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Detonation? #1556367 12/30/13 10:23 PM 12/30/13 10:23 PM
Joined: Dec 2008 Posts: 1,285 okla. sam64 OP pro stock
sam64 OP pro stock Joined: Dec 2008 Posts: 1,285 okla.	Is this a sign of detonation?only 2 pistons have this 6&8. Spark plugs look ok,fat if anything.they are off my sr headed 512 low deck running 110 fuel. 7977401-image.jpg (321 downloads)

Re: Detonation? [Re: sam64] #1556368 12/30/13 11:05 PM 12/30/13 11:05 PM
Joined: Jan 2005 Posts: 2,540 Milwaukee WI T TRENDZ master
TRENDZ master T Joined: Jan 2005 Posts: 2,540 Milwaukee WI	Not detonation.... Debris. Something went through the engine. "use it 'till it breaks, replace as needed"

Re: Detonation? [Re: sam64] #1556369 12/30/13 11:07 PM 12/30/13 11:07 PM
Joined: Aug 2003 Posts: 43,228 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,228 Bend,OR USA	Pitting can be the early signs of detonation, pull those two rods and pistons out and look real hard at the rings and ringlands for damamge Which intake and carb are you running? Also which brand and spark plug heat range? Can you add a good close up picture of those two plugs? BTW,if the rod bearings fall out of the rods, no crush left, that is a sure sign of detonation also Last edited by Cab_Burge; 12/30/13 11:09 PM. Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: Detonation? [Re: Cab_Burge] #1556370 12/30/13 11:27 PM 12/30/13 11:27 PM
Joined: Dec 2008 Posts: 1,285 okla. sam64 OP pro stock
sam64 OP pro stock Joined: Dec 2008 Posts: 1,285 okla.	Quote: Pitting can be the early signs of detonation, pull those two rods and pistons out and look real hard at the rings and ringlands for damamge Which intake and carb are you running? Also which brand and spark plug heat range? Can you add a good close up picture of those two plugs? BTW,if the rod bearings fall out of the rods, no crush left, that is a sure sign of detonation also done chunked the plugs,m1 intake w 1050 dom jetted 90 square,timing was 38 deg.the head looks the same on those 2 cylinders.yes the bottom end will come apart later,using the heads on a 499 lowdeck.

Re: Detonation? [Re: sam64] #1556371 12/30/13 11:31 PM 12/30/13 11:31 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Quote: Is this a sign of detonation?only 2 pistons have this 6&8. Spark plugs look ok,fat if anything.they are off my sr headed 512 low deck running 110 fuel. I think that is early signs of detonation... if you look close you can see it gets worse the farther out it goes towards the edge of the piston

Re: Detonation? [Re: MR_P_BODY] #1556372 12/30/13 11:34 PM 12/30/13 11:34 PM
Joined: Dec 2006 Posts: 3,396 Pa Hot 340 master
Hot 340 master Joined: Dec 2006 Posts: 3,396 Pa	Whats the head look like? Was it possibly making contact?

Re: Detonation? [Re: MR_P_BODY] #1556373 12/30/13 11:38 PM 12/30/13 11:38 PM
Joined: Dec 2008 Posts: 1,285 okla. sam64 OP pro stock
sam64 OP pro stock Joined: Dec 2008 Posts: 1,285 okla.	it's right at.040 quench,i guess maybe I don't need that much timing.this was my first real attempt at race motor[not just a flat top 440 w a cam]lol.

Re: Detonation? [Re: sam64] #1556374 12/30/13 11:50 PM 12/30/13 11:50 PM
Joined: Jan 2005 Posts: 2,540 Milwaukee WI T TRENDZ master
TRENDZ master T Joined: Jan 2005 Posts: 2,540 Milwaukee WI	you will need to look, but i'd bet that the pits are actually dents. the heads and pistons will be mirror image patterns. "use it 'till it breaks, replace as needed"

Re: Detonation? [Re: TRENDZ] #1556375 12/30/13 11:57 PM 12/30/13 11:57 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Quote: you will need to look, but i'd bet that the pits are actually dents. the heads and pistons will be mirror image patterns. If this was debris it should have marks on the cyl wall also in that area.... JMO

Re: Detonation? [Re: TRENDZ] #1556376 12/31/13 12:07 AM 12/31/13 12:07 AM
Joined: Dec 2008 Posts: 1,285 okla. sam64 OP pro stock
sam64 OP pro stock Joined: Dec 2008 Posts: 1,285 okla.	Quote: you will need to look, but i'd bet that the pits are actually dents. the heads and pistons will be mirror image patterns. yes pretty much,the head looks the same as the piston but the cylinders don't look bad.it's odd that it's only those 2 cylinders.at least this one made 8 passes,last one ate the cam in 2 passes.

Re: Detonation? [Re: sam64] #1556377 12/31/13 12:12 AM 12/31/13 12:12 AM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Quote: Quote: you will need to look, but i'd bet that the pits are actually dents. the heads and pistons will be mirror image patterns. yes pretty much,the head looks the same as the piston but the cylinders don't look bad.it's odd that it's only those 2 cylinders.at least this one made 8 passes,last one ate the cam in 2 passes. I would expect the head to look similar if its detonation but not the cyl wall

Re: Detonation? [Re: sam64] #1556378 12/31/13 02:08 AM 12/31/13 02:08 AM
Joined: Jun 2004 Posts: 6,780 Alabama Mopar-Al master
Mopar-Al master Joined: Jun 2004 Posts: 6,780 Alabama	For it having only 8 passes, it seems to have a lot of oil and gas residue on that piston. I assume you cleaned them off a bit to? Looks like hot spots detonating.

Re: Detonation? [Re: sam64] #1556379 12/31/13 03:43 AM 12/31/13 03:43 AM
Joined: Mar 2013 Posts: 197 Nor-Cal L loaderpro member
loaderpro member L Joined: Mar 2013 Posts: 197 Nor-Cal	The next time you pull that engine down you need to smooth out ALL the sharp edges from around the valve reliefs and the crown , this will increase airflow and help to reduce detonation. Sharp edges on any race piston is a definate no-no. This is a CP 14-1 piston with the edges gone. 7977858-SR13.75-1CPpiston.jpg (118 downloads)

Re: Detonation? [Re: MR_P_BODY] #1556380 12/31/13 12:32 PM 12/31/13 12:32 PM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	Quote: Quote: Is this a sign of detonation?only 2 pistons have this 6&8. Spark plugs look ok,fat if anything.they are off my sr headed 512 low deck running 110 fuel. I think that is early signs of detonation... if you look close you can see it gets worse the farther out it goes towards the edge of the piston collapsed top ring land, no bearing crush, will tell the tale. Fastest 300

Re: Detonation? [Re: loaderpro] #1556381 12/31/13 11:28 PM 12/31/13 11:28 PM
Joined: Dec 2008 Posts: 1,285 okla. sam64 OP pro stock
sam64 OP pro stock Joined: Dec 2008 Posts: 1,285 okla.	Quote: The next time you pull that engine down you need to smooth out ALL the sharp edges from around the valve reliefs and the crown , this will increase airflow and help to reduce detonation. Sharp edges on any race piston is a definate no-no. This is a CP 14-1 piston with the edges gone. I will look into doing that.and thanks to all that replied.happy new racing year to all!!

Re: Detonation? [Re: sam64] #1556382 01/02/14 12:06 AM 01/02/14 12:06 AM
Joined: Mar 2006 Posts: 9,851 MI, usa dvw master
dvw master Joined: Mar 2006 Posts: 9,851 MI, usa	Remove the ring and look at the ring grooves. In my experience if it's detonating the upper grooves will be pitted as well. Doug

Re: Detonation? [Re: dvw] #1556383 01/03/14 03:44 PM 01/03/14 03:44 PM
Joined: Sep 2009 Posts: 500 MD JACK1440 mopar
JACK1440 mopar Joined: Sep 2009 Posts: 500 MD	We have a simular situation going on also. Pulled the heads to send them out for port work. When I looked a #6 piston I noticed it looked sunk in and also hand the dings so, we pulled her out. When we knocked that piston out we found a broken skirt and the piston was melted and sunk in the center. We had blown a head gasket ealier in the season due to a timing blunder that blew between #4 & #6. My guess is the piston was like that then. Anyways when we pulled a couple rod caps the bearings looked worn also, #6 being the worse and just starting to flake. That was with a 1150 Dom and 100 jets, 38 deg timing, 110 gas. My thinking is to go a step or 2 colder on the plug. Crazy thing is the car ran a 9.95 the last time out. 7983370-piston.jpg (112 downloads)

Re: Detonation? [Re: JACK1440] #1556384 01/04/14 04:07 AM 01/04/14 04:07 AM
Joined: Apr 2007 Posts: 1,165 Central Ohio, USA Bigbeep super stock
Bigbeep super stock Joined: Apr 2007 Posts: 1,165 Central Ohio, USA	To the OP. What compression ratio were you running? Remember, the more squeeze means less timing usually. I made this mistake when I built my first 440 with any squeeze. Tuned it just like it was an 11.5 to 1 engine and beat the bearings out, wrist pins, and busted mains on 2 and 4. The crack on main #2 went from the bearing saddle about 3" into cylinders 1 and 3. Thankfully it was a filled block and it slowed down before something real bad happened. Beep 7984303-IMG_0413.JPG (101 downloads)

Re: Detonation? [Re: Bigbeep] #1556385 01/04/14 11:56 AM 01/04/14 11:56 AM
Joined: Sep 2009 Posts: 500 MD JACK1440 mopar
JACK1440 mopar Joined: Sep 2009 Posts: 500 MD	ouch. we are in the 12.5-1 range on compression

Re: Detonation? [Re: JACK1440] #1556386 01/04/14 04:23 PM 01/04/14 04:23 PM
Joined: Jun 2006 Posts: 5,163 CT GTX MATT master
GTX MATT master Joined: Jun 2006 Posts: 5,163 CT	Detonation, 38 degrees is too much timing for closed chambered heads and good quench, it would probably be faster with 34 degrees and not detonate. Now I need to pin those needles, got to feel that heat Hear my motor screamin while I'm tearin up the street

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