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IH LB 1.5-2.5 engine help

cajun1lung

Registered
I just picked up a 1945 IH LB 1.5-2.5 engine and don't know much about it. The internals appear to be in good shape. Has compression and spark. The gas tank is rotten and needs some clean up on the mixer. I hope to try and start it this weekend after changing oil and cleaning mixer. Questions I have are.
1. When I spin engine over I hear a loud clang from magneto every time the magneto fires. Looking inside the magneto all looks good and I see the piece snap causing clang. Looks like that is what it should be doing. Is this normal?
2. When I roll engine backwards it comes to a sudden stop like there is a catch that stops it from spinning backwards. Is this normal?
3. How much compression should there be? There is compression when I spin the engine over, valves seem to be operating. Should it be kind of tough to get past the compression stroke when spinning engine over?
Thanks in advance for any advice.
I am new to this forum and these old engines. I have always enjoyed watching them run. This was an old barn find on a property I used to hunt. I am glad I was allow to take the engine as the barn is now collapsed.
 

forney00c

Registered
Welcome to the Stak! The clanging noise coming from the magneto is the impulse, and it is normal. It helps give a hotter spark at low RPM for starting, but will disengage once the engine is running.

These old engines are low compression. I've heard several times that if you spin the engine against compression and let go of the flywheel, it should bounce back. If it doesn't, then you'll want to look I to valves and possibly rings.

As far as the catch when turning it backwards, I'm not too sure what to think about that. You should be able to spin it backwards easily until you come up on compression again.
 

cajun1lung

Registered
Thank you for the quick response. I thought this was normal for mag but wasn't sure. It doesn't bounce back on a slow spin when it gets to compression stroke, I will try to start like it is before tearing into it.
Yes it definitely hits something solid when I roll it backwards after about 1 revolution. I pulled the inspection cover off but didn't see anything that looked broken inside. Although I didn't spin it over while looking inside.
 

Pat Barrett

Subscriber
Age
71
Last Subscription Date
01/02/2020
And I'll try to give you a pointer. Be very gentile with the brass nut that screws into the mixer/carb. The threads in the carb are easy to strip as the body is pot metal like. Same goes for tighting it back up.
 

Jeremy Hartle

Subscriber
Last Subscription Date
07/10/2019
Pats rite. Be careful with that pot metal mixer. Messing the threads up is real easy. I wouldnt try to start it though until you determine why it wont turn backwards.
 

cajun1lung

Registered
Ok, thanks for advice. I will pull cover and drain oil and take a good look inside. The mixer is actually in good shape. I pulled needle and fuel line out and they came out easy. I noticed the choke cap appears to be pinned and not removable. A lot of crud in breather box falling out. Unless there is a way to take the choke cap off, I will have to do best I can to clean inside.
 

Mike in NC

Moderator
Age
46
Last Subscription Date
05/13/2009
Welcome to the Stak!!

Our LB will turn backwards until it comes up to compression and it stops.

Below is a link to a PDF manual for the LB.


IHC LB Manual
 

cajun1lung

Registered
never tried to spin backwards fast, but if I roll it backwards after about one revolution it stops suddenly with a metal to metal clang. I read one post where one guy had a broken govener but didn’t mention anything about spinning it backwards. I have never had a reason to spin an engine backwards, but I spun it backwards accidentally and saw what happened, so I did it again not knowing if it should or shouldn’t and it does it every time.
 

Preston Wells

Subscriber
Age
59
Last Subscription Date
02/05/2020
The impulse pawl on the mag might be what is causing the engine to turn not turn backwards. You could remove the mag from the engine and roll it backwards to see if this eleminates that issue. You will however be taxed with having to time the mag back to the correct position when you reattach it to the engine. Just a thought.
 

cajun1lung

Registered
Thanks. Was wondering if that might have something to do with it. I will look over everything close before trying to start. Thanks for everyone’s input. I hope to have it running soon. I will post pics as soon as I figure out how to.
 

FarmallPaul

Subscriber
Last Subscription Date
01/01/2020
Exactly what Pat said. I had to do mine a couple years ago, so my memory isn't that great. I was trying to find a pic or post that shows it better. It seems like there was a post somewhere that explained everything. Maybe somebody has that. The trick is to cut a slot in a piece of conduit and use it as a tool to wind up the spring.Your spring will look something like the attached pic. :crazy:
 

Attachments

cajun1lung

Registered
If the impulse spring is broken, will the mag still snap when engine is spun in right direction? It is doing that now and I do have spark.
 

Pat Barrett

Subscriber
Age
71
Last Subscription Date
01/02/2020
Well, from here, it sounds like the spring is not broken and the reverse problemis some where else.
 

Andrew Mackey

Moderator
Last Subscription Date
05/14/2017
I would get a hold of abore scope, and have a look inside the crankcase. There may be a part broken inside that is pushed out of the way when the engine is turned in one direction, but provides an obstical when reversed. A hard kick back may cause undue damage, and if it is something loose in the crankcase, it may also cause damage if it is knocked about if the engine is running. It sounds like it may be a governor weight coming incontact with a crank shaft counter weight. nly a borescope will tell.
 

cajun1lung

Registered
I actually have a bore scope and after I flush the crankcase with diesel I will do just that. This was my next step hoping not to find any parts in the bottom after draining the oil.
Thanks everyone for all the good info. This is not my first time around an engine, I have rebuilt many just not this old. This is turning into an interesting project. So far I have learned more from everyone here than I have searching the internet. Thanks
 

Pat Barrett

Subscriber
Age
71
Last Subscription Date
01/02/2020
New fuel tanks are available for your engine. A lot of people will cut the 1/4" Copper line from the carb to inside the check valve, in the tank and slip a short length of 1/4" id fuel hose to connect the two back together. This way you don't mess up those sensitive threads in the carb if you need to remove and clean the check falve from the fuel tank. You may have to remove a short section of the tube to allow for some flex in the rubber fuel hose.
 

cajun1lung

Registered
The top of the tank is rotted through. I cut the fuel line with a hacksaw to remove tank. I then removed mixer and air box. I was able to remove fuel line fitting from mixer with no problems. Had a steel fuel line. I did not remove the fitting from tank. Is the check valve on the end of the fuel line in tank? If so I will probably need a new one. All what I could see with that fitting through the holes in the tank looked real ugly. Actually I just found a manual with a breakdown of all parts and it looks as though that is how it is. I will pull it out of old tank and see if it is usable.
 
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