[1965tripleblack]

Engine is 327 with 30-30 cam (variant). True 10.85 - 11.15 measured/calculated SCR. Pump high test 93 PON. Vac advance disconnected, initial 10 degrees, centrifugal add 21 degrees, all in at 2500, total 31 degrees.
Detonation at cruise, tip-in. Occurs between 3000 and 5000 RPM.
Idle speed 900 RPM.
Idle vacuum 7 in-hg @ 900 RPM.

[SWHEATON]

10 deg base & 31 total,it must run like a slug wit timing that retarded with perf cam.

Running a trueh 10.8 -11.8 comp with a cam in ran rangE of the old 30-30 cam thats not that hot/doesnt have that much duration to effectively lower cyl pressures much no wonder it detonates its self to death WITH UP TO 11.5 COMP on today's crappy way different fuel that motor was never designed to run on.

You have to remeber todays fuels have been oxygenated/ethenoled/lead removed/and it's significantly lower octane too and you motors 40 yr old tech is not designed to run it,period.

Hek,gm put a sticker in the chevelles wit low to mild perd 396's with 10.25-1 comp to run a minimum of 98 octain ful and your trying to get that setup to run on 93 with higher compression.

Yes,you can run 11.0 on 93 but that with a lot more cam effectively lowering cyl pressures some/a lot of gear like 373-411 reducing load on motor/stall coverter also reducing load some due to more slippage,better perf AL heads & perf pistions perf cam all designed to run more efficiently in todays fuels bnit not your motor with upto 11.5 comp with fairly short camtiming which is a rcp for detonation disaster.

Do not run the motor any more untill you have a lot more octane avail so you can then advanced the base/total timing to where it belong too . I have seen detonation break/crack psitons in the past and id hate for that to happen to your nice little 327 .So be patient and stop running it untill you get the proper higher octane fuel and or proper fuel addititve/Kemco to bost the octane for proper octane with up to 11.5 comp with your fiaqry milde cam with fairly short cam timing/duration.

And its running on like heck when shut down due to it needing considerably more octane and also from the base & total timing being way too retarded for cam being run.

Only vortec heads on sbc require a less timing like 14 deg base & 32-34 total .

The problem is you likely backed timing way off to try to stop dretonation whic jsut makes it run worse,run on when shut down because motor is heating up from retarded timing and too low of an octane fuel for up to 11.5 comp and somewhat short cam timing.

But you can fix this easily ,run Kemoco lead supreme boster that's real lead & boost's octane to over 100 octane dpeneding on mix ratio.

See the Kemco lead supreme website for details,dont bother with the cheepo low quality over the counter store boosters,they cant handle your 11.5 comp on short camtiming setup but the kemco lead supreme 130 real lead booster can.

Try 1qt with 15 gals 93 fuel max to see if that stops the ping,that mix is roughtly 98-99 octane.

NOTE:I SENT YOU AN EMAIL ON THE KEMCO INCLUDING CONTACT INFO TOO.

Then you can run the timing that motor needs like at least 16 deg base timing to run with the 21 deg mech in dist by 2500 for 37 deg total whic is a great timing curve to start with for that motor and cam. 36-38 deg total by 2500 is fine for a perf setup like your aslong as your running enough octane which your not by a long for given setup.

You also need to run the vac adv to ful lintake vac all the time for additonal timig at idle that cam needs for better idle/cooler running motor esp in traffic /better fuel ecnomy/better throttle responce too /. Have the vac adv limin=ted for 12-134 deg max for 50 deg +- when all timing is in.

Now with more octane with the kemco booster,a lot more timing like a min of 16base /37-38 total ,& a vac adv with 12-14 de max additional timing hooked to full int vacuum all the time your motor should run a lot better /feel stronger/idle better/stop running on/run cooler/and also stop detonating too .

But if you dont get timing right ,vac adv hooked to full int vac all the time that's limited to 12-14 deg max,and run a lot more octane too by adding the kemco or use race fuel untill your kemco order comes in you will be chasing your tail trying to bandaid your problems by tuning the motor to make up for not having enough octane in the fuel along whr having to run very retarded timing with even a mild perf cam that needs a lot ore timing then it currently has.

Scott

[Tom Mobley]

10.8 CR? What were you expecting? That CR required 100 octane gas back when and still does.

[SWHEATON]

" A True 10.85 - 11.15 measured/calculated SCR "

No way Jose' On 93 pump fuel with fairly short cam timing with up to 11.5 comp.

Just curious,what's the rest of your motors/cars setup like carb/intake/heads/trans(Stall if auto trans)/gear ratio/intended use mostly street, or street/ strip ,or mostly strip,etc.

Scott

[1965tripleblack]

"NOTE:I SENT YOU AN EMAIL ON THE KEMCO INCLUDING CONTACT INFO TOO."

Scott,

Thanks very much for that. I called today to order 1 quart to see how well it works. If it works as you say, and as advertised, then I'll be one VERY happy camper.

Your post above is chock full of very good advice re:timing. You hit the nail on the head as far as your timing predictions, and they correlate well with what I have found and experienced so far. I will have to use an adjustable vac advance can, and will follow your advice for about 50 degrees cruise timing.


"Just curious,what's the rest of your motors/cars setup like carb/intake/heads/trans(Stall if auto trans)/gear ratio/intended use mostly street, or street/ strip ,or mostly strip,etc."


DRY cranking compression engine "cold" (about 65 degrees F):
1-215---------------2-235
3-215---------------4-230
5-220---------------6-215
7-225---------------8-220

Carb is a Q750 double pumper. Intake is a 1970 DZ. Heads are race ported 461's with 2.02/1.60 Manley valves. Trans is close ratio Muncie 4 speed, 3.70 gears, headers, low restrict exhaust. Intended use street/strip, about about 60% street/40% strip.......no use below about 50 degrees F.

Meanwhile:

I road tested the car with 100LL avgas doped 93 octane, which gives me about 96-97 PON.
No WOT detonation, no tip in detonation.......no run-on.
That's all she needed!
I have the timing at 15 initial, plus 23 all in @ 2500, no vac advance....for now.

[pnugene]

Your engine will have much better street manners if you hook up vacuum advance per Scott's suggestion. Better throttle response and runs cooler too.

[OutCast]

I only run 9.5 compression, and still throw in a jug of Kemco for every $25 worth of premium.

When I hit it with a 150 shot of nitrous, I don't even think about detonation. Kemco is good stuff. Buy a case of it, and I think they ship it for next to free.

[SWHEATON]

Hi Joe,those are some pretty high cranking compression #'s you have there.

Also,keep in mind with only getting 1 qt kemco to try it with 14-15 gals " MAX " 93 fuel which should get you approx 98 octane or so.

But i know from exp with using kemco in my motor and other motors i work on that it will work in your case,just needs the correct 93 fuel to kemco mix.

If it still pings any with 1qt to 14-15 gals 93 fuel then try a little stronger mix next time arround thats approx 100 octane but it still a lot cheaper then running /mixing race or aviation fuel too.

My motor is bascially a stock 396 woith .030 bore to 402 3 forged slugs,has approx 9.8-10.0 comp ,cam is mild perf hyd flat tappet with with 222/226 deg dur @.05,.525/.525 gross lift,112 deg LSA.

This cam is a lot hotter then the stock 396/325hp cam is & is still a fair amount hotter then the 396/350hp cam too but idle's decent/mostly smooth but authoritative sounding letting you know it has a perf cam in it when warmed up with approx 14-14.5 " vacuum @ 950-1k rpm idle.

750cfm tweaked q-jet on stock semi hi rise intake and extrude honed ex manifolds with flowmaster out the back thru stock tials & stock chrome tips. 2.5" pipes fron to back.

Heads have mild pocket porting and manley raceflow undercut swirl polished valves.

I would like to run headers to take full adv of cam/pocket porting/better flowing valves but then i get away from the originality of the this #'s car i have owned for 31 yrs.

I approximate pwr/trq in my motor thats now a 402 post .030 bore without headers @ 360-370hp/425-430lbs trq and with headers approx 375-390hp/440-460lbs trq.

Also runnng 3.31 gear in 12 bolt posi ,26" tires,& M20 muncie .

Timng,running 20 deg base + 18 deg mech in dist all i by approx 2500 for 38 total along with vac adv for 51-52 deg at cruise.

Use 1qt kemco with 17-18 gals 93 fuel for approx 97 octane fuel to tame ping at WOT only & doesn't ping at normal cruise or even when accelorating some at cruise,it only pings @ WOT mostly on hot day without any Kemco & with kemco all is ok/no ping.

The motor runs a lot stronger in this trim then it ever did in stock 396/325hp trim.

Scott

[SWHEATON]

John,real nice run,motor sounds strong running nice and clean up trough to top end rpm.

Whats rpm at finish line,6,500ish + - a little or am i way off?

Scott

[yellow heap]

With those cranking psi numbers you would barely get by with ALUM heads and thats only if you build the motor for it- with iron heads and pump gas
My 225 psi Al headed 383 only barely works on premium with a ARCTIC cooling system,oil cooler,tight gear spread,careful attention to spark timing/Air fuel ratio/outside temp,a tight quench clearance with modern chamber, tuning for the seasons,and a very alert driver