More 3810 and 3367 Holley questions

[Bob S.]

Greetings - I'm further into planning the return of both these carbs to original configuration and operation.

Two questions:
1. Is the throttle lever configuration for the 3367 and 3810 carbs exactly the same? (I expect it is, but if someone has both, knows them to be original, and could confirm this, I would greatly appreciate it.) I suspect my 3367's lever (which lacks the lug at the end opposite where the throttle rod attaches) is not the correct orignal configuration...it's shown on the assembled carb in the thumbnail below.

2. I've been lead to believe the '3810' stamping on my 3810's throttle body (near the left front corner) did not occur on all 3367/3810 carbs, and that, in fact, it is relatively uncommon to have it. Does anyone have either a 3367 or 3810 they know is original which does NOT have the List number stamped in the throttle plate?

Thanks in advance for any help!

Regards,
Bob

3810 Lever (left): 3367 Lever (right):

[Bob S.]

Re: More 3810 and 3367 Holley questions

This shot shows one of several differences I see: a portion of the 3810's lever that's is missing from the 3367's lever:

[Gerard F.]

Re: More 3810 and 3367 Holley questions

Bob,

Although I don't have a 3367 carb to compare with, the 3810 throttle shaft I think was unique to the 67 carbs, and different from the 66 3367 carb. I think the difference was in that automatic transmission stud you point out.

Not sure how the 66 automatic transmission handled the kickdown for automatics.

There is a different part number in the holley manual for the throttle plate assembly on a 3810 vs 3367. And the Chicago Corvette catalog lists a different part number for the throttle shaft between 67 and 66 carbs.

The first picture looks like a 3810 throttle shaft (except it looks like it has been repaired). You might consider restoring it as the replacements seem to have a different bearing/seal setup. I think the replacements are setup for the brass bushings but haven't figured that one out yet.

On the stamping of 3810 on the throttle plate, all I can say is that my original throttle plat has 3810 stamped on one corner, actually looks like it was stamped with two strikes. Someone on one of the previous posts said that all production 3810's were stamped on the throttle plate.

[Bob S.]

Re: More 3810 and 3367 Holley questions

Hi Jerry.

In talking to Holley's tech service / custom shop yesterday, I was informed the "3810" baseplates were stamped only occasionally in production. In fact, he went so far as to say it was "rare" for them to be stamped. I figure our NCRS brain trust can produce evidence to either confirm or refute that......

On the subject of the different throttle shaft configurations, it was acknowledged that both exist, but the interesting point was that there are not supposed to be any 'seals' on the primary shaft. Because of the vacuum secondaries, only the secondary shaft should have (4) seals. In light of this, maybe the 2nd throttle shaft configuration you've "discovered" can be used interchangeably??? This makes it appear the seal's purpose is to reduce friction so the throttle shaft moves freely / smoothly rather than seal against air entering.

Bob

[Gerard F.]

Re: More 3810 and 3367 Holley questions

Bob,

Remember that photo I posted with the 3810 replacement shaft with the 3 grooves in it. If you talk to the Holley tech again, please ask him about the 3 grooves and what is their purpose.

I notice that the replacement shaft fits a lot more loosely into the throttle plate than the original shaft, and even without the teflon tape. Maybe it is undercut for use with the brass bushings.

Here's the photo again:



It should be noted that the original shaft on the bottom inthe picture lacks the kickdown stud noted above. It looks to me that someone phyically removed it, as the hole where it was is distorted. That's the reason I acquired a new shaft. This carb was used on a different car and had a manual choke before I restored it to original. Perhaps the stud interfered with something.

[Bob S.]

Re: More 3810 and 3367 Holley questions

Jerry - As I mentioned on the phone earlier, Ron at Daytona parts indicated to me the use of the nylon throttle bushings depended on the fit of the primary shaft to the bore. The bushings were installed to compensate for looser fits. They were apparently always used on the secondary shaft to reduce friction. So far, nobody's told me the 3-grooved and wide grooved shafts are not interchangeable....at least without the nylon bushings. I'm unclear if there's sufficient clearance for the 3-grooved shaft to be used with bushings.

Later, in talking to Al at Chicago Corvette, he stated that the baseplate List# stamp wasn't done at Holley, but was done on rebuilds to keep track of parts belonging to a specific carb. Are you confident your 3810 baseplate on the '67 you've owned since '68 originally came with the List# stamp? If so, that would discount Al's info. He described the baseplate differences that I see comparing my 3367 and 3810 in the accelerator pump pivot area. According to him the '3367 baseplate configuration was for 1966 only. Additionally he described the throttle lever differences shown in my earlier post.

I'm so confused, I'm going to stop worrying so much about the internal carb configuration, and concentrate on:

1. whether the baseplate List# stamping was on 100% of the OE parts, just a fraction, or only done in service for the 3367 and 3810 carbs.

2. baseplate assy differences in the throttle lever and at the accelerator pump pivot between the 3367 and 3810 as they left the factory.

I'd greatly appreciate a pictures that anyone with a known original 3367 carb could post of the throttle lever and the accelerator pump pivot area of the baseplate.

I'd also appreciate hearing from those with known original 3810's on whether the baseplates left St. Louis with the carb List# stamping.

Regards,
Bob S.

[John H.]

Re: More 3810 and 3367 Holley questions

Here's the only photo I have of the left side of a 3367 (not mine), and it also shows the hole at the bottom end of the lever; on 66's, the stud for the kickdown linkage on a Powerglide was added at St. Louis (see M35, sheet A8 in the '66 A.I.M.). This changed for '67, and the 3810's had the stud on the lever from Holley regardless whether they wound up on a Powerglide or not.

[Bob S.]

Re: More 3810 and 3367 Holley questions

John - Thanks for the explaination about the kickdown stud difference. The lever you posted appears identical to the one on my 3367.

Regards,
Bob S.

[Gerard F.]

Re: More 3810 and 3367 Holley questions

Bob,

The 3810 carb on my 67 is not the original carb on my car, so I can't say that the original throttle plate from the factory was stamped with the 3810.

However, the carb that I have is dated within 2 months of my car's production date, and has all the indications (body and screw heads) of a production carb. It has 3810 stamped on the throttle plate as well as on the metering block.

Whether these stampings were done at a repair shop as Al says, I don't know. The carb had been modified for a manual choke, and came with smaller jets as if it were used on a smaller engine. This is how it looked like when I got it:



After a few new parts, scavenging parts from other carbs, and refinishing,
this is what it looked like:


This is the project that got me into plating. And that's the same choke pull off.

I know that there are some guys out there that have their factory 3810 on their 67, maybe they can chime in on the stamping on the throttle plate.

I'll also post some photo's of the 3139-1 (for a 65-66 396 Chevelle&Pass), we spoke about, to show how closely it resembles the 3367.

[Bob S.]

Re: More 3810 and 3367 Holley questions

Jerry - How did you go about having your carb parts refinished/replated after the mating surfaces were machined flat?

Bob

[Brian M.]

Re: More 3810 and 3367 Holley questions

I'll take a look at my throtle plate over the W/E, I know it has the kickdown stud. (3810)

[Gerard F.]

Re: More 3810 and 3367 Holley questions

Bob,

I had the main body refinished before I had the surfaces planed, but you could do it in either order. In fact, the coloring finish on the mating surfaces would help with a little corrosion protection.

For the potmetal on the main body and the fuel bowls, the refinish is not really plating but a coloring with dichromate. You just have to get the zinc die-cast potmetal down to a fresh zinc surface and dip it into the dichromate. I use beadblasting for the prep.

Here's the process:



Beadblasted followed by the dip:



Looks easy, but many, many hours of trial and error to get it right.

[Gerard F.]

Here's the 3139-1

Bob,

that we talked about this morning. Don't mistake this for a 3367, but as you will see it has a lot of identical parts as the 3367.







This 3139-1 is date coded 661 which would mean that it is for a late 66 Chevelle or Passenger car with a 396 engine. Take a look at that comparison chart, the fuel bowls have identical part numbers as the 3367.
So if you are looking for 3367 fuel bowls, here you go.

[Timothy B.]

Re: More 3810 and 3367 Holley questions

Bob, If it will help I can take some pics of my 3810 but it's a replacement carb dated 1976 I think. I am still sorting problems with mine, had a backfire when I started the engine and now I suspect power valve, car runs like s---. The car is at my mothers house in the garage so pics may take a day, I have not had any time lately to play.

[Bob S.]

Re: More 3810 and 3367 Holley questions

Tim - Thanks for offering to post a pic of your carb. Maybe I'm obsessing over something of limited importance since it's not addressed in the '67 JG. Or maybe this is an exercise in futility due to production inconsistencies back in the '60's, and the shortage of clear evidence 40+ years later....

I'm trying to figure out whether the List# stamping on the carb baseplate is correct as the cars left St. Louis. The fact the 3367 for my '66 has no List# stamp and the 3810 for my '67 does is what got me started on this. (Although both carbs are correctly date coded for the build dates, I have no knowledge of either carb's history.) The answer will affect the parts I seek/use for the carb refurbishments.

There's evidence from John Hinkley that at least some 3810's left the factory with the baseplate stamp, so it would be interesting to see if anyone has a known original 3810 not having it. I'm also interested in what people with known original 3367's can report on their baseplates....known original baseplates with or known originals without the Last# stamp??

Bob