# IH 574 Low on RPM's



## Dukmn80 (Aug 7, 2017)

Hey Guys,

I have a IH 574 that had been sitting for years that we are trying to get going. We have added an aux gas tank, cleaned all the gunk out of the lines, fuel pump and fuel filter. Full take down and cleaned the carb (Zenith). The carb will run a little raw fuel thru it, but we will address that later. Points and cap are clean. Replaced the coil as it was bad. It will fire up and run fairly clean, however full throttle will only get up around 1k RPM's. 

Any ideas of what to try now?


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## BigT (Sep 15, 2014)

Hi Dukmn80, welcome to the tractor forum.

Your governor rod may need adjustment. Remove the governor rod from the carburetor linkage and see if it throttles up ok. Take care that the engine doesn't over-rev with the governor disconnected. Use your hand on throttle linkage at the carburetor to control rpm.


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## Dukmn80 (Aug 7, 2017)

Thanks for the quick reply. I will give that a try this afternoon and report back.


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## Dukmn80 (Aug 7, 2017)

No good there. Disconnected the governor rod and still only getting to 950-1000 RPMs.


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## HarveyW (Sep 15, 2014)

Does your tractor have a fuel pump? If so, you might think about replacing it.

Is the throttle butterfly opening full? 

Maybe you have a restriction in the intake somewhere.

Is your distributor advancing spark?


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## Dukmn80 (Aug 7, 2017)

It does have a fuel pump, and it seems to be moving fuel like it should when I pull the line off the carb. I can try bypassing the fuel pump and going direct from the aux tank to the carb using the gravity method.

I believe the butterfly is opening fully, but we can verify that.

As for the intake, I'll look into that. Might as well check for leaks while we're at it.

We will check the timing on it later today as well.


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## BigT (Sep 15, 2014)

Is the battery fully charged? Try running a hot wire from battery hot terminal direct to the coil input terminal, see if that helps.

Are the plugs black? Does the choke help revving? You may a lean fuel issue.

You may have a vacuum leak at throttle packing/shaft or elsewhere. Spray starting fluid (ether) to check. Maybe you have a lean main jet setting. Pull the plug out of the bottom of the carburetor bowl and do a flow check. You should be able to fill a pint jar in 3 minutes.


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## Dukmn80 (Aug 7, 2017)

The battery is fully charged. 
We did run a hot wire direct from the battery to the + Coil terminal, but it didn't make a difference. 

The plugs are black, but not bad. I will go ahead and clean them up just to be sure.
The choke does not help, in fact it usually makes it sputter out. I still have an issue with some raw fuel running thru the carb. (the air cleaner line is unhooked currently)

Vacuum leak is possible and I will be checking for that today as well.
As for the jets, we have adjusted them several times with minimal impact (less than 100 RPM variance).
I can do a flow check as well.


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## 40fordy (Jul 27, 2017)

Timing off? Check your distributor.


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## Dukmn80 (Aug 7, 2017)

The timing marks are very hard to see. It looks like there is a B, a bunch of tick marks, then an A. I see a few places where it looks like a number is, but I can't really make them out. Does anyone have a picture of the marks, or know what order they should be in?


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## 40fordy (Jul 27, 2017)

Each small line mark is 1°. It would be best to clean the timing marks with fine Emery paper so you know where you're starting. Somewhere between A and B should be 0 for TDC. At low rpm (~500), using timing light, you should be 0-1°btdc. Ideally, timing should be set at high idle (~2200-2400 rpm).


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## Dukmn80 (Aug 7, 2017)

I'll try cleaning some more and hopefully be able to see. We did adjust the timing as we could see that the distributer had been moved due to different colored paint and it's way better but still only getting 1750 rpms max. I was hoping someone knew if there is like 20 degrees in each direction from center to the A or B.


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## 40fordy (Jul 27, 2017)

I believe TDC or 0 Mark is 10° from B and 30° from A. Timing should be ~20° A at ~ 2300-2400 rpm.


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## Dukmn80 (Aug 7, 2017)

So after cleaning real good with paint thinner, there is "A", 40, 30, then I think 20, then I can't tell for sure on the next 3 marks, but I'm assuming the rest goes, 10, 0, 10 and the for sure "R".
Can someone verify if that's correct?


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## Jeremy Vance (Aug 14, 2017)

I believe that's correct, did you adjust it, did it help?


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## Dukmn80 (Aug 7, 2017)

I got it at what I believe to be 20 degrees. I'm up to almost 2000 RPMs. Still short of the 2200 or whatrver PTO is marked at on the guage. It's running very smooth and starts tight up now. I hooked up the bush hog and did a little test mow. Seemed to do just fine. Thanks for the help!


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## Jeremy Vance (Aug 14, 2017)

Awesome you could still do a little tweaking bro, and get her just right!!


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## Dukmn80 (Aug 7, 2017)

We tried adjusting the timing on further, along with the throttle linkage and the governor linkage. But didn't really gain much. Moving the governor by hand does yield higher RPMs, but i cant seem to get it to do it on its own. Probably will take another wack at it at some point. Getting the tank off, cleaned and back in service will be the next project. We have been running off a 3 gallon aux tank for testing purposes.


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## 40fordy (Jul 27, 2017)

Glad it's running better, good luck with your tank cleaning.( That's my next project).


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## sixbales (May 18, 2011)

On my diesel, I adjusted the governor governor linkage to get a bit higher RPM. I used my I&T manual to do this job.


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## Diwali (Dec 26, 2015)

I guess you already know but, for clarification, the timing marks mean: A for Advance and R is for Retard.


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## RC Wells (Dec 26, 2008)

Try a different tachometer, such as the one on a dwell meter. The mechanical tachometers will not always register full RPMs after setting and drying out over the years.


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## Dukmn80 (Aug 7, 2017)

I had the same thought about the RPMs but checked it with the dwell meter and it matched up.


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## RC Wells (Dec 26, 2008)

Reach in the carburetor throat and see if you can wiggle the venturi assembly. Sometimes they simply wear loose from vibration, and if that occurs it is time to replace the carburetor.

If the venturi is snug, then start leaning down the main jet and see if that gives you RPM rise. If it does, double check the float level. If the float level is good, and the needle and seat are not leaking, run the tractor under moderate load and read the plugs after an hour of use to be sure it is not running lean or rich. If you do not know how to read the plugs, there are a number of articles on the net on the subject - it is becoming a lost art.

If all checks good after these steps and it is not reaching full RPM, advance the timing a degree at a time until it runs where it should.


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