Re: Cam Choice in a 396
Not surprised at all that your stock 396/3225hp pings like hell on 93,that motor has very short camtiming resulting hi cyl pressures resulting in ping.
I had that same exact crane cam in my 396 for many yrs prior installed straight up/dot to dot and as Chris suggested it would be a very good inexpesive choice for a good perf cam.
My motor was a bone stock 396/325hp with stock 10;25:1 comp with m20 & 307 geared 12 bolt at the time and that cam alone really woke that motor up a lot.
The stock 396/325hp cam is somewhere like 198/198 deg dur @.05,.398/.398 lift on 114(?) deg lsa & the 396/350hp cam is 214/218 deg dur @.05,.461/.480 lift,114 or 115 deg lsa.
Now compair those stock gm cams to the crane cam (228/228 @.050 .544/.544 112 LSA)and you can see it's definately more agressive but not wild.
That cam had approx 13" vac at idle and when the motor just warm enouhg to come off the choke but not fully up to op temp yet it would idle kink ratty/souonded hot but after motor and oil was up to full op temp it would idle farily decent @850-900rpm in neutral with a slightly coppy but authoritative sound letting you know something was under the hood.
Run approx 18 deg inital/18 deg mech adv in dist in by 2800 with auto trans for 36 total.Also run a vac adv with approx 12-14 deg additional timing thats fully activated at idle for better idle,throttle resp,and fuel economy .
Thats the timing curve and vac adv setup i ran with that crane cam in my 396 and it didnt ping on 93 fuel.
But when i camed it down a smidge in recent rebuild to comp 222/224 deg dur @.05,.525/.525 lift,112 deg lsa with approx 9:8-10:0 comp thats when it would ping under WOT with 36 deg total,but under normal driving part throttle cond even with vac adv it would not ping.
But i guess reducing the dur @.05 by approx 6 deg was just enough to push the motor over the edge ceating a tad more cyl pressur being just enough to ping,i cut it a little to mild on cam. (DANG!!)
Motor runs great with that comp cam and i just run some kemco to allow me to still run the full ign timing curve.
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)
Last edited by SWHEATON; Jan 16th, 08 at 11:12 AM.