7044262 Cruise Surge after rebuild

[Ponchojoe]

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

[mcx]

...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.

[77cruiser]

Does it have one in the base?

[Kenth]

Is it a Rochester made or Carter made 7044262?

[Ponchojoe]

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

[Kenth]

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

[Ponchojoe]

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

[Ponchojoe]

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

[tayto]

try hitting preview before you hit post

[Ponchojoe]

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