Inliners International Forums General Discussion Engines Smogged '77 250 I6 - Retrofit to pre-smog specs?

Yeah, like Integrated-J, my Camaro did not come with a cat. The previous owner removed it. But I still have a functioning EGR valve. I might try disconnecting it to see what improvement I get in in fuel economy, since DueceCoupe and Jay recommended it. I plan to swap out to a non-integrated head and 292HD exhaust manifold in my stepwise build plan, at which time I would loose the EFE and EGR anyway as the stock Mono-Jet manifold or Offy manifold do not have provisions for the EGR (and THE Co 292HD 2.5" exhaust or Stovebolt cast headers don't have EFE provisions on them).

I hadn't thought about taking off the hot air tube in the summer time. That makes sense. I think the 3rd gen Nova may have more space under the hood than the 2nd gen Camaro. My Thermac air cleaner lid barely clears under the hood of the Camaro, so a taller air filer won't fit. Part of it is probably due to the dip in the contour of the 2nd gen hood which limits it further. On my old '76 Camaro which had a 305 with a 2GC 2bbl, you had plenty of room to swap out the 2.5" filter for the 350's 3 7/16" air filter and lid with room to spare.

I see DueceCoupe is in CA, so he has an air pump on his. Those of us in the other 49 states didn't have the air pump on ours.

My best results so far is in the HEI. Mine had dried out caked on grease on it, so the advance was really sticky. I rebuilt it and used wheel bearing grease to replenish the top end and the advance worked fantastic. I added a quality cap and rotor to it, along with replacement plugs and wires. Then I switched out the stock springs for the stronger set of springs from an Accel advance kit, and there was a definite seat of the pants improvement and fuel economy, with no knocking. I'm putting an adjustable vacuum advance on it next set at 20 degrees advance, and changing the 6 degree initial advance to 10 degrees next. Then trying the next weaker springs after that if there's no knocking.

Also consider the cooling system too. The previous owner had already swapped out the stock brass and steel radiator for a replacement plastic and aluminum one, which shaves some pounds off. And you can swap out the fixed factory 4-blade fan for the later truck 3-blade clutch fan like Integrated-J did, or take the fan off and wire in an electric fan or two like I did. I may do a comparison between the stock fan and those two options this month, to measure the fuel economy improvement between each.