Carb adjustments

[Sundawg3]

I was looking at the carb diagrams yesterday and wondering about the accelerator pump, thanks Rickf. The Michelins were on when I bought it, I hear they are great tires and no longer made. I wanted the US military tire look so those were changed out a couple days ago. I have the Michelins for sale on my website bradsaircraft.com. In the pilot supplies section. They have a lot of tread left and no weather checking. I'm just one person so the freight guys don't give me good rates but they should be priced right considering I have to pay for shipping. Price is lower if someone wants to pick up in Batavia Ohio. This Mutt has been in Indiana for the majority of it's life so I was told. Good catch on the data plate Rickf. The was my first contact to the Mutt Guru after I bought it. He educated me on the history of this one and data plates. Right now I'm in the process of a court ordered title, once I have it I have three other data plates (one that's correct) I'll install with the screws it's supposed to have. The BMV will not allow screws so I'm waiting until the bureaucracy clears. The current data plate says 65 but Guru tells me it's a 67. All bill of sales, purchase orders, etc... have the 65 info and I'm ass deep into the BMV, court thing so it's going to stay a 65.

[rickf]

You are learning. If you can get any title at all, even if it says it is a 53 you take it!!!! Mine is a 64 but my title is a 67. YOU know what it is and most people looking at it will know it is and A1 or A2 at least if they are into them at all. The year of the vehicle is not really as much of a big deal as it is in some of the other worlds. The straights were all the same, the A1 was the same as the straight except it had turn signals and the A2 had the updated suspension and the later style modular lights and fenders. You really only have the three styles of M151 with minor differences within each style, like added emissions or a change in a suspension arm to make it stronger. And that was only done one year in 60 or 61 so there are not many of us that will ever see that. On those tires the one thing you need to watch out for is age and how hard the tire compound has gotten. If they are too old and hard you will find it is like driving on wooden tires, with the same amount of traction. NONE!!!! I had a set of 40 year old NDT's on mine and I could go out on the pavement and with very little effort spin the rear tires and then powerbrake it and just sit there with the rear tires spinning on dry pavement with very little power applied and they were not smoking or anything. They were so hard they just slid like a piece of wood on asphalt!

[Sundawg3]

When I bought it I stopped at a friends house with 40 acres. We took it up some steep hills and through the woods. The tires did fine I just don't care for the look. I should have tossed them at the tire store the other day but have read they are sought after by some. Especially our maple leaf friends to the North. Honestly I don't want to ship them but didn't want to trash them since someone might want em. I want them out of my garage so anyone wanting to pick them up can pay what they think they're worth of bring a bottle of whiskey and we can chat.

[rickf]

Oh, They work great off road but old hard tires are a death sentence on road. Th NDCC tires, even new, are pretty sketchy on a wet road also. If that is what you got then go very easy on a wet road as they have zero side traction on the wet. I am changing mine out for a set of 215/85R-16 all terrains for next season. I will keep the military tires on the original rims for parades and shows.

[Sundawg3]

Ordered a carb kit off eBay, from China, for $11.64 shipped. Took a couple weeks to come in but couldn't find a kit here??? Opened the carb last night and found the accelerator pump diaphragm looking almost new. The stand pipe side holes, 6, were a bit gummed up. Cleaned installed new gaskets, float pin, and other parts then reassembled. I did find the idle mixture screw rubber seal was split. Runs like a champ now. No stuttering or prolonged use of choke.

[rickf]

Rapco and Red River I know have the old NOS carb kits. The kits I use when I do the rebuilds for people are from Norfar, they are direct from Zenith and are new production so are compatible with modern alcohol fuels. You never said anything about carb problems that I remember but from the sounds of it the idle circuit was dirty. That is a common issue with these carbs. Especially if you run it without an air cleaner hooked up or if the air cleaner needs to be serviced and is low on oil.

[halftracknut]

Horst, We always call that a Dupont overhaul rattle can wrench htn take the carb apart clean it ...order the big overhaul kit and install everything...put 2 gas filters...happy motoring....they run the best on av gas

[Sundawg3]

Rickf,

Again you are correct, the air cleaner was low on oil. I don't understand what oil in the bottom of the air cleaner does for the intake system? The air is drawn in from the top, through the top cleaner and into the carb.

[Sundawg3]

Scratch the last. I understand now.

[Sundawg3]

The Mutt starts and idles perfect since the carb partial rebuild with one exception. Starting in first it stumbles a bit before second and again stumbles a bit before third unless I mash the gas peddle then it smooths out. Maybe the main jet is dirty? Did I miss that on the rebuild? Anyone with a picture of the suspected problem would be greatly appreciated.

[rickf]

That is going to be in the idle circuit. The main jet will not be involved until almost full throttle.

[rickf]

There is a lot more to a carb rebuild than just take it apart, blow it out and replace parts. I have been doing them for 60 years now and I can tell you there are no shortcuts. Unfortunately I can't tell you every step involved in the process, that would take hours. It takes me roughly 3.5-4 hours to fully disassemble a mutt carb down to the bare housing, clean and check all the parts and then cook it in the ultrasonic cleaner for an hour. Clean it out again and finally blow out and dry all of the passages. The reassemble all of the parts, including the throttle shaft seals and choke shaft seals, center the throttle plate, File the mating surfaces of the flanges. Only then can I get to the point of installing the float, needle and seat and setting the float levels. That is not everything but it gives you an idea of what a professional rebuild involves. I can tell you what circuit is causing the problem but since I was not the one to do the work I can't tell you where to look.

[Sundawg3]

Thanks Rick. I understand what’s involved in a professional rebuild. I have well over 30 years aviation background. We don’t mess around either. You staying it’s the idle circuit and the email I received from the Mutt Guru told me what I’m looking for. I read the technical manual incorrect on the float settings and he was the first to tell me the idle mixture screw needs to be 1 to 1 1/2 turns out from the stop. If that’s in the manual I must have missed it. This thing has been a blast to play with but it seems I get two things done and add six more to the list.

[rickf]

It is all about attention to detail.

[Sundawg3]

Next on the list are the items Rickf and Mutt Guru suggested. Plug gap, I believe this is a no brainer as well as the valve clearance. I've read the manual for timing and points adjustments. It's been over thirty years since I've done points. Any help would be greatly appreciated. The manual says to use a spring gauge for 20 ounces (I think) to check the points open?? Plus rotating the distributor to open the points, followed by adjusting the timing according to the manual. Questions are: do I need to use the original timing light with #1 adapter and idle at 500 RPM tools or can I use a new style timing light and RPM gauge?

I'm assuming I can pull the plugs for no compression to check the plug gap and do the valve clearance while rotating the crank. Then do the points check followed by installing the plugs to run for timing check with a new style light on #1 cylinder? The light should hit the timing mark at 500 RPM which will put the engine at 6 degrees before TDC?