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Trying to pick a cam for my 505 but how do I tell PV? #1378229 01/29/13 06:03 PM 01/29/13 06:03 PM
Joined: Jan 2003 Posts: 4,283 Danville, NH M Mopar_Mike OP master
Mopar_Mike OP master M Joined: Jan 2003 Posts: 4,283 Danville, NH	without actually buying a cam, putting it in, putting clay on the piston, only to find out there will be PV issues, is there a way to tell before I pick the cam? I have all the specs of the build. Thanks! RS23L7 4-Speed

Re: Trying to pick a cam for my 505 but how do I tell PV? [Re: Mopar_Mike] #1378230 01/29/13 07:42 PM 01/29/13 07:42 PM
Joined: Jan 2003 Posts: 75,004 U.S.S.A. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,004 U.S.S.A.	Is the shortblock together yet ?

Re: Trying to pick a cam for my 505 but how do I tell PV? [Re: JohnRR] #1378231 01/29/13 07:48 PM 01/29/13 07:48 PM
Joined: Jan 2003 Posts: 4,283 Danville, NH M Mopar_Mike OP master
Mopar_Mike OP master M Joined: Jan 2003 Posts: 4,283 Danville, NH	yeah RS23L7 4-Speed

Re: Trying to pick a cam for my 505 but how do I tell PV? [Re: Mopar_Mike] #1378232 01/29/13 07:51 PM 01/29/13 07:51 PM
Joined: Jan 2003 Posts: 16,376 D dogdays I Live Here
dogdays I Live Here D Joined: Jan 2003 Posts: 16,376	You need pistons, not rings, on the rods installed in the block on the crank everything bolted down but not necessarily ready to go, but you need bearings...if shortblock is already assembled that's OK too. With valves in the head you're going to use and lightweight springs on the valves, bolt the head down and bring a piston to TDC. Then using some kind of measuring instrument, measure the distance you can push the valve down before it touches the piston. Do that for each cylinder if you want to be careful. Now you know the maximum the valve can be open at TDC. With that information your cam grinder "should" be able to tell you if the piston-to-valve clearance will be OK with a particular cam installed on a particular center line. Of course that requires you to know where the real TDC is, but if you are going to be close, it never hurts to measure a bunch! R.

Re: Trying to pick a cam for my 505 but how do I tell PV? [Re: dogdays] #1378233 01/29/13 07:58 PM 01/29/13 07:58 PM
Joined: Aug 2011 Posts: 2,857 Pattison Texas CSK master
CSK master Joined: Aug 2011 Posts: 2,857 Pattison Texas	VALVE does not hit piston at tdc it hits after tdc,if its going to 1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5

Re: Trying to pick a cam for my 505 but how do I tell PV? [Re: CSK] #1378234 01/29/13 08:07 PM 01/29/13 08:07 PM
Joined: Jan 2003 Posts: 16,376 D dogdays I Live Here
dogdays I Live Here D Joined: Jan 2003 Posts: 16,376	If you don't know what cam you're using, you have no idea where that's going to happen. But you can find out the distance at TDC. You could even find out the distance at 10 degrees BTDC and 10 degrees ATDC so R/S ratio doesn't mess things up. R.

Re: Trying to pick a cam for my 505 but how do I tell PV? [Re: dogdays] #1378235 01/29/13 11:31 PM 01/29/13 11:31 PM
Joined: Aug 2009 Posts: 456 corpus christi tex C Cheatham mopar
Cheatham mopar C Joined: Aug 2009 Posts: 456 corpus christi tex	in past with every thing assembled iv rotated the engine at several points and make something to grab the rocker arm and open it by hand and feel it hit the piston then you can guess or install a indicator and know the clearance

Re: Trying to pick a cam for my 505 but how do I tell PV? [Re: Cheatham] #1378236 01/29/13 11:38 PM 01/29/13 11:38 PM
Joined: Jun 2005 Posts: 6,257 gulfport, ms, west mi rowin4 master
rowin4 master Joined: Jun 2005 Posts: 6,257 gulfport, ms, west mi	On my 505 I have a 650 lift Crower solid lifter cam, 1.5 ratio rockers, flat top pistons, over .100 piston to valve clearance with the cam set straight up. it's ok to butt heads, just don't do it with a butthead

Re: Trying to pick a cam for my 505 but how do I tell PV? [Re: Mopar_Mike] #1378237 01/30/13 12:33 AM 01/30/13 12:33 AM
Joined: Aug 2003 Posts: 43,157 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,157 Bend,OR USA	Quote: without actually buying a cam, putting it in, putting clay on the piston, only to find out there will be PV issues, is there a way to tell before I pick the cam? I have all the specs of the build. Thanks! Not really, way to many variables as far as you degreeing the cam or not, piston valve relief depth, head thickness, piston deck hieght and a lot more variables I've treid installing a flat tappet cam with 268 duration at .050 on the intake lifter installed straight up(degreed )on a 108 LSA cam,(intake max lobe lift at 108 ATDC) it hit the piston at around 15 defrees after top dead center, I put a bigger duration solid roller cam in, 272 at .050 on a 108 LSA in at two degrees advanced, intake lobe at 106 degrees after top dead center and it had .060 V. to P. clearances It pays to know what you got Never ASSUME anything on motors with after market parts Last edited by Cab_Burge; 01/30/13 01:39 AM. Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: Trying to pick a cam for my 505 but how do I tell PV? [Re: Mopar_Mike] #1378238 01/30/13 12:55 AM 01/30/13 12:55 AM
Joined: Jan 2003 Posts: 31,023 Oregon A AndyF I Win
AndyF I Win A Joined: Jan 2003 Posts: 31,023 Oregon	Measure the valve drop at TDC. Then compare it to the tappet lift at TDC provided by the cam mfg. That should get you close enough for most engines.

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