Holley Carb Question
Thread Starter
Safety Car
Joined: Jun 2004
Posts: 4,652
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From: Lakeland Florida
Holley Carb Question
Hello,
I am posting in the technical section because it is engine related.
I have a Holley carb on my 73 454. How do I identify it? I think it is a 4175, but I dont know the CFM rating for it. I am looking for numbers and serial numbers, and can only find the ones shown. Also, there are two large spots of what looks like JB weld covering up the areas where the adjustment screw or nut should be.
Any help on identifying this carb, 4175 or other, and how to determine the CFM rating would be appreciated.
kdf
Passenger side view
Top down view
This has a number on it. fY18B99
I am posting in the technical section because it is engine related.
I have a Holley carb on my 73 454. How do I identify it? I think it is a 4175, but I dont know the CFM rating for it. I am looking for numbers and serial numbers, and can only find the ones shown. Also, there are two large spots of what looks like JB weld covering up the areas where the adjustment screw or nut should be.
Any help on identifying this carb, 4175 or other, and how to determine the CFM rating would be appreciated.
kdf
Passenger side view
Top down view
This has a number on it. fY18B99
Tech Contributor
Joined: Aug 1999
Posts: 14,379
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
It's a 4175. The ID is the list number stamped into the forward side of the choke airhorn towards the drive's side - get me that number and I can give you all the specs on the carb.
Lars
Lars
Thread Starter
Safety Car
Joined: Jun 2004
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From: Lakeland Florida
Hello,
Thanks Lars,
This is the carb that I wrote to you about recently. I am trying to get all the information to you so that I would know what it is I am sending!
I looked through my Holley book last night and the best I could match it up to was the 4175. If its the wrong CFM, then sending it to you to work on would not fix the problem of it being the wrong size to begin with.
Thank you for the information on the location. I will get this number tonight when I get home.
kdf
Thanks Lars,
This is the carb that I wrote to you about recently. I am trying to get all the information to you so that I would know what it is I am sending!
I looked through my Holley book last night and the best I could match it up to was the 4175. If its the wrong CFM, then sending it to you to work on would not fix the problem of it being the wrong size to begin with.
Thank you for the information on the location. I will get this number tonight when I get home.
kdf
Tech Contributor
Joined: Aug 1999
Posts: 14,379
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
The carb, which is a spreadbore, can be either a 4165 or a 4175 - tough to tell from the photos. The 4175's are 650 cfm, but the 4165's can be as big as 800. Check the list number, and I can give you the info - all Holleys have a list number stamped into the airhorn.
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Tech Contributor
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From: At my Bar drinking and wrenching in Lafayette Colorado
Ken -
As the guys have noted above, the 7002-1 is a 650 cfm 4175 (spread bore) carb. That's a little small for a performance application on a big block. The only advantage that carb has is that it is a direct-replacement for the spread bore Q-Jet (which is 750 cfm), so it fits the stock manifold, and you have no hood clearance issues. If you are not concerned about maximizing peak performance and just want the car running well, the carb will run fine once correctly set up. The stock Q-Jet will probably provide a better level of performance.
As the guys have noted above, the 7002-1 is a 650 cfm 4175 (spread bore) carb. That's a little small for a performance application on a big block. The only advantage that carb has is that it is a direct-replacement for the spread bore Q-Jet (which is 750 cfm), so it fits the stock manifold, and you have no hood clearance issues. If you are not concerned about maximizing peak performance and just want the car running well, the carb will run fine once correctly set up. The stock Q-Jet will probably provide a better level of performance.
Thread Starter
Safety Car
Joined: Jun 2004
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From: Lakeland Florida
Hello,
Thank you for your input. I do have some type of clearance issues with this carb.
The carb is sitting on a 1/2 inch thick phenolic gasket. This is needed in order to gain clearance due to the throttle linkage hitting the intake manifold.
The linkage hangs down below the carb. In order to gain clearance the previous owner installed a 1/2 thick black phenolic gasket between the intake manifold and the carb. This gives the clearance needed for the linkage, but will not allow the ring that fits on top of the air cleaner, or the air cleaner to hood seal/gasket that is used on 73-75 air filters.
I was looking at it and think that I can take the linkage off and turn it upside down, which would give me the clearance, and then I can remove the 1/2 thick gasket, and allow me to use the air cleaner ring and gasket again.
But then I will still have a 650cfm carb on a 750cfm stock carb spec engine. So I think I will start looking for a 750 CFM qjet carb first in order to a) get the correct CFM carb, and b) get the stock engine look, although not numbers matching.
Also, any idea on why there is the large glob of metal/JB weld on top of the bowls? Shouldnt that have some type of screw on it to help with the float adjustments?
Thank you,
KDF
Thank you for your input. I do have some type of clearance issues with this carb.
The carb is sitting on a 1/2 inch thick phenolic gasket. This is needed in order to gain clearance due to the throttle linkage hitting the intake manifold.
The linkage hangs down below the carb. In order to gain clearance the previous owner installed a 1/2 thick black phenolic gasket between the intake manifold and the carb. This gives the clearance needed for the linkage, but will not allow the ring that fits on top of the air cleaner, or the air cleaner to hood seal/gasket that is used on 73-75 air filters.
I was looking at it and think that I can take the linkage off and turn it upside down, which would give me the clearance, and then I can remove the 1/2 thick gasket, and allow me to use the air cleaner ring and gasket again.
But then I will still have a 650cfm carb on a 750cfm stock carb spec engine. So I think I will start looking for a 750 CFM qjet carb first in order to a) get the correct CFM carb, and b) get the stock engine look, although not numbers matching.
Also, any idea on why there is the large glob of metal/JB weld on top of the bowls? Shouldnt that have some type of screw on it to help with the float adjustments?
Thank you,
KDF
Drifting
Joined: Jul 1999
Posts: 1,542
Likes: 43
From: Plano TX
The JB Weld on top of the bowels is to stop fuel leaking past the well plugs. Over time they will leak a bit and JB Weld works fine or replace the bowl.
FYI- since the return spring is at the top of the throttle arm you could remove some of the lower section to give you manifold clearance since yours appears to be manual car with no kick-down linkage.
FYI- since the return spring is at the top of the throttle arm you could remove some of the lower section to give you manifold clearance since yours appears to be manual car with no kick-down linkage.
Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
Ken -
The big block manifold is known for throttle lever interference. The Q-Jets used on the big blocks had the lower part of the throttle arm cut off at the factory in order to clear the manifold. I can always tell when someone sends me a small-block Q-Jet that is being used on a big block, because the throttle arm has had the lower part bent to crap. Just cut off the lower part of the throttle arm just like the factory did and relocate the return spring to the top of the lever.
The JBWeld is sealing off the plugs in the bowl. Your carb does not have externally-adjustable float levels, so Holley put steel plugs in the top. These will sometimes seep fuel, so people seal them off with JB.
The big block manifold is known for throttle lever interference. The Q-Jets used on the big blocks had the lower part of the throttle arm cut off at the factory in order to clear the manifold. I can always tell when someone sends me a small-block Q-Jet that is being used on a big block, because the throttle arm has had the lower part bent to crap. Just cut off the lower part of the throttle arm just like the factory did and relocate the return spring to the top of the lever.
The JBWeld is sealing off the plugs in the bowl. Your carb does not have externally-adjustable float levels, so Holley put steel plugs in the top. These will sometimes seep fuel, so people seal them off with JB.
Thread Starter
Safety Car
Joined: Jun 2004
Posts: 4,652
Likes: 80
From: Lakeland Florida
Thank you,
Sounds like an easy fix. I can remove the bottom part of the linkage, take out the 1/2 inch phenolic spacer below the carb, put the carb back on, add the air cleaner ring to the top of the air cleaner, and finally install the air cleaner to cowl induction hood seal.
Sounds great.
Thanks for your help. Photos of the completed job should be up by Sunday.
KDF.
Sounds like an easy fix. I can remove the bottom part of the linkage, take out the 1/2 inch phenolic spacer below the carb, put the carb back on, add the air cleaner ring to the top of the air cleaner, and finally install the air cleaner to cowl induction hood seal.
Sounds great.
Thanks for your help. Photos of the completed job should be up by Sunday.
KDF.
Instructor
Joined: Dec 2004
Posts: 216
Likes: 1
From: Lapeer Michigan
It looks like they used JB weld to stop a gas leak, or a stripped float jet.
I would remove the JB weld and fine out why its there.
There is a gasket washer under the screw head and one under the adjustment nut.
The motor would like a manual secondary carb with a manual trans, the one you have is a vacuum secondary.
If it a 650 I would put on a 780 1450 Holley.
Locar makes a real nice throttle linkage setup that hooks up opposite with the cable on top.
I would remove the JB weld and fine out why its there.
There is a gasket washer under the screw head and one under the adjustment nut.
The motor would like a manual secondary carb with a manual trans, the one you have is a vacuum secondary.
If it a 650 I would put on a 780 1450 Holley.
Locar makes a real nice throttle linkage setup that hooks up opposite with the cable on top.
Drifting
Joined: Jul 1999
Posts: 1,542
Likes: 43
From: Plano TX
Do not remove the JB Weld. This is to eliminate a leak through the plug. As Lars mentioned yours is a side inlet with internal adjustment for the float height so the hole is pluged.
Be thankful the carb isn't leaking through the float plugs, accelerator pump cavities or the bowl mounting screws. Leave as is and enjoy.
Dave
Be thankful the carb isn't leaking through the float plugs, accelerator pump cavities or the bowl mounting screws. Leave as is and enjoy.
Dave
Thread Starter
Safety Car
Joined: Jun 2004
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From: Lakeland Florida
Dave ,
I think I will leave it as is until I get a 750 cfm Q-Jet. I was looking at the Ecklers catalog and found P/N A5924 Rochester Qjet for 1971-72 454 or P/N A5929 for 1974 454. $270 - $295.
There is no part number for a 1973 454 engine. I think the 1974 should be similar becasue of the EGR valve requirement.
kdf
I think I will leave it as is until I get a 750 cfm Q-Jet. I was looking at the Ecklers catalog and found P/N A5924 Rochester Qjet for 1971-72 454 or P/N A5929 for 1974 454. $270 - $295.
There is no part number for a 1973 454 engine. I think the 1974 should be similar becasue of the EGR valve requirement.
kdf
Drifting
Joined: Jul 1999
Posts: 1,542
Likes: 43
From: Plano TX
1bad80 - I would agree except the 4175 and 4165 series carbs do not have external adjustments for the float. The epoxy is only covering the plug as from the images there is no screw or lock nut. There is not enough epoxy to cover up those parts.
i've had several of these series carbs (vacuum and double pumper secondaries) and have experienced them leaking though the plug and have fixed them the same way.
Dave
i've had several of these series carbs (vacuum and double pumper secondaries) and have experienced them leaking though the plug and have fixed them the same way.
Dave
Tech Contributor
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From: At my Bar drinking and wrenching in Lafayette Colorado
Originally Posted by 1BAD80
it is on the float adjuster.
Dave is right - that 4175 does not have a float adjuster, and it's not a center-hung float. The float can only be adjusted be removing the float bowl and bending the float arm. The location where the external adjuster is normally located has a steel press-in plug installed there by Holley - similar to a freeze plug - and this steel plug will often leak. Standard fix for a "weeping" bowl plug is to JBWeld it.
Instructor
Joined: Dec 2004
Posts: 216
Likes: 1
From: Lapeer Michigan
I stand corrected, sorry Dave. 
IM the one that should have looked at the picture's better.
One can see it doe's not have any float adjustment.
Plus the plug is next to the metering plate.
I agree the standard fix for a "weeping" bowl plug is to JBWeld it.
IM the one that should have looked at the picture's better.
One can see it doe's not have any float adjustment.
Plus the plug is next to the metering plate.
I agree the standard fix for a "weeping" bowl plug is to JBWeld it.