450 ihc timeing problem

Pete L · Sep 15, 2011

I need some help,have a 450 gas that keeps dieseling when I shut it off,i've advanced the timing and retarded the timing and it does not solve the problem. What might be my next step?Thanks,Pete.

David G · Sep 15, 2011

It is not the timing, set it correctly and leave it alone. The idle is set too fast, or it is carboned up, or both.

Anonymous-0 · Sep 15, 2011

try a higher octain fuel when these tractors came out gas was over 100 octain at the pumps and most 450s ive been around run best on atleast 93 pump gas.set your timing back to specs and try that and see if that helps

JRSutton · Sep 15, 2011

Agreed with others - could be carbon build up - check the plugs to make sure you're not running too rich, building up carbon.

While you're at it, check what plugs you're using, and make sure they're the correct ones for that engine.

That problem can be made worse if you're idle speed is too high. When you shut the engine, there's enough momentum to turn a few more times, and hot spots (in carbon or whatever) can keep igniting it.

If you're running too lean - that can be a problem , leaving too much oxygen in the cylinders.

Higher octane gas may help, but may also just be hiding a problem.

If it continues to be a problem after checking all that, I'd consider pulling the head and make sure there aren't any cracked valves, or other sharp metal edges causing trouble - and/or get rid of any real bad carbon deposits.

Andrew Z · Sep 15, 2011

My 450 has had some light engine work done to it and will diesel on reg. 87 gas, steped up to mid and super dont have that problem any more

Andrew

Janicholson · Sep 15, 2011

With respect there was fuel available at 100+ octane, Sunoco260 comes to mind, But farm fuel was far from racing fuel. 80 octane would be more correct, if measured with R+M/2 procedure. Jim

Janicholson · Sep 15, 2011

Set the idle as low as possible and still be smooth and steady. Play the apeed screw and mixture screw. (timing at TDC static)
and it should not run on. Jim

the tractor vet · Sep 15, 2011

First check the dist for a working advance . Next set the timing at full throttle for full advance . NEXT make sure that you have the correct heat range on the plugs. Next fine tune the carb . set the main jet at four and a half turns off the seat and maybe five. next fine tune the ideal mixture screw with the engine warmed up and as you do this start backing down the curb ideal to 450 RPM . then like others have said and i have said many times before up the grade of gas. And on yours 89 will do fine Myself and all my friends customers we get the 93 for our gas tractors but we are running 460-560-706's and 4 S/MTA's with higher compression pistons then most run. along with 400 and 450 heads. So we just get the 93 octane and use it in all .

kossuth · Sep 16, 2011

(quoted from post at 16:49:58 09/15/11) I need some help,have a 450 gas that keeps dieseling when I shut it off,i've advanced the timing and retarded the timing and it does not solve the problem. What might be my next step?Thanks,Pete.

'd set the timing and then I'd run some seafoam through it. http://www.seafoamsales.com/how-to-use-sea-foam-motor-treatment.html There is a good chance it's just really carboned up. Alot of carbon in the combustion chamber can create hotspots which can cause your dieselling.

450 ihc timeing problem

Pete L

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David G

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Anonymous-0

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JRSutton

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Andrew Z

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Janicholson

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Janicholson

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the tractor vet

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kossuth

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