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#1
09-06-2020, 04:11 PM
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#13 D-port valve shroud removal
Any benefits to removing the valve shrouding in trying to prevent detonation? How many CC’s would that typically remove? Would figure that and a good polish of the chamber would help.
__________________
 "NSDQ"
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#2
09-07-2020, 05:48 AM
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The high comp heads are not shrouded by much, especially if you are running enough valve lift to get them clear of the deck of the head.
Along these same lines of thought in terms of shrouding if I where going all out I would mill the heads .050" and if need be get dished Pistons made to get the compression to what I was looking for. If you care to match the corner of the chamber adjacent to the Intake and Exh valve to the head gasket, but be careful to not undermine the gaskets fire ring. Any sharp edges that stick out into the chamber should be rolled over to the tune of .015", be be careful of the edge / eyebrow above the Intake if the motor is going to be NA as that sharp lip serves to shread up streams of wet flow back in a finer and more combustible state. If the motor will be boosted then this lip/edge can be rolled over more. Polishing the chamber can add up to 2 CCs to the volume depending on how ruff the machine work is now in there on average. If your using these heads on a Turbo build I would sooner get the valves Heat barrier coated by Swain tech and your pockets are deep enough send the heads to them to get the chambers coated by that same process.
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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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#3
09-07-2020, 10:48 PM
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670 heads 82cc
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#4
09-08-2020, 10:08 AM
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Quote:
__________________
"NSDQ"
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#5
09-08-2020, 12:19 PM
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Please note that the chambers in the 670 heads on the Intake valve side start off looking different then your castings.
They eyebrow above the Intake valve as in your 13 castings is not there. In the 68 and up heads when the factory needed to get chamber volumes above 76 CC they first brought out the top of the chamber more towards the fire ring of the head gasket as can be seen when comparing a 6X-4 head with a 6X-8 head. Next to get more chamber volume they depended the floor of the chamber. In short with your castings you should rework the Exh side of the chamber also to lessen the chance of blowing thru a chamber wall if you replicate what was done in this guy's 670 heads! |
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#6
09-08-2020, 01:27 PM
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These heads have already had a valve job done on them and prepped. I haven't had a chance to pull on off the motor yet. I am not going to do anything with them till I get the chambers measured and see what it has in it for pistons. They are supposed to be 0.030 over forged pistons, just not sure if that is true, or if they are dished yet. Also need to measure how far down in the hole they are. Would feel okay if I can be at 9.6 to 9.8 SCR.
__________________
"NSDQ"
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#7
09-08-2020, 05:55 PM
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Quote:
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