250 runs rough with air filter installed?

[83gmc4x4]

I have a 1972 GMC with a 250 I-6. When I first went to look at the truck it ran really rough, but when i removed the air cleaner it ran fine. When i picked the truck up i changed the air filter along with adding HEI and it ran good for a few days but then started running rough again. Wouldnt idle with out feathering the gas, back firing through the carb and such. I took the air cleaner off again and it runs fine. Airfilter is still clean. I see that there is a small valve located in the air cleaner assembly. I beleive that it may be shutting and starving the motor of air? Is there any reason i shouldn't remove the valve and plug the vacuum line? Or change to an open element air cleaner?

Sorry for the long post.

Thanks
JR

[BCOWANWHEELS]

I cut off the horn on the air filter on my i-6 and plugged the line. Also make sure of your fuel pressure at carb,4-6 psi, double check timming.

[83gmc4x4]

Much appreciated! Thanks!

[yuccales]

Might want to remove air cleaner, then grab the carb and give it a shake. If it feels loose, check the two mounting nuts and check the two screws that hold the base to the carb body. I'm sure more good ideas are on the way! Good luck to ya'.

[83gmc4x4]

I'll give that a shot also!
Thanks

[Achevytruck]

when i was really young that older one ton truck my dad used to have i do rember he also keep the Air cleaner off the engine