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#1
02-10-2022, 01:20 AM
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7K3 Heads cc Est
I have a pair of 7K3 heads that were shaved .030. The original cc volume was 96. Would any one have an idea what they may be now?
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#2
02-10-2022, 01:59 AM
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90ccs.
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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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#3
02-10-2022, 02:37 AM
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Thanks.
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#4
02-10-2022, 07:23 AM
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For every .006” milled off you get a 1CC reduction .
I can assure you that your heads where not dead on 96 CCs to start with , figure more like 97.5 CCs or maybe even 98.3, and then since they have likely had a valve job, and if that valve job was cut to make use of near the full OD of each valve you can then add another 1 to 1.3 CCs to the total chamber volume. Also another thing that is too often overlooked is the CC volume that resides in the piston to wall clearance from the top of the piston to the top of the first compression ring, and then CCs there’s the that reside in the needed back clearance for that top compression ring. Figure another 1.5 CCs for that. Adding these up in my opinion your at best your at 100 CCs without the 5 CC reduction from the .030” mill , and out whatever the valve notch or dish volume is in the pistons. In my opinion a lot of guys who are just engaged in a lightly hopped up street rebuild are darn close to having 1/2 a point less compression then they think they have !
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I do stuff for reasons. Last edited by 25stevem; 02-10-2022 at 07:28 AM. |
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#5
02-10-2022, 01:56 PM
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Thanks 25stevem. Heads were rebuilt with new valves etc. I have them on a 68 428 that has a .030" bore. Just curious if they are worth running as I can get a set of rebuilt 64's that have never been run for a great price. Still thinking of picking them up for a spare set of heads as I also have a 421 I am looking to rebuild and have no clue on what the heads on it are let alone the shape. Guy I bought it off of said they were 62's but I cant see a 62 on the centre exhaust port and cant get to the heads for a date code yet as I am renovating my garage. Might just have to B*** up and climb in there and see what I have. Hope they are not 1965 castings.
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#6
02-10-2022, 07:18 PM
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The 64 castings with there likely 90 CC chamber volume would be the way to go, and plus those castings have all the needed exh flange bolt holes to run headers .
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I do stuff for reasons. |
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#7
02-11-2022, 05:03 PM
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I agree with you on that. The heads with a new rebuild as well as the carb and manifold are under $2k CDN so a very good deal.
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