Briesch Hired Man ... Cam problem + other

[mcswainm]

Hi,

First post as you can see. A freind an I are building the Hired Man from casting. We are trying to "time" the valve opening and closing per plans but cannot get it to work. Anyone else had this problem? Also cannot locate Clinton points (#135-0129-50) used on plans. Anyone have a source for those? How about electronic ignition? Anyone used and have a source for module?

Mike

 

[gbritnell]

Hi Mike,
On most hit and miss engines the timing is set by adding more clearance to the rocker arm. I know this is not the ideal way to do it but apparently the designers don't get into this area too accurately. I have built the Hired Man engine and built the cam to the original drawings and have about .125 clearance between the adjusting post on the rocker arm and the end of the valve. Paul Briesch was the designer of this engine and he more than some was quite particular about his drawings.
As far as the points, I can't remember what I used. If that's what the drawings called for then that's what I used but I built mine 30 some years ago. I know some fellows use a set of Chrysler points on their engine. They make a very small set suitable for hit and miss engine. The other option would be to go electronic which would require making a disc to hold the magnet for tripping the Hall sensor. Here is a link to one source for electronic engine parts.
http://www.cncengines.com/index.html
gbritnell

 

[rklopp]

I built a Hired Man. I made the cam to the print and it works fine. Instead of points, I used Jerry Jowell's H&M Hall effect setup with a sparksaver. The main timing is by a magnet on the cam gear, while the sparksaver is by a magnet on the pushrod return spring anchor. The sparksaver shuts off the spark when the engine is coasting. The Clinton engine company disappeared decades ago, so I doubt you'll find Clinton points at the lawnmower shop.

 

[mcswainm]

Ok, I'll check clearance on the rocker arm. This may be a crazy question but the valve is staying open too long. Will a larger rocker arm gap decrease the valve open time?

 

[gbritnell]

Yes because if you think about it say the rocker arm to valve has .06 clearance. The cam shape is the same. Now you increase the clearance. It means the cam will have to turn farther in degrees to open and close the valve. (take up the clearance).
gbritnell

 

[mcswainm]

Just finished the engine and tried to start with a drill. Having a couple issues.
One is the spring tension on the govenor weights. Anyone have a pn for the spring?

Also, cannot get the carb adjusted. While holding the govenor open? (fires all the time) it runs for a short while then dies. Never getting very fast. Have tried a vapor carb as well as a jet carb. With the different carbs it runs differently but still only short times.

Any suggestions on carbs?

Mike

 

[Gordon]

Carb problems

I am in the process of building this engine. My dad built one back in 1985 and he could never get it to run. When the castings became available again I bought them because I wanted to build one like his. He also built the Olds engine and I built that one so I wanted to do this one too. When he died I inherited the engine and finally got it to run by using another carburetor of my own design. I think that the problem is that the carburetor as shown on the engine says grind a venturi but does not show how and the drawings do not actually show a venturi.

As far as starting the engine with an electric drill. This is not a good method. These engines are slow speed and the drill runs it too fast and throws off the ignition timing. I have had the best results with turning the engine over to just before it fires and giving it a rapid twist to make it fire.

 

[mhirst121]

I am on with two more of these engines at the moment. The other two i made ran first time, they are a great little engine and well proven to be good runners. I set the cam up by moving the small gear then adjust the bolt in the end of the rocker to give correct valve opening. I modified the end of the carb air intake so it has a disc on the bottom that can be turned to close off the air for easier starting and to give adjustment for better running.

Stick with it as once you get it going they are lovely little engines. One other thing i found was to use a slightly stiffer spring in the latch lever than the one mentioned in the drawings from a tyre vave. By using the stronger spring you get a better feel on the governor springs.

Martinh