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ChadS
07-08-2003 15:16:40
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Re: Re: Re: Re: Re: M Farmall timing in reply to Woody, 07-08-2003 14:02:39
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Alright, I will tell you. I am going to base this upon a tractor that is simular to yours that I built not to long ago. To give you a little history, the tractor was a 47 M with a 4.1/8 bore pistons High compression M%Ws. Stock stroke. I know there may be alot of comments, some good, some bad,some helpful, some not. When I started this build up, the tractor was only 55 hp. I ended up with 75 when I was done. I milled the head 125, to build a little compression. I got about 195-200 psi from the head, and I also installed a 25 thousandths copper head gasket. I belive that a stock head gasket thickness is over .070 thick. without tunning the carb, it came up to about 65. Now I was ready to build a carb for it. Lets start with the tools you need. An excellent investment, a full set of "numbered drill bits" #1-100. The bits are as small as a needle, up to 5/16. Any good hardware store should have these bits.. Get a quality rebuild kit. one that has all the replacement parts. I have a good connection with a resonable price for this kit, (around 30 dollars) So, lets dig in to the carb, you do not haveto remove the throttle body from the manifold, if you choose not to. most of the modifications are done to the bowl, and the metering stem, and venturi. With the bowl removed, remove the main jet adjustment screw and brass fitting. remove the metering stem.(brass stem located in the center on the bowl. SH-450 should have a brass piece use a flat screw driver and a 3/8 socket/ratchet to remove stem. Now, with these parts removed, you are ready for the drill bits. Start by finding the jet size withthe small drill bits. Once you have found the jet size, remember the starting size. I usually, start by increasing the jet size by 5 sizes (5 drill bits larger than the stock jet size bit) I would recommend since you do not have a dyno, you should start at 3 bits instead of 5. Take it slow. drill the main jet out. then on the metering stem, you will see 3 sets of holes down the side of the stem. only enlarge the 2 bottom holes by 3 drill bits larger that stock. Ok the stem is done. Make sure you clean the bowl from the shavings from the drilling. I would recommend finding a superM or a 400 venturi, but no larger than a 450. I have the IH part # for the venturi, will post it later. Reinstall the stem, and the main adjustment screw. replace gasket and veturi in the bowl, install bowl on throttle body. Ok, set the adjustment screw at about a turn out. Start engine. let it warm up. Open up throttle all the way. now, back out the adjustment screw to see if it will smoke. (ritchening the fuel) If it acts like you could flood the engine with the adjustment screw you did it right. if not, and you are able to back the screw all the way out with the engine changing tone much you may need to increase the main jet size a little more. Ok, lets say you got it right, you back out the screw, she will load up(Rich fuel condition) turn screw in until the engine runs smooth, be careful not to lean it out too much! Any way, I also suggest getting rid of the stock governor spring and replacing it. I offer a performance spring that works really well in any tractor we put it in. The reason I recommend this, it will improve throttle/governor responce without having to rework the governor. I hope I helped a little more. any questions?, comments, leave a post and let's discuss it!! ChadS
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