with pertronix. Both have running perfectly.

Dick,

I mic'd everything carefully, all clearances seem just fine, no evidence of any interference, improper distributor depth or alignment, etc. I didn't check the camshaft end play but it seems that excess play here would just result inthe cam floating up and down and not result in undue twisting stress on the key. The only thing I can think of is that the shape of the keys has something to do with it.

The brass keys I was using are square cut at the shoulder where they transition from the camshaft slot to the dist slot, the width at the cam end of the key allowed some side-to-side play lengthwise in the cam slot, and the dist end of the key was narrower than the dist shaft.

The replacement key I made, using an original nylon key as a pattern, is wider at the cam end, wider at the dist end and the transition between the two is a tapered shoulder instead of a square cut.

My theory is that the shape of the brass keys allowed the key to float to one end of the cam slot which resulted in the upper portion of the key being off-center in the dist shaft, which results in force being unequally applied to the upper section of the key, twisting it off.

Only thing I could think of.

Here's a photo of the two keys. Although it looks like the brass key on the right is taller than the nylon one, that is due to the twisted off upper portion not fitting well on the lower, it started out the same height as the nylon. You can see from the marks on the nylon key both the width of the dist shaft and how it bears on the shoulders of the key, and how much wider it is than the upper portion of the brass key.

Tim

[Super Sportster]

Tim,
I was just thinking off the cuff without looking at the engine. The only engine apart I have to look at is an early steel key cam, may pull the dist. out of the late powerhead on the work bench w/nylon key just to have a look. Interesting that the brass key sheared, I think I would try one with the taper like the nylon key. How much run time did you have before the brass sheared? I'm running one of each, steel key and nylon key, and when I get the one off the work bench that will be another nylon keyed cam, and I'm hoping it will run fine.

[Super Sportster]

Nylon key

A couple of pictures from the one on the work bench, some slight differences. Yours has the taper from the transition, mine has the radius corner. Looks like your brass key was cut square(?) Square corners have a tendency to shear which is why we always radius corners when inserting plate on a barge or ship.
Just another thought:TwoCents1: