Carb tuning how-to?

[Tootallmike]

Guys,

After my success with the new distributor I'd like to give the whole engine a tune up.

Months ago I saved the following order of tasks to carry out (with thanks to whoever I copied & pasted it from ):

1. Change oil in air cleaner;
2. Clean out the fuel filter (at carb);
3. Re-set valve clearances;
4. Re-gap spark plugs;
5. Re-set points gap (if not using electronic ignition);
6. Set ignition timing with strobe light;
7. Check all ventline connections are secure.

When all these are done, in that order, then is the time to "do" the carb.

So my question is having done all that, what's the best way to 'do' the carb?

I know what the TMs say but I'd also like to hear it from people who've done it as there are sure to be different opinions...

Thanks in advance for any thoughts!

- Mike

[raymond]

I find that I have to set the idle mixture on mine different in the summer than in the winter if I really want to hit that "sweet spot". I have to run maybe 1/2 to 3/4 turns (more than the TM says) in or out on the screw to make it run richer in the winter and leaner in the summer. May have to with the fact that cold air is more dense than warm air and will thus need more fuel to get the same smooth idle.

[Horst]

Mike,

As you for sure know, that carb is a very simple design. As such, there is not much you can do, I am afraid, other than setting the idle mixture correctly. As you have a new carb, there is no cleaning in order. Old carbs can have dry, leaking rubber seals at the throttle shaft or a bad membrane for the acceleration pump.

If I were you, I would try to get one or two other carbs, sometimes take-outs can be really cheap. Clean them and try them on your MUTT. The versions I would recommend are either the 13660B or A or the 13841. The first two ones are the later emission types, the third one is the last non-emission. Both have different jettings. As a carb is changed in only a few minutes, a little try-and-error might give you nice results. But that is only my opinion based on my own experience with those carbs.

[rickf]

Horst, I don't know if you noticed when you were driving mine how hard it pulled. There is no bog whatsoever. That is one of the newer aftermarket carburetors. I am very happy with how it runs. very smooth idle also.
Rick

[vtdeucedriver]

Rick, what carb do you have???? I still got my hesitation even with the choke part of the way out.

[rickf]

Jeff, I have the Zenith replacment carburetor that only has one numbr on top. No ORD number. I got mine from KC Gonzo.
Rick

[Tootallmike]

Thanks all for the thoughts,

I should have said - I'm not disappointed or unhappy with the way it drives, I just want to be sure the 'performance' is optimised. I've not driven another MUTT so I've no idea how it should drive but since I'm used to 1940s trucks, tanks and Land Rovers it seems like a sports car. I love the exhaust note when it's pulling hard uphill and it goes over 50mph which already makes it the fastest vehicle I own!

When the task list said 'do' the carb, I thought it meant 'tune it', whereas I guess what it meant was if all the other ideas had failed it was time to rebuild it. No need in this case - I'll adjust the idle, set up the choke and that's all I can do. Easy

Incidentally I still have the original carb from this MUTT. One side of the casting for the float pivot was broken so the float didn't always sit straight and consequently it sometimes flooded. I identified the problem at Beltring three years ago (pre-rebuild) and repaired it with Chemical Metal and it worked fine. Perhaps I should get an overhaul kit for that carb just to compare the performance.

- Mike

[Horst]

Rick,

Absolutly I noticed that. That's why I said it really runs nice. I had once also tried one of the ORD number-less carburetors and it did just do fine. I should have been more clearer. There is nothing bad about the carb Mike uses. Just trying different ones, as it is so easy and quick to do, might yield even better results. But there are carbs out there, the very early emission type ones, which are not the best ones to be used.

[vtdeucedriver]

how many turns out does the TM say........................mine still hesitates with a load, esp in 4th gear.

Rick, how much was the carb???

[rickf]

I really couldn't tell you what I paid for the carb since it was part of a BIG trade deal for a whole bunch of stuff going both ways. Contact Bernie at kcgonzo@aol.com and he will take care of you. Tell him rick sent ya. he may charge you double but he will talk nice.

[rickf]

how many turns out does the TM say........................mine still hesitates with a load, esp in 4th gear.

Rick, how much was the carb???

Jeff, If I remember correctly you have had this carb apart quite a few times haven't you? Have you replaced the accelerator pump and checked the power valve directly opposite the center of the pump diaphram? Very gently make sure the ball is able to move in the valve, do not damage the small spring.
Rick

[vtdeucedriver]

Yea a bunch of times. I may have damaged that spring. The ball was frozen and it got it free by pusing it with a small pick. I will mess with it again today as yesterday I ran out of gas in my neighborhood

So I will put in alot more gas and try it again. But I got it out on a flat road and 4th gear was a dog. You can hear it starving for air as I need the choke out probably more than it should be to make it run ok. I believe the carb is still junk and I should have thrown it long ago...............

[rickf]

That would be starving for GAS with the choke out and yes I think you should just toss that one and find another or one of the ones like I have of you have the resources. Like I said I don't even know what he charges for them since mine was had in a large trade deal. I have never found a carb that I could not repair, BUT, I have found a LOT of them that the cost of repairing it would be more than replaceing it. If the main body is damaged then the carb is junk. The biggest damage area I find is from the idle mixture screw being forced in too far and galling the passageway.
Rick