Thanks for the input. Not having a lot of experience with this model I appreciate these comments. I just assumed that the big four cylinder engine should run like a giant Model A ford but as you say they might all have different behaviors. I'm using the original Ensign, been through it and even tried a Zenith s5 but really nothing changed. And, as you mentioned the idle needle does nothing. I have it timed a few degrees off the Mag mark so I guess this is about the best I can do.

I have two Sixtys. One idles like a Swiss watch, it also pulls a load well. The other one idles liked a cammed up race engine, but smooths out really nice under load and pulls really well. Frankly it drives me crazy that one doesn’t idle like the other. Like you I’ve tried about every trick I know. I have yet to compare the two engines cam timing with a dial indicator, but I suspect the rough idling one has the cam advanced more than the smooth one.

There is another rough idling one north of me, my rough one came from very near it. I suspect that there was a mechanic up there that was advancing cams a bit to gain a bit of power. Maybe this winter I’ll get around to comparing the two engines.

Enjoy your Sixty.

BP.

"Bruce wrote:

I have two Sixtys. One idles like a Swiss watch, it also pulls a load well. The other one idles liked a cammed up race engine, but smooths out really nice under load and pulls really well. Frankly it drives me crazy that one doesn’t idle like the other. Like you I’ve tried about every trick I know. I have yet to compare the two engines cam timing with a dial indicator, but I suspect the rough idling one has the cam advanced more than the smooth one.

There is another rough idling one north of me, my rough one came from very near it. I suspect that there was a mechanic up there that was advancing cams a bit to gain a bit of power. Maybe this winter I’ll get around to comparing the two engines.

Enjoy your Sixty.

BP.

I timed the cam gear according to the service instruction, didn't seem to change anything, then I moved the gear one tooth ahead, didn't change anything, then I moved it one tooth back, didn't change anything. The only thing I can think of now is worn rings, I don't know, doesn't seem to be that complicated. No way to check compression that I know of.

The changes made from Sixty 101A through PA 13516 included several changes to valve timing, with the intention of increasing power. The final iteration was up to 72 horsepower - with valve timing at 10 degrees past TDC (changed from 0 degrees).

I admire you for doing 3 tear downs of the Sixty engine and trying different valve timings with little noticeable changes. The changes you made would not show up in the idle but in the power output.

The timing changes I am talking about are in the spark. Find a Bosch 35 degree magneto with a manual reset on the impulse and try running on the impulse and see how it idles then.

Good luck.

p.s. - I sent you a PM several days ago.

Phil;
I replied to your msg, yes I'd like to see anything you have. Thank you.

ron