The Stovebolt Site Forums The Shop Area Engine Shop No Mo Stumble, Hesitation or Carb Problems

Some time ago I made the decision to try a Carter W-1 carburetor in place of the original first series Rochester ‘B’ that belongs on my truck because of the problems that plagued these early ‘B’s. I found a good core and spent the better part of a week learning about this Carter carb.
So after all this meticulous work it’s given me fits because it ran lean. I've been chasing a hesitation/stumble/lack of power with my
1950, 216 for more than a year now. The truck runs best when the choke is pulled out 3/8” to 1/2”. I was meticulous in the restoration of this W-1 carburetor so I really couldn’t understand why it performed so poorly.
In January I rebuilt another of the same model for a friend, and once again I spent several days soaking and checking every internal passage and adjustment and I gave him back a W-1 that performs just beautiful on his 1950, 216. Last week I swapped his carb for mine and lo and behold, it performs just perfectly on my engine.
So this week I did an autopsy on my W-1 684 to try to nail down the problem. I think I may have found it!
When I originally rebuilt mine I took pictures of all the jets and plugs to make sure that they all went back in the proper location. Today I noticed when I was removing the Nozzle Assembly that the Nozzle plug was actually a 122-47s Discharge Disk Check Assembly with the brass disk in it. After checking the hole I found that it is only .093” plus the fact that the flow is restricted by the brass disk. According to the shop manual the Nozzle Plug is supposed to have a .130” to .150” hole and of course I’m assuming that there is no restriction in it either. Apparently someone had been into this carb before (boy, what a surprise) and either lost or replaced by mistake, the Nozzle Plug with an Inlet Check Valve. Since it was the first W-1 that I’d worked on I never gave it a thought last year.
The Nozzle plug looks very much like the Inlet Check Valve so I figured I could simply remove the disk from that Inlet Check Valve and re-drill it to .150” to feed the Main Nozzle? It apparently has held the Main Nozzle in place so far since I’ve driven the truck for several thousand miles and other than it running lean it runs fine.

Here are a few pictures of the bad guy in the hi-speed circuit.
http://www.pbase.com/dennygraham/under_hood&page=5

So after several Rochesters, and a couple of Carters, I finally have a SWEET running 216. My test-drive this evening felt like I was driving a completely different truck. Idles smoother, accelerates smoothly nice and strong pull, no stumble, no hesitation, more power than I expected from a 216 with 60,000 miles on it. She popped up to 60mph just beautifully. But now I’m gonna have to start watching out for John Law with all this new found power at my fingertips.

Denny Graham
Sandwich, IL

For many years I attributed my much lower cost per mile than average on spending lots of hours in my shop trouble shooting. That is something I learned on gas GMCs 50 years ago and it evolved into Cummins Diesels. However when I work on my jalopies, I don't trouble shoot, I merely try to figure out what the previous owner screwed up.

Hmmm. Sounds familiar. I too have a Rochester B that stumbles on acceleration. Any suggestions? Supposedly, it was "factory rebuilt" when I bought it. It idles perfectly and works great when I accelerate slowly. However, when I give it gas quickly, it stumbles. I don't mean to hijack the thread, but maybe your experience can help. Thanks.

During a search, I found the following comment on Rochester B's at this Land Rover website :

"There is a pressure valve inside the carburetor body that consists of a steel ball and a spring. There is a metal rod across the top of the opening to keep the parts in place. A rebuild kit comes with a new ball and spring. Be advised that the spring rate is different than the original and replacing it can cause problems. Leave this pressure valve alone if you can when rebuilding the carburetor If you need to open up the passage reuse the old spring."

I don't know if it will help anyone, but more info. never hurts.

I have a Rochester B on my truck. It always had a stumble just off of idle.
I finally got rid of the stumble by blocking the vacuum advance port and setting the timing with a vacuum gauge.
It also got rid of the occasional pop at the tail pipe.

Jim

norcal49er-

Sounds like your problem might be the accelerator pump. I'm still a little "wet behind the ears" with these old trucks, but that sounds like a common issue. The mixture is getting too lean on hard acceleration. I believe that the shop manual calls for the carb to be tuned using vacuum gauge, as Jim mentioned.

Has anyone ever tried using the colortune product to tune their engine? Seems like a neat product...

Denny, it just goes to show that perseverance pays off.

Denny,

Holy Cow!!! YOU may have just supplied the answer to my prayers!

My 1.5 ton, with the freshly rebuilt 216, and I just went for a 450-mile trek. On the way back, it started running hot, simultaneously (gradually) losing power and bucking and wheezing. Giving it some choke brought it back to life, AND cooled it back down. So the conclusion was that the carb, for SOME reason, was running lean, probably. There was talk of drilling out the main jet, but hadn't gotten there yet.

We've been trouble-shooting this problem for two weeks, now. Just finished re-timing the thing, adjusting the valves, checking the plugs. Got great vacuum, 22 lbs. at idle, and now smooth (a few valves were off a little). Also, found the points hold-down screw loose, and the points WIDE open.

Now, we're playing with the distributor advance, trying to set it according to vacuum (per instructions in a post here), which doesn't really compute with me, so I'm gonna set it back to factory static. Regardless, the test drives show smoother performance, but still a hesitation, mostly in the upper half of the rpm range.

I rebuilt the W-1 myself, and it's my first rebuild, and I didn't know WHAT the heck I was doing, so I bet I made the SAME mistake. It's almost impossible to tell the difference in some of those kit parts. Heck, even the Carter Rebuild instructions don't make it perfectly clear. Not only that, but I'm not HALF as clever, or careful, as you are, but . . . I'm working on it!

THANKS FOR POSTING ON THIS - I'M EXCITED!

-Michael

Well Michael, I'd certainly look into the high-speed circuit. It's not that much trouble to pull the main nozzle plugs and double check it. Even though it has a .150” hole drilled in it, this is just a plug that I'm talking about to hold the nozzle in place, not a jet. I wouldn't start re-drilling any jets, you could really be asking for trouble there unless you have a source for spare Carter W-1 parts to replace them with.

These W-1 carbs do perform well just as the carbking, Jon H. has been posting here over the years. So just make sure ya got all the proper parts in the proper places and you won't believe how well that 216 runs with a W-1.

On that ignition if you’re methodical and just follow a few simple steps, like plugs clean and adjusted to .035”, a good wire set with no corrosion, a good cap and rotor the same way, i.e., no corrosion, the points adjusted .018”-.022”, a good coil and the timing set at the ball, there isn't any reason that it shouldn't be a reliable vehicle. I check my valve lash every thousand miles or so and more often right after a valve job, .008” and .014” good and hot.

My '50, 216 has 62,000 miles on it, 10,000 that I put on over the last couple of years. I routinely drive it spring to fall at 55-60mph on 100 mile trips almost every weekend to shows. Yesterday morning we took a nice trip up old state route 23 here in north central Illinois. On some short stretches we were running along at 65 mph, with my 4.10 gear that calculates to right around three grand and the engine sounds nice and smooth.
Good luck,
Denny Graham
Sandwich, IL

Thanks, Denny.

On the outbound leg to Indy, Rosie did between 40 and 50mph. Calculated 11, then 13, mpg for the first two fuel stops. Loud, yes. No tach, but seemed comfortable enough. Of course, that's with insert bearings, hardened valve seats, and aluminum pistons, so my machinist says it should be ok.

Yep, I'm learning about the routine maintenance of the ignition system, et al. Once you get in the routine, it's all fairly simple.

Ha! How many of today's 16-year old punks can time a '41 Chevy?!!

OK, no offense to the 16 year olds . . . I can't program my MP3 player.

I guess balance in all things, huh?

-Michael

Wow you guys are setting your points .018" to .022" maybe I'll try that and see if it will sart easier, hopefully I didn't interupt your thread here, thank you there Bolters..

Factory spec on new points was .022", .018" is the setting if they've been in service for a while, I would suspect because of erosion. I've also seen non GM literature years ago, like that from Blue Streak that calls out .016". If ya start nit picin' one or two thousands on an engine of this caliber then your a whole bunch more particular than I ever was or ever will be. Of course you want to be as close to the factory spec as you can get but between one or two mils on the points and a couple of degrees either way on the timing I doubt whether 99.9% of the owners could tell the difference in performance, power wise or in their gas mileage.
I've set the points simply by eye and the timing and mixture just by ear and again, barley noticeable difference in performance, but I’ve been messing with this stuff for nearly 60 years.
Denny Graham
Sandwich, IL

Oh yes, I forgot to mention this, about the mileage. Over thousands of miles I put on with the restricted high speed main nozzle in the W-1 my fuel mileage averaged around 13mpg. I ‘m only on my second tank of gas with the restriction removed and although the truck is running like a brandy new vehicle (I love it) my mileage has dropped to around 11mpg. That’s only with one tank so it’s really not all that accurate, I’ll have a more accurate average after a few more tank fulls have been calculated. I also need to take a reading on the plugs to see how they are handling the richer mixture. With the restricted high-speed circuit they actually burned a nice tan every time I checked them. But I was pretty much hand adjusting the mixture by choking here down most of the time, especially when bringing her up to speed once there or at idle, I would push in the choke.
I’m sure 62,000 original miles has some effect on the mileage and it will be interesting to see just how good we can tune it after the short block has been re-built.
Denny Graham
Sandwich, IL