Cliff's Quadrajet Parts and Rebuild Kits

Quadrajet Problem Solving => Diagnose a Quadrajet carburetor problem => Topic started by: Ponchojoe on July 10, 2020, 07:26:13 AM

Title: 7044262 Cruise Surge after rebuild
Post by: Ponchojoe on July 10, 2020, 07:26:13 AM

Hi Cliff.
I rebuilt my brothers 7044262 a couple of months ago with your kit due to hesitation at take off which was definitely the accel pump and a broken flap spring.  After driving it for a week or two it now has a cruise surge in it we cannot find. This happens around 30 to 40 mph.
The car is a 74 LeMans GT 455 T400 with 3.42s. It has the rv cam in it from previous owner so nothing radical, kinda like an 067 the way it sounds.
Any ideas what to check? We

Title: Re: 7044262 Cruise Surge after rebuild
Post by: mcx on July 13, 2020, 05:37:58 AM

...recheck the float level.
...that casting doesn't have a APT system, so swap in a slightly richer primary rod, retest.
...play around with the power piston springs, retest.

Title: Re: 7044262 Cruise Surge after rebuild
Post by: 77cruiser on July 13, 2020, 05:46:24 AM

Does it have one in the base?

Title: Re: 7044262 Cruise Surge after rebuild
Post by: Kenth on July 13, 2020, 08:30:00 AM

Is it a Rochester made or Carter made 7044262?

Title: Re: 7044262 Cruise Surge after rebuild
Post by: Ponchojoe on July 14, 2020, 08:51:23 AM

Thanks for the insight, The piston was was sticking so I polished it a bit but maybe the bore needs it as well. Are 71 jets appropriate for a 455? I

Title: Re: 7044262 Cruise Surge after rebuild
Post by: Kenth on July 15, 2020, 08:25:48 AM

Carter-made qjets are cast in poorer porous materials than those made by Rochester, and it is common for buns to appear in the most unexpected places, including the hole for the power piston. Therefore, the hole should be inspected and sanded / ground if necessary, not the power piston.
Also, the idle circuit is somewhat leaner in the Carter unit with .036" idle tubes, .055" upper idle air bleeds and .043" idle channel restrictions where Rochester uses .038" idle tubes, .059" upper idle air bleeds and .049" channel restrictions.
The main circuit upper air bleeds in air horn is .047" for Carter and .083" for Rochester.

I have found these units works well with .038" idle tubes, .051" upper idle air bleeds, .055" idle channel restrictions, .070" upper main air bleeds, .073" main jets with #43-#45 primary rods and DA or CE secondary rods. CK sec. rods works fine on std engines.

FWIW

Title: Re: 7044262 Cruise Surge after rebuild
Post by: Ponchojoe on July 16, 2020, 04:40:16 AM

Thanks for the info Kenth. I used triple 000 steel wool to polish the piston. I did find last night that the spring clip that puts tension on the primary rods had moved and was actually hitting the gasket so it would not allow full piston travel downward. I don

Title: Re: 7044262 Cruise Surge after rebuild
Post by: Ponchojoe on July 16, 2020, 04:44:32 AM

Why does this site keep cutting off my replies???

Title: Re: 7044262 Cruise Surge after rebuild
Post by: tayto on July 16, 2020, 05:54:38 AM

try hitting preview before you hit post

Title: Re: 7044262 Cruise Surge after rebuild
Post by: Ponchojoe on July 20, 2020, 12:56:32 PM

Pulled it apart, reset float level, changed primary piston spring to a heavier version and added 72 jets. It could still use an idle air mod but it runs well now.
Thanks