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Re: 915 and 516 CC's [Re: Sport440] #1604300 04/09/14 12:11 AM 04/09/14 12:11 AM
Joined: Feb 2005 Posts: 4,314 Prospect, PA BSB67 master
BSB67 master Joined: Feb 2005 Posts: 4,314 Prospect, PA	How much do you think the seat and valve combined are ground on a wore out set of heads? Last edited by BSB67; 04/09/14 12:26 AM.

Re: 915 and 516 CC's [Re: BSB67] #1604301 04/09/14 12:55 AM 04/09/14 12:55 AM
Joined: Jan 2003 Posts: 6,591 Canton, Ohio S Sport440 master
Sport440 master S Joined: Jan 2003 Posts: 6,591 Canton, Ohio	Quote: How much do you think the seat and valve combined are ground on a wore out set of heads? Not "Wore out", Just a valve job like you stated. Back at you. How much do you think the seat and the valve combined are ground on Just a valve job? Between the two, if its just a valve job as little as .010 maybe .020 if its surfaces are worn. Not anywhere close to the .250 x.980 sloped .000 to .250 x 4.08 divot combined surface area of my valve reliefs that equates to 5cc in my KB 237,s Valve job = touch the seat and the valve. .2cc Valve reliefs = Big .250 x .980 x 4.08 Slanted gutter. 5cc Last edited by Sport440; 04/09/14 03:09 AM.

Re: 915 and 516 CC's [Re: BSB67] #1604302 04/09/14 03:12 AM 04/09/14 03:12 AM
Joined: Jun 2013 Posts: 870 Keizer, Oregon U.S.A. E elmor353 OP super stock
elmor353 OP super stock E Joined: Jun 2013 Posts: 870 Keizer, Oregon U.S.A.	My 67 440 has never been decked and I'm getting .065 -.070 on all cylinders.

Re: 915 and 516 CC's [Re: Sport440] #1604303 04/09/14 08:34 AM 04/09/14 08:34 AM
Joined: Feb 2005 Posts: 4,314 Prospect, PA BSB67 master
BSB67 master Joined: Feb 2005 Posts: 4,314 Prospect, PA	One of us is doing the math wrong. I too would guess 0.010" to 0.020" 0.020" drop of both valves is almost 2 cc. If my math is wrong, please let me know. Surface area of the entire valve verses the notch is not a good comparison. My point is that if someone is getting 84 cc on a set of 915s, it might be be that it has had one or two NAPA valve grinds. Maybe just factory variability...I don't know

Re: 915 and 516 CC's [Re: elmor353] #1604304 04/09/14 11:53 AM 04/09/14 11:53 AM
Joined: Jan 2003 Posts: 4,395 The Pale Blue Dot Skeptic master
Skeptic master Joined: Jan 2003 Posts: 4,395 The Pale Blue Dot	Quote: Can anyone tell me how many cc's the combustion chambers are on these heads? The sets I've measured were between 80-82 cc

Re: 915 and 516 CC's [Re: BSB67] #1604305 04/09/14 01:50 PM 04/09/14 01:50 PM
Joined: Jan 2003 Posts: 6,591 Canton, Ohio S Sport440 master
Sport440 master S Joined: Jan 2003 Posts: 6,591 Canton, Ohio	Quote: One of us is doing the math wrong. I too would guess 0.010" to 0.020" 0.020" drop of both valves is almost 2 cc. If my math is wrong, please let me know. No your Math is correct, decided to check it myself instead of guesstimate. At 0.010 on both a 2.14 and 1.81 valve = 1.011 cc At 0.020 on both double that = 2.022 cc My eyeball measurement wasnt very correct Thanks for the correction

Re: 915 and 516 CC's [Re: Sport440] #1604306 04/09/14 07:53 PM 04/09/14 07:53 PM
Joined: Feb 2005 Posts: 4,314 Prospect, PA BSB67 master
BSB67 master Joined: Feb 2005 Posts: 4,314 Prospect, PA	I used 2.08 and 1.74 as we are talking about factory heads so my numbers are a bit less. I too was a little surprised at the magnitude of the volume change with small changes in the valve depth.

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