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Estimate on how much to mill heads? #718706 06/07/10 11:44 PM 06/07/10 11:44 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	Even though when I bought my CNC Hughes Victors they said their work included milling the heads back to the original chamber size (75 cc is what Edelbrock advertises), they looked "big" to me. So, tonight I measured the two end chambers of one head and came up w/ 82 cc for both (fractionally more for the one chamber that shows more drop-out from the CNC program). Can anyone give me a reasonable estimate of how much should be milled to reduce the chamber volume per 1 cc? Now that I know they're actually bigger, I think I'll just take 'em down to 78 cc, same as w/ my Stage VIs, and leave the CR at 10.8. P.S. What got me thinking I needed to measure my heads was noticing that Hughes has recently changed their CNC Victor description to say their program increases the chamber size and for additional $ they'll bring the chamber down to what ever your target volume is. I wonder at what point they realized that 75 doesn't equal 82?

Re: Estimate on how much to mill heads? [Re: BradH] #718707 06/08/10 12:06 AM 06/08/10 12:06 AM
Joined: Jul 2009 Posts: 237 Redding,CA USA 440charger500 enthusiast
440charger500 enthusiast Joined: Jul 2009 Posts: 237 Redding,CA USA	I think milling .010th is about -1.5 cc's. maybe someone else will chime in to verify it.

Re: Estimate on how much to mill heads? [Re: BradH] #718708 06/08/10 12:37 AM 06/08/10 12:37 AM
Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey J jamesc master
jamesc master J Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey	level the cylinder head with an accurate level (machinist). fill the chamber with fluid to the volume you want the chamber to be. take a 0-1" depth mic that's been zeroed and place it on the head with the spindle just off the edge of the chamber. slowly turn the spindle down until the fluid just jumps up onto the spindle and take your reading. that is how much you need to cut the head to get the desired volume. if the mic is too close to the fluid level to get a good read you can put a spacer of known thickness (valve bucket shim, gage block etc.) under the mic and just subtract that from your reading.

Re: Estimate on how much to mill heads? [Re: jamesc] #718709 06/08/10 12:45 AM 06/08/10 12:45 AM
Joined: Jun 2005 Posts: 6,257 gulfport, ms, west mi rowin4 master
rowin4 master Joined: Jun 2005 Posts: 6,257 gulfport, ms, west mi	Good tip it's ok to butt heads, just don't do it with a butthead

Re: Estimate on how much to mill heads? [Re: rowin4] #718710 06/08/10 08:02 AM 06/08/10 08:02 AM
Joined: Feb 2007 Posts: 6,295 U.S. M moparniac master
moparniac master M Joined: Feb 2007 Posts: 6,295 U.S.	My new indys were corrected back to 75cc brad and on the heads it said .020 was taken off to get them back to 75cc ..... also wallace has a calc for this Mopar Performance

Re: Estimate on how much to mill heads? [Re: BradH] #718711 06/08/10 11:02 AM 06/08/10 11:02 AM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	I think Indy's spec of milling .006" for each 1 cc is close enough, considering they have similar chamber shapes and volumes --> 4 cc = .024"

Re: Estimate on how much to mill heads? [Re: BradH] #718712 06/08/10 02:02 PM 06/08/10 02:02 PM
Joined: Jan 2003 Posts: 75,042 U.S.S.A. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,042 U.S.S.A.	Quote: I think Indy's spec of milling .006" for each 1 cc is close enough, considering they have similar chamber shapes and volumes --> 4 cc = .024" think it would need that much ? an open chamber 906 Rule of thumb is .005 for every 1 cc ????

Re: Estimate on how much to mill heads? [Re: JohnRR] #718713 06/08/10 03:20 PM 06/08/10 03:20 PM
Joined: Dec 2008 Posts: 1,200 UK 6 602heavy pro stock
602heavy pro stock 6 Joined: Dec 2008 Posts: 1,200 UK	To get a set of Indy heads from 75cc to 66cc i had to cut .080" off the head.

Re: Estimate on how much to mill heads? [Re: JohnRR] #718714 06/08/10 03:23 PM 06/08/10 03:23 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	Quote: Quote: I think Indy's spec of milling .006" for each 1 cc is close enough, considering they have similar chamber shapes and volumes --> 4 cc = .024" think it would need that much ? an open chamber 906 Rule of thumb is .005 for every 1 cc ???? Think wide (open chamber) vs. deep (closed chamber).

Re: Estimate on how much to mill heads? [Re: JohnRR] #718715 06/08/10 03:25 PM 06/08/10 03:25 PM
Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey J jamesc master
jamesc master J Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey	the indy chamber is smaller and has less effect when milled, with the 906 you're getting a lot of chamber reduction when cut.

Re: Estimate on how much to mill heads? [Re: jamesc] #718716 06/08/10 03:26 PM 06/08/10 03:26 PM
Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey J jamesc master
jamesc master J Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey	UGH...treed again

Re: Estimate on how much to mill heads? [Re: jamesc] #718717 06/08/10 04:43 PM 06/08/10 04:43 PM
Joined: Jan 2003 Posts: 75,042 U.S.S.A. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,042 U.S.S.A.	Quote: the indy chamber is smaller and has less effect when milled, with the 906 you're getting a lot of chamber reduction when cut. That's right , for some reason I was thinking that the smaller chamber wouldn't need as much

Re: Estimate on how much to mill heads? [Re: BradH] #718718 06/08/10 05:42 PM 06/08/10 05:42 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	I was actually hoping it would take a LOT of milling to bring the chambers down. See, I had this little(?) problem last night where the head didn't stay put where I'd left it and... it landed on an OEM '70 4-bbl iron intake. Naturally, it ended up chamber-side down, so there are some scratches and small gash marks on the surface that I'd like to see go away.

Re: Estimate on how much to mill heads? [Re: BradH] #718719 06/08/10 11:04 PM 06/08/10 11:04 PM
Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey J jamesc master
jamesc master J Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey	Brad, depending on where the marks are i wouldn't sweat it. personally i try not to put the compression in the head but rather the piston, deck, gasket whenever possible. i hate cutting heads for CR.

Re: Estimate on how much to mill heads? [Re: jamesc] #718720 06/09/10 09:25 AM 06/09/10 09:25 AM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	Unfortunately, one of the "gashes" is right on the edge of the combustion chamber where the gasket "fire ring" would be.

Re: Estimate on how much to mill heads? [Re: BradH] #718721 06/09/10 10:34 AM 06/09/10 10:34 AM
Joined: Jan 2003 Posts: 75,042 U.S.S.A. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,042 U.S.S.A.	Quote: Unfortunately, one of the "gashes" is right on the edge of the combustion chamber where the gasket "fire ring" would be. have it welded ?

Re: Estimate on how much to mill heads? [Re: JohnRR] #718722 06/09/10 10:59 AM 06/09/10 10:59 AM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	Quote: Quote: Unfortunately, one of the "gashes" is right on the edge of the combustion chamber where the gasket "fire ring" would be. have it welded ? If necessary... but I hope that's not required.

Re: Estimate on how much to mill heads? [Re: BradH] #718723 06/09/10 11:11 AM 06/09/10 11:11 AM
A Anonymous Unregistered
Anonymous Unregistered A	Quote: Unfortunately, one of the "gashes" is right on the edge of the combustion chamber where the gasket "fire ring" would be. how about a large bore gasket like 4.560? it would also help lower the compression.

Re: Estimate on how much to mill heads? #718724 06/09/10 12:00 PM 06/09/10 12:00 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	Quote: how about a large bore gasket like 4.560? it would also help lower the compression. I'll consider all options at this point. Still feeling really STOOPID for having let the freakin' head fall over in the first place. Some things are so easily preventable... and yet they still happen.

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