The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 78 Suburban surging then dies on long grade

burnin oil · 06-26-2020, 12:34 PM

Full time 4x4 that is pretty good. I had a blazer that was stock 400sb, t350, np203 and 3.07s. 8mpg in town and 6mpg interstate. I swapped ina 4spd and np205 along with rebuilding the 400 and got up to 14mpg interstate.

It sounds like your PVC is clogged up or sticking. I would just throw another one on and go from there. Do some research and you can get different PVC valves that open earlier etc. No sense spending $100 on the adjustable deal in my opinion when $20 will buy 3 or 4 PVC valves.

06-26-2020, 12:34 PM	#34
burnin oil Registered User Join Date: Jan 2013 Location: Eastern TN Posts: 1,919	Re: 78 Suburban surging then dies on long grade Full time 4x4 that is pretty good. I had a blazer that was stock 400sb, t350, np203 and 3.07s. 8mpg in town and 6mpg interstate. I swapped ina 4spd and np205 along with rebuilding the 400 and got up to 14mpg interstate. It sounds like your PVC is clogged up or sticking. I would just throw another one on and go from there. Do some research and you can get different PVC valves that open earlier etc. No sense spending $100 on the adjustable deal in my opinion when $20 will buy 3 or 4 PVC valves.