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#41
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Quote:
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. |
#42
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And of course proclaiming you have a 428 vs a 400 just sounds cooler at the local cruise or car show!
Sent from my SM-G965U using Tapatalk
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68 Firebird-- Street/Strip - 400/461 Eagle Forged Bottom End & Ross Flat top pistons. KRE 325 CFM D port, Ultradyne 263/271 @.050, .4267 lift. Crower Solid roller lifters and 1.65 stainless rockers. Quickfuel 1000 on Torker2 intake and 2" open spacer. Hedman 1.75" headers. TH400 w/brake. Ford 9" w/3.80 gears & 28x9 Hoosier pro bracket drag radial. Best ET: 1.35 60ft, 6.29 @ 107.20 mph, 9.99 @132.33 mph. 3,300 race weight |
#43
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Quote:
From what I've experienced, minimizing and equalizing quench height is also important, which is why "zero decking" and squaring the block is important. As to the sealing tech, I'd just use a standard Cometic gasket. I didn't mean to imply anything fancy here. Years ago, long before I even knew the definition of "quench", I had a '68 Firebird 400 with the stock #16 heads. I got it from the original owner with 70k miles on it. With its ~10.25:1 CR, I had to retard the ignition timing a bunch to run it on CA's 92 octane at the time. I later rebuilt the engine with generic dished pistons which had a ~3/8" lip around the perimeter and the rest of the area was dished, which meant very little quench area. I believe those pistons reduced CR to 8.5:1. I used an 068 cam in place of the orig 067, so not much difference. I was quite disappointed when that engine had almost the same octane appetite as it had with the stock pistons, and now made less power as well. |
#44
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It just depends on how the chamber is designed.
I've done the bowl type dish on a 428 build decades ago when I used #13 heads on the engine. The chamber is so large on the 13 that the 3/8 lip around the parameter of the piston took up nearly all of the quench the cylinder head had to offer. That one came out to 9.7:1 compression and it ran great on 91 octane for years with a very small 218 @ .050 camshaft. The 670 head with it's much smaller chamber, I agree I'd dish a piston differently, just as described which would more likely end up with more of a "D" shaped dish. |
#45
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Here At Last
Picked up my 428 yesterday at Fastenal (great shipping service BTW).
YH code casting 9786135 turns out to be date-correct for my car L016 Dec 1, 1966. Intake is J216 Oct 21, 1966. Was pulled from a '67 Grand Prix with about 70K miles on it some 30 years ago and sat in a shop waiting for rebirth. Even has the AC brackets, which will come in handy. Can't wait to start the build, but it looks like we'll be moving soon so it will be a while....
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Mark Las Cruces NM ___________________________ Current Project: '67 Catalina Convertible 400 4-spd |
#46
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Cool deal.
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#47
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If I had that 428 I'd keep the 670 heads and run a 4.25" stroker kit to complement the 4-bolt mains and then sell the 4" stroke crank for a high premium to one of those guys that believe there's something magical about it. I'd run big dish forged pistons with enough volume to drop the compression ratio down to no more than 9.3:1.
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Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon. |
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