IH 674 gas tractor - runs like %$#@...

[Howitzer]

My brother has an old IH 674 gas chore tractor (I believe it has a c200 engine).

The thing has ran like crap for years. He got the head rebuilt, put a carb kit in it and thing still fouls spark plugs like crazy. It spits and misses a lot. He replaced the distributor with a used one but that didn't seem to fix much.

He thinks it needs a replacement carb, I wonder if it has a worn cam shaft that might be messing up the valves or distributor timing. He has also in the past noticed it was having fuel ending up in the engine oil.

Any advice on how to proceed? He's scratched his head about this old tractor for too long...

 

[wore out]

A compression check and a cylinder leakdown test would provide a lot of info, and a timing light would show if the distributor and it's centrifugal advance are doing their jobs.

 

[rustred]

Well for starters the cam lift should have been noticed when setting the valves. Is the valves set correct to spec? Why do we never get info as to what was done and how things are or were set. U can throw all kinds of new parts at an engine , that still wont make it run if you dont know how to perform the job. Then the points are they set to spec? Is the timing set to spec? Was the carb soaked and cleaned properly. What spark plugs are in it ? Plug wires ok? Does it have a thermostat in it ? And me my first thing to do is a compression check , even though u said he did the head. And just running around with it not getting to operating temp. Fouling plugs will be normal. Is it an oil burner , theres another reason. A few things to chew on.

 

[used red MN]

Are the plugs oily with a somewhat wet black residue and a lot of accumulated carbon on them that means you are passing oil most likely up past the rings. Does it use any oil? If so, probably means that instead of just doing the head he should have went on and put rings in as well? If Or do the plugs. have a dry black powdery substance on then then it is likely getting to much fuel.

 

[Mike Van]

Gas in the engine oil - Bad fuel pump? How else could it get in there? Years ago my 574 [gasser too] was really running bad, i did all the easy stuff [plugs, points, etc] was getting ready to order a carb, about 200.00 at the time - A friend that i miss dearly was at my place one day, told me before i threw $$$ away on the carb to adjust the valves. Boy was he right - Tractors run fine ever since.

 

[Howitzer]

When we installed the rebuilt head, I believe we set the valve correctly, I could be wrong. We should reset them.

 

[Howitzer]

I'm hoping we set the valves correctly. We should set them again to confirm.

As for the points and timing, good question - we will have to confirm.

Carb - I believe we cleaned it pretty good and installed the carb kit.

Spark plugs - my brother has been using Champions, but has had to change them a number of times due to fouling.

Plug wires condition - I don't think he's changed them, maybe he should.

Compression test - we need to perform one.

Oil burner? Not that I'm aware of.

Thermostat? I believe it has one.

 

[Allan in NE]

If its fouling plugs, its pumping oil. Time for an overhaul?

Allan

 

[Howitzer]

Well I'm warming up this post. My brother decided to purchase a new Zenith 14996 clone carb off of ScAmazon. We put it on the 674 today and it ran alot better. The problem is that when we shut it down, the carb starts to leak considerable amounts of fuel out the main air intake port. We took off the float bowl and tried to free up a possible sticky float needle and/or float. It didn't make any difference - the carb still leaks fuel like crazy when the tractor isn't running. My brother says the old carb did the same thing. Fuel in the oil is still an issue too. Anyone know what's going on? Is the carb faulty and need to be returned? Maybe the floats are faulty...

?????

 

[used red MN]

Often a brass or metal shaving can be created when attempting to connect the fuel line to the carb. Sure there should be a fine screen on the fitting on the carb that the fuel line screws into to but sometimes filings can make it past those. If that or any other debris imbeds in the rubber tip of the float needle you get leak by. Not sure how often this happens with carbs but I have bought cheap China air tools and found metal shaving in them that remained due to inadequate cleaning after machining at the factory. There is also a possibility that the needle seat is not screwed tight enough to seal against its gasket.

 

[Howitzer]

Often a brass or metal shaving can be created when attempting to connect the fuel line to the carb. Sure there should be a fine screen on the fitting on the carb that the fuel line screws into to but sometimes filings can make it past those. If that or any other debris imbeds in the rubber tip of the float needle you get leak by. Not sure how often this happens with carbs but I have bought cheap China air tools and found metal shaving in them that remained due to inadequate cleaning after machining at the factory. There is also a possibility that the needle seat is not screwed tight enough to seal against its gasket.

Could this updraft carb just be collecting unburned fuel in the carb's throttle body by gravity and then the fuel drips out?

 

[Howitzer]

Often a brass or metal shaving can be created when attempting to connect the fuel line to the carb. Sure there should be a fine screen on the fitting on the carb that the fuel line screws into to but sometimes filings can make it past those. If that or any other debris imbeds in the rubber tip of the float needle you get leak by. Not sure how often this happens with carbs but I have bought cheap China air tools and found metal shaving in them that remained due to inadequate cleaning after machining at the factory. There is also a possibility that the needle seat is not screwed tight enough to seal against its gasket.

When we installed the new clone carb, we didn't have the air cleaner/ducting tubing hooked up yet. We ran it with the air cleaner/ducting tubing disconnected (tractor ran quite good) and then we shut the tractor down. Within 15 seconds, a distinct fog/stream of gases slowly came out the main intake throat of the carb body, then fuel started to drip out the main intake throat of the carb. We did try to free up a possible sticky float needle, but it didn't seem to help.

 

[rustred]

Post them fouled plugs. Can be due to rings worn out. Have u monitored the oil usage ?

 

[Mike Van]

Those clones, you know sometimes you get something a lot less than the original. If this was my problem, i'd take the carb off, set it up on a bench with the bowl off, use some small hose & small funnel, hold the float up, see if gas runs out around the needle & seat. If it's running in from somewhere else, maybe the casting is cracked?

 

[Howitzer]

Post them fouled plugs. Can be due to rings worn out. Have u monitored the oil usage ?

I'm going on what my brother tells me. He used the tractor yesterday for a few hours and he said it ran pretty well. He didn't check the plugs afterwards, I told him he should pop them out and have a look. I'll get him to take a pic. He also said he needs to change the oil as he thinks there's a fair amount of fuel in the engine oil (hopefully a new carb will solve this fuel in the engine oil problem).

 

[Howitzer]

Those clones, you know sometimes you get something a lot less than the original. If this was my problem, i'd take the carb off, set it up on a bench with the bowl off, use some small hose & small funnel, hold the float up, see if gas runs out around the needle & seat. If it's running in from somewhere else, maybe the casting is cracked?

When we thought the float needle was sticking, we removed the carb and blew into the carb fuel inlet (by mouth) with it upright - the float needle appeared to be sealing OK. When we inverted the carb to open the float needle, we could blow air into the fuel inlet.