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Re: Piston Wall Clearance
[Re: RapidRobert]
#110385
08/26/08 01:32 AM
08/26/08 01:32 AM
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Joined: Jan 2003
Posts: 309
Maracaibo,Venezuela
GTMaracucho
OP
super street
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OP
super street
Joined: Jan 2003
Posts: 309
Maracaibo,Venezuela
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Quote:
on their(KB) site they want .004 piston to wall clearance on the top ring for each inch of bore with forged(not hypereutectic) pistons(If I am reading their site correctly,it was a little confusing) which would put you at .016" for a street normally aspirated application(the top ring). At .012 you are tighter than they recommend but I dont know if your rings are butting & causing the problem or not but the more I think about it I would be inclined to think the rear mounted battery & long cables are the culprit. When its warmed up it cranks too slow & this is the issue right? At that point in time could you pull the plugs & see how it cranks & also with the plugs out put a socket & breaker bar(or torque wrench) on the front harmonic dampener bolt & see how hard it is to turn ? or easier yet at that point in time get a jump directly to your starter & dont use your trunk battery & see what it does. It is midnight here & I am going to have to sign off. I will get back to you tomorrow. Post what you find out.
Thanks for your help..... Now I have in my hands somethink to do tomorrow
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Re: Piston Wall Clearance
[Re: GTMaracucho]
#110387
08/26/08 02:48 AM
08/26/08 02:48 AM
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Joined: Feb 2007
Posts: 2,315
MOPAR HEADQUARTERS IN ALDEN NY
hemigod426
top fuel
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top fuel
Joined: Feb 2007
Posts: 2,315
MOPAR HEADQUARTERS IN ALDEN NY
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ptw on kbs is 2-4 thou there designed to be tighter than forged i set up at 4-6 thou ptw, its where the top ringland in piston is machined that it comands twice the end gap for expansion if you dont follow that piston top will break off when under load and up to temp
MOPAR OR NO CAR
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Re: Piston Wall Clearance
[Re: hemigod426]
#110388
08/26/08 08:54 AM
08/26/08 08:54 AM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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You didn't read the original post. He says the pistons are KB FORGED. He says he has 0.007" piston-to-wall clearance, I think that's too much, but it's the maximum in the KB chart for drag racing, 4" piston. He says he has ring gap of 0.012". The chart says 0.004" per inch of bore diameter, that would be 0.016" so the ring gaps are too tight.
R.
Last edited by dogdays; 08/26/08 08:58 AM.
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Re: Piston Wall Clearance
[Re: dogdays]
#110389
08/26/08 10:18 AM
08/26/08 10:18 AM
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Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383
Too Many Posts
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Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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he also said hard turning when hot...could it be a timing issue instead of a clearance issue?
**Photobucket sucks**
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Re: Piston Wall Clearance
[Re: RapidRobert]
#110391
08/26/08 11:13 AM
08/26/08 11:13 AM
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Joined: Feb 2003
Posts: 12,675
Columbia, CT
moper
I Live Here
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I Live Here
Joined: Feb 2003
Posts: 12,675
Columbia, CT
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.007 on the pistons is ok, loose and mabye noisey when started cold, but ok. .012 on the top ring is bad, and technically, leaving the 2nd ring a little bigger than the top will help ring seal. So with a 360 (4.03 when bored .030 over) I'd be setting the top ring at .017 and the 2nd ring at .020. Also, always round up when you get a "point something" (4.03x.004= .01612, or .017). You want to err to the large side on any performance engine.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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Re: Piston Wall Clearance
[Re: RapidRobert]
#110392
08/26/08 01:03 PM
08/26/08 01:03 PM
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Joined: Jan 2003
Posts: 309
Maracaibo,Venezuela
GTMaracucho
OP
super street
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OP
super street
Joined: Jan 2003
Posts: 309
Maracaibo,Venezuela
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Quote:
Quote:
he also said hard turning when hot...could it be a timing issue instead of a clearance issue?
excellent idea! Could it actually be something thatsimple as overadvanced timing  On our stock car we had to engage the starter THEN switch on the ign to get it to crank when things were hot. If he grounds the coil wire & then cranks we'll have the ans to that.
I have 34° and MSD 6 Digital Plus with retard option
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Re: Piston Wall Clearance
[Re: RapidRobert]
#110399
08/26/08 09:55 PM
08/26/08 09:55 PM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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When its hot and cranking slow unhook the MSD box and then crank it to verify if it is an over advanced ign. You have forged pistons and not hypertech pistons so then I agree the top ring gap should be .016 to .017 and the .007 Piston to wall clearence is a bit on the loose side at .007 but it will work. Will most likely be a bit noisey when cold like was said but it will be ok as it's not to tight. If you find the eng is tight and its not the ign then I would think about that .012 top ring gap you have in it. Good luck , Ron
Last edited by 383man; 08/26/08 09:56 PM.
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Re: Piston Wall Clearance
[Re: 383man]
#110400
08/27/08 07:18 PM
08/27/08 07:18 PM
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Joined: Jan 2003
Posts: 309
Maracaibo,Venezuela
GTMaracucho
OP
super street
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OP
super street
Joined: Jan 2003
Posts: 309
Maracaibo,Venezuela
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OK Gents.... Today I talked with my mechanic and he said that the first ring is .017" & second is .022". I started and warm up the engine, then I pull out all spark plugs and turn manually and the engine is very..very hard to turn. Maybe on this week end we pull out the engine and check everything again. I'm thinking go to more clearance on Piston to wall, what about .010"?? 
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