Okay, so in researching for my future engine build, I am first looking at cams. Well, reading till my eyes glaze over and I begin bleeding out my ears....
I am leaning more toward a custom grind.
Given, the Jeep has 2.73 gearing (and honestly, not looking to do the desired gear change/OD swap anytime soon, if ever), I am wanting to help all I can on the torque range.
A possibility of swapping axles to a 3.31 set is way more probable (even though OD/3.73s/Truetracs F/R would be a dream setup).
With my gearing and tire size (235/75/15), I'm running from 1500 rpms at 50mph to just under 2200 at 70. Focusing on that realistic range at highway speeds, I need a cam that makes max torque in that range. Correct?
So far, few are really designed for that low. Schneider comes in mind. Seems Engle cams falls in favor with the AMC crowd. Their 52-54 comes highly recommended. One guy on ifsja has this cam and loves it. Dyno numbers show a fairly flat torque graph through 3500 rpm, then it drops.
My only concern is the exhaust lift at .501 being above the magic .50 (yeah, barely) that they say you can safely run without heavier springs.
Here are the contenders so far:
Engle 52-54 (custom grind)
Duration:251/261
Lift: .482/.501
Duration @ .050: 208/216
Lobe Centers: 112
RPM range ?-3500
Lunati 260 (stock grind)
Advertised Duration (Int/Exh): 260/260
Duration @ .050 (Int/Exh): 210/210
Gross Valve Lift (Int/Exh): .470/.470
LSA/ICL: 110/106
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 1000-4800
Schneider Cams 252-56H (custom)
Duration 252-256
Intake Duration (.050”): 194
Exhaust Duration (.050”): 204
Intake Valve Lift*: .424"
Exhaust Valve Lift*: .448"
Lobe Separation: 110
RPM Range: 1000-3500
According to babywag, the stock cam has 425/.425 lift. Of course, I know nothing else other than the duration being 196 (found on the interwebs, so may/may not be true).
Question about the stock cam. Why was it so horrid?
I've read the timing was retarded for emissions. Seems the few specs I see aren't bad when compared to the other low end power combos.
Next is what compression ratio I need. That is a whole other session of ear bleeding/glazed eyes.
It seems that CR follows the advertised duration with higher durations meaning higher CR.
So, given I'm looking at lower duration, I'm probably looking 8.5:1?
I understand (I think) the cam determines this for the most part, but can a decent set of pistons bump the CR to a respectable number?
Should I really concern myself with that?
Sorry for all of the noob questions, but I really want to do this right the first time.
Also, if you have real world experience with any of the above cams, chime in.
Thanks!