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#1
03-21-2001, 03:39 PM
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Tried my 412 ci pontiac with the NOS at 150hp yesterday,ran great but upon plug inspection all 8 had signs of detonation...
Motor has MSD 6al system,sep. fuel system for NOS with 110 oct.fuel and timing total is 36 degrees with 4 degrees backed out using mSD retard box..I'm currently using Autolite #25's and NOS said to drop in heat range 4 more sizes when I step it up to 250hp... Has 780 vac. secondary holley,w/ perf. RPM manifold.motor is real 9.2 to 1 compression. Heads are 6X with heat X overs filled,Ross pistons Eagle rods,Ultra dyne cam with 112 lobe center at; intake at .050 = 243 w/518 lift w/ 1.5 rockers,and exhaust is ; 251 w/ 530 lift...Installed at 103.5 What would the plugs part # be for NGK's or Autolites 4 steps colder with a non- extended tip be... http://photo.starblvd.net/zanko20 Thanks for all replies,KS - out..
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https://www.flickr.com/photos/197745168@N07/ "There's nothing more unsatisfying than watching an electric car go down the dragstrip." |
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#2
03-21-2001, 03:39 PM
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Tried my 412 ci pontiac with the NOS at 150hp yesterday,ran great but upon plug inspection all 8 had signs of detonation...
Motor has MSD 6al system,sep. fuel system for NOS with 110 oct.fuel and timing total is 36 degrees with 4 degrees backed out using mSD retard box..I'm currently using Autolite #25's and NOS said to drop in heat range 4 more sizes when I step it up to 250hp... Has 780 vac. secondary holley,w/ perf. RPM manifold.motor is real 9.2 to 1 compression. Heads are 6X with heat X overs filled,Ross pistons Eagle rods,Ultra dyne cam with 112 lobe center at; intake at .050 = 243 w/518 lift w/ 1.5 rockers,and exhaust is ; 251 w/ 530 lift...Installed at 103.5 What would the plugs part # be for NGK's or Autolites 4 steps colder with a non- extended tip be... http://photo.starblvd.net/zanko20 Thanks for all replies,KS - out..
__________________
https://www.flickr.com/photos/197745168@N07/ "There's nothing more unsatisfying than watching an electric car go down the dragstrip." |
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#3
03-21-2001, 09:11 PM
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NGK's, drop down two sizes from stock, close the gap to .032/.035. Take 6 degress out (2 for every 50hp), Then advance while reading plugs. Also, if the car doesn't pick up ET with a timing advance, put it back, safer is better.. Install 1.65 rockers. What's your fuel pressure (In high gear) and do you have a return system? Watch your plugs "real close" with that manifold as it is not a true 360 type and lean cylinders could result. Get rid of the Vacuum sec carb (or make sure it's modified to hit super quick) as it could react slow in the secondaries and cause a lean condition in the rear cylinders. I have also found that the back of the carb jets need fatten'd up to get equal burn rates on all the plugs in the higher HP levels of NOS. Hope this helps, Later
------------------ NOS is like American Express.....You don't leave home without it. http://www.angelfire.com/fl4/pontiacdude428 |
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#4
03-22-2001, 12:22 AM
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Thanks Dude,
I removed and inspected all 8 plugs this time and # 6 was nipped... I got some UR-5's to run W/O NOS, and will try some UR-55,s next NOS pass... I do run a return line on the main fuel system,but not on the NOS fuel system,it is located in the stock (old) battery location.. And both are rock steady at 61/2 psi all threw the pass... I agree with you that the manifold may be a problem,most of my driving is street no NOS,what other manifold do you recomend??? Thanks,KS - out. http://photo.starblvd.net/zanko20 [This message has been edited by KS circutguy (edited 03-21-2001).]
__________________
https://www.flickr.com/photos/197745168@N07/ "There's nothing more unsatisfying than watching an electric car go down the dragstrip." |
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#5
03-22-2001, 11:45 PM
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how about BOsh PLatinum plugs and NOS are they ok ? oh and anybody ever tried hooking one of those knock sensor things up on a pontiac maybe it would help you tune something like this with out hurting the motor.
[This message has been edited by 77TA (edited 03-22-2001).] |
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#6
03-23-2001, 01:34 AM
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I cannot stand any Bosh product,and I think platinum plugs are a waste of extra money.
I change plugs tooooooo often even if they were worth it. Although they are standard in many new cars,for my performance, conventional motors I only run standard type plugs,Autolite,AC,or V-power NGK's... In tuning a NOS system,it is not unusual to nip (fry the end off) of afew plugs till ya get it right... That is why you should ALWAYS pull all 8 plugs after a pass,as an MSD will still fire a plug with no electrode.. And if the car makes another pass like that its big time trouble! My main problem was 2 fold >too much timing. >wrong secondary spring (was too stiff). Hope this answers yer ?? And thanks DUDE,you called the secondary leanout right on the money.. [img]/infopop/emoticons/icon_biggrin.gif[/img] KS - out... http://photo.starblvd.net/zanko20
__________________
https://www.flickr.com/photos/197745168@N07/ "There's nothing more unsatisfying than watching an electric car go down the dragstrip." |
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#7
03-23-2001, 07:40 PM
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NEVER, NEVER run platium plugs with NOS. EVEN the NOS manufactures say no. They can't take the heat.
------------------ NOS is like American Express.....You don't leave home without it. http://www.angelfire.com/fl4/pontiacdude428 |
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#8
03-28-2001, 07:53 PM
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well darn so much for my idea that platinum plugs should last me forever on the motor. I must say though if it gets bad enough to burn up the plugs whats it doing to the rest of the motor !!!
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