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#1
02-21-2014, 01:51 PM
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Are these factory pistons?
Wondering if the pistons in my 350 are original factory or not. When I bought the car, I pulled the motor, but I didn't disassemble the rotating assembly. Everything looked good to me so I put it all back together with new gaskets. At the time, I didn't think about it, but now I'm curious.
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1972 Pontiac Lemans 350 Qjet Summit 2800 |
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#2
02-21-2014, 02:02 PM
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Factory 350 pistons did have those same shallow valve reliefs, I'd say original.
Still standard bore 3.875"? Then definitely. |
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#3
02-21-2014, 06:49 PM
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My factory 350 pistons look exactly the same, but not nearly so clean. I've always wondered what's up with the dimple in the middle. I don't recall ever seeing that on a factory 400 piston.
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"...ridge reamer and ring compressor? Do they have tools like that?" |
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#4
02-21-2014, 07:13 PM
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Center point for the lathe?
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Some guys they just give up living And start dying little by little, piece by piece, Some guys come home from work and wash up, And go racin' in the street. Bruce Springsteen - Racing In The Street - 1978 |
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#5
02-21-2014, 07:57 PM
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OK, so they are factory pistons. The reason I asked was, like b-man said, the valve reliefs are really shallow. I have a set of factory 400 pistons and those reliefs are much deeper. So I wasn't sure. Now for another question. I've read in different places that the stock valve reliefs are around 6.6, 6.7cc's. These have to be less than that. Anyone know what they are? Maybe 3 or 4cc's? I'm gonna swap out my 7H1 heads for something with a little more compression. I've been using this compression calculatorhttp://www.wallaceracing.com/cr_test2.php putting in different combustion chamber and head gasket sizes. I wanna make sure all my #'s are correct.
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1972 Pontiac Lemans 350 Qjet Summit 2800 |
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#6
02-21-2014, 09:34 PM
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Quote:
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1967 GTO, 432 (428+.030), 4-bolt mains, factory Nodular crank, scat rods, icon dished pistons, Lunati HR 243/251@.050, .618/.622 lift, Edelbrock 72cc round port heads, 10.5:1, offy 2-4 intake, Edelbrock 650cfm carbs, Super T10 trans (2.64 first), BOP 10 bolt w/ Eaton posi and 3.36 gears |
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#7
02-22-2014, 02:46 PM
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Quote:
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1972 Pontiac Lemans 350 Qjet Summit 2800 |
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#8
02-22-2014, 10:55 PM
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Quote:
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Paul Carter Carter Cryogenics www.cartercryo.com 520-409-7236 Koerner Racing Engines You killed it, We build it! 520-294-5758 64 GTO, under re-construction, 412 CID, also under construction. 87 S-10 Pickup, 321,000 miles 99Monte Carlo, 293,000 miles 86 Bronco, 218,000 miles |
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#9
02-23-2014, 03:49 PM
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The CC for the OE 350 pistons valve reliefs are stated as like 1cc,so yes they are much shallower than the 400/428/455 piston valve reliefs are.
And yes,they look like OE cast 350 pistons to me as well. FYI: Some years of 350 pistons dont have any valve reliefs @ all. HTH Bret P. |
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#10
02-23-2014, 08:11 PM
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Quote:
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1972 Pontiac Lemans 350 Qjet Summit 2800 |
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#11
02-24-2014, 03:12 AM
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Yep,1cc.
TRW/FM L2339F 350 forging specs state such,and those are "stock replacement" forgings that are NHRA legal for stock eliminator,so yeah the OE pistons would also be right @ that same cc for the valve reliefs. Now if one wants to also include the gap above the top ring,there may be another cc or two to be found there if splitting hairs on the chamber cc situation. HTH Bret P. |
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