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Mezzanine
Mezzanine Reader
8/7/13 10:25 a.m.

To carburetors everywhere: I'm sorry; I was wrong. I called you all kinds of names and criticized your function. I deliberately mispronounce your name to imply it is something foreign to me.

It was the frustration speaking. I take it back.

This weekend, when I was sitting in my ’66 Dodge truck, half blocking an intersection while waiting for AAA to show up with a tow truck, I had lots of time to surf the net on my phone looking up suggestions and guides on the process of rebuilding a carb. What I found was not terribly helpful- the two videos I watched on YouTube were rife with Bubba-isms and relied too heavily on an assumed comprehension of its viewers. I won’t lie: I’ve always hated carbs as they never seem to run right, and I’ll be damned if I could ever make an adjustment do what it is supposed to. But hey- I’m a smart guy. If bubba can do it, why can’t I?

My old truck has a two barrel Stromberg WW. It has always weeped a little fuel out onto the intake, so I bought a rebuild kit a few years back, but never had any motivation to actually rebuild it. I was scared. Besides, I only drive the thing to the dump and the hardware store once a month at best. The truck finally dying in the middle of the road this weekend finally gave me the motivation I needed. I didn’t know for certain that the carb was the cause, but when I opened the hood and saw it puking gas all over the 318 Poly, I thought it might be a good place to start.

After the tow dropped me back at my house (less than two miles from where it died), I tore right into it. The rebuild kit I bought had somewhat cryptic instructions as they were meant to suit the whole development range that the WW carb saw over the years. The top gasket had obviously let go, and the float was adjusted way too high. Everything else looked pretty good, but I cleaned and replaced everything I could. The setting specs listed in the instructions didn’t really make any sense for the accelerator pump, but the other measurements seemed ok. Oh yeah: did you know that some carbs use leather still? Yeah. Mine does. Animal hide.

With nothing left to do on the carb, I pulled an ignition lead and checked to make sure the truck still had spark. I forgot that the fuel pump is mechanical and would pump with even without the carb- when I cranked the engine over, the supply line belched gas in the general direction of the open intake manifold. The amazing thing is that the engine actually fired to life for a few turns! After I got over my amazement, I mopped up the excess gas on the top of the engine and bolted the Stromberg back up, apprehensive about getting the thing to start. I made an effort to prime it by squirting some gas into the main jets to fill the bowl and buckled down for a long evening of trying to get the damn thing to run.

After double-checking all the connections, I made sure the choke was set and hopped into the cab for the first attempt. I turned the key and it started right up within one crank of the engine.

Just like that. It warmed up fine. I needed to adjust the idle a little. I went for a short shake-down cruise and everything seemed to be working as it should. It ran better than it ever has in the five years I’ve owned the truck.

I’ve since had a chance to get it good and hot and haul a small load. It stumbles a little when you first press the accelerator from a stop (TorqueFlite 727 Automatic transmission) like it is getting too much gas, and I have the idle higher than it probably should be to keep it from dying on sudden deceleration. Still some tweaking to do there. I hate that it is all guesswork from here on out. I’m tempted to actually take the thing into a shop for fine tuning. I thought about putting the thing on a dyno for a proper tune, but that just sounds ridiculous. This is a seriously crusty truck that I paid $1 for, but I do like things to be done properly.

So yeah. I have to take back some of the bad things I’ve said about carbs. That thing actually works fairly well. Now if I can just figure out why the transmission wants to stay in second gear for only a few seconds or skip right to third, I’d be a happy man. Anyone want to tell me how to set the kick-down linkage?

Vigo
Vigo UltraDork
8/7/13 10:38 a.m.
I’ve since had a chance to get it good and hot and haul a small load. It stumbles a little when you first press the accelerator from a stop (TorqueFlite 727 Automatic transmission) like it is getting too much gas, and I have the idle higher than it probably should be to keep it from dying on sudden deceleration. Still some tweaking to do there. I hate that it is all guesswork from here on out. I’m tempted to actually take the thing into a shop for fine tuning. I thought about putting the thing on a dyno for a proper tune, but that just sounds ridiculous. This is a seriously crusty truck that I paid $1 for, but I do like things to be done properly.

It is probably actually a lean condition. It's not guesswork if you put an air fuel ratio gauge on it. I put a wideband on my CRX that i put a weber conversion on and it's hugely helpful. Or you could do the absolutely cheapest thing and put in a 1-wire oxygen sensor and read the signal with a voltmeter.

I generally set the kickdown linkage by adjusting until i get to my preferred WOT upshift rpm and just learning to live with whatever kickdown behavior that goes along with. Im guessing you probably havent stayed WOT in your truck long enough for it to upshift 2-3 on its own? Do you have a tach?

ArthurDent
ArthurDent HalfDork
8/7/13 10:47 a.m.

That stumble might the be accelerator pump. Does it go away with very gentle acceleration.

Rob_Mopar
Rob_Mopar SuperDork
8/7/13 11:23 a.m.

On the kick-down linkage, the lever on the trans should be bottomed out (pushed toward the back of the truck) at WOT. Set it there and take it for a drive. I suspect your linkage is set too far forward now causing the fast up-shift.

On the carb, when you took it apart to rebuild it, did you take the idle mixture screws out to clean out the passages? If so, where are they set now? Carb rule of thumb, screw them in fully (gently, no need to gorilla them down), then back off two complete turns. If its rich, turn each in 1/2 turn at a time. If it's still lean, 1/2 turn out at a time.

Edit: Forgot to add, if you have the idle speed set too high you'll be pulling fuel from the boosters, not the idle circuit. There are slots in the throat of the carb where the throttle blades rest at idle. They control the signal going to the idle circuit. If they are fully uncovered the idle mixture screws won't do a thing. The carb now thinks its on the primary circuit.

GameboyRMH
GameboyRMH UltimaDork
8/7/13 1:15 p.m.

Carbs aren't horrible and I like the roadside-repairability. You can usually get them running with a screwdriver, no spare sensors or code readers necessary (although that's a lot less hassle these days with smartphones and OBD2-BT adapters).

Mezzanine
Mezzanine Reader
8/7/13 3:19 p.m.
Vigo wrote:
It is probably actually a lean condition. It's not guesswork if you put an air fuel ratio gauge on it. I put a wideband on my CRX that i put a weber conversion on and it's hugely helpful. Or you could do the absolutely cheapest thing and put in a 1-wire oxygen sensor and read the signal with a voltmeter. I generally set the kickdown linkage by adjusting until i get to my preferred WOT upshift rpm and just learning to live with whatever kickdown behavior that goes along with. Im guessing you probably havent stayed WOT in your truck long enough for it to upshift 2-3 on its own? Do you have a tach?

No tach. And yeah, I've run it at WOT lots of time- this is GRM, is it not? It shifts properly at WOT.

I'd either need to get a tailpipe o2 meter or get out the welder, because a '66 sure as snot doesn't have any O2 bungs in the exhaust. I'll probably add the latter to the list at some point.

Rob_Mopar, thanks so much for the advice- I'll certainly play with it this weekend to see if I can get the idle and kick-down adjusted properly. I did clean out the idle screws, and ran them back in to where they were originally. If I recall, I am really close to your suggested starting point.

ArthurDent, I believe you're right- I adjusted the linkage on the accelerator pump last night and it seemed a bit better. I need to get the truck good and hot to replicate the circumstances again.

Thanks for the feeback guys!

Ranger50
Ranger50 PowerDork
8/7/13 3:50 p.m.

Carbs suck. The simple ones just make ya fat.

Mezzanine
Mezzanine Reader
8/7/13 4:05 p.m.
Ranger50 wrote: Carbs suck. The simple ones just make ya fat.

Actually, for the sake of clarity it is the engine that is sucking... Carbs just provide the means for metering the fuel for a given suck.

oldopelguy
oldopelguy SuperDork
8/7/13 6:01 p.m.

The Stromberg WW is my favorite carb, mostly from growing up in 60's Dodge trucks and dad fighting his with every other available carb on them but mine with a WW always running well.

Watch your fuel consumption too, that carb is particularly sensitive to fuel level in the bowl. It doesn't take much change in float level to go from 17 mpg to less than 10. Same thing for a pinhole leak in the float.

With automatic transmissions I have always had best luck with the biggest accelerator pump shot setting, whichever combination of linkage holes you need to use to get there. You might also find that you can bring down the idle setting on the carb and give your timing a bit more advance to bring the rpm back up a bit

Toyman01
Toyman01 MegaDork
8/7/13 6:07 p.m.
Ranger50 wrote: Carbs suck. The simple ones just make ya fat.

Carburetors aren't too bad. Their problems you can solve with a blow gun, a couple of gaskets and some cleaner.

Be glad it wasn't a Quadrajunk though.

Toyman01
Toyman01 PowerDork
8/7/13 6:09 p.m.

Also, off the top of my head, the Dodge kick down linkage is pretty specific about how it's set. If memory serves me correctly, there is an assembly on the back of the intake or block that needs to be pinned when you are setting the linkages. I know it's that way on my business partners 65 Fury.

irish44j
irish44j UberDork
8/7/13 7:19 p.m.

I hated the Stromburgs on my GT6. Could never get them right or something was always stuck.

The day I switched to twin SU 1.75s was a good day. Tuning them perfectly was very easy, they stay in tune well, and they make more power :)

ultraclyde
ultraclyde Dork
8/7/13 8:02 p.m.

Carbs are great. Simple, mechanical genius. It's just fear of the unknown

I second the idea of increasing the accelerator stroke. I almost always ran it at it's richest setting on any carb'ed vehicle I had, sometimes bending the linkage to get an even bigger shot. It's damn hard to get enough out of an accelerator pump to cause a badly-rich situation, but too-lean is very common. As was said above, if it works great on slow accel but stumbles when you pop it, you need more shot.

tuna55
tuna55 UltimaDork
8/8/13 4:45 a.m.
Toyman01 wrote: Be glad it wasn't a Quadrajunk though.

novaderrik
novaderrik UberDork
8/8/13 6:01 a.m.

forget the wideband... you don't need it... normal everyday people were adjusting carbs with vacuum gauges and screwdrivers for 10 decades before anyone figured out how to hook an oxygen sensor to a gauge and marketing them as the latest and greatest tuning tool that you absolutely cannot live without..

one thing that i figured out a long, long time ago (1991, when i was 16 and trying to get the thermoquad on my 78 Cordoba to work properly) is to do the final setting of the idle mixture screws with the vehicle in gear with someone holding the brake pedal. if you don't have an assistant you trust, putting the front bumper up against a tree with the car idling in gear will hold the car in place...

also, keep in mind that you have to have the ignition properly set up and functioning in order to get the carb fully dialed in- sometimes going so far as to put a timing chain in the thing so the cam isn't 20 degrees retarded...

Alan Cesar
Alan Cesar SuperDork
8/8/13 8:01 a.m.
Mezzanine wrote: What I found was not terribly helpful- the two videos I watched on YouTube were rife with Bubba-isms and relied too heavily on an assumed comprehension of its viewers. I won’t lie: I’ve always hated carbs as they never seem to run right, and I’ll be damned if I could ever make an adjustment do what it is supposed to. But hey- I’m a smart guy. If bubba can do it, why can’t I?

This makes me think we should do a primer on carburetors in the magazine.

JoeyM
JoeyM Mod Squad
8/8/13 8:04 a.m.
Alan Cesar wrote:
Mezzanine wrote: What I found was not terribly helpful- the two videos I watched on YouTube were rife with Bubba-isms and relied too heavily on an assumed comprehension of its viewers. I won’t lie: I’ve always hated carbs as they never seem to run right, and I’ll be damned if I could ever make an adjustment do what it is supposed to. But hey- I’m a smart guy. If bubba can do it, why can’t I?

This makes me think we should do a primer on carburetors in the magazine.

As someone who just pulled all the (e)lectronics off an L24(e) and put the dual-carb intake of a 240z onto it.....yes, I would like that article.

Mezzanine
Mezzanine Reader
8/8/13 9:37 a.m.
Alan Cesar wrote:
Mezzanine wrote: What I found was not terribly helpful- the two videos I watched on YouTube were rife with Bubba-isms and relied too heavily on an assumed comprehension of its viewers. I won’t lie: I’ve always hated carbs as they never seem to run right, and I’ll be damned if I could ever make an adjustment do what it is supposed to. But hey- I’m a smart guy. If bubba can do it, why can’t I?

This makes me think we should do a primer on carburetors in the magazine.

Abso-freaking-lutely.

I think it is safe for me to speak for generation Y and the millennials that we need some confidence in this department. I'm ready to take on most any fuel injection issue, but when it comes to these old-fangled carburetors I was damn scared to touch it.

Be sure to cover multi-carb balancing and tuning.

Mezzanine
Mezzanine Reader
8/8/13 9:42 a.m.
novaderrik wrote: one thing that i figured out a long, long time ago (1991, when i was 16 and trying to get the thermoquad on my 78 Cordoba to work properly) is to do the final setting of the idle mixture screws with the vehicle in gear with someone holding the brake pedal. if you don't have an assistant you trust, putting the front bumper up against a tree with the car idling in gear will hold the car in place...

Thanks for the tip on adjusting the idle in gear- I've got the thing running like a top sitting still, but it is always in gear that I have any challenge.

To the other comments on the accelerator pump position, I think I have that wrong- I have the linkage in the hole closest to the throttle shaft, which will yield the lowest supply as it moves the least. I'll move it out to the second or third hole to see how that does.

wspohn
wspohn Reader
8/8/13 11:50 a.m.

Fuel injection is so much better than carbs it is hard to justify ripping it off and sticking the equivalent of a guy pouring gasoline out of a pop bottle into a pipe on the poor engine. I deal with carbs a lot (my fleet has 17 carbs I have to tune as opposed to 4 FI engines, but I love the fact that FI just works, adjusts itself many times per second to suit driving conditions, and does not contribute to one of the biggest sources of engine wear, keeping the chole on too long.

dean1484
dean1484 MegaDork
8/8/13 3:34 p.m.

Hi.. . . My name is Rochester Q. Jet. I have been waiting for many years for this apology. I am really not that bad a guy. If people just took the time to get to know me even understand me they would see that I am not nearly as bad as the rumors say I am. I may be a bit temperamental and need an occasional adjustment but if you were as old as me you would need a little adjustment to.

One other thing don't believe anything that girl Holly sais about me. We dated for a while and that was it. . .. I swear. I have no idea where all those little Webbers came from. . . .Honest.

Kenny_McCormic
Kenny_McCormic SuperDork
8/8/13 3:47 p.m.

Double check your timing, adjust the idle mix to highest idle(dwell/tachometer comes in handy here)then richer a touch. Adjust idle down to specced, probably something like 800 rpm. Should be golden.

rebelgtp
rebelgtp UltraDork
8/8/13 3:50 p.m.
Alan Cesar wrote:
Mezzanine wrote: What I found was not terribly helpful- the two videos I watched on YouTube were rife with Bubba-isms and relied too heavily on an assumed comprehension of its viewers. I won’t lie: I’ve always hated carbs as they never seem to run right, and I’ll be damned if I could ever make an adjustment do what it is supposed to. But hey- I’m a smart guy. If bubba can do it, why can’t I?

This makes me think we should do a primer on carburetors in the magazine.

I think that is a great idea. I use to know a guy that was a freaking wizard when it came to carbs. He could make just about any engine with a carb just sing. Unfortunately I never took the time to learn his secrets and now that I am diving into carbs for the Olds there is a bit of apprehension on my part. I am still diving into it to see what I can do on my own. I have a rebuild kit for the Q-Jet on its way and Cliff's book as a reference.

Vigo
Vigo PowerDork
8/8/13 4:16 p.m.
forget the wideband... you don't need it... normal everyday people were adjusting carbs with vacuum gauges and screwdrivers for 10 decades before anyone figured out how to hook an oxygen sensor to a gauge and marketing them as the latest and greatest tuning tool that you absolutely cannot live without..

Where exactly do you think carbs got their reputation? From people using AFR gauges on carbs?? No, it came from people NOT using afr meters, and it came from about a bajillion man hours of labor wasted fumbling around with carb changes that you couldnt determine the side effects, or even MAIN effects of, without wasting a bunch of time and gas driving around in all sorts of conditions to find out what worked and what didnt.

There's plenty of stuff you can't set by ear on a carb. For example, this Weber i put on my CRX is supposed to be jetted and set for this engine blah blah blah and yeah, when i installed it i was able to get it to a decent idle AFR 'by ear', and WOT afrs were acceptable as well, but cruise afr was 12-13. Gee, i wonder if that coincides with EVERYONE on the crx forums complaining about poor mpg with a weber? Wanna guess how many of them had a wideband? Mine now cruises at 15:1 and i didnt have to waste a bunch of gas and re-live everyone else's failures to figure it out. You have to be really dang good (which comes from many hours of failure learning how to get good) to old-school your way to the same quality of result as any dweeb with a wideband can get in one day with a jet kit. Even a narrowband is helpful, and you can get a single-wire o2 and weld a nut to your downpipe for like ~$40 total and just read it with a voltmeter if that's what you want. A real wideband is only $150..

And although i didnt get any credit for being the first to point out that it was probably a lean condition regarding the accelerator pump, i will say YOU'RE WELCOME to the OP anyway.

Alan Cesar
Alan Cesar SuperDork
8/8/13 4:44 p.m.
rebelgtp wrote:
Alan Cesar wrote:
Mezzanine wrote: What I found was not terribly helpful- the two videos I watched on YouTube were rife with Bubba-isms and relied too heavily on an assumed comprehension of its viewers. I won’t lie: I’ve always hated carbs as they never seem to run right, and I’ll be damned if I could ever make an adjustment do what it is supposed to. But hey- I’m a smart guy. If bubba can do it, why can’t I?

This makes me think we should do a primer on carburetors in the magazine.

I think that is a great idea. I use to know a guy that was a freaking wizard when it came to carbs. He could make just about any engine with a carb just sing. Unfortunately I never took the time to learn his secrets and now that I am diving into carbs for the Olds there is a bit of apprehension on my part. I am still diving into it to see what I can do on my own. I have a rebuild kit for the Q-Jet on its way and Cliff's book as a reference.

When I briefly owned a (Hell Project) V8olvo, I was having trouble with the ignition system. When my dad came over, he helped me install a cheap HEI-style conversion I got on eBay (the previous owner retrofitted points ignition because he was a survivalist nut), then he tuned the carb a bit. He'd twist a screw, rev the engine, listen, twist a screw some more, repeat, twist another screw. Within five minutes, the thing was running like a top. Blew my mind.

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