The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 250 runs rough with air filter installed?

83gmc4x4 · 01-22-2012, 04:39 AM

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

01-22-2012, 04:39 AM	#1
83gmc4x4 Registered User Join Date: Jun 2010 Location: Parsons, KS Posts: 36	250 runs rough with air filter installed? 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