You will need 91 octane (preferably 93) gasoline and a mixture of
octane booster/lead subsitiute-TEL additive or a mixture of 91/93
premium unleaded and 108 race gas, your choice. Anything less can lead
to scuffed cylinder walls (or worse).
I run an (now old) hydraulic Crower 297HDP in my SCJ. .588/.588
236/244 duration @.050" lift.There is no passing it off as a stocker
and has plenty of the "hamburger stand" idle characteristics and BARELY
enough idle for the brakes. As StuK can attest the cam works well BUT
the motor is a little over cammed and I'm giving up much low-end torque
for an extended RPM range. (6500RPM). I recently put the stock exhaust
manifolds and h-pipe on the car. It basically castrated the motor with
this cam. I'll be swapping out cams later this year.
Like CJ recommends, the stock CJ cam is OK but its not quite enough
for the 428. Pick something hotter than a stocker but not quite as
lumpy as mine and you'll be fine. Comp Cams 265DEH is getting good
reviews over on the FE truck forums...but its a trucky cam. The 275DEH
would work well too if you want an aggresive idle. We've put in the
Comp Cams Extreme Energy XE262H on a CJ build that worked very well
with manifolds and stock exhaust system...but not with pump gas. The
next step up (XE 274H) would be helpful in bleeding off some cylinder
pressure at low RPM.
ANY CAMSHAFT WITH OVER .500" LIFT IN ANY FE NEEDS 427 TYPE ADJUSTABLE
ROCKER ARMS. PERIOD. The idiots on the tech lines will tell you that
your good to .530". Don't do it.
Check out this link and the Cam Doctor analysis of an original (albeit
worn) CJ cam.
http://www.428cobrajet.org/id-cam.html
A word about compression ratios. I have TRW L2445's in my motor. (OK,
the secret is out) They're a 10.1:1 PI slug that drops the compression
slightly compared to the CJ pistons. With 72cc chambers, the pistons
about .015" down the hole and a modern composite head gasket my actual
compression ratio is 9.91:1. My motor with its reduced compression and
way too F'n big cam will BARELY run on pump premium with octane
booster. If you mix 5 gallons of leaded 108 RM/2 race fuel its
perfectly happy.
That being said, the ONLY pump gas concoction I can get my car to run
on is a mxture of Castle Products ZOOM octane booster and Real-Lead (or
CD-2) Lead additive with a full tank of 93 premium umleaded. I've tried
them all over the past 17 years.
I could deck the block and bring the pistons to zero deck which should
help with detonation. Swain technology is also local here and I could
have the piston tops, chambers and valve heads coated which may also
help with the problem as well.....untill then I just keep feeding it
the best gas I can get and doctor it accordingly. I'd love to see some
of these 10:1 plus, iron headed FE's run on todays unleaded, oxygenated
pump premium alone. I have yet to see one that gets away with it
without long term problems.
Good luck with it.
-Mike.
