In article <MrFvf.1039$5g1.800@fe02.lga>, Carl <cpncopper@yahoo.com>
wrote:
> keller428@hotmail.com wrote:
> > 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.
> >
> question: when the time comes (hopefully this spring) would it be worth
> my while (advisable?) to use a lead substitute even though i had
> hardened seats added? the economics of it is the thing will be barely
> driven so the amount of lead substitute would be minimal (i havent
> checked prices on the stuff yet) but what sort of mess might i have
> leaving the tank full of unleaded/octane booster/lead substitute over a
> period of time?
> i'm not a chemist but i personally am thinking *yuck*
> someone
"Someone"? Izzat all I am? Just a someone? <boohoo and sniff sniff>
> asked about deck height, etc. i dont have those numbers but the
> piston box i bought said 10.25:1. i might have thought that was the
> stock compression by mistake but i'm not going to squabble about .4
> points of compression. it doesnt seem significant but i'm sure i'll be
> corrected :)
It's not significant as far as your build goes, just a matter of
clarification in case anyone reading this wants to know the exact
number per the factory. In any case, the piston type has little to do
with the actual deck height of *your* engine. The subject of quench
distance has been brought up because of your concern over running on
pump gas. A dialed-in quench will increase efficiency (more power) and
thusly inhibit detonation. There is no way of knowing if you'll need
additives until the engine is running and properly tuned.
> is race gas leaded? in all my years of racing off road on various 2
> strokers i never did run race gas like some of the others.
There are high octane versions of both leaded and unleaded around.
Again, understand that the idea of knowing what your deck height is
fairly important.
CobraJet
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