New life for an old 340 (stock stroke)

RAMM said
No doubt and I can talk about this for quite some time. I have actual numbers concerning this in a real life carb'd muscle car situation. Would you believe 20.9 MPG with a 112 LSA cam (and superior power and mannners) vs. 18.9 MPG with a 110 LSA cam? Yes this was steady state HWY driving and expertly documented. I do not advocate tight LSA's for anything other than a true competition engine . As I also said a few years ago--Cubes DO NOT EAT DURATION--however this is not the thread for that discussion. J.Rob

Oh I can believe it.. .I lucked out 4+ decades ago in my first build and ended up with 114LSA cam with short durations... the Arab oil embargo caused a lot of cam change when fuel more than doubled overnight and you could only get 5-10 gallons per fill up max! That cam with the bigger breathing 351C parts like you have here made a flexible, wide RPM range engine... 19 mpg on the interstate, towed my rally car all over with it, and chased Porsche's and beat factory 440 GTX's time and again LOL. I really enjoy this type of design and these types of outcomes.

RAMM said
You're welcome. Well we can try 35-36 total which is what most small blocks like and do a dyno test and observe a 2-3 tq/hp loss. Then we dial back the timing to 29-30 total and observe the same trend. Then we dial exactly 32 back in and perform the same test and observe power come back like clockwork. Good question though because there is more to it than that . It is subjective though, I found the engine started better @ 32 and sounded better and idled better and was more responsive slightly jazzing the throttle etc.... Also when you roll in on the throttle at the start of the test and watch the TQ and whether it falls or climbs or stays rock steady tells you a lot as well. But that is hard to explain. J.Rob

I can believe it.. the combustion process is dynamically changing with even slight changes... sounds like optimizing around 'driveability' and throttle response.