756 questions

I have some questions about my "67 756 gas that I bought last year. It ran a little rough when i bought it, so I tuned it up. It still runs a little rough at idle, but seems to smooth out with more throttle. My mechanic says it is a burnt exhaust valve. I"ve run several cans of Seafoam through it...seems better. How can you tell if a valve is burnt? Is there some simple checks? If it is carbon build up, is there a better way to loosen it?

Also, the TA is out on the low side(I swear it was working when i bought it) and the clutch is adjusted as far as it goes to get the right free play. Do I need to replace the clutch right away? It doesn"t slip and I only use it to push snow and do light acreage work.

If that is the same setup as the SMTA, out on the low side means the ramp and rollers are bad. Won't hurt to run it on the high side, and if you only push snow with it probably won't matter. You just won't get the benefit of the TA

The 756 uses the hydralic TA,not the old mechanical one.The tractor will runa long time with no TA,but eventually the hi side will fail(it took over 10 years for mine to go)run the tractor till the clutch is completly out of adjustment and starts to slip.

Ya can run a compression check of each hole and that will tell ya. And the main reason for a burnt exhaust vale is the wrong engine oil being used . use ONLY a low ash 30 w in I H gas tractors . Use only 93 octane gas in them. That is the minim octane that should be used in them. when they were new reg gas was 95 octane and high test was 105 and up some of the cheaper grade were around the 93 back then . Ing. timing is most important on the later 4 cylinder and 6 cylinder engines and you set the timing at high idle . Your best friend for this tractor is and owners manual and atleast and IT manual. Your fuel requirements and oil requirements will be covered in the owners manual , tune up info in the I T manual . Clutch adjustment and stuff like that will also be covered.

That is good news. I don't need the ta for what i do. I'm still kind of ticked that either I didn't know it was out or it went out right after I got it...

You said yours lasted 10 years...was it fully adjusted out, too? Just wondering if we had about the same thickness of clutch disc left...

I've read your previous posts regarding the low ash oil and high octane gas - I will keep that in mind going forward. I guess that I am not convinced that a valve is burnt. I was wondering what some symptoms would be. It seems to run fine once it gets past idle.

The local mechanic set the points and timing...i just did the easy part...plugs and cap, air filter, etc. I was wondering if maybe the timing and/or points are not gapped right. I think he knows his stuff, but, I have a slight feeling that he isn't being straight with me. Not sure if he is just trying to get more business...

Is there something i can use that will help the valves..if they are gummed up or sticky..not burnt? The seafoam through the carb seemed to help some...

I would also check for a vacuum leak around intake to head gasket and around the throttle shaft.

Well a burnt valve is a burnt valve , it will have a miss to a dead miss . The only way to tell is a compression test on all cylinders. And does your LOCAL wrench know that the engine timing is set at wide open throttle ????? , you set timing at full advance at full throttle . I was up at One of the guys place that came on here looking for help on his 796 gasser that had smoke coming out from under the hood. Found that problem and a lot more . Had to rebuild his carb and adjust his clutch and trans brake and dump valve . Had it running and it had a light miss and with the help of his neighbor having a timing lite as mine got dropped and broken and i have not got my new one YET we checked his timing and it was set at 28 degrees advance at idle and when you upped the engine speed it went off the scale . Got it set back and it runs like a top . Your 291 sets at 18 degrees BEFORE TDC at HIGH idle or wide open throttle . More then likely you are probably more then and hour from me as i am in N.E. Ohio or i would work ya in and check it for you. I have to go back up to Greg's and do some work on his brakes and also work on his neighbors tractor . Keep one thing in mind here there is no magic cure all in a can . That tractor is probably in need of a good tune up and not just plugs and points. Like a valve adjustment and checking the distributor and just going over everything.

Thanks for the advice. I will look around the site on how to do the compression test as I've never done one. I have a SMTA that I've had for 11 years...never needed anything...got lucky on it. I'm in eastern Nebraska...definitely over an hour away.

Yep ya are a LITTLE over and hour away. But here is a little while i will be making a service call to Lebelle Mo. to work on a Oil All Over and try and get some what of a hay crop done for a vary close friend So once i am that far out from home who knows We might be able to work something out.