cwjones

IH gas 301 timing

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Hello all. I am a newbie here and I have what I feel like is a simple question. Working on a gas 806 and I set the timing by ear and was pleased to only be off 2 degrees from book specs. The tractor likes to sputter when I rev it up. Doesn't seem to change much when it warms up or when cold. I was told that the engine timing shouldn't change whether at idle or wide open. Is this true? If so I have another issue because it changes about 15 degrees from idle to wide open. I took the distributor apart, cleaned and lubed the weights that seem to be free. What am I missing?

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The weights that you cleaned are part of your mechanical advance --which will certainly change the timing (advance) as the motor

increases RPM's ,   Does your manual have  specs for base timing and high idle timing ?

look here engine timing 301 gas - General IH - Red Power Magazine Community

 

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you didn't say what the 301 was out of but when you lubed the weights, you cold see the plate they were mounted to had a number stamped on it that was the degrees advance if it was a 15 that would be how much it should change. and yes you need the time to change as the rpm goes up

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I don't recall the degrees of timing advance on the 301 in tractor or combine. BUT, the whole deal is that what ever the shaft is marked like previous poster said, is the degree the timing should be adjusted to AT FULL Throttle.  Working correctly, (which most old worn distributors don't) the timing would fire at or very close to top dead center with a low idle speed of about 500 rpm and gradually advance with engine speed until full advance was reached just before rated engine speed.  So, i'm betting it is 17 or 19 degree total advance on that engine.   

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Sputtering can be caused by the plugs. New ones are not immune to it either.

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The number on the distributor advance plate is the amount of distributor advance. If the number is 15 the total advance on the crankshaft will be 30°.

 

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Thanks everyone. My distributor is working correctly then. I will try another new set of plugs then I will have it narrowed down to the carb or possibly the governor. Again thanks for the help. 

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On ‎7‎/‎26‎/‎2017 at 4:23 PM, Owen Aaland said:

The number on the distributor advance plate is the amount of distributor advance. If the number is 15 the total advance on the crankshaft will be 30°.

 

I disagree the distributer in my c263 is marked 22 when I time my engine at 22 at wide open  at low idle it hovers around tdc. And I know my M has a 40 degree marked shaft and I am darn sure its not running 80 degrees advance other brands of distributors maybe but not ones of IH manufacture.

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On ‎7‎/‎27‎/‎2017 at 7:11 PM, R190 said:

I disagree the distributer in my c263 is marked 22 when I time my engine at 22 at wide open  at low idle it hovers around tdc. And I know my M has a 40 degree marked shaft and I am darn sure its not running 80 degrees advance other brands of distributors maybe but not ones of IH manufacture.

Correct.  The number on plate in distributor is engine degrees advance. 

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HAA! this subject is good timing (get it??).  i just went thru this on my recent tractor overhaul. I switched to diesel mindset MANY years ago. I had to brush off the cobwebs to troubleshoot my rebuild. my advance was stuck wide open and it ran horribly across all speeds (of course). once i tuned it, it runs nice (of course).

ideally (theoretically) , the timing is set at the advance at the lowest RPM (idle) as listed in the manual. if everything is proper, (weights, springs, etc)  the timing will advance where it should  all the way up to top speed. My tractor is mechanical advance ONLY and no vacuum advance (that would be in an automobile). I hardly ever run at idle (definitely without load) so I tweak the timing to be where it is supposed to be at my optimum running speed (for me i chose PTO =540 which works out to around 1800-2000rpm). So i set my advance to the book recommendation at 2000 rpm (which happens to be about 18 degrees). as for the rest of the timing, the curve for the remaining rpm spectrum will be what it will be - unless you try to manipulate the springs, weights, and stops. Once timing is set, then I tune the carb. If your timing is correct and your sputtering at different throttle loads, you may be too rich or too lean by the carburetor tuning or by an ulterior means such as having the choke partially closed, a dirty/clogged air filter, bad carburetor, vacuum leak, burnt valve,  bad plugs etc etc. as others suggested.

My C-135 book recommends 2 degrees advanced at 400 rpm and goes up to about a max of 24 degrees at 2200 rpm (from what i can recall). 

If i interpret your question another way, I think you may have meant:  will/should the timing change if the throttle/load changes while the engine remains at a constant speed - and that answer is that it shouldn't. The mechanical advance amount will remain constant relative to engine RPM regardless of load. on another note -  it would change with load only if it had a vacuum advance. so whether your pulling a house or being pulled, at a given engine speed the mechanical advance will be constant.

Having said all that, If your advance is changing with load that means your RPM is changing-  if its more than a couple hundred rpm  then your either pulling too much load or your engine is not tuned properly or getting "worn-out". you should give the engine throttle the time time to reach steady state if the load can be steady - this should be a few seconds for that reaction time. here is more interesting FUN-  the governor reacts ONLY by changes in RPM (even very slight changes) from the target speed. the bigger the swing in rpm, the bigger the reaction  and the bigger the throttle (closing and opening). This is the cool part- notice how the engine can get loaded and remain under heavier throttle? watch your tachometer. the engine speed will actually be lower than what your target that was set at no-load. It would be cool to document the original engineers design map by mapping out how much throttle our tractors are using per rpm drop (if you had the hood removed and can maintain your work, measure the throttle position, the tach, and hold your beer at the same time). - or get a pto dynomometer.

thats the cool part about tractors - that's their "personality"

Hope this wasnt too long winded - these topics are the only fun I have throughout the day.........

Kevin

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Here is an example of advance data for the early IH 4 cyclometer line. I don't see why a 6 cylinder would be much different.  I have the c-135 engine that I was discussing earlier. 

IMG_6842.JPG

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