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#1
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Best alternative to the cast 8vr?
I've read many posts about the infamous 8vr cast piston, but rarely do I see any good alternatives listed? Stock rebuild 400 R/A III, looking to hopefully drop the compression slightly(to run well on pump 93). What would guys recommend, that won't break the bank, and possibly lower my compression? Btw, it's a '70 with #12 heads. Thx!!
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2006 GTO/silver, 1969 Judge/Carousel Red, 1970 Judge/Black, 2002 T/A CETA..... |
#2
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#3
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I used a forged flat top on my 70 RA III and then machined a small dish in it. It's zero decked as well. 10.13:1 compression and runs nice on 91 octane.
I have no idea what won't break the bank, it's all expensive to do and do it right anymore. |
#4
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Thanks for the info, guys. It's a stock rebuild, basically a street cruiser. Wasn't looking to spend $700-800 on forged pistons, if I can help it. The L2262F's do seem like a reasonable choice, but compression may be an issue. I assume these 2262's would give me approximately "stock compression", all other things being equal?
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2006 GTO/silver, 1969 Judge/Carousel Red, 1970 Judge/Black, 2002 T/A CETA..... |
#5
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#6
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Ok thanks. We have 93 around here. It's been "ok" for my GTO's so far, just don't want to increase the compression above stock. I know there's a lot of factors that go into it. Like previously mentioned, a L2262f "dished out" would be perfect, but at that point, I might as well look into other forged "-cc" options. 🤔
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2006 GTO/silver, 1969 Judge/Carousel Red, 1970 Judge/Black, 2002 T/A CETA..... |
#7
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There are a few options
What I would do is figure your compression with an online compression calculator using a flat top piston and your planned bore size. Don't forget to include the number of cc's for the valve reliefs as it varies somewhat between piston brand and type. Use a zero deck in the calculator so you know your base point. Then if your compression is still too high then figure what size dish you will need to achieve your compression goal. Then tell your machinist to deck the block to zero deck. https://butlerperformance.com/i-3164...%3Fq%3Dpistons https://butlerperformance.com/i-3015...%3Fq%3Dpistons https://butlerperformance.com/i-2445...%3Fq%3Dpistons https://www.summitracing.com/search/...ac?keyword=400 piston&ar=1&kr=pontiac 400 piston https://www.summitracing.com/parts/d...b/make/pontiac https://www.summitracing.com/parts/d...b/make/pontiac Among others
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Tim Corcoran Last edited by Tim Corcoran; 05-01-2024 at 03:32 PM. |
#8
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If you end up machining a dish you'll need those forged units. $7-800 for a set honestly doesn't sound horrible given the prices these days.
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#9
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Break the bank.
Bust it open. Order up a set of Ross or Icon custom forged pistons made to the compression height, dish volume and bore size you need. I wouldn’t order them until the block is decked (to determine compression height) and after your machinist determines the final bore size. In the end if you buy a heavy press-pin TRW/Sealed Power/Federal Mogul piston and then cut a dish in it you’re pretty much within a hundred or two dollars of a better full-floating pin forged piston that uses a more modern ring pack anyway.
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1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
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#10
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The best true 8VR economical replacements, which are still a dual purpose 8VR, but a better VR design with the same compression height as an L2262F, would be these:
https://uempistons.com/product/6407/...Set-IC9946.030 |
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#11
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Ken '68 GTO - 464 - Ram Air II heads - 236/242 roller - 9.5” TSP converter - Moser 3.55 Truetrac (build thread | walk around) '95 Comp T/A #6 M6 - bone stock (pics) |
#12
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I appreciate all the info. I kinda had the feeling that I'd probably need to spend more $$$ to get the right set-up. Looks like the Icon (+14cc) forged might work out nicely. 1.720" comp height & probably 10:1 or less compression with my #12 heads. Once the machine shop gets me some numbers, I can do some more accurate calculations. 👍
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2006 GTO/silver, 1969 Judge/Carousel Red, 1970 Judge/Black, 2002 T/A CETA..... |
#13
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2006 GTO/silver, 1969 Judge/Carousel Red, 1970 Judge/Black, 2002 T/A CETA..... |
#14
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If you get in that range somewhere it should be fine on pump. I'm using the melling 068 which checks about spot on. A bit small in my opinion but has been happy for years |
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#15
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With a 4.120” to a 4.150” bore and a 3.750” stroke and a 72 Cc head every 4 CCs will change the compression close enough to a 1/4 point in regards to a street motor .
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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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#16
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Agree with you would spend more cutting some pistons' dish.
Another thing you will spend more on is prepping a set of factory rods over replacements. Don't even think twice about using factory rods, you will be sorry in the long run. .
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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 |
#17
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Yes, this day and age, if I were to build an engine like that again, I would order a custom made piston to do the job and be done with it, so long as I don't have to wait 6 months for a piston to show up
Back when I did it, that was over 20 years ago and at that time it was just easier and cheaper to order a forged flat top and just machine the dish I needed to get the engine where it needed to be for what I was doing with it. |
#18
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I remember the 2262s were like $15 each back in the day!
.
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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 |
#19
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Never, for a L2262F!
Even just the pins where close to 10 bucks each.
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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! |
#20
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PAW used to sell them cheap, I still have receipts, last set I got from them were like $150 a set and remember complaining about it. That was in the 80s.
I had a Summit flyer on my garage wall for years, they had great prices when they started up. Headman headers were $49 a set. .
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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 |
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