Help IDing this Holley - The 1947 - Present Chevrolet & GMC Truck Message Board Network

award280 · 05-23-2008, 02:21 AM

Hey gang.

I need some help figuring out what Holley I have here. I've gotten the all the numbers that are stamped on the thing and the closest I could find was a 580 that was sold on the 66-67 Corvettes. But when I got the rebuild kit for that carb, it turned out it wasn't for a matching carb. If any of you guys could point me in the right direction so I can finally get this thing tuned. If I slowly accelerate, it is fine, but it I get on it, it falls on its face. I'm not sure if I'm running lean or rich or whatever. Anyway, before I digress any further....

If any of you guys could tell me which adjustment screw is for the idle and which one is for the power circuit.

f.monroe · 05-23-2008, 02:58 AM

Looks like a basic 600 vac secondary Holley config . The small screws on the metering plate are where you adjust the idle fuel mixture . If you have a vac gauge , adjust them to obtain max vacuum . If not turn them in until it starts to change the idle then back then out one full turn . Adjust the float levels so that they are in the siteglass range . I used to adjust mine so that the level of fuel was at the bottom of the hole and if the truck was rocked a little , the fuel would spill out . The bolt with the compressed spring on the driver side by your return spring bracket is the adjustment for the accelerator pump . Push it to make sure it squirts gas . That way you will know if the diaphram is good . If so , adjust it so that there is little to no slack between the bottom of the bolt and the accelerator pump arm . Those are basic adjustments . You can get more info from some others that are more knowledgeable than me on Holleys but that is how I used to do it when I had a Holley years ago . Frank

Pushrod226 · 05-23-2008, 06:25 AM

Looks like a mixture of holleys. A modified sounds better. You'll have to remove the carb from the intake to find out what size throttle blades/bores are on it so you can determine what cfm it is.

It's sometimes difficult to determine what exactly it is once the choke housing has been lopped off. Based on what I see, I'd venture to guess it's a 600.

Most of the vacume secondary holleys didn't have a secondary metering block so its kinda hard to say whether its original or not.

http://www.holley.com/data/TechServi...%20Listing.pdf

There's some info there. I also recomend getting a book that details how to rebuild and modify holleys.

From what you say though I'd be lookin at the primary accelerator pump and the power valve making sure everything is setup to work together.

Don't give up to quickly, even a brand new carb out of the box will require some tuning to the power valve and jets.

As said above, vacume guage required.

05-23-2008, 02:21 AM	#1
award280 Registered User Join Date: Jun 2006 Location: Austin, TX Posts: 5	Help IDing this Holley Hey gang. I need some help figuring out what Holley I have here. I've gotten the all the numbers that are stamped on the thing and the closest I could find was a 580 that was sold on the 66-67 Corvettes. But when I got the rebuild kit for that carb, it turned out it wasn't for a matching carb. If any of you guys could point me in the right direction so I can finally get this thing tuned. If I slowly accelerate, it is fine, but it I get on it, it falls on its face. I'm not sure if I'm running lean or rich or whatever. Anyway, before I digress any further.... If any of you guys could tell me which adjustment screw is for the idle and which one is for the power circuit. Last edited by award280; 05-23-2008 at 02:23 AM. Reason: linking pics

05-23-2008, 02:58 AM	#2
f.monroe Senior Member Join Date: May 2004 Location: Caldwell,Tx. Posts: 3,648	Re: Help IDing this Holley Looks like a basic 600 vac secondary Holley config . The small screws on the metering plate are where you adjust the idle fuel mixture . If you have a vac gauge , adjust them to obtain max vacuum . If not turn them in until it starts to change the idle then back then out one full turn . Adjust the float levels so that they are in the siteglass range . I used to adjust mine so that the level of fuel was at the bottom of the hole and if the truck was rocked a little , the fuel would spill out . The bolt with the compressed spring on the driver side by your return spring bracket is the adjustment for the accelerator pump . Push it to make sure it squirts gas . That way you will know if the diaphram is good . If so , adjust it so that there is little to no slack between the bottom of the bolt and the accelerator pump arm . Those are basic adjustments . You can get more info from some others that are more knowledgeable than me on Holleys but that is how I used to do it when I had a Holley years ago . Frank __________________ Born and proudly residing in a Red State ! Last edited by f.monroe; 05-23-2008 at 02:59 AM.

05-23-2008, 06:25 AM	#3
Pushrod226 Registered User Join Date: Mar 2008 Location: Joliet IL. Posts: 64	Re: Help IDing this Holley Looks like a mixture of holleys. A modified sounds better. You'll have to remove the carb from the intake to find out what size throttle blades/bores are on it so you can determine what cfm it is. It's sometimes difficult to determine what exactly it is once the choke housing has been lopped off. Based on what I see, I'd venture to guess it's a 600. Most of the vacume secondary holleys didn't have a secondary metering block so its kinda hard to say whether its original or not. http://www.holley.com/data/TechServi...%20Listing.pdf There's some info there. I also recomend getting a book that details how to rebuild and modify holleys. From what you say though I'd be lookin at the primary accelerator pump and the power valve making sure everything is setup to work together. Don't give up to quickly, even a brand new carb out of the box will require some tuning to the power valve and jets. As said above, vacume guage required.



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