Expensive but effective way to fix detonation??
#1005589
06/03/11 12:49 AM
06/03/11 12:49 AM
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Joined: Nov 2004
Posts: 81 Oklahoma City
Spraygoon
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Oklahoma City
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70 cuda 4 speed 3.54 gear 440 6 pack Mopar 484 cam, Hooker Super Comp headers. I feel the combo I have now is not very detonation tolerant, I have fattened the mixture and run colder plugs and can still not make it take more than 28 degrees total without the plugs looking like porcupines. Currently has 452 heads with KB 237 Silvolite pistons. With the 88 cc chambers and the piston .010 in the hole and a 5 cc valve relief, this gives me 9.7 CR. I am considering using the Source 440 aluminum heads with a closed 80 cc chamber. If I swithched the heads only, my qeunch would be about .050 ( gasket + .010)much better than what I had with the 452"s (is .150 even considered quench??) but boosts CR to about 10.5 which even with the aluminum heads I feel I may be back in the same situation. I have heard aluminimun heads are worth a point in compression but even if thats true my true effective CR would be 9.5, not much less than 9.7. KB makes a forged piston with a 12cc dish which would give me 9.6 CR with the 80 cc chambers and I couldalways cheat with a gasket .010 or so if I wanted, or I coud get the heads milled a bit to get it up some. Not looking to build a drag engine or something for max power, just looking for a nice running engine that I don't have to worry about detonation. Any thoughts. I realize I am looking at about 2k to do this I just can't endure the clatter and the consequences anymore, who knows, I may be able to lean it out a bit and/or run a hotter plug to keep things cleaner. BTW jetting is "stage 2 as per moparts forum guy (very helpful) not sure what the plug is but reccomendation came from the same source as the jetting. SO what do you think??
Paul Reber
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Re: Expensive but effective way to fix detonation??
[Re: 73rrak]
#1005591
06/03/11 01:03 AM
06/03/11 01:03 AM
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Joined: Nov 2004
Posts: 81 Oklahoma City
Spraygoon
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"Stealth Headed" are those aluminum? I hate corn too. Are your heads open or closed chambers? Piston style???
Last edited by Spraygoon; 06/03/11 01:06 AM.
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Re: Expensive but effective way to fix detonation??
[Re: ahy]
#1005593
06/03/11 01:11 AM
06/03/11 01:11 AM
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Joined: Nov 2004
Posts: 81 Oklahoma City
Spraygoon
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I agree, with the closed chamber heads I could check piston to valve clearance and then mill the heads to get 10 or so. According to the CR calculator I would need to heads down to about 77 cc's to get an even 10. Not sure what that means millingwise but might be possible. Sorry I misread the compression height on the 12 cc pistons so I would get 9.833 with the new heads and the 12 cc dish pistons and .050 quench.
Last edited by Spraygoon; 06/03/11 01:25 AM.
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Re: Expensive but effective way to fix detonation??
[Re: Kern Dog]
#1005595
06/03/11 01:31 AM
06/03/11 01:31 AM
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Joined: Nov 2004
Posts: 81 Oklahoma City
Spraygoon
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I'm sure there is a balance somwhere, seems you would make more usable power without the prescence of detonation since the plugs and combustion chambers should stay cleaner (hopefully).
Paul Reber
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Re: Expensive but effective way to fix detonation??
[Re: Spraygoon]
#1005597
06/03/11 02:44 AM
06/03/11 02:44 AM
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Joined: Mar 2007
Posts: 3,285 West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
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Throw a Snow water injection system on it.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's 1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: Expensive but effective way to fix detonation??
[Re: 73rrak]
#1005600
06/03/11 11:58 AM
06/03/11 11:58 AM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
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Cheapest easiest fix it to run 85% corn fuel (E-85) you will make more power and contrary to the guys bashing it on here it help control detonation NOT cause detonation. There are lots of guys running 15 or 16 to one on e-85 with no problem. When I am in OK city visiting my folks I use it in my cars, it is every where down there. I ran it all the time in Tennessee and I wish it was available here. It also carrys more oxygen with it so you can richen up the mix and make more power with no engine mods nessacary so it is way cheaper than tearing you engine apart and replaceing heads and pistons.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Expensive but effective way to fix detonation??
[Re: Kern Dog]
#1005605
06/04/11 02:01 AM
06/04/11 02:01 AM
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Joined: Feb 2007
Posts: 1,025 Las Vegas, NV
dodgeboy11
super stock
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super stock
Joined: Feb 2007
Posts: 1,025
Las Vegas, NV
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Quote:
I have 10.8 to one squeeze in the 493 in the Charger. Edelbrock aluminum heads, MP '509 cam. Performer RPM intake, BG 850 carb and TTI headers. I'm also limited in my advance timing. In my case, its 30-31 degrees. I've been running Champion RC12YC plugs as per the Edelbrock instructions. I have a set of RC9YCs, but I have yet to swap them in. Several members here have suggested colder plugs for my detonation issues. Its been unseasonably cool here lately, so detonation has been limited. I'll swap them in soon though. THEN I'll know if they helped at all. I've wondered for years: Do you make more power with LESS compression and more spark advance ..... OR more compression and LESS advance?
You make more power with more compression and the least amount of timing. But let me explain my response. The less timing you need the more efficient your combustion chamber is. Notice I said "need". If your engine needs less timing because it's detonating, that doesn't make it an efficient chamber. I built a 360 with magnum R/T heads. Pistons come out of the bores between .003" and .005". .039" head gaskets gives me a fairly tight quench. I was running 39 degrees locked timing because it started fine and I didn't have access to a dyno. Well I finally put it on a chassis dyno and started playing with it. Dropped the timing and it made more power. Finally settled on 34 because I didn't think it'd ever like less. Yanked the motor out to freshen and put it on an engine dyno exactly as it came from the car. Finally made best power at 31 degrees. Proper quench and a good chamber make great power. It never even attempted to detonate that I could hear and there were no indicators upon teardown that detonation was an issue. Finally built a 440 for my truck. KB flat tops that come out .007-.009" 452 heads and piston to head clearance average about .110" This engine made best power at 38 degrees total. Well, that's where I stopped anyway. My elevation is high enough that the compression isn't an issue. Running cold NGK plugs (can't think of the number offhand) They will load up when it's cold, but once the engine is up to temperature and cleared out, it runs fine. Ideally, I'd have quench type heads (preferably Victors, Indy or Brodix), pistons that were out .003" and a dyno to sort it all out with. Other than that, all you can do is start at the beginning. Throw in a colder plug. Go extreme if you must and go warmer from there. Keep the timing at 28 degrees and no lower. That'll save your exhaust valves from overheating. If it still detonates, verify your cam timing. Do you have the 108 lobe separation cam or the 112? If the 112, that could be part of your problem. What jets, exactly, are stage 2? Might be worth taking it to a shop that has a chassis dyno and paying them to sort it out. Make sure they have the equipment to test it with O2 and all that.
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Re: Expensive but effective way to fix detonation??
[Re: Spraygoon]
#1005608
06/04/11 07:52 AM
06/04/11 07:52 AM
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Joined: Jan 2006
Posts: 8,162 USA
360view
Moparts resident spammer
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Moparts resident spammer
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It is useful to know which of the eight cylinders is detonating.
The inexpensive 'Fires in Oil' sparkplug extension sleeves can be used to find which cylinder is the most prone to pinging. The extension sleeve has an effect like retarding the ignition timing in that particular cylinder, plus it adds a couple cc's to the combustion chamber, which slightly drops compression ratio.
Another trick to narrow down the source of detonation is to temporarily use 2 cycle synthetic oil. This more expensive 'ashless' oil has a much better 'blending' octane rating that 4 cycle oil, and if the pinging goes away on a test drive with the 2 cycle oil in there, it indicates an oil control problem in one or more cylinders.
Since you are still using a conventional distributor and cap, once you find the troublesome cylinder(s) it is possible to modify the interior posts on the cylinder cap to retard the ignition timing cylinder by cylinder.
As you approach the 'ideal' ignition timing for a cylinder's performance, called the 'Mean Best Torque' or MBT timing, you will find that there is about a six degree span over which torque does not increase or decline... kind of a flat plateau instead of a sharp peak. The timing needs to be on the 'retarded' edge of this plateau, because unlike torque not changing, detonation likelihood increases even faster with ignition advance as you approach the limit.
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