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#1
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Lost a rod nut
This is on my 62 Mercury 260 V8, but figure the question would apply to any make.
Im rebuilding the 260 for my Mercury. On cleaning the pistons last night I found one of the nuts had fallen off the bolt. I must not have threaded it on enough when I tore the engine down, or my kid needed it for one of his projects. Anyway it appears to be a 5/16 24tpi nut. Common enough, but worried about throwing balance off just using a random grade 8 nut. Not to mention since there is no washers on these nuts, I dont know if a rod nut is something unique? Anyway correct me someone if Im overthinking it. Searching the internet I have had no luck so far finding a single rod nut. Id hate to buy a whole set of bolts/ nuts for one single nut. Any ideas? Thanks.
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71' GTO -original 400/4-speed/3.23 posi 13.95 @ 102.1 on street tires @ 4055lbs. 63 LeMans- 69 400 w/ original transaxle. 2.69 gears. |
#2
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As long as it's a grade 8 nut of the same thread pitch that's all you need to be concerned about.
Of more concern is the rod bolts. If this round of assembly is the 5th time there getting torqued up and the motor will be buzzedup above 5k then the bolts should get replaced and the Rods resized as needed.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#3
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Keep trying to find/buy a single Rod bolt-nut combo for the nut. The Thread class need be 2B or 3B, not 1B. I would guess 3B.
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The Following User Says Thank You to Half-Inch Stud For This Useful Post: | ||
#4
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I may have a good used Pontiac stock rod nut laying around or on a stock rod, H,Stud has a valad concern on class of threads
I wouldnt worry to much about balance on a near stock build stock balance tolerances are usually quite wide
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A man who falls for everything stands for nothing. |
#5
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His 260 cid Ford engine uses 5/16” rod bolts, so the 3/8” nuts from a Pontiac are of no help.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#6
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Time to find a wrecking yard that will allow you to disassemble one of their core engines, and get a nut. Or maybe a engine machine shop that has some stock SBF rods hanging around.
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#7
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Grainger
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Johnny US Army Retired 1978 T/A 463 Pontiac, KRE 74cc 292CFM D-ports, Lunati VooDoo, V-max lifters, TKII, ATM 850 E85 carb, TCI TH-350 race tranny, 3600 converter 3.73 12 bolt 11.63@116.68mph 1981 T/A 4-speed 406 Pontiac, Merrick ported 6X heads, Comp 270S cam, Crosswind intake 750 Street Demon, 3.42 30 spline Eaton posi street car. 1980 Formula 350 Pontiac back burner project 1972 LeMans 350 Pontiac |
#8
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Does ARP sell single nuts?
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#9
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Well, after mucho searching, I did find this -
https://www.summitracing.com/parts/a...-8602#overview The rods were resized when the engine had its only rebuild back around 1980. The bolts/nuts are black , similar to ARP. They don’t look factory. But nothing in that link says they’re “rod nuts”.
__________________
71' GTO -original 400/4-speed/3.23 posi 13.95 @ 102.1 on street tires @ 4055lbs. 63 LeMans- 69 400 w/ original transaxle. 2.69 gears. |
The Following User Says Thank You to 67drake For This Useful Post: | ||
#10
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I'd just get another nut, torque it down and call it good. Unless you're winding the thing up to 7000rpm+ I'd says it's fine.
__________________
"Those poor souls have made the fatal mistake of surrounding us. Now we can fire in any direction" 1970 Trans Am RAIII 4 speed 1971 Trans Am 5.3 LM7 1977 Trans Am W72 Y82 1987 Grand National |
#11
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I doubt this thing will ever be above 4500, maybe 5000. Just a stock rebuild on an old cruiser with 3.00 gears and a two speed automatic.
__________________
71' GTO -original 400/4-speed/3.23 posi 13.95 @ 102.1 on street tires @ 4055lbs. 63 LeMans- 69 400 w/ original transaxle. 2.69 gears. |
#12
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If concerned about weight, remove another nut and match the weight
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Will Rivera '69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears 66 Lemans, 455, KRE D-Ports, TH350, 12 bolt 3.90 gears '64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears (Traded) '69 LeMans Vert, 350, #47 heads: Non-running project |
#13
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Quote:
Don't overthink it. Put another nut on it, torque it like you would any other rod bolts, and run it.
__________________
"Those poor souls have made the fatal mistake of surrounding us. Now we can fire in any direction" 1970 Trans Am RAIII 4 speed 1971 Trans Am 5.3 LM7 1977 Trans Am W72 Y82 1987 Grand National |
The Following User Says Thank You to 72projectbird For This Useful Post: | ||
#14
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Tensile strength on those ARP nuts you found are rod bolt/nut territory. Two most common are 180k & 220k.
Places like Crower sell individual rod nuts. If you're worried about balance, replace them all with the same type so they at least match. You may not have end to end rod 'balance' but it won't negatively impact rotating assembly balance. .
__________________
. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#15
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Don’t even waste one heart beats worth of time over any concern about balance!!
Some high end race motor builders intensional over balance or under balance a motor by a easy 3 times more then what a nut that size weighs! I can’t believe some people are even bothering to mention anything about it.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#16
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Thanks guys. I found a seller selling individual ARP nuts, without paying Summits $11 handling charge,so I went with that. I won’t worry about the balance, it was just a question. Better safe than having an “Oh Sh*t” later.
__________________
71' GTO -original 400/4-speed/3.23 posi 13.95 @ 102.1 on street tires @ 4055lbs. 63 LeMans- 69 400 w/ original transaxle. 2.69 gears. |
The Following User Says Thank You to 67drake For This Useful Post: | ||
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