I am going for power and relative economy from the original '89 roller 305 daily driver.. here is what I have.. TBI edelbrock performer manifold W/ EGR , upgraded to 350 injectors/ pressure reg./chip, I use a TBI spacer and 3x14 K&N cleaner, I have World Product Torquer 305's with 58cc chamber 1.94/1.6 valves, heddman headers W/ y-pipe, HIGH FLOW cat, and 3" flowmaster cat-back, ... IF I USE A BIG CAM, WHAT WILL MY GAS MILEAGE DO ??... I've heard that it will stay the same... and I've heard that it will go down a little, and I've heard that it will drop DRAMATICALLY.. the cam specs are [comp cam XR269HR ... hydrollic roller cam with a lift of .495/.503 at a duration of 218/224 @ .050 Lobe seperation is 112 (for the computer) 108 centerline ] I would appreciate ANY advice, ideas, thoughts,
Is the cam too big for a 305?? Will it KILL my mileage??
THANKS IN ADVANCE

 

Thats a pretty good size cam for a 305. Maybe to much cam. I would comment more but I think Ill leave this one to the gods.

TTT

 

That much cam will certainly require a major chip overhaul. And, if you still have the stock grocery-cart gears, your gas mileage will REALLY suck, and it will be kind of gutless all the time, except on the freeway.

The XR264HR would be a better choice.