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#27942 09/03/2003 2:54 AM | Joined: Apr 2002 Posts: 13 Junior Member | | Junior Member Joined: Apr 2002 Posts: 13 | I own a 54 GMC truck and have had nothing but trouble with my Zenith downdraft carbs. Keep flooding out, run great and then flood out all of a sudden. I have taken them back to the carb shop twice and still the same result. I was told to dump the carb and purchase a Holley 390 CFM carb and new 4 barrel mainfold from Patricks. I was also told that the correct carb is the Holley 8007. Has anyone tried this and will it eliminate my troubles or cause me a whole new set of problems??? I have heard that the 4 barrels flood out too. Confused
My enigne is a 248 with the head casting # 2194819.
Thanks | | |
#27943 09/03/2003 3:43 AM | Joined: Jul 2000 Posts: 504 Member | | Member Joined: Jul 2000 Posts: 504 | I had my Zenith carb rebuilt by a reputable carb man , my GMC runs great.. They are simple carburetors. I think you need a new carb shop, not a new carb. If you need the name of a guy that can straighten out your carburetor, let me know. [email protected]
Bill M
53 GMC Hydra-Matic
Home Page
http://home.comcast.net/~bd97/index.html
When you argue with a fool, two fools are arguing..
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#27944 09/03/2003 5:10 AM | Joined: Jul 2002 Posts: 385 'Bolter | | 'Bolter Joined: Jul 2002 Posts: 385 | I'm with Bill on this one, it sounds like the shop is looking to make some extra revenue off you. Are you running an oilbath air element; if so how is the oil level? I rebuilt my Zenith myself and since then I've only had one complaint: It's sensitive to tank sediment and the float sticks when the fuel filters need to be replaced. Have you checked the fuel pump and filters? I found so much sand in my fuel system I was expecting a beach ball and surfboard to pop out of the lines.  | | |
#27945 09/03/2003 7:21 AM | Joined: Feb 2000 Posts: 5,215 'Bolter | | 'Bolter Joined: Feb 2000 Posts: 5,215 | Hook up a in line fuel filter just in front of the carb inlet and I'll bet your problem goes away.
A carburator will not just flood out for no reason. The float must stick open for fuel not to shut off. The only way I know for a float to stick is, dirt in the needle and seat, or float is full of fuel and sinking to the bottom.
A new manifold and carburator may take care of this problem, most likely not, but will introduce five times as many new ones. For instance, linkage, fuel lines, heat to manifold, jet changing, tuning.....
Try repairing the carb yourself. They are very simple and have few moving parts. You will find the problem as soon as you pull the top off. Don't dump it over first. Leave the fuel in so you can see what's in the fuel bowl and if the needle is stuck open.
Don't be afraid to ask for help if you get stuck. Joe | | |
#27946 09/03/2003 12:51 PM | Joined: Aug 2000 Posts: 800 Shop Shark | | Shop Shark Joined: Aug 2000 Posts: 800 | I just got my '45 straightened out. PO had a Carter carb on it that was too big and it had different linkages, etc. Got a rebuilt Zenith the other day and the truck is running like a top. GMC didn't send your truck out from the factory with a Holley. And they didn't much worry about emissions back then. As the other guys said, the right carb and linkages and an ounce of prevention should help you go a long way.  | | |
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