IHC info help...

   / IHC info help... #1  

mrcaptainbob

Platinum Member
Joined
Mar 21, 2002
Messages
593
Location
Jackson County, Michigan
Tractor
Bolens HT-20
I have a machine with an IHC 4 cylinder engine model C-135.
I managed to find the tune-up parts for it, but am having a difficult time getting info for carb adjustment and other tune-up specs. Any suggestions?
 
   / IHC info help... #2  
I don't know the exact specs, perhaps someone has a reference manual and can post them.

But if you don't get any specific info posted, I think you can use these specs and be pretty close.

spark plug gap: .028
point gap: .014
timing at idle: I would leave timing alone unless you've a good reason to change it. You can time an old engine by ear, but it's kinda tricky. Have to be careful to not advance it too far. I do it by loosening up the distributor, advancing it until the engine starts to lope, then retarding it until the exhaust sound gets kinda throaty, and then find the happy mediun that's closer to the throaty sound then to the loping.

I suspect the spec would be around 5-10 deg btdc at idle, but don't hold me to it. Often an old engine with a good amount of carbon build up runs better at something other then the spec. anyway. Definitely do not advance it to the point where it gets hard to start or pings under load when hot.

Idle mixture adjustment: 1/2-1 turn out from lean drop. Lean drop is that point in the adjustment when the idle speed just starts to drop while turning the idle adjustment screw in. To find it, start by turning out a turn and noting the idle speed. If it increases, continue turning out until there is no increase. Then turn in, the idle will increase slightly and then drop off. This is lean drop. Turn out between 1/2 to 1 turn, to where it sounds best.

Order of adjustment: point gap, then timing, then the
mixture. Final adjustment of timing, if needed, after mixture.

HTH,
Dave
 
   / IHC info help...
  • Thread Starter
#4  
Thanks for the suggestions, Karmakanic. I did manage to find all the tune up parts a few weeks ago and set everything to what is usually 'normal' (as you suggested). I wish it had the carb adjustments like you describe. Since it's propane fed, however, the 'carb' is a bit different. It appears to have two butterflies: one for air, one for the propane. Although they are connected to each other, the connection is adjustable. It's that adjustment that I'm trying to find out, (along with the timing). It looks as if one butterfly opens at a greater rate than the other. I'm still diggin' for info. Thanks for the suggestions.....
 
 
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