ATTN: ALL BTR Builders (Gravely Model L)

RicksRides said:
Wayne from my understanding stroke is same in all just the bore is different if you give me the serial # off your motor i can tell you exactly what model and year model L was 5hp model L I was 6.6hp and model L S was 7.6 hp if there are no serial numbers itll be a model L and would be 1938 or earlier and should be looked at as a museum piece as there were only 2464 of them made prior to marking them with numbers. 2465 was the 1st # marked in 1939. 2465-95441 are 1939- 1954. M5566 - M 31000 are 55- mid 58 these are all 5 hp. M 31001-2M51800 are 59-66 all number until this are made by studebaker in south bend indiana they also made the Avanti. # J7600 and up are 7.6 hp made between 67 -75 with the cast molds from studebaker but not at studebaker. hope this helps
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Thanks Rick. Where are the numbers located on the engine? I can't find anything on my cases bul "L101 on one case amd L102 on the other.

Guy I got it from thinks it's a late 50's or early 60's . It has a 1950 chrysler 240 standard piston in it. Thay are a much cheaper replacement than an OEM piston.

Just guestimating from the outside diameter of the jug, I would say that the bore looks like 3 1/4 or 3 3/8 inches
 
Hi Rick, I have 20 or so L's myself, and have been mulling over the same idea for a bit. I'm just curious, have you noodled out how to address the magneto issue. In present config, it would stick out the port side about 10"( a guess). I thought about turning it and shifting it to the front of the engine and using a timing belt, but then rotation comes into play. Is there a workable alternative?

Thanks, Ellis
 
Ellis easy enough actually , Just cut the mag shaft and leave enough to mount a small sprocket using 12 tooth #35. then mount mag off the side of the motor making sure to keep square & true. Use another 12 tooth #35 on the piece of the mag shaft you cut, use a couple bearings and wahla jackshaft with gear at one ens and mag connection at the other. hope you can follow my crappy drawing. 1st pic is front veiw 2nd is a top veiw. This placement will keep it up and out of the way. You will need to make a bracket to mount the mag into position off the motor. The bracket can be mounted to the engine cases.
 

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That looks to be one of the ideas I had in mind, Rick. My thinking was, that would reverse the direction of the mag shaft. Will the Wico's "fire" in reverse? BTW, the pics were fine, thanks!

Ellis
 
No need to reverse. Mount facing same direction as it was mounted on tractor face to face, so to speak. And I believe both brands of mags used on these will fire in either direction
 
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I think I'm gonna mount mine in front of the engine and drive it off the right side of the crankshaft.

Or, like Rick sez, you can cut the long mag drive about 4" shorter and even mount it back with the coupling and a custom bracket.

These magnetos have a "snap" impulse for starting, and they cannot run in the other direction.

Here's some pix of what I'm thinking of doing. Check out my lil Speedex tranny.

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LOL, somebody please give me a tutorial about how to post my pics standing up.
 
Wayn I ve always had the understanding these would run backwards my mistake simple enough to check simply spin backwards???. Have you checked to see what the gear ratios in the speedex are? thats a gearbox from a tractor ?? maybe gear way to low might wanna check
 
Hey Rick, that tranny is a miniature automotive type. Has a H shift pattern and 3rd gear is 1:1 ratio, so all gearing is done with sprockets and pullies as usual.

Yes, most any mag can make spark running backwards, but the points don't last as long. Something about the points arcing to a different polarity than their design.
Also the impulse coupling would not work backwards, and the mag needs at least 300 rpm to spark, that means the engine has to be turning 600 rpm to start without the impulse coupling working. The impulse coupling causes the mag to spark at almost zero rpm, and makes the engine dangerously easy to start.
 
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I see thanks for clarifying. The starter is the next issue electric start or not??? where and how to mount etc... any thoughts
 
the speedex is an H pattern 3 speed w/reverse that should come in handy for backing up the beast youre looking to build, Im going with twin L S 7.6 horse and yours may still be heavier lol rick
 
RicksRides said:
I see thanks for clarifying. The starter is the next issue electric start or not??? where and how to mount etc... any thoughts
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Have you seen any of the electrec start model L's?
I'm thinking about trying to devise a kickstart from a gravely electric start sprag crankshaft sprocket and a short chain and spring connected to a kicklever.
If ya want e-start, consider this:
The stock Gravely starter is an automotive starter and very heavy. You could use an older Nissan starter and flyring and prolly loose 15 lbs. The moderm lil perminant magnet field startermotor will start almost anything with a motorcycle size battery.
I adapted one to a Continental A-75 aircraft engine once, and it would start it with a 12 AH battery .
You could mount a small Kubota dynamo to keep up the battery. Hmmm I just noticed that the Kubota starter is about 1/2 the size of the Nissan...
 
you me a kicker like the ole cushmans and maytag motors had on them? Ive got a couple maytags but they dont have any real power and real low rpm
 
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Ive even got an old 10 hp 2 stroke that runs on kero ( and some other fuels) out of an ol military generator but its seriously bulky and heavy
 
wayne z said:
Have you seen any of the electrec start model L's?
I'm thinking about trying to devise a kickstart from a gravely electric start sprag crankshaft sprocket and a short chain and spring connected to a kicklever.
If ya want e-start, consider this:
The stock Gravely starter is an automotive starter and very heavy. You could use an older Nissan starter and flyring and prolly loose 15 lbs. The moderm lil perminant magnet field startermotor will start almost anything with a motorcycle size battery.
I adapted one to a Continental A-75 aircraft engine once, and it would start it with a 12 AH battery .
You could mount a small Kubota dynamo to keep up the battery. Hmmm I just noticed that the Kubota starter is about 1/2 the size of the Nissan...
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Kubota stuff is up there in price 235 for a new 12 amp alt.
 
RicksRides said:
Kubota stuff is up there in price 235 for a new 12 amp alt.
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You don't hafta buy the new stuff. Especialy from Kubota. Plenty of old ones around cheap. And NOS stuff. Check Ebay or tractor salvage sites.

I bought a great shape 10 amp dynamo for 60 bucks from a tractor salvage company . It was about 3 years ago.
 
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Ok, I've been trying to find model L literature that shows bore and stroke ect to discern the internal differences of the 6.6 and the 7.6 engines. Not much luck so far.

I did find out that if it has a slanted spark plug, it's prolly a 6.6 and if it has a vertical plug it's a 7.6
Is the difference just i the head? larger valves maybe?

I have a 6.6 and would like to convert it to 7.6
 
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