[70ALLRIZE]

I posted this earlier probably in the wrong forum, so I'm re-posting.

Hey everyone,

I'm wondering, is there such a thing as an "engineering master" carburetor? There's this website that claims that when Rochester was building Quadrajets with specific specs for each engine, that "after the design was completed, the master was created. The Engineering Master. This was said to be hand carried by the executives to the automotive company for final approvals."

The website went on to state, "Once approved and signed off, they were carried back to the plant, painted gold to indicate they were ready for production. Every single carburetor produced with that code that year had to meet the specification tolerances to that single Engineering Master. They were then placed in storage where they were to be kept forever. They should never be sold or leave the facility.

Is there any truth to this claim? Apparently, some of these "masters" were recovered after the factory closed. I have not been able to find any other references to these "engineering master" carburetors anywhere on the internet.

[Pav8427]

Watching. I asked a very similar question over at V8Buick. Worth reading for more insight.
Have been reading up on Quads for a few years and havent heard of that one before. I know there were engineering carbs to perfect the set ups for each application.
What web site was it? Would always like to know more.

Would guess the 'Gurus' will chime in.

[70ALLRIZE]

Originally Posted by Pav8427

Watching. I asked a very similar question over at V8Buick. Worth reading for more insight.
Have been reading up on Quads for a few years and havent heard of that one before. I know there were engineering carbs to perfect the set ups for each application.
What web site was it? Would always like to know more.

Would guess the 'Gurus' will chime in.

Here's any example for a '70 Buick with pictures: https://quadrajetpower.com/buick-197...eering-master/

Another example for a '70 Pontiac w/o pictures: http://https://quadrajetpower.com/po...eering-master/

So, a couple of further things to note; 1) some of the carbs listed as Engineering Masters have pictures and some don't - why? and 2) in the description it states, "They could be build and functional for a vehicle if you desired, or can be left as the incredible piece of history that they represent." So are they not functional as is? Also, how much extra $$ to build one?

And lastly, does anyone have any feedback or experience with quadrajetpower.com? Are they reputable and can be trusted? I don't know anything about this company.

[77 TRASHCAN]

The guy that owns Quadrajet power had a bunch of the carbs you are speaking of. I believe he sold them all....been a while...

[70ALLRIZE]

Originally Posted by 77 TRASHCAN

The guy that owns Quadrajet power had a bunch of the carbs you are speaking of. I believe he sold them all....been a while...

Hmmm, well there are still several engineering master carbs listed on his website for Pontiac, Buick, Chevy, etc. Is this guy trustworthy?

[70ALLRIZE]

In fact Quadrajet power has one listed on ebay here

[70ALLRIZE]

Originally Posted by Pav8427

Watching. I asked a very similar question over at V8Buick. Worth reading for more insight.
Have been reading up on Quads for a few years and havent heard of that one before. I know there were engineering carbs to perfect the set ups for each application.
What web site was it? Would always like to know more.

Would guess the 'Gurus' will chime in.

PAV8427
After thinking I posted in the wrong forum (non-Pontiac motors) I did start getting some replies. Here's the other thread: https://forums.maxperformanceinc.com...89#post6325089

[Pav8427]

There are a few good Quadrajet builders out there. Some not. I have no experience with Quadrajetparts, but believe he is one of ones with a good rep. Search here for quadrajets and you will find others.
Price wise I believe that they are comparable depending on the actual core you start with.
Is there a specific number you had in mind?
That would help.
Depending on the caliber of car you could always tackle it yourself. Lots of good info here and out there.

[nashcar]

I’m sure Cliff Ruggles has the answer.

[Cliff R]

I've had a few of what I call factory "test" carburetors sent here, supposedly these carburetors were used by Rochester for testing but never had fuel thru them.

I would say the ones I had here were exactly that. They had modifications made to them that would have been well beyond the scope of abilities of any "builders" that I know of. These modifications included moving the location of idle airbleeds, for example. With each movement the old holes were plugged with what looked like a very good epoxy setting up like "lava rock" and completely impervious to fuel from what I could tell.

One I remember in particular was a Pontiac carb, pretty sure it was a 1968 7028265 which would be a 400 non Ram-Air manual transmission carburetor. In addition to some obvious modifications the person making the mods used magic marker and put abbreviations on it in several places. Highly unlikely it was a fake simply by where the holes were drilled, plugged, and relocated to. Specifically the lower idle airbleeds were one place they spent some time. I know from building thousands of these units that the size precise location of the lower IAB's is critical in the "recipe" for idle and off-idle fuel plus how much fuel continues to feed the engine thru the exposed portion of the idle transfer slots at light engine load.

That particular test carb was given modern components compatible with this new fuel and returned exactly to it's original configuration with no modifications done to it anyplace. It also ran flawlessly on my test engine and was remarkable one of the best right off the bench units i can ever remember testing.

It's likely that Rochester modified carbs like the one I had here, but instead of obtaining a huge pile of them, spent time with the same unit to keep the testing consistent with predictable results. The final product most likely served as the prototype or "master" for the rest of them made with the same part number. If that was the case there would have been a lot these "masters" produced, simply because each carbs was a specific unit for a specific application, and there were a LOT of applications to cover. Once the prototype or "master" was finished I have no idea what was done to them after the model year run, like the "hand carrying to executives" for final approval, etc. It is likely that IF they were building them for other than GM, like the Ford 429 Cobra Jet models, for example that they would have had to deliver them to Ford for testing to make sure they made the grade, etc........

[carbking]

I cannot remember what Rochester called them, but yes.

The Rochester versions had an orange letter painted in a rough orange square on the pump side of the carburetor toward the back.

The carbs generally would have a cloth tag wired onto the linkage.

Mark Smith in Texas had a bunch of them, including some of the prized Pontiac versions.

Other carburetor companies had "production masters" as well. I have Carters as early as 1930, as well as the legendary Stromberg 97 and 81 in my collection.

Some of the Strombergs, as well as a the "prototype" (different than a "production master") Carter 4 barrel, may be seen in my Virtual Carburetor Museum:

https://www.thecarburetorshop.com/Ca...ual_museum.htm

After acquiring the remains of Stromberg, we had more than 300 prototypes and production masters. And probably had 30 or more Carters (I still have a set of production masters for the Cadillac V-16 in the late 1930's).

When Carter was destroyed by Federal Mogul in the mid-1980's, Federal Mogul ordered Carter Engineering to ship all of the remaining prototypes, and production masters to Carter Precision as reference. Carter Precision was a commercial rebuilder, and promptly sold them off as "rebuilts". I was able to get a few before they were shipped.

Mark and I spoke many times about the Rochester production masters. Due to information on the cloth tags, we were able to dispel some myths about "rare Pontiac carburetors" listed in the Pontiac Master Parts Manual, but never seen (because they were never made, other numbers took their place).

Of course, one has no control of these items after they have been sold, but I have always been of the opinion these, especially the really sought after numbers, should go into an individual collector's museum for a permanent reference.

Jon.

[70ALLRIZE]

Thanks Cliff and Carbking for the great information! Do these "masters" perform as is or do they need some sort of rebuild?

Cliff is Mark Northcutt still the go to guy at Quadrajet Power LLC in Texas that I should seek out for help (I saw you mention him in an earlier post)?

[Cliff R]

Mark Northcutt owns Quadrajet Power in Texas, yes.

Any NOS or the "master" carbs would need most of the internals replaced with modern components. The parts I'm using now are not the same that we used back in 2003 when I started this business. Around 2005 we saw a distinct change to many of the parts and were having trouble getting them to hold up in ethanol. Accl pumps (pulling apart) and accl pump seals (swelling up and failing). Newer production brass floats sinking from leaking at the soldered seams was another issue.

What I'm using and selling now is 100 percent ethanol compatible, not ethanol "resistant" and it comes with a lifetime warranty.......

[70ALLRIZE]

Originally Posted by Cliff R

Mark Northcutt owns Quadrajet Power in Texas, yes.

Any NOS or the "master" carbs would need most of the internals replaced with modern components. The parts I'm using now are not the same that we used back in 2003 when I started this business. Around 2005 we saw a distinct change to many of the parts and were having trouble getting them to hold up in ethanol. Accl pumps (pulling apart) and accl pump seals (swelling up and failing). Newer production brass floats sinking from leaking at the soldered seams was another issue.

What I'm using and selling now is 100 percent ethanol compatible, not ethanol "resistant" and it comes with a lifetime warranty.......

10-4 Cliff. I completely understand the situation now. Thanks for being so helpful taking the time to share your knowledge!

Thanks also to all the others posting who have taken their time to help answer my questions. You guys rock!