As far as mileage goes have no idea cant keep my foot out of it have not had them very long.
They idle perfect better then my 50s and street manors seem great.I would think its all in the chip I run a extender extreme and turbo bob makes 1 hell of a chip.
What's this 210-214 roller in your sig.? I'd like to know more about it.
Sorry Stu about the off topic...I have 72's with Steve Y's MaxEffort and it idles as smooth as stock (900-1000 RPM). Still get about 20 mpg on the highway when easy on it. It's all in the chip!
HTH, CaptRob
I'm running 72's using the T+ and Extender (extreme) chip and idles, runs very good with around town drivability far better than any other chip I've ran.
I've run 72's with my own chip for over 2 years now. Fast passed Maryland's IM240 smog test once, flunked the second time (found a plug wire burnt in two at the plug, sigh, leaky headers , and I didn't put the cat on, just to see - I'll put it on and should fast pass again). Drive great, around town mileage is about the same or a little worse than redstripes, highway mileage is the same. Got 22 and 24 mpg on two trips from MD to NC a couple of years ago. Got 18 mpg pulling a UHaul from MS to MD last Christmas, once I learned to keep my foot out of it and just drive 55-60 mph. I love 'em, and won't ever have to buy bigger.
It came with the engine when i bought the short block,I think it like the old ATR cam 309 r or something like that.I do have the cam card I could scan for ya if ya want it let me know.
The time in my sig is the best to date broke my axel next time I went out.Have about 1500 miles on the block cam seems to pull real hard in the upper rpm's & idles great.