Re: Race engine-marks on cylinder walls
[Re: Pacnorthcuda]
#3017061
02/20/22 11:30 AM
02/20/22 11:30 AM
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Joined: Feb 2005
Posts: 20,174 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,174
PA.
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Nothing new there. I had a .030 (360) 408 combo with Diamond pistons that on its third rebuild the bores were so bad I wore out two sets of stones somewhat cleaning it up then hit it with my dingle berry hone. I saw some of the strangest marks in those bores Iv’e ever seen. That engine ran 9.73@135mph at 2880 pounds in my Duster and 10.10@3200 pounds in my sons car.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: Race engine-marks on cylinder walls
[Re: pittsburghracer]
#3017068
02/20/22 11:55 AM
02/20/22 11:55 AM
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Joined: Jan 2003
Posts: 9,997 Frostbitefalls MN (Rocky&Bullw...
gregsdart
master
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master
Joined: Jan 2003
Posts: 9,997
Frostbitefalls MN (Rocky&Bullw...
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My first thought was, would Line 2Line skirt coatings help eliminate this? L2L coatings are applied about . 003 too fat, and they wear in as the motor is run through a set of warmups, then increasing loads at running temp, increasing rpm and load in steps. This wears in the coating to exactly fit at full temp. I used it to cover a gap in a rehoned block, 4.5043 size, reusing 4.500 pistons. Over 900 hp out of that 550 inch 440-1 head motor. I am sold on it, seeing great results. Cost $300 plus the ride to L2L.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: Race engine-marks on cylinder walls
[Re: B1MAXX]
#3017087
02/20/22 12:56 PM
02/20/22 12:56 PM
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Joined: Dec 2005
Posts: 11,564 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,564
Fulton County, PA
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I don't know how many times I freshened my stuff. Every winter. Polish the crank, berry-ball the cylinders, rings and bearings.
No idea how big the bores were. Never measured it after the initial build. Never saw marks like that. I did have it Hardblok'd to the bottom of the water pump holes. Maybe that helped.
Last edited by CMcAllister; 02/20/22 12:57 PM.
If the results don't match the theory, change the theory.
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Re: Race engine-marks on cylinder walls
[Re: B1MAXX]
#3017092
02/20/22 01:08 PM
02/20/22 01:08 PM
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Joined: Feb 2005
Posts: 20,174 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,174
PA.
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Nothing new there. I had a .030 (360) 408 combo with Diamond pistons that on its third rebuild the bores were so bad I wore out two sets of stones somewhat cleaning it up then hit it with my dingle berry hone. I saw some of the strangest marks in those bores Iv’e ever seen. That engine ran 9.73@135mph at 2880 pounds in my Duster and 10.10@3200 pounds in my sons car.
The only difference here is that these are cast pistons, should be around .001. No more than .002 max. What happens is the skirts collapse. Run a mic down the skirt if it doesn't keep getting wider, the skirts are collapsed. If it keeps getting smaller, a cracked skirt is in its future.These pistons have the oil supplied to the rings through a large window behind the oil ring. The silvolite line is a stock replacement piston like 80 bucks for a complete set. Or just get a set of forged pistons, mic the bores and hone the block as needed. These dog gone blocks are getting harder to find every year and some are scraped for silly issues. It’s not a spaceship going to the moon so don’t sweat the small stuff.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: Race engine-marks on cylinder walls
[Re: Clanton]
#3017138
02/20/22 02:38 PM
02/20/22 02:38 PM
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Joined: Aug 2003
Posts: 43,174 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,174
Bend,OR USA
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A ball hone will still leave the low spots Usually not That was one of the reasons I quit using them I bought and use a Lisle mechanic hone that will straighten out the cylinders with enough work as already mentioned above Those handheld drill motor driven hones take forever to remove material A little better than nothing though
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Race engine-marks on cylinder walls
[Re: Lon207]
#3017143
02/20/22 03:06 PM
02/20/22 03:06 PM
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Joined: Jan 2003
Posts: 8,180 Detroit, MI
CokeBottleKid
master
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master
Joined: Jan 2003
Posts: 8,180
Detroit, MI
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Whats your P2W? Also what was the combo? Boosted? Nitrous? The marks at the top remind me of a 302 I took apart a year or so ago, foxbody motor (forged pistons stock) guy was running boost with probably too much timing. Bent the top ring lands down on 4 cylinders, rings then dug grooves in the bores near the top of the bores around the peak pressure location. They were like .005" deep.
Last edited by CokeBottleKid; 02/20/22 03:11 PM.
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Re: Race engine-marks on cylinder walls
[Re: Lon207]
#3017154
02/20/22 04:20 PM
02/20/22 04:20 PM
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Joined: Jun 2008
Posts: 3,916 usa
lewtot184
master
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master
Joined: Jun 2008
Posts: 3,916
usa
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Thanks for all the input. Correction on the pistons, these are the KB107 Hypereutectic ones, not silvolite.
I measured the marks and they appear to be about .002" deep. It was bored at .040 over. bores measure .045 now, the marks measure .046~.047
It did sit for several years, hence the couple of cylinders show some pitting near the top of the bore.
thanks again for the replies that's probably going to put piston to wall about .007". that's pretty loose for those pistions. my KB literature gives unlimited circle track clearance between .0025"-.0045" for a 4.10" bore. Top ring end gap should be .032+".
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Re: Race engine-marks on cylinder walls
[Re: lewtot184]
#3017159
02/20/22 05:38 PM
02/20/22 05:38 PM
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Joined: Feb 2005
Posts: 20,174 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,174
PA.
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Thanks for all the input. Correction on the pistons, these are the KB107 Hypereutectic ones, not silvolite.
I measured the marks and they appear to be about .002" deep. It was bored at .040 over. bores measure .045 now, the marks measure .046~.047
It did sit for several years, hence the couple of cylinders show some pitting near the top of the bore.
thanks again for the replies that's probably going to put piston to wall about .007". that's pretty loose for those pistions. my KB literature gives unlimited circle track clearance between .0025"-.0045" for a 4.10" bore. Top ring end gap should be .032+". Forged piston time and send it.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: Race engine-marks on cylinder walls
[Re: pittsburghracer]
#3017166
02/20/22 06:20 PM
02/20/22 06:20 PM
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Joined: Aug 2011
Posts: 2,860 Pattison Texas
CSK
master
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master
Joined: Aug 2011
Posts: 2,860
Pattison Texas
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so 300 laps, in dirt, that will do it , was it running Methanol ?
Last edited by csk; 02/20/22 09:10 PM.
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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