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#1
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lightweight wrist pins for trw pistons
I think I have read about people using lighter weight wrist pins in the old TRW forged pistons- The only .980 pins I can find are 3" long, and the stock pins from the TRW's are 3.25. Will the 3" units work? does anyone have a part number for lighter .980 pins that work with the TRW's?
Darcy |
#2
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In the old days lots of people put the Mopar 340 "light weight pins" in the Pontiac cast connecting rods and used higher quality rod bolts.
The pin was positioned on the rod so that it matched a factory Pontiac piston installation with 1/8th less pin on each side. Plenty of support on the piston bosses. The pins were much lighter vs the factory pins 3.25 length at 250 grams and less than the TRW Ram Air pins 200 grams. The MOPAR .9842 pins weighed 140 grams. That weight difference helped with the normal HEAVY Pontiac Piston assy. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#3
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Call Jim Butler. About 25 years ago, I got a set from him that were much lighter than what came with my TRW pistons. I could not believe the weight difference. I ran them for years with stock polished rods and ARP bolts, and the motor spun up faster. Tell him you want his lighter tool pins for TRW pistons.
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#4
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Or get modern, lightweight pistons with lightweight pins.
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#5
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Didn't I read around here awhile back that current TRW pins are lighter than the old 250 gram pins?
I did the Mopar pin deal back when I built my first 400.
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---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
#6
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It's been like that for many years.
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The Following User Says Thank You to PAUL K For This Useful Post: | ||
#7
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This is the street section, so I don't think you're racing it.
If you already have TRW pistons and rings, and they are good, I'd run them. New pistons would cost you $600 + $100 new rings or $80 just for new pins. My TRWs were like new and I already had them. Jim told me to just get new pins and that will make a big difference. He was right. |
#8
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The only pins that were available when my engine was done were heavy Ohio pins. Had them forever. Has not hurt me.
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#9
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The current TRW pins are much lighter than the original pins sold in the 80's. By about 57 grams if I remember right. Easy to spot, the ID of the pin is way larger on the new pins. Not saying they are "light weight" but the newer "standard" pins are much lighter than 30 years ago.
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#10
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57 grams is a nice reduction in weight vs the OLD TRW Pins but the "200 Gram" pins are still heavy vs the 140m gram .984" MOPAR pins or a custom weight pin today.
For a street car, I would just stick with the pins that came with the pistons which should be 200 gram pins. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#11
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I had a conversation with Butler a couple years ago about this he said back in the day they use mopar pin 984 size and honed the rod and piston to 984. Note the mopar pin are 3’’ long ( trw/speedpro ) Pontiac pins are 3.25’’ long. He said it ok to use a 3’’ pin just press the pin evenly in the piston bore. Now the pins he recommend now was Keith black 0980x300k 149 grams ($4.99 ea) from summit.
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The Following User Says Thank You to t money For This Useful Post: | ||
#12
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Great info all- Thanks!
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#13
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A story that I was told when looking into this 3.25 vs 3 inch pins. The late great Pontiac engine builder Jim Taylor would cut lock clip groves in the piston bore of trw/SpeedPro to floated the pin and then cut the pins shorter making them lighter
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#14
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Quote:
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#15
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I have to agree with this. I did at one time buy pins from Butler, but the cost difference pushes the piston/pin assembly into the range of new better pistons.
Shorter pins are usually used with spiral locks, so no, you can't interchange to my knowledge. .
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. 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 |
#16
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Quote:
My we've come a long way. Unless it's a total budget motor that I won't ever rev past 5500 RPM, there's no way I'd bother with stock rods nowadays, and I certainly wouldn't bother having that work done to accommodate those pins.
__________________
---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
#17
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The "old" light weight pins Butler has he and Barney Moravitz in San Antonio had and they were about .981ish and fit the old forged rods they had heat treated as they would also be a hair larger once resized. That supply ran out. I had a set of pistons honed for them but did not like the forged rods so went to cast rods and had both pistons and rods honed for the Mopar pins. IN the stockish 400 in the 81 TA. Kids drove it to high school and I still drive it some.
To do over I'd just get lighter pistons and pins.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#18
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Ya, I've got a set of minty used +.030 455 TRW's, and a set of Eagle push pin h beam rods, and yes this is a low budget build, so I think I'll go with those Keith Black .980 x 3" 150 gram pins-
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