'67 L-79 Holley Questions...

[Gerard F.]

Re: '67 L-79 Holley Questions...

Bob,

I guess you would call them the shaft seals. On my 751 3810, I found the seals to be just heavy clear tape wrapped around the shaft, 2 places on the primary shaft and 4 places on the secondary shaft. I'm told that they were teflon impregnated.

I have obtained a set of replacements and they appear to be white strips of plastic, flexible but more rigid than the tape on the original.

Have also obtained a new replacement primary throttle shaft for a 3810 (as the original had a bunged up throttle lever). This has a different setup for the seals, and looks like it is set up for 3 O-rings on each side of shaft at the bearing surfaces.

So I'm still scratching my head on assembling the original throttle body base, while the replacement throttle body is on the car and working fine.

Let me know what you find when you pull the shafts.

[Bob S.]

Re: '67 L-79 Holley Questions...

Jerry - As I said, it's been 30+ years, but what I recall for the new throttle shaft seals matches your "white strips of plastic" description perfectly. I recall they were folded/doubled over....but not quite in the middle when I received them. Could your old ones have deteriorated and thinned with age due to heat, loads, etc ??? Unfortunately, I have no recollection at all what my old ones looked like when I removed them in the mid '70's.....

Thanks for your reply; I was worried it might me difficult to locate replacement seals.

Bob

[Timothy B.]

Re: '67 L-79 Holley Questions...

Bob,
I am glad the wheel turned out good for you. It's nice to have a complete correct set, I thought that wheel was in nice condition.

Glad to help out, Tim

[Clem Z.]

Re: Now '66 and '67 L-79 Holley Questions...

Thanks for the input guys!!

You've hit on another question I should have asked in my first post.....what do the stampings on my '67 metering block, "L18501", "8485" and "1947" mean, if anything, other than the fact it's a replacement?

Since the 3367 carb from my '66 does not have "3367" stamped in the baseplate is that a replacment too? Since I don't have a '66 JG, can I assume the '66 3367's correct metering block stamping is also "4743" (as mine has)?

I guess I hijacked my own thread to expand it from '67 to make it cover the '66 also......

Finally, other torques I can anticipate needing are for the baseplate assembly screws and for the (secondary) metering plate "clutch head" screws.......anyone know what these are? I know I'm being fussy about this, but since Holley component warping seems to happen often, and I already have 5 or 6 torque wrenches in my toolbox, why not use 'em?

Regards,
Bob

the L18501 is model 600 CFM holley and that is what that 8485 metering body came from

[Clem Z.]

Re: '67 L-79 Holley Questions...

here is the fixture i use to straighten holley metering bodies

[Bob S.]

Re: Now '66 and '67 L-79 Holley Questions...

the L18501 is model 600 CFM holley and that is what that 8485 metering body came from

Thanks Clem - Is that to say the 8485 metering body is from a 600 cfm Holley, but just not the 3810 for a Corvette?

I pretty much have the carb stripped down at this point. (I won't have the last 3 clutch head screws out to get the secondary metering plate off until I can retrieve my clutch head bits from another location this weekend.)

Anyway the primary throttle shaft/lever assy has seen better days. The shaft is bent slightly, and the lever is loose where it attaches to the shaft. It's also apparently been brazed back together somewhere along the way. (Honest, it was just driven to church on Sundays by a little ol lady!)

Jerry - the shaft seals were worn pretty thin as you described yours were. Actually there were 4 seals on the secondary shaft, but only one on the primary shaft!

Bubba's had his hands on this carb too; there were a total of 4 o-rings on the transfer tube, one on one end and no less than 3 on the other!

Bob

[Bob S.]

Re: '67 L-79 Holley Questions...

here is the fixture i use to straighten holley metering bodies

That's a cool fixture Clem!! Glad to see that straightening a warped metering block can be done pretty easily! Thanks for sharing!!

Bob

[Clem Z.]

Re: '67 L-79 Holley Questions...

That's a cool fixture Clem!! Glad to see that straightening a warped metering block can be done pretty easily! Thanks for sharing!!

Bob

maybe i should patent it.

[Clem Z.]

Re: Now '66 and '67 L-79 Holley Questions...

Thanks Clem - Is that to say the 8485 metering body is from a 600 cfm Holley, but just not the 3810 for a Corvette?

I pretty much have the carb stripped down at this point. (I won't have the last 3 clutch head screws out to get the secondary metering plate off until I can retrieve my clutch head bits from another location this weekend.)

Anyway the primary throttle shaft/lever assy has seen better days. The shaft is bent slightly, and the lever is loose where it attaches to the shaft. It's also apparently been brazed back together somewhere along the way. (Honest, it was just driven to church on Sundays by a little ol lady!)

Jerry - the shaft seals were worn pretty thin as you described yours were. Actually there were 4 seals on the secondary shaft, but only one on the primary shaft!

Bubba's had his hands on this carb too; there were a total of 4 o-rings on the transfer tube, one on one end and no less than 3 on the other!

Bob

i have a 8485 metering body in front of me and it is stamped 18501. the holley parts book list a 4743 for a 3810

[Timothy B.]

Re: '67 L-79 Holley Questions...

What's the best way to tell if a power valve is blown. I just started my 67 and had a backfire. The car runs like crap, I am wondering if spark plugs now need replacing. I put my finger over the rear vent tube and gas shot out out of the air bleeds, is that normal?? I did it on the front and the engine died.

[Gerard F.]

Re: Now '66 and '67 L-79 Holley Questions...

Oh my gosh Bob,

With 4 O-rings on the transfer tube, the fuel bowls must have leaked like a sieve. I put one extra in one time, and just couldn't figure out why the fuel bowl gasket was showing and the thing was leaking, until I took the extra one out.

On the throttle shaft, I think if you get a replacement 3810 primary throttle shaft, it may have a different seal setup. The one I got (from Mztrcarb) about a year ago has 3 small grooves on each end where the seals would go. Sure looks to me like it is setup for O-rings.

Wonder if they changed the seals to o-rings on the later models or replacements, instead of the flat pieces of nylon wrapped around the shaft?

I'm glad I went to a whole new throttle base plate to get it on the car. It really wasn't that much more than the new shaft, considering trying to find the right seals.

Clem, you ought to patent that fixture. I guess you then put the whole thing with the meeting body into a press or a vise to bend it flat?

[Bob S.]

Re: '67 L-79 Holley Questions...

What's the best way to tell if a power valve is blown. I just started my 67 and had a backfire. The car runs like crap, I am wondering if spark plugs now need replacing. I put my finger over the rear vent tube and gas shot out out of the air bleeds, is that normal?? I did it on the front and the engine died.

Timothy - I'm not sure about fuel shooting out of the air bleeds when you plug the secondary vent with a finger, but I recall clearly seeing someone post somewhere the finger plugging test on the primary vent causing an immediate stall as a sure fire indication of a ruptured power valve. This especially likely since you had a backfire!

Good Luck!

Bob

[Bob S.]

Re: '67 L-79 Holley Questions...

Timothy - I couldn't figure out how to post just a link, so I copied what a search turned up below on a ruptured power valve test:


#5
September 29th, 2007, 12:19 AM
Jim Trekell (22375)
Extremely Frequent Poster
Join Date: March 1st, 1993
Posts: 3,069


Re: Backfiring with new carb.
Steve it is possible that you have a ruptured power valve. All it takes is a backfire while starting the car or a stumble with a cold engine to send pressure the wrong way and rupture a power valve. Quick check, remove the air cleaner lid, start the car, and put a finger over the vertical vent for the front fuel bowl. If you 67 dies almost as soon as you put your finger over the vertical vent, the power valve requires replacement. I know whenever my 68 327/350 with owner installed Holley has the after firing in the exhaust that my power valve has ruptured, the finger test just verifies it for me. A good power valve will let the engine run for awhile with the fuel bowl vent blocked with your finger, but blocking the vent will eventually stop the engine from running. Later model Holley's have a check valve installed to help prevent the ruptured power valves.

[Bob S.]

Re: Now '66 and '67 L-79 Holley Questions...

Oh my gosh Bob,

With 4 O-rings on the transfer tube, the fuel bowls must have leaked like a sieve. I put one extra in one time, and just couldn't figure out why the fuel bowl gasket was showing and the thing was leaking, until I took the extra one out.

On the throttle shaft, I think if you get a replacement 3810 primary throttle shaft, it may have a different seal setup. The one I got (from Mztrcarb) about a year ago has 3 small grooves on each end where the seals would go. Sure looks to me like it is setup for O-rings.

Wonder if they changed the seals to o-rings on the later models or replacements, instead of the flat pieces of nylon wrapped around the shaft?

I'm glad I went to a whole new throttle base plate to get it on the car. It really wasn't that much more than the new shaft, considering trying to find the right seals.

Clem, you ought to patent that fixture. I guess you then put the whole thing with the meeting body into a press or a vise to bend it flat?

Jerry - Oddly enough, neither bowl leaked! They were stuck pretty tight....probably from not being removed in quite a long time. I guess I'll see when I get it back together whether it leaks, or not.

I may wind up buying a new throttle body assembly and either using it or scavenging it for parts (if I'm able to salvage my throttle body casting.) But before I do that, I'm going to visit a local 'old school mechanic' who I've heard is very good w/Holleys. Maybe he has some old Holley parts lying around.....

Bob

[Gerard F.]

Here's what I ran into on the Throttle Shafts,

Bob:



The shaft on the bottom is the original one from my 3810. (it was replated in zinc but I never got around to coloring the spring and the lever)

The curly tape were the shaft seals I took off when I disassembled it. The tape is about 2" long, quite different from the white plastic or nylon strips you get today. Was thinking that maybe someone improvised these seals, as the carb is not my original but a correctly dated carb for my car. The secondary had 4 similar tape seals but narrower.

The upper one is a replacement throttle shaft for a 3810 and other 67 carbs, which I acquired last year. Note the grooves in the shafts where the seals should be. Here's a close-up:



Doesn't that look to you that the replacement one is set up for O-ring seals.

So, I'm scratching my head over the seals, while the replacement throttle assembly is working great on the car.