1953 IH R112. SD220 engine. 1st start in 35 years. Changed all fluids. Rebuilt carb (I did it). Machine shop rebuilt head. My buddy adjusted valves. Truck will fire off immediately and will run with very little throttle applied. Leave off the throttle and it dies. 50% or more throttle and it sprays a constant mist of fuel out the top of the carb while it bogs horribly. Don't know if this means anything but putting hand over carb it stalls out. Pinched the fuel line and it still misted fuel out the top until it went dry and shut down. What are the most likely culprits and why would it blow a mist out the top of the carb? Any other testing I can do?
- Thread starter nrowles
- Start date
rusty6
Well-known Member
- Location
- East central Sask.
Over fueled by the sound of it. Float level too high maybe? Or needle not seating properly? I'm no expert as I can't even get the Holley carbs on my Internationals to perform as I'd like them. But they do run better than yours.
"Misting out the top of the carb even when fuel is shut off 'til it dies" would indicate a valve (or possibly camshaft) issue.
If an intake valve is set too tight, "popping back" through the carb will occur when the cylinder fires, on the other hand, if an exhaust valve isn't opening when it's supposed to, after the compressed charge is lit off, the exhaust gasses will "pop" back through the carb when the intake valve again opens.
A "flat" exhaust cam lobe can cause this.
First, check the simple stuff, firing order and timing, then run through the valve clearance setting procedure again, if OK, might as well check valve lift with a dial indicator to verify valves are operating as they are supposed to. HOPEFULLY, you can find some valve lift "specs", but even lacking them, check and jot down the "lift" of each valve and see if any deviate from the others.
If an intake valve is set too tight, "popping back" through the carb will occur when the cylinder fires, on the other hand, if an exhaust valve isn't opening when it's supposed to, after the compressed charge is lit off, the exhaust gasses will "pop" back through the carb when the intake valve again opens.
A "flat" exhaust cam lobe can cause this.
First, check the simple stuff, firing order and timing, then run through the valve clearance setting procedure again, if OK, might as well check valve lift with a dial indicator to verify valves are operating as they are supposed to. HOPEFULLY, you can find some valve lift "specs", but even lacking them, check and jot down the "lift" of each valve and see if any deviate from the others.
rusty6
Well-known Member
- Location
- East central Sask.
I can't remember the figures but valve clearances are given in the operator's manual for these trucks.
Steve@Advance
Well-known Member
Have you checked the exhaust for back pressure?
Something may have nested in the exhaust, packed with acorns.
Sticking valves can also cause blowing back through the carb.
Something may have nested in the exhaust, packed with acorns.
Sticking valves can also cause blowing back through the carb.
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