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1986 LMC 1200 Muffler issue

Sylvia Tunaskas

New member
To replace or not replace? The muffler keeps coming off in the deep snow. The initial front / header pipe connection is the culprit. Instead of matching the muffler inlet to the header pipe size (approx 2") they just flared the end of the header pipe and stuffed it into the inlet to the flare and clamped it. I had some parts made to eliminate the muffler and replace the flared connection with a pipe that fits inside the header pipe and is flared to match the rest of the setup to the tailpipe connection. Is there a potential problem running with out a muffler? The noise with it off is not deafening, and truthfully I did not know it was missing until I got under it and saw it missing. My major concern is the hot exhaust dumping by the bell housing and getting trapped in the engine compartment. If it is working hard and under load it starts to sputter / starve until I throttle back. If you open the engine covers and let things cool down things, work well until the heat builds up again. Some similars cats in the area (1500's) do and do not have mufflers. Trailering it and taking it to a shop is not an option at this time. Any comments or suggestions would be appreciated. Thanks.
 

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Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
if you have a naturaly asperated engine i would not run with out the muffler that muffler looks trashed i would suggest an enexpensive glass pack or resonator to hold a bit of back pressure in the exhaust so as not to warp the valves with cold oxygen rich air the stuttering sounds like vapor lock that can be resolved with some steel fuel lines if your muffler comes off the best way to fix it is to clamp it and than tack weld the joint that will keep it from moving and loosening up
 
I ended up putting an electric fuel pump on my Spryte because it vapor locked at higher altitudes. I agree with tack welding the joints, end of problem.
 

shovanl

Member
SUPER Site Supporter
1200 are pron to vaper locking the more heat you can keep out of the engine compartment the better it will run
 

Sylvia Tunaskas

New member
Thanks for all your comments and suggestions. As the cat is at a remote location I had no access to welding equipment. In order for the exhaust to be repaired "properly" it would have required hauling the trailer up to the location, loading the cat, hauling it 60 miles to a shop (getting oversize load permits) and taking it back. I was not up to the "dance" so was looking for an on site fix. We were able to replace the old muffler assembly with the parts pictured. The header pipe is 2". Instead of clamping four sections to replace the muffler set up, we only had to double clamp two sections. The gap from the header pipe to the tail pipe connection is clean and there is plenty of clearance from the snow.

It turns out that the stalling issues were not from vapor lock, but from a clogged / dirty filter. In the service manual it shows a sediment bowl and an electrcal cut off fuel valve between the tank and the manual fuel pump. My cat had been modified and those parts were not there. An electric fuel pump was added between the tank and the manual fuel pump. There was a small metal filter screwed into the tank side of the electric pump. In order to remove the filter you had to remove the pump and put it in a vice. To make a long story short it took four trips to figure it out. The fix was to replace the filter between the tank and electric pump with a larger, see through one that was not screwed directly into the electric pump. I also replaced the filter in the manual fuel pump too. (NAPA filter wrench #77-0192) The wrench made it a breeze to take the cannister off. It now runs well and is venting the exhaust out the rear tail pipe.

In back flushing the fuel system I ran across an unusual fitting where the fuel line goes into the float bowl. On the tank side it had the connection from the fuel pump line. That narrowed down to a small opening. On the float bowl side there was a moveable shaft. It appeared that the pressure of the fuel coming in moved the shaft forward and the fuel was able to flow through four opposed openings into the float bowl. Is anyone familiar with this set up?

Thanks again for your helpful comments.
 

muleman

Gone But Not Forgotten
GOLD Site Supporter
Sounds like a spring loaded check valve in the bowl. It keeps you from losing prime. Probably off a diesel setup for something else.
 

PrecisionMarine

New member
In back flushing the fuel system I ran across an unusual fitting where the fuel line goes into the float bowl. On the tank side it had the connection from the fuel pump line. That narrowed down to a small opening. On the float bowl side there was a moveable shaft. It appeared that the pressure of the fuel coming in moved the shaft forward and the fuel was able to flow through four opposed openings into the float bowl. Is anyone familiar with this set up?

Thanks again for your helpful comments.

I think you may be referring to the needle and seat. If I recall correctly, single bbl. Holleys use a removeable N&S at the float bowl (the brass part in a bag in your first link.) Inside the carb bowl, the float acts on a pivot to open and close the N&S. How far in or out the N&S is affects fuel level- a little rich or lean if it's reinstalled with a different gasket, or the if the original gasket is compressed more or less. The N&S isn't usually removed unless rebuilding the carb and you can set the float level by inverting the top half before reassembly.
 

redsqwrl

Bronze Member
GOLD Site Supporter
Not to pile on but don't forget about battery welding. You mention that you are unable to weld in its current location.
Keep in mind:
A couple of 12 V DC batteries will make suitable spot welds in the field.

In my off roading days I carried Stinger, rods and eye protection in the scout to insure that old binder would stay together.

Here is a random video off of you tube....
[ame="http://www.youtube.com/watch?v=O_hLobwoyhE"]YouTube - Using 3 car batteries to weld (Video #1)[/ame]

Mike
 

Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
130 amps and 1/8 inch rod is a little hot for exhaust one of those little battery operated wire feeders would be better
 

Sylvia Tunaskas

New member
dds, not sure about your question. Will assume it is about the needle / seat issue / identification. If you click on the bottom link in #9 and look at the top right picture you will see a brass / shiny fitting. That is / was the item identified as the needle / seat.

Thanks for the welding suggestions. My past experiences with spark / fire around gas engines has left me with a profound fear of "possible fire" (probable in my case). Over the years and mistakes I have made, I choose to remain "celebate" in that area!!

Thanks to all for your help.
 
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