500ci plus stroker, 550 hp 440 block

[Spyder]

Far better grinds tailored for the larger diameter Mopar lifter , Comp will cost you 30+ HP in Mopars
I used a Lot of Engle & Lunati cams , Lunati used to have a lobe selection section so you could tailor you own cam from Proven .904 lifter designs , Comp bought Lunati now unfortunately so I am not sure what is available from them anymore .
I used a TF60 /TF57 110*solid grind in a lot of street builds , friggin awesome cam basically a baby roller .

When I contacted them about getting a Lunati grind last winter they told me they still had all the profiles and it was just a (I think) 60 dollar upcharge for custom grind. Maybe 150? I forget exactly, but they said they would still make all of them by request.

 

[Spyder]

the best I ever got from a factory 440-6 was 14 MPG at 55MPH. it drops to 11 MPG at 65 MPH. Back in the 1980s, I made several road trips between northern & southern california (800 miles) and made an effort to get the best mileage I could. no matter what I tried, it took 3 fuel stops each way. but less than 4 tanks full.

I haven't really done enough driving without a bunch of burnouts and hard acceleration to be sure, but every time I do the math on mine it shows 9-10mpg. I've got a handful of things I want to do in the next month or two and then hope to drive it a whole bunch this summer and fall.

 

[SomeCarGuy]

It has been said that peak cylinder pressure should occur at around 15° past TDC for optimum power. This number depends on rod/stroke ratio. The more efficient burn chamber and longer rod ratio both allow less timing. Less timing means less "negative work" against the piston on the compression stroke, resulting on more power.
There is 180° between TDC and BDC.
Look where the piston is at at 40° BDC, where the older slower burn headed motors needed to run for peak power and the more modern chamber only requiring 30° or so timing.
A tighter quench increases the speed of the "jetted" air/fuel mixture past the spark plug gap, igniting more fuel/air in a streak, requiring less timing also.
If you look at a big block chebbie and big block Mopar cylinder heads, the bb chebbies are much superior in flow, but how did the Mopars run anywhere near them? Longer rods and longer intake runners because of Mopars taller decks.
Lots of magazine articles have been done, mostly about chebbies, comparing 5.565", 5.7", and 6" rods. In an "apples" to "apples" test, the longer rod always makes more H.P.
Look for articles by Jim McFarland and David Vizard, they are among the best, most meticulous writers ever
On my dyno, I have done several such tests of rod ratios, but I am even more "anal" than most. I.E: same brand custom pistons of the same weight, and small end rod weight to eliminate as many variables as possible.
I always run the longest rod that I can stuff in my competition engines.
According to Jane Combs, an ex engineer at Ross Pistons, I was the first to run the top of the oil ring above the top of the pin hole to allow for a longer rod.
She also claimed that I was the first she heard of to mill the top quench area of Mopar open chamber heads to the same depth and order step cut pistons to maximize (tighten) the quench so I could run about .025" to the head at street compression ratios.
These tests were run my dyno, my experiences, and my opinions, your results may vary depending upon how your tests are conducted.
You may notice that UEM has been marketing Mopar "step type" pistons a few years after I did it. I don't believe they copied my idea, I believe intelligent minds, when left to their own devices usually come up with similar or the same conclusions to the same problems.
"TO EACH HIS OWN THING!"
TIMINATOR

Except that’s not the case. Long rods certainly don’t “always make more hp.”



These guys kept things the same as possible and discuss the theories people have had over the years.

Ends up it’s just not something to be concerned with. You added other things to the equation, so yes, if you run a longer rod than before, plus do work on quench, etc, you might be seeing it as the rods being a difference maker when you did other changes.

 

[TIMINATOR]

Only one change at a time, and dyno it. That's the only way to test. The scientific method!
I was just mentioning other things that I have tried. As far as engine masters goes, there are not any two identical engines in there enough to draw any conclusions from.
Different clearances, oils, oil wright's, additives, types of hones, deck clearances, polished or coated chambers, pistons' deck clearances, rotating and reciprocating weights, ignition, carb tuning, manifold and head mods, ring gaps, types, ring loading, valve seat angles, width, windage issues, port shapes and finishes, cylinder to crank centering/offset (very popular with 2 stroke engines), piston pin offset, port flow, tumble, and swirl, valve front and back cuts, valvetrain and valve weights, valvetrain rigidity, cylinder wall ridgity, blocks iron alloy composition, spring pressure, type of spring and material, oil pump volume, flowed oiling system, head temp, intake temp, spark plug gap, type of gap, protrusion, spark shrouding, spark duration, flame propagation, valve shrouding, cam lift, duration, ramp shapes and rates, type of cam, type of lifters, type and size of headers, same with collectors, fastener torque, deck plate hone types, and more, but my fingers are tired....
Bottom line, you can't draw any conclusions on any of these, and more variables, unless only one change is done at the same time to the same engine, by the same person. Period.
TIMINATOR

 

[Xcudame]

Funny that Diamond pistons makes a 383 piston to run a stock 440 rod with a stock 383 crankshaft. Don't think they'd bother if there wasn't some advantage to a longer rod.

https://www.diamondracing.net/shop/pistons/bb-mopar-383-piston-kit-4-280-in-bore-1-516-in-ch-3-00-cc-std-pin/

 

[TIMINATOR]

Much shorter skirt. Prolly 150 gms. lighter