Carb Problems - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72hoopti · 08-06-2012, 03:24 PM

I have a zz4 crate motor with a new edelbrock 600 and have had nothing but problems with it. The carb wants to stumble, has problems starting after motor has been run, and has half the guts than the holly that I replaced it with. Anyone else have this problem?
I have replaced the springs in the carb and put a thicker gasket below the carb. I have searched high and low for a vac. leak but to no avail. I have pulled the PCV valve hose off and it still runs. Put two rags over the carb to choke it and it won't die! Any advice is appreciated...

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cdowns · 08-06-2012, 03:31 PM

what do the sparkplugs look like?
type of gas pum
ffuel filter?
gas tank and lines clean and freash gas?

72hoopti · 08-06-2012, 03:43 PM

Everything you mentioned is Brand new. Edelbrock suggested the 73x42 metering rods. However, I have tried all of their " kits". Sprayed all over for vac leak and can't find anything....
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GASoline71 · 08-06-2012, 03:47 PM

Quote:

Originally Posted by 72hoopti

I have a zz4 crate motor with a new edelbrock 600 and have had nothing but problems with it. The carb wants to stumble, has problems starting after motor has been run, and has half the guts than the holly that I replaced it with. Anyone else have this problem?
I have replaced the springs in the carb and put a thicker gasket below the carb. I have searched high and low for a vac. leak but to no avail. I have pulled the PCV valve hose off and it still runs. Put two rags over the carb to choke it and it won't die! Any advice is appreciated...

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There's your problem! Bolt the Holley back on...

Gary

72hoopti · 08-06-2012, 03:49 PM

Well Gary, that won't solve my issue with this carb.
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GASoline71 · 08-06-2012, 03:55 PM

Very true... but if you have a known good running carb... why keep messing with this one?

Also... what's the ignition system condition? New as well? What's the timing set at? A lot of "carb" issues can atually turn out to be timing/ignition related.

Gary

Wrenchbender Ret · 08-06-2012, 04:28 PM

Those are good carbs. Check the accel. pump shot. They use a leather cup that can dry out from setting. Is the carb flooding after you shut it off? That carb does not like a lot of fuel pressure. About 4-5 lbs. Have you put heavier springs under the metering rods? You may need to change to a smaller metering rod or a larger jet. That engine probably has quite a bit of cam. It may need a quicker spark advance &/or more timing.

oldblue1968chevy · 08-06-2012, 07:47 PM

Whats the condition of the carb? What is the fuel pressure it sucks if its not @ 5-6psi.

Are the floats set correctly

5.5 is what eddy recomends i think

72hoopti · 08-07-2012, 11:13 AM

Well, after a long night turning screws, "starting from scratch", the hoopti is running and running without the stumble and hesitation.

Timing is all up to specs according to GM performance. Put the advanced springs and weights in distributor and made some difference.

My biggest complaint now is there's no guts behind it anymore, with this carb, the truck is a dog!

I am going to put a fuel pressure gauge on it... Will get back shortly
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GASoline71 · 08-07-2012, 01:17 PM

That could be timing as well... what is the "spec" that GM says needs to be used on the ZZ4? Could also be fuel delivery.

Also as stated above... the Edelbrock carbs don't like much pressure above 5.5 PSI. So shoot for that... you might need a pressure regulator.

Gary

Wrenchbender Ret · 08-07-2012, 04:27 PM

Make sure the secondary throttles are opening. If the choke is not opening all the way it can be blocking the sec. from opening. Or your linkage may not be opening the throttle all the way.

oldblue1968chevy · 08-08-2012, 03:53 AM

I have an eddy..it works...(after it was set and regulated).

If I had to do it again Id get a edelbrock fuel pump that puts out the proper psi a fuel regulator is just going to clutter things up.

If/When I start driving my truck again

I believe Im going to try to find something other than edelbrock (probably a holley)

So.Cal.Super · 08-08-2012, 08:46 AM

Quote:

Originally Posted by oldblue1968chevy

I have an eddy..it works...(after it was set and regulated).

If I had to do it again Id get a edelbrock fuel pump that puts out the proper psi a fuel regulator is just going to clutter things up.

If/When I start driving my truck again

I believe Im going to try to find something other than edelbrock (probably a holley)

I was told by my Carb guy that running a regulator will take the pulse out of your fuel system (with mechanical pump) and can increase your mpg by as much as 1

I was not able to prove that, but just thought I would share.

08-06-2012, 03:24 PM	#1
72hoopti Registered User Join Date: Sep 2009 Location: Redwood City, CA Posts: 24	Carb Problems I have a zz4 crate motor with a new edelbrock 600 and have had nothing but problems with it. The carb wants to stumble, has problems starting after motor has been run, and has half the guts than the holly that I replaced it with. Anyone else have this problem? I have replaced the springs in the carb and put a thicker gasket below the carb. I have searched high and low for a vac. leak but to no avail. I have pulled the PCV valve hose off and it still runs. Put two rags over the carb to choke it and it won't die! Any advice is appreciated... Posted via Mobile Device

08-06-2012, 03:31 PM	#2
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Carb Problems what do the sparkplugs look like? type of gas pum ffuel filter? gas tank and lines clean and freash gas? __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

08-06-2012, 03:43 PM	#3
72hoopti Registered User Join Date: Sep 2009 Location: Redwood City, CA Posts: 24	Re: Carb Problems Everything you mentioned is Brand new. Edelbrock suggested the 73x42 metering rods. However, I have tried all of their " kits". Sprayed all over for vac leak and can't find anything.... Posted via Mobile Device

08-06-2012, 03:49 PM	#5
72hoopti Registered User Join Date: Sep 2009 Location: Redwood City, CA Posts: 24	Re: Carb Problems Well Gary, that won't solve my issue with this carb. Posted via Mobile Device

08-06-2012, 04:28 PM	#7
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,228	Re: Carb Problems Those are good carbs. Check the accel. pump shot. They use a leather cup that can dry out from setting. Is the carb flooding after you shut it off? That carb does not like a lot of fuel pressure. About 4-5 lbs. Have you put heavier springs under the metering rods? You may need to change to a smaller metering rod or a larger jet. That engine probably has quite a bit of cam. It may need a quicker spark advance &/or more timing.

08-06-2012, 07:47 PM	#8
oldblue1968chevy Grandpa in the rustmobile... Join Date: Nov 2008 Location: Spokane WA/Viola TN Posts: 11,422	Re: Carb Problems Whats the condition of the carb? What is the fuel pressure it sucks if its not @ 5-6psi. Are the floats set correctly 5.5 is what eddy recomends i think __________________ John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4

08-07-2012, 11:13 AM	#9
72hoopti Registered User Join Date: Sep 2009 Location: Redwood City, CA Posts: 24	Re: Carb Problems Well, after a long night turning screws, "starting from scratch", the hoopti is running and running without the stumble and hesitation. Timing is all up to specs according to GM performance. Put the advanced springs and weights in distributor and made some difference. My biggest complaint now is there's no guts behind it anymore, with this carb, the truck is a dog! I am going to put a fuel pressure gauge on it... Will get back shortly Posted via Mobile Device

08-07-2012, 04:27 PM	#11
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,228	Re: Carb Problems Make sure the secondary throttles are opening. If the choke is not opening all the way it can be blocking the sec. from opening. Or your linkage may not be opening the throttle all the way.

08-08-2012, 03:53 AM	#12
oldblue1968chevy Grandpa in the rustmobile... Join Date: Nov 2008 Location: Spokane WA/Viola TN Posts: 11,422	Re: Carb Problems I have an eddy..it works...(after it was set and regulated). If I had to do it again Id get a edelbrock fuel pump that puts out the proper psi a fuel regulator is just going to clutter things up. If/When I start driving my truck again I believe Im going to try to find something other than edelbrock (probably a holley) __________________ John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4



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