Re: My 915's cc'd pretty big, is this typical?
[Re: 73DAD]
#2906870
04/05/21 01:25 PM
04/05/21 01:25 PM
|
Joined: Jan 2003
Posts: 25,879 Rio Linda, CA
John_Kunkel
Too Many Posts
|
Too Many Posts
Joined: Jan 2003
Posts: 25,879
Rio Linda, CA
|
Kinda funny that the closed chambers are closer to the advertised volume of the open chambers. (79.5 cc)
The INTERNET, the MISinformation superhighway
|
|
|
Re: My 915's cc'd pretty big, is this typical?
[Re: 73DAD]
#2906885
04/05/21 02:29 PM
04/05/21 02:29 PM
|
Joined: Jan 2003
Posts: 31,050 Oregon
AndyF
I Win
|
I Win
Joined: Jan 2003
Posts: 31,050
Oregon
|
I finally cc'd a set of 915's I had rebuilt at the local machine shop a couple years ago. I had the 1.6" exhaust valves replaced with 1.74"s & new seats obviously. They skimmed the decks to square them up. I gauged the retainer to spring-seat height with the stock locks & retainers at 1.880".
One head came in at 80.5cc & the other at 82cc. I thought that seemed pretty big for closed chambers. Is this what you guys have typically seen?
I have a pretty high quality 100ml glass burret & can be confident in my measurements to +/- 0.1cc The chambers are as-cast. Factory parts from that era were all over the map. If you want a factory big block engine to meet factory specs you have to re-machine a bunch of parts.
|
|
|
Re: My 915's cc'd pretty big, is this typical?
[Re: 73DAD]
#2906888
04/05/21 02:43 PM
04/05/21 02:43 PM
|
Joined: Feb 2005
Posts: 4,316 Prospect, PA
BSB67
master
|
master
Joined: Feb 2005
Posts: 4,316
Prospect, PA
|
I finally cc'd a set of 915's I had rebuilt at the local machine shop a couple years ago. I had the 1.6" exhaust valves replaced with 1.74"s & new seats obviously. They skimmed the decks to square them up. I gauged the retainer to spring-seat height with the stock locks & retainers at 1.880".
One head came in at 80.5cc & the other at 82cc. I thought that seemed pretty big for closed chambers. Is this what you guys have typically seen?
I have a pretty high quality 100ml glass burret & can be confident in my measurements to +/- 0.1cc The chambers are as-cast. I have 2 sets of 915s. 2.080 intake and 1.74 exhaust. They have had a clean-up pass or two on them, but minimal removal. one set is about 78, the other about 77.
|
|
|
Re: My 915's cc'd pretty big, is this typical?
[Re: BSB67]
#2907057
04/05/21 10:50 PM
04/05/21 10:50 PM
|
Joined: Aug 2003
Posts: 43,228 Bend,OR USA
Cab_Burge
I Win
|
I Win
Joined: Aug 2003
Posts: 43,228
Bend,OR USA
|
Measure the thickness of the outer head bolt bosses and see how thick, tall, they are now and please post them. I'll bet a nickel they are closer to .960 to.950 now than they where new
Last edited by Cab_Burge; 04/05/21 10:51 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
|
|
|
Re: My 915's cc'd pretty big, is this typical?
[Re: 73DAD]
#2907151
04/06/21 08:33 AM
04/06/21 08:33 AM
|
Joined: Jun 2008
Posts: 3,916 usa
lewtot184
master
|
master
Joined: Jun 2008
Posts: 3,916
usa
|
Measure the thickness of the outer head bolt bosses and see how thick, tall, they are now and please post them. I'll bet a nickel they are closer to .960 to.950 now than they where new I'll do that if my memory cooperates. I wish I had cc'd them before sending them out to be machined, just to have the data. What do you guys suppose unmilled open chambers cc at? 95?? 100?? on average 88-90cc's.
|
|
|
Re: My 915's cc'd pretty big, is this typical?
[Re: lewtot184]
#2907260
04/06/21 12:23 PM
04/06/21 12:23 PM
|
Joined: Jun 2014
Posts: 3,202 Md.
carnut68
master
|
master
Joined: Jun 2014
Posts: 3,202
Md.
|
I had a set of 906s they cc @ 91. Some 902s I had. Only cut 10 cc @85.
America First!
|
|
|
Re: My 915's cc'd pretty big, is this typical?
[Re: 73DAD]
#2907474
04/06/21 09:19 PM
04/06/21 09:19 PM
|
Joined: Feb 2005
Posts: 4,316 Prospect, PA
BSB67
master
|
master
Joined: Feb 2005
Posts: 4,316
Prospect, PA
|
Measure the thickness of the outer head bolt bosses and see how thick, tall, they are now and please post them. I'll bet a nickel they are closer to .960 to.950 now than they where new ........What do you guys suppose unmilled open chambers cc at? 95?? 100?? From the factory in 1967 -9, or in 2021 after 120,000+ miles and a valve gind or two. Some folks seem to think these are the same.
|
|
|
Re: My 915's cc'd pretty big, is this typical?
[Re: 73DAD]
#2907625
04/07/21 10:26 AM
04/07/21 10:26 AM
|
Joined: Jan 2003
Posts: 14,506 So. Burlington, Vt.
fast68plymouth
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 14,506
So. Burlington, Vt.
|
When you want to know what the chamber volume is for your heads........ you check them.
This is just engine building 101.
I recently had two sets of brand new TF270’s in the shop. The chambers are CNC machined. The chamber volume spec is 78cc.
On one set the chambers were 78cc......... the other set was 76cc.
I hear of people checking 516 heads that are well under 80cc.
I’ve never seen an uncut set under 81cc........ and have seen a few at closer to 84.
You check them........ they are what they are.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
|
|
|
Re: My 915's cc'd pretty big, is this typical?
[Re: 73DAD]
#2907690
04/07/21 01:34 PM
04/07/21 01:34 PM
|
Joined: May 2005
Posts: 136 Ontario, Canada
500ciBee
member
|
member
Joined: May 2005
Posts: 136
Ontario, Canada
|
Measure the thickness of the outer head bolt bosses and see how thick, tall, they are now and please post them. I'll bet a nickel they are closer to .960 to.950 now than they where new I'll do that if my memory cooperates. I wish I had cc'd them before sending them out to be machined, just to have the data. What do you guys suppose unmilled open chambers cc at? 95?? 100?? My 906 heads measured out at 92cc.
1970 Super Bee prostreet. 383, SMR 727, Dana 60 4:88. Building a 512 low deck.
|
|
|
Re: My 915's cc'd pretty big, is this typical?
[Re: 500ciBee]
#2907827
04/07/21 08:08 PM
04/07/21 08:08 PM
|
Joined: Aug 2003
Posts: 43,228 Bend,OR USA
Cab_Burge
I Win
|
I Win
Joined: Aug 2003
Posts: 43,228
Bend,OR USA
|
Measure the thickness of the outer head bolt bosses and see how thick, tall, they are now and please post them. I'll bet a nickel they are closer to .960 to.950 now than they where new I'll do that if my memory cooperates. I wish I had cc'd them before sending them out to be machined, just to have the data. What do you guys suppose unmilled open chambers cc at? 95?? 100?? My 906 heads measured out at 92cc. How thick are the outer head bosses now? I had a set of "516" close chamber heads converter to 1.74 exhaust and some bowl work done for a 440 bracket motor years ago, I ended getting a use set of 906 heads that had some poring work and bigger valves in them and swap them onto that motor, I ended up checking the CC on both sets of heads while doing the swap and the 516 had right at 90.0 CC and the 906 had right 74.0 CC The 516 set had taller outer head bolt bosses than the 906 did I ended up learning from that you can tell if a heads has been cut very much based off of the head bolt boss thickness EDITED: One of the older Mopar HP bible section on BB stated that to remove 1.0 CC form a open chamber head like the 906 to remove .010, I think, from the head surfaces for each CC and to remove .012 from the intake side of the heads to keep the intake manifold fitment correct I should have dug that book out before posting this but I can't remember which book and where all those books are stored now, CRS
Last edited by Cab_Burge; 04/07/21 08:12 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
|
|
|
Re: My 915's cc'd pretty big, is this typical?
[Re: Cab_Burge]
#2907866
04/07/21 10:44 PM
04/07/21 10:44 PM
|
Joined: Feb 2016
Posts: 201 PA
Scully
enthusiast
|
enthusiast
Joined: Feb 2016
Posts: 201
PA
|
Measure the thickness of the outer head bolt bosses and see how thick, tall, they are now and please post them. I'll bet a nickel they are closer to .960 to.950 now than they where new I'll do that if my memory cooperates. I wish I had cc'd them before sending them out to be machined, just to have the data. What do you guys suppose unmilled open chambers cc at? 95?? 100?? My 906 heads measured out at 92cc. How thick are the outer head bosses now? I had a set of "516" close chamber heads converter to 1.74 exhaust and some bowl work done for a 440 bracket motor years ago, I ended getting a use set of 906 heads that had some poring work and bigger valves in them and swap them onto that motor, I ended up checking the CC on both sets of heads while doing the swap and the 516 had right at 90.0 CC and the 906 had right 74.0 CC The 516 set had taller outer head bolt bosses than the 906 did I ended up learning from that you can tell if a heads has been cut very much based off of the head bolt boss thickness EDITED: One of the older Mopar HP bible section on BB stated that to remove 1.0 CC form a open chamber head like the 906 to remove .010, I think, from the head surfaces for each CC and to remove .012 from the intake side of the heads to keep the intake manifold fitment correct I should have dug that book out before posting this but I can't remember which book and where all those books are stored now, CRS Open chamber is .0042" per cc, closed is .0062" per cc, 286 and 518 .0064" I think.
|
|
|
|
|