The Stovebolt Site Forums The Parking Lot '60-'66 Trucks Bendix Stromberg carb replacement

Hi all,
I’m new to posting on this forum but have read some great insight regarding trucks like my GMC 1966 pick up. I’m looking to replace the Bendix Stromberg WW on my 305 V6 big block but I’m having a tough time finding a carburetor to fit the current intake manifold.

I’d like to replace the current carb with another 2bbl and liked the Holley 2bbl #7448 with 350 CFM. I can’t seem to find an adapter to accommodate the current manifold four bolt pattern. Has anyone had success replacing a Stromberg on this type of engine?

I’m not sure if I should have a manifold adapter machined or replace the manifold all together? The current four bolt pattern is:
3 1/4 X 1 7/8. I would appreciate any thoughts & advice. Thx

Tjmac23

Why bother replacing something that works right and was engineered for that engine? I ran lots of 7448's on round track engines where they were designed to act like a restrictor plate on a Chevy 350 to limit the benefit from expensive cylinder head modifications and level the playing field for low-bucks entry level racers. Those carbs are tunable, but getting one to work right for a specific engine without a lot of tinkering is about as likely as finding a chicken with lips. The bits and pieces in the tuning kit that I still have stashed away somewhere represent around $500.00 worth of parts. You can have your Stromberg professionally rehabbed for a lot less than making the Holley work- - - - -sort of! Stromberg VS Holley is sort of like Ferrari VS Yugo.
Jerry

Thanks for comments. I agree this engine was originally marketed as a half million mile work horse. The reason I’m looking to replace the Stromberg is because after cleaning and rebuilding, some of the parts (fuel seat assembly) won’t assemble because the carb fitting is almost completely stripped and the pump rod looks to have been bent 100 times.

Apparently Edelbrock doesn’t make 2bbl any longer so logical option is Holley. The question I have is 350 CFM or 500?

Appreciate the insight.

Tjmac

A full bushing of the throttle shaft is alk a bendix Stromberg needs. I have run every half [censored] carb swap suggestion on a d yno. Nothing works as claimed. A,proper rebuilds all you need. The 6066 gmc forum is more worthless than most. So don't do anything that group says.

That needle seat problem is very fixable- - - -make a couple more posts to get access to private messages, or drop me an email (in my profile).
Jerry

Edit: I found three reasonably-priced rebuildable cores on Ebay in about 15 minutes of searching. "It ain't rocket surgery" to get the right part and avoid all the Rube Goldberg tinkering.

For what it's worth, I did the Holley swap on my '65 305 V-6 and was *very* glad I did as the improvement was dramatic. Personally, I thought the Stromberg/governor set up was crap. Others may like the Stromberg, but I did not and it put a smile on my face to send it to the land fill. As for tuning and set up, I thought it was simple. Sweet and I (mostly Sweet ...) were able to get the Holley set up quickly, easilly. Almost right out of the box.

I can't comment on any merits of the Stromberg as I saw none. My truck ran and drove *vastly* superior after I did this easy upgrade.

You will need to find the adapter plate (I am pretty sure it was the Mr. Gasket adapter, Part# 720-1937 The Holley 500 swap is an easy project and the improvement is significant and worth the investment. You will need a new air cleaner and you will have some plumbing to do -- both easy stuff, I thought.

Here are a couple of pictures of mine. Not sure the red RTV was a good idea, but it didn't cause an issue... You might be able to get useable info from the picture of the adapter plate. I don't recall having much of an issue finding one -- google it.

Good luck and don't look back. Ditch the Stromberg!


John

Hands-on experience is always welcome. I'm wondering if the governor was an attempt to keep all the pieces of the engine in one place in fleet applications where less-than thoughtful drivers had a tendency to plant their right foot on the floor and leave it there all day? The old V6's were torque monsters that didn't like getting wound up tight. They definitely don't do small block V8 stuff and stay together for long. At 4000 RPM with 100% volumetric efficiency (impossible) that 305 would be flowing just over 400 CFM. The 500 CFM carb will let it wind up into parts-scattering speed in a heartbeat, especially in the lower gears. It's just too tempting for a driver who doesn't have to buy engine rebuilding parts to keep his foot down instead of shifting at the proper time.

It would be interesting to see comparison dyno runs with both carbs.
Jerry

Good points, Jerry. In my application, the Holley helped the 4000 series truck cruise at 65 MPH at 3,000 RPM (weight was right around 12,000 lbs.) However, the engine would *not* hold 65 on much of a hill. Load the water tank (Truck's max GVW) and the truck went to about 19,500 to 20,000 lbs (depending on what I had for lunch). At that point, 65 became more of a challenge.

I would think in a little truck, the Holley would help him cruise a lot better while keeping the RPMs manageable?

Cruise RPM is a function of gearing, not carburetion, unless the engine is intentionally overspeeded. Governing the max RPM is almost always done to protect the engine from over-revving in lower gears when the truck is pulling a heavy load. A lot of the older work vehicles sort of self-governed top speed by running out of power even on level ground. Just whisper "hill" and most of them had a chill! The Freightliner I drove foe a while was like that- - - -it had a top speed of around 65 due to final drive gearing, even when running bobtail- - - - -and the worn out 318 Detroit 2-cycle didn't pull very well, either!
Jerry

I have run a 305 on a d yno with a Holley 500. And a brand new Stromberg. The Stromberg pulled better #s up to 3200rpm. . Thi biggest problem with old Stromberg ww. Carbs is the aluminum throttle plate wears out and you can't tune It. Most I find have .020 slop. Then they lean out.. The Stromberg is hands down one of the best old 2 barrels made. I can say from experience. Having owned 30 + gmc v6 trucks..i currently have 3. A 60. A 65 and a 66. I also had a grandfather that owned a gmc dealership until the early 80's. I have hotrodded these. Built one off v6 engines. Currently I have a 384 cube v6 mix of a 379. And the 351e parts. It pulled 285 hp , But best of all just over 420lbs of torque at 1700 rpm. It's running reworked 351e heads. 9.2 compression. Stock points dizzy. And a 351E Stromberg www Carb. Also a single 3 inch exhaust.

Truckfarm -- that's all great, but we're talking stock 305 here in a pickup and we mere mortals. I think it best to respond to the OP with something realistic. And for we mere mortals, perhaps ditching the Stromberg and replacing it with the Holley is the simpler way to the same end. The Stromberg may be a great "old" design that works great ... but if that's only when it isn't worn out (which most are by now) then where's the advantage? And most of us average schmoes don't have the wherewithal (or acres of junk farm trucks laying around) to mix and match to get high performance. For the OP, who I can identify with (just a guy with a truck and the average house garage maybe), the Holley still sounds to me like the better answer.

Jerry -- (giggle...) you mentioned a 6-71 in a discussion about better performance .... wa hahahaha !!! who says you aren't a big kidder??

I have 2 stock 305's that each get 5-6 thousand miles per year. Any good shop can rebuild a Stromberg properly. Is in fact a far better carb than the Holley 500. Carbking is a member here. And has said the same thing here. And on other forums. The Old Buick and Pontiac guys love the factory installed ww Carbs. I still buy my kits at Napa. About 20 bucks. Bush the throttle. It's about 5 bucks for the bushings. And my old gmc trucks start up like they have fuel injection. I just don't see the point in modified parts that have no gains if all conditions are equal. Plus it usually sets a guy back 2-300 bucks to loose low end torque. This is the same mentality that folks have about the quadrajet. Throw an excellent carb away and put a Chinese copy of an afb. Makes no sense.

John, a "318" is an 8V-71. I believe most of the 6-71's got called "238", the most common HP rating. Either one can be made to perform- - - -just ignore the factory-specified top governed RPM by about 200, and then threaten to do a little surgery on your driver with a dull box cutter so he can hit the high notes in the church choir if he actually uses it. That keeps the injector rack fully extended all the way to the factory shift point RPM.
Jerry

Jerry,

Got it. I never did get much of a handle on calling the Green Leakers by their CID's rather than their series designators ...

Truckfarm ... um, one of the first rules we teach in Public Affairs School is this -- You may be right, but never argue with someone who buys ink by the barrel. Nevertheless, You are blessed to have me here. A sane web site owner would have deleted you by now.

All joking aside, I hope, through our banter, that we have given the OP some food for thought.