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This is a counterfeit, innit?

2.3K views 23 replies 12 participants last post by  Skinny Nose Jack  
#1 ·

It's supposed to be a Holley 780 dbl pumper but after reading through threads and seeing what the numbers on genuine carbs look like, I'm beginning to realize that I got duped. Can any of the carb gurus confirm?
 
#4 ·
#16 ·
it gave me some trouble the other day which is what started this whole inquiry.. I let it warm up and then it sputtered and died once I put it in gear, then wouldn't restart. I was going to take my nephew out in it and let him drive so he was disappointed. I figured I should get better acquainted with this carb and then read all the threads and articles about knockoffs. What made me suspicious about the shop was he said it would be cheaper to replace then tune or rebuild, he kept the vehicle for months and then didn't give me back my old carb. I was charged just under 800$ for the carb and he said that there would have been a core charge, I had a lot of other stuff going on at the time so I said F##k it and just took it home. I know alot of the problems may be from letting it sit and only starting once in a while.
 
#18 ·
Thanks you all for your input. it seems to be working ok at the moment. I need to learn more about carbs as I have only ever worked on small mikuni motorcycle carbs and have little experience with anything else. From what I have gathered it is a 750 w/ vacuum secondaries and is a pretty good match for a slightly modified 350 and th350 combo. I don't know what cam I have or stall in the trans. the diff is a 10 bolt w/ 273 ratio (i believe). I will post more pictures as there are some questions I still have about the set up with the performer manifold, adapter plate and vacuum connections. My throttle linkage is atrocious as you can see in the photos I have posted so I will fix that. so again thanks for the help and any other advice you may have.
 
#22 ·
3310 is a 780 dual feed vacuum secondary. Various versions of the 3310 were used on hi-po 396, 427, and I think 302 engines with a GM specific list number. A standard 750 double pumper is list 4779. As far as I know they did not come on any production GM engines.
 
#23 · (Edited)
View attachment 344926 View attachment 344927 View attachment 344928
It's supposed to be a Holley 780 dbl pumper but after reading through threads and seeing what the numbers on genuine carbs look like, I'm beginning to realize that I got duped. Can any of the carb gurus confirm?
Jack according to my Holley books your carb is a 750 vacuum secondary 4160 style Holley. The 3310-1 780 is a 4150 style with full metering blocks for primary and secondary, this is not what you have. Every other 3310-2, 3, 4 ect right up to your -16 is a 750 style 4160 Holley. Your 4160 only has a metering block on the primary side, your secondary float bowl bolts directly to the main body without a metering block and without removable main jets. Your 4160 utilizes a thin plate attached to the main body hidden under the secondary float bowl that has passages that meter fuel instead of jets. To alter fuel metering you take the number stamped on the plate to a Holley chart that tells you what the equivalent jet size is.

FWIW 68 Z28 were GM #3923289-DZ List 4053. This was one I used years ago.
Image

The older carbs were not shiny zinc coated like the newer carb you have, used flat head straight slot screws for float bowls unlike the hex head bolts the new ones use and had smooth tops on float bowls and vac secondary actuator, compared to the new ones all cast with Holley logos in them including the main bodies. So the shiny new ones are easy to seperate from the originals when you know what to look for. Your 750 is a very common carb for a 350 street motor. I would not be concerned and continue to use it. Call Holley and ask about the laser etched numbers on the air horn vs stamped numbers.

According to Jerry MacNeish in 1967 the 302 used a different carb List 3910 #3916143 for Norwood built cars, List 3911 #3916145 for Los Angeles cars with AIR emissions.

I built a pair of 4150 600 carbs. One has a newer main body with the zinc coating, the other is an older main body without zinc. Other than that they are the same. For comparison you can see the rough surface zinc coating on the newer carb below.
Image
 
#24 ·
Jack according to my Holley books your carb is a 750 vacuum secondary 4160 style Holley. The 3310-1 780 is a 4150 style with full metering blocks for primary and secondary, this is not what you have. Every other 3310-2, 3, 4 ect right up to your -16 is a 750 style 4160 Holley. Your 4160 only has a metering block on the primary side, your secondary float bowl bolts directly to the main body without a metering block and its removable main jets. Your 4160 utilizes a thin plate attached to the main body hidden under the secondary float bowl that has passages that meter fuel instead of jets. To alter fuel metering you take the number stamped on the plate to a Holley chart that tells you what the equivalent jet size is.

FWIW 68 Z28 were GM #3923289-DZ List 4053. This was one I used years ago.
View attachment 345001
The older carbs were not shiny zinc coated like the newer carb you have, used flat head straight slot screws for float bowls unlike the hex head bolts the new ones use and had smooth tops on float bowls and vac secondary actuator, compared to the new ones all cast with Holley logos in them including the main bodies. So the shiny new ones are easy to seperate from the originals when you know what to look for. Your 750 is a very common carb for a 350 street motor. I would not be concerned and continue to use it. Call Holley and ask about the laser etched numbers on the air horn vs stamped numbers.

According to Jerry MacNeish in 1967 the 302 used a different carb List 3910 #3916143 for Norwood built cars, List 3911 #3916145 for Los Angeles cars with AIR emissions.

I built a pair of 4150 600 carbs. One has a newer main body with the zinc coating, the other is an older main body without zinc. Other than that they are the same. For comparison you can see the rough surface zinc coating on the newer carb below. View attachment 345004
I had figured it was a 4160 750CFM after hours of videos and reading. I've had my head buried in carburetor lore for days now. I still don't know much as there is so much to know. At this point I'm keeping it the way it is so I can focus on other things she needs. I kind of hope it's a fake because I lit that guy up on yelp.