v6 carb problems

[retodd7711]

My '62 has had a "flat" spot in the powerband about 200-300 RPM above idle.
So today I tried to adjust the 2 screws on the bottom of the carb.
Didn't work out too good.
Now it will idle but when I open the throttle it will bog down and not accelarate. I never could get it back to pre-adjustment operation.
I've also got gas leaking from the rod on the front, top of the carb.
(See pic #2)
In other words I screwed up
So I decided to get a rebuild kit and start over.
The only kit I can find listed for my truck is a Stromberg.
Question #1. Can someone I.D. this carb for me? #23-133 on top front.
Question #2. What is the starting point for adjustment?
Example tighten screw, then rotate counterclockwise 2 turns, then fine tune.
Thanks in advance, Todd

[slorio]

Todd:
The guys on 6066gmcguy.org can give you some help with that Stromberg. However, when you get to the site, also checkout their discussion of swapping the Stromberg for a 2 barrel Holley. They rave about that conversion.
regards,
Steve
New Orleans

[64swb]

the carb on your truck is a stromberg model ww. the holley 2bbl conversion talked about above is a good swap as well if you don't feel like rebuilding the ancient stromberg. i have a 500cfm 2bbl on the 351 v6 in my 63 gmc and im quite pleased with how it runs.
-chris

[jbgroby]

Retodd,

The best thing I ever did was switch to the 500 CFM holley carb. Here is a link to see the switch. It's not hard but you do need the dual barrel intake, and a $16.00 adaptor plate. You will probally be able to fine one on ebay or the 60-66 web site.

http://rides.webshots.com/album/560082574YsEssM

Also here is the engine rebuilt link with the dual intake also.
http://good-times.webshots.com/album/568422172LCyGEI


Jake

[welsh kev]

What jbgroby said. I fitted a Holley 500 to my 63; the whole job took less than an hour, ran sweet straight out of the box.

Some of the guys on Jolly's site will tell you that you should also fit electronic ignition and various other mods to go with the Holley, but I haven't and my truck is a first time starter which now does about 25% better gas mileage. It also revs better and has increased power considerably; to be fair my old Stromberg was in the same condition as yours but I do think they're too small a carburetor anyway.

I used an air cleaner from a later Chevy C-20 or similar as the original will not fit the Holley. Looks reasonably "period" and works fine.

I find that the Stromberg makes a good doorstop in my garage!

Just noticed from your pics that you have the pot metal thermostat housing on yours. I would strongly suggest that you change it for a cast iron one as modern coolants rot the pot metal and they leak. Again a quick and easy modification with considerable benefits.

[retodd7711]

Originally Posted by welsh kev

What jbgroby said. I fitted a Holley 500 to my 63; the whole job took less than an hour, ran sweet straight out of the box.

.

Did you have to get another manifold, or will the adaptor work on my intake?

[jchav62]

I've never messed with one of these old carbs before, but from what you are saying, sounds to me like you have a worn spot in the accelorator pump. By looking at it, looks like you can bend that rod (going from the bottom of the throttle linkage to the front, top of the carb) a little straighter to get it out of the worn spot. I would also check to float level. As for the adjustment, my Dad always taught me to screw them all the way in, come out 1 1/2 turns, then fine tune from there. Seems to work for me.

Seems like everyone else would rather have the Holley conversion, I happen to have a Holley 2bbl in my garage with a rebuild kit. I bought it for one of my projects, then plans changed.

[jbgroby]

I also did the change out to the petronix upgrade to get away from points and condenser. One other thing I did to improve milage was to change out the rear end from 3.92 down to 3.23 - WAY BIG CHANGE! She ain't screaming at 3000+ at 70 MPH in 4th gear like she use to.

Total cost of componets was under $600 for the carb, intake and petronix kit.
Jake

[retodd7711]

Thanks guys for all your help so far.
I triedd the 1 1/2 turns trick, nothing changed, which leads me to believe that's not the problem.
When I open the throttle, I'm not seeing gas squirt from the discharge nozzle.
Either the check valve is clogged or I've got a piece of dirt in the nozzle.
It will rev up if you feather the throttle softly so the accelarator check ball may be clogged.

If a cleaning and rebuild kit doesn't change things, I may go the Holley route.
Problem is $$$ right now.
Why don't I have any money?
Here's why. That was a bathroom.

[welsh kev]

From personal experience, you could throw a heap of time and money at the Stromberg and get nowhere. It's old and tired, it's outdated and even when new it apparently wasn't very good.

I'd say that I've pretty much recouped the cost of buying and fitting the Holley in 18 months, in terms of better gas mileage. That's just the money side; the truck is also more reliable, more powerful and more driveable. Don't forget I'm on the expensive side of the Atlantic as far as parts are concerned, had to pay import taxes as well.

If it is any consolation I too had a bathroom like that once. In fact I still have part of my house like that today. Who cares? My truck runs good and that's all that matters!

[retodd7711]

OOHH!
We got the wheels turning now!
1. Find a carb I can afford
2. Find an adaptor plate
3. We might be peeling out of the garage in no time!
4. Drop kick that Stromberg over the fence
P.S. Did anyone notice the electric wire that was behind the shower that had an obvious water leak?

[welsh kev]

Originally Posted by retodd7711

OOHH!
We got the wheels turning now!
1. Find a carb I can afford
2. Find an adaptor plate
3. We might be peeling out of the garage in no time!
4. Drop kick that Stromberg over the fence
P.S. Did anyone notice the electric wire that was behind the shower that had an obvious water leak?

Carb off e-bay. There are quite a few reconditioned ones advertised most days.

Adaptor plate from Mr. Gasket. Part # 720-1937.

Don't kick the Stromberg TOO far; scrap metal prices are looking up!

BTW, you'll find that the throttle control linkage will fit straight on with a little judicious filing; don't junk that big return spring either 'cos you'll need it!

Link here for the "how-to" on the gmcguys site, my thanks to Jolly for this;

http://www.6066gmcguy.org/holley.htm

I know the one in question is on a 351 engine but as someone above said it'll work fine on yours.

Don't fret about the bathroom; I had my house re-wired a few years ago and it was seriously scary. I think some of the old wiring had been there since Edison's time!

Couple of other things I just thought of which are important. Firstly, you will need the correct union on your fuel line; the Stromberg and Holley are different ones. I had mine made up at a local engineering shop.

Second; while you're dong this, install a good in-line fuel filter. Half the problems you're having with the Stromberg will likely be from crud in the gas tank being picked up and blocking the float valve; a good in-line filter will eliminate this. Make sure you get one which can deal with high gas flow.

I'm sorry I can't post any pics of my set-up to help you, but the truck is about 120 miles away having some body stuff done.

[retodd7711]

Welsh Kev, Thanks for the great info.
After thinking about this I went to the garage and I have a 4412 Holley I was gonna put on my boat that will be a good match for the GMC.
I ordered an adapter plate.($20 shipped)
I may get out of this pretty reasonably.
Good advice about the filter.
The last gas receipt I have is for '95
So it was pretty gunked up.
Amazing it still ran good, Have to get that gas tank cleaned.

[welsh kev]

4412 is what I have on mine. That's the 500 CFM type.

If you need a rebuild kit for the carb, part reference number is 37-474. I'd recommend getting a Holley catalog (will you Americans never learn how to spell? )as it's full of useful information about setting up.

[jbgroby]

Retodd,

A quick word on the throttle linkage. I tried with no luck to make a over the counter linkage work. IT WILL NOT. This is because you need to put in a dog leg bend into the linkage.

However, I custom bent and filed mine from a piece of flat 1/2"x1/8" thick aluminum I bought from Home depot. If you would care I will make you one just like mine for your conversion. Look at the bell linkage and make sure you have the same set up in the past picture (dirty engine). Take a look at my photos showing the linkage. You can see where you have to bend it as well as remove some material. Let me know and I can make you one, NO charge for making it, just what the material $6-7.00 and shipping $3-4

Jake
jbgroby@charter.net

[retodd7711]

jbgroby-- Man, that's nice!
Someday......
Yes I would like that linkage, P.M. me your info and payment. I'll jump right on that.

[factorystock]

2 things to look for on a Stromberg carb are the accelerator pump and float level. The accelerator pump is controlled by the vertical rod coming out the front top of carb.Should spray fuel out 2 nozzles when rod is pushed down firm and quick.(disconnect linkage). The float is behind the brass fuel inlet fitting.Carb rebuild kits come with new accelerator pumps and float level guages.

[TwiggyTheDrummer]

I'm definitely making the switch soon. And jpgroby, it's nice to see another with the plaid valve covers. You even have the same breather on them.

[monolith]

Man am I glad to have found this thread!

Just got the '64 started and fuel came shooting out of the accelerator pump.

was looking for what it would take for a rebuild- but I think I'll buy a holley instead.

[old_1966_GMC]

what about he manual choke how would that work on my truck withe the carb

[jbgroby]

After we swiched over to the new Holly, we found the exact spot the manual needed to be set at, I never have to touch it, start up in about 1 second.

[creep]

I did the swap on my 63 and didn't have to modify the throttle linkage at all but the stock choke cable was a little too short.

[Corts60]

I might be a little late for the conversation, but it definitely sounds like an accelator pump issue...also, I always adjust my idle/mixture screws with a vacuum gauge. It is way easier and accurate.

-Cort

[Vintage Windmills]

Old thread I know, but I'm curious what jets you guys are running in the holley 500's with V6's, anyone know? Would it be different between a 305 and a 351 or just dictated by altitude?
Also I see Mr Gasket adapters listed as just 1937, not 720-1937. I think they are the same?

I've got a 67 with a 305 and another 67 with a 351.

Jud

[MusicMan70]

Vintage, I'm pretty sure I went with a #68 from a #73 for my 305A.