Tachometer

[Lyle]

I have a perfectly working mechanical tachometer of appropriate vintage for my 1952 M38.

Can any buddy share how to configure a tach generator.

Since the L134 doesn’t have a tachometer gear I’ll need to take an electric signal from points to a generator that’ll spin the mechanical tachometer.

Unless there is some add-on to the engine to support a mechanical tach.

Thx.

[4x4M38]

Just curious, where are you going to mount it Lyle?

[wesk]

This fellow found a way to make a mechanical tach work with his L-134:

A Willys 4-134 L Engine in the Sky
By Rachel Wednesday, November 2nd, 2016 https://blog.kaiserwillys.com/a-willys- ... 9218750000
My name is Kenny Crider and I live in a small town of Swifton in Northeast Arkansas. I am a 61 year old Crop Duster Pilot / Farmer and tinkerer. My Airplane is a plans built ship, designed by a man named Bernard H Pietenpol back in 1929. Many thousands of sets of plans have been sold these past 80 plus years, and Mr. Pietenpol (deceased) is recognized as the father of Americas homebuilt aircraft movement. I began my build in November of 2013 and the first flight took place Oct. 16 2016, just short of three years later.
The aircraft was origionally designed to be powered by a Model A ford engine, and many have been and are still being built with this engine option. More modern engines have been used and over 30 different engine types have been used over the years. When I started my build I considered the Model A, but didn’t like the worrisome babbit bearings and fact that special machine shops must be used to build the engine. I had an old 1947 Jeep that had been parked because of a tired engine and decided to do a little research to see if it might be a suitable substitute.
After some research I found that maybe it would work, with a modern oiling system, a robust crankshaft and a simple design, plus parts were very available. The folks at Kaiser Willys helped me with parts for the overhaul and my local machine shop did any needed freshening of the crank and valve seats. The engine is very near stock except for the firing system which was converted to use an aircraft type magneto driven off the crank shaft, and a tachometer drive was built simply by drilling a hole in the bolt that holds the cam shaft gear in place then threading a receptacle for the tach cable end. I found an oil pan without the stump shield to save weight, and removed the oil filter to also save weight, a small cover over the distributor mounting hole finished the conversion. Since it was important to have the carburetor to be as low as possible so that a gravity flow fuel system could be used, a new intake was designed and an up-draft carburetor replaced the original Carter unit. As the pictures will show a Willys 134L has flown. It will never take over more modern engines in aircraft manufacture, but the little jeep may find another way to please.

[Lyle]

Wes,

Is this what you are thinking?
http://www.texasindustrialelectric.com/ ... dapter.asp

Any ideas on how to drill cam bolt and associated hole in timing cover?

I’ll also check with John Bizal as I’ll need all the help i can get!

Cheers Lyle

[wesk]

Actually I had hoped you would see the better way and simply buy an electrical Tach. The use of the L134 in the Pietenpol Homebuilt Aircraft article was offered to show you it can be done but is not very feasible with an automotive application. That application installed the tach drive cable thru the timing cover into the end of the cam shaft which would be tough to make work in a jeep chassis installation with the radiator fan in front of the timing cover. Even if you solve the tach drive at the engine issue you still have to determine which engine RPM element you are using versus what the indicator uses for an assumed basic element (figure) Or, is your tach going to interpret the rotational signal correctly so it can display actual crankshaft RPM?

This is what an angle drive for use at the engine's tach drive tip would look like:

https://www.aircraftspruce.com/catalog/ ... rives2.php

[Lyle]

Wes,

I’ve found a number of elbows like the one you sent (thx).

I need to confirm the following:

1) how many revolutions the cam takes for each revolution of the crankshaft

2) how many rpms does the tachometer need to see.

I also sent an email to John Bizal to see if he could help with the fabrication.

[Lyle]

Found another method:

https://www.glendinningprods.com/wp-con ... 23d&4cf23d

[wesk]

That's a heck of a lot of work to just find out what the engine noise is already telling you! Notice just like the airplane application, the marine inboard engine application has no cooling fan at the front of the engine to interfere with the angle drive.

I need to confirm the following:

1) how many revolutions the cam takes for each revolution of the crankshaft

2) how many rpms does the tachometer need to see.

1 - You'll have to do the math on cam gear vs crank gear tooth count to find ratio.

2 - You'll have to get the specs for your tach from the manufacturer of the tach.

[Lyle]

Just curious, where are you going to mount it Lyle?

Because I have the gas heater that on the front cowl I have limited space on the dash. So I’m thinking find someone with the ability to punch out a cup to go over the tach and then place it on the stearing column.

[Lyle]

That's a heck of a lot of work to just find out what the engine noise is already telling you! Notice just like the airplane application, the marine inboard engine application has no cooling fan at the front of the engine to interfere with the angle drive.

I need to confirm the following:

1) how many revolutions the cam takes for each revolution of the crankshaft

2) how many rpms does the tachometer need to see.

1 - You'll have to do the math on cam gear vs crank gear tooth count to find ratio.

2 - You'll have to get the specs for your tach from the manufacturer of the tach.

The tach is 2:1

Working on cam gear. Any miss-match I can accomplish with one of them many right angle cable adapters.

[Lyle]

Tach needs 2:1 (half engine speed)
Camshaft rotates at 2:1 (half engine speed)

So a 1:1 90 degree elbow is what is needed.

I’ll drill the hole In the timing bolt and line-up the hole in the timing cover.

Call it excessive but I had my engine’s entire rotating assembly including pressure plate balanced.

Cheers

[kristaga]

What solution did you end up with?