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#1
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Piston skirt
Pics of skirt scuffing ,what are your thoughts?
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76 T/A 455, cnc chamber E heads,OF hyd roller ,yella terra shaft rockers 11.47 119 Last edited by joes455; 03-05-2024 at 10:46 PM. |
#2
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What stroke. How Much use?
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1969 carousel red firebird 455, richmond 5 speed 1964 540 gto 1971 lemans sport convertible 1972 Maverick under slow construction |
#3
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All pistons are almost exactly the same .4.21 stroke not much use less than 500 miles,cylinder has same mirror image mark at very bottom center.the horizontal line is the bottom of cylinder edge at full stroke.Had what sounded like a rod knock with very little throttle.rods looked good.thinking bore to tight at bottom Its a hard block
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76 T/A 455, cnc chamber E heads,OF hyd roller ,yella terra shaft rockers 11.47 119 |
#4
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Mine were way worse, but with a 4.75 crank.
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65 Lemans Street Car - 521, T400, 3.70 9". 10.13 @ 135. 3770 lbs. Drag Week 14, 15, 17 63 Lemans Race Car- 8.81 @ 151, 5.60 @ 123(SOLD) 67 Bonneville ragtop 74 Firebird - 455, e heads, TK0600 in process |
#5
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Was bottom of bore properly deburred at original assembly? Have you measured or just assumed tight bottom?
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1969 carousel red firebird 455, richmond 5 speed 1964 540 gto 1971 lemans sport convertible 1972 Maverick under slow construction |
#6
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Our nitro engine had severe scuffing like your picture; only worse. We solved that with extra piston to wall clearance. The pistons have less mass in the up-and/down direction than they do sideways across the pin bosses. So when the pistons are getting heated, they ovalize from unequal temperatures and get tighter at inboard and outboard edges.
Eric
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"Everybody has a plan until they get punched in the mouth" noted philosopher Mike Tyson Life begins at the end of your comfort zone. The mind, once stretched by a new idea, never returns to its original dimensions. |
#7
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More pics
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76 T/A 455, cnc chamber E heads,OF hyd roller ,yella terra shaft rockers 11.47 119 |
#8
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Here u go
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76 T/A 455, cnc chamber E heads,OF hyd roller ,yella terra shaft rockers 11.47 119 Last edited by joes455; 03-05-2024 at 10:46 PM. |
#9
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Bottoms are debured.measure .0005 to .001. On the tight side I got to recheck specs
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76 T/A 455, cnc chamber E heads,OF hyd roller ,yella terra shaft rockers 11.47 119 |
#10
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On a hard block engine you must run .002 more piston to wall clearance and .002 more ring end gap. Dan told me it is right there in the piston instructions. The engine I am doing right now has .006 clearance vs .004 if not hard blocked.. You will hear the pistons until the engine is warm.
Don,t do the extra ring gap and you might have a real problem. |
#11
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What piston material and what skirt clearance?
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I could explain all this to the girl at the parts store, but she'd probably call the asylum. White '67 LeMans 407/TH350/Ford 3.89... RIP Red '67 LeMans. 407/TH400/Ford 3.25 |
#12
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Checked clearance and bottom of cylinder is too tight adjacent to the scrub marks on the cylinder .0045 I need .006 top of bore is .005 so how can I get what is required
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76 T/A 455, cnc chamber E heads,OF hyd roller ,yella terra shaft rockers 11.47 119 |
#13
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I have a rigid hone with the required stones but don't want barreling
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76 T/A 455, cnc chamber E heads,OF hyd roller ,yella terra shaft rockers 11.47 119 |
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