Leaking Holley Carb

[Bob Gaines]

Thanx again, guys! Peter L., not being as familiar with these carbs as I hope to be, help me to decode mine, b/c i thought it was correct.
All numbers, etc are cast/raised, not stamped/engraved.
C30F-9510-AA (is this Ford part number?)
List-4174 (double pumper, 4150 and correct from what I've read. No?)
854 (May 4, '68)

thanx again. taking notes to learn.
Newbie, steve meltzer

You mis read the engineering number which is C8OF . Yes it is for C =1960's and the 8 is for the year in the 60's . It is not a double pumper.

[Lincoln tech]

Thanx again, guys! Peter L., not being as familiar with these carbs as I hope to be, help me to decode mine, b/c i thought it was correct.
All numbers, etc are cast/raised, not stamped/engraved.
C30F-9510-AA (is this Ford part number?)
List-4174 (double pumper, 4150 and correct from what I've read. No?)
854 (May 4, '68)

thanx again. taking notes to learn.
Newbie, steve meltzer

C3OF would mean 1963 ?

[98SVT - was 06GT]

...... since the OP stated that it was a double pumper. Not the correct carb to start with anyway.

Light bulb moment - why aren't we looking at the accelerator pump diaphragm?

[Coralsnake]

That list number corresponds to the 428 CJ / 4 speed carburetor

[Lincoln tech]

...... since the OP stated that it was a double pumper. Not the correct carb to start with anyway.

Light bulb moment - why aren't we looking at the accelerator pump diaphragm?

Now those I have seen leaking , should be easy to diag since it looks like he has the carb removed . I still don't get how the inspector saw the power valve leaking I think he meant accelerator pump , something is fishy here .

[Royce Peterson]

C30F-9510-AA (is this Ford part number?)
List-4174 (double pumper, 4150 and correct from what I've read. No?)
854 (May 4, '68)

The picture clearly shows the numbers to be C8OF 9510-AA.

[Peter L.]

 That is indeed the correct carb for a Cobra Jet. Perhaps you were referring to the fuel transfer line on the right side of the carb. Common mistake. A 'double pumper' would have an accelerator pump on the rear bowl as well.
As I posted earlier, that is a $$$ carb, and definately worth repairing correctly.
  Good luck!

[Steve Meltzer]

Gawd I hate the taste of crow before noon! Clearly i saw the 2° metering block and the fuel transfer line and (never having had a Holley other than 4160s) I assumed there was a second A-pump. The 2° metering block makes it a 4150, right? Or do I have that wrong as well?
Maybe my X-wife was right: it's a wonder I made it this far in life w/o her! thanx again. steve

[Steve Meltzer]

Oh yeah...and two more things 1) I did think it was leaking from the A-pump diaphragm, and replaced it. Confident now, it's not leaking from there. B) How did the inspector know/think the leak was from the PV? Beats the feces out of me, as you can't see the PV in the bowels of the metering block. When queried about just that, he said "b/c that's a common site for Holley leaks". s

[98SVT - was 06GT]

.....How did the inspector know/think the leak was from the PV? ....he said "b/c that's a common site for Holley leaks". s

One sneeze (backfire) can kill the power valve. About 10 years ago Holley came up with a fix and has used it since them. You can modify the older carbs with their kit. https://www.holley.com/products/tools/carburetor_tools/parts/25-100QFT

[Royce Peterson]

I've been working on Holley carbs for 50 years and have yet to see a blown power valve. It seems to be something that happens a lot on the internet.

I have occasionally seen power valves that have rotted out from age. In those cases I was rebuilding the carburetor anyways and the power valve was headed for the trash can.

Fuel leaks externally could be from a half dozen places. The transfer tube and it's bowl adapters, metering block or bowl gaskets, and the eight gaskets on the bowl screws. A carburetor that expensive deserves special care from someone who knows what they are doing.

[Lincoln tech]

I've been working on Holley carbs for 50 years and have yet to see a blown power valve. It seems to be something that happens a lot on the internet.

I have occasionally seen power valves that have rotted out from age. In those cases I was rebuilding the carburetor anyways and the power valve was headed for the trash can.

Fuel leaks externally could be from a half dozen places. The transfer tube and it's bowl adapters, metering block or bowl gaskets, and the eight gaskets on the bowl screws. A carburetor that expensive deserves special care from someone who knows what they are doing.

You took the words right out of my mouth  They also sell a power valve block off plug.

[trotrof1]

+1 on the bowl screw gaskets. You might need to wipe dry the bowl assembly well and scrutinize closely to catch it.

[98SVT - was 06GT]

I've been working on Holley carbs for 50 years and have yet to see a blown power valve. It seems to be something that happens a lot on the internet.

It happens or they wouldn't have made the change. I popped one way back when. I had the timing way off during the start of a fresh 440 for my Road Runner almost lost my eyebrows on that one. But maybe a Ford won't sneeze hard enough.......

[shelbydoug]

I've been working on Holley carbs for 50 years and have yet to see a blown power valve. It seems to be something that happens a lot on the internet.

It happens or they wouldn't have made the change. I popped one way back when. I had the timing way off during the start of a fresh 440 for my Road Runner almost lost my eyebrows on that one. But maybe a Ford won't sneeze hard enough.......

Not only does it happen but it happens quite often, not on my internet, on my Holleys. Consider yourself fortunate.