cam
01-18-2008, 11:40 AM
#2
D.R. THE PATHETIC DORK
Join Date: Jun 2007
Location: West Virginia
Posts: 30,863
RE: cam
lift is not a determining factor of ptv it is cam timing that'll affect ptv more than anything..but what size cam are you thinking of and are you planning on putting 1.7's on top of that??
01-18-2008, 11:44 AM
#3
3rd Gear Member
Join Date: Sep 2007
Location:
Posts: 798
RE: cam
Yep, gross valve lift is not the reason for piston to valve clearance problems.
It is during the period of overlap when the exhaust valve is closing (as the piston is coming up) and the intake valve is opening. They are both open at the same time for a short time while the piston is at top dead center.
The 1.7:1 ratio is a bit harsher on valve springs, so keep that in mind.
Get a good valvetrain...
It is during the period of overlap when the exhaust valve is closing (as the piston is coming up) and the intake valve is opening. They are both open at the same time for a short time while the piston is at top dead center.
The 1.7:1 ratio is a bit harsher on valve springs, so keep that in mind.
Get a good valvetrain...
01-18-2008, 01:11 PM
#4
Thread Starter
Join Date: Jan 2008
Posts: 3
RE: cam
I'll look tonight to see specs on cam, at work now and can't remember. Sold my 89 GT and just bought this 90 coupe(been looking for a coupe for a long time)and the guy had the stock heads ported, with heavier springs and 1.7's put on them. I bought a cam for my old 89 but didn't get it in before I sold it. It's a crane but I believe it matched pretty close to the e-cam ford offers. Thanks in advance.
01-19-2008, 01:14 PM
#5
Thread Starter
Join Date: Jan 2008
Posts: 3
RE: cam
OK, I just looked at the cam card. Its a Crane Cam and has .311 cam lift and .498 at the valve. 282 avertised duration. So correct me if i'm wrong, but that should be roughly .529 with the 1.7s. Can anyone tell me if this is going to be too much lift. I know I should do a piston to valve check to be sure but just thought someone would know off the top of their head. Engine has stock pistons and unmilled heads that have mildly ported and polished and stiffer springs installed(not sure which ones). Thank you.
01-19-2008, 03:31 PM
#6
D.R. THE PATHETIC DORK
Join Date: Jun 2007
Location: West Virginia
Posts: 30,863
RE: cam
ORIGINAL: sec
OK, I just looked at the cam card. Its a Crane Cam and has .311 cam lift and .498 at the valve. 282 avertised duration. So correct me if i'm wrong, but that should be roughly .529 with the 1.7s. Can anyone tell me if this is going to be too much lift. I know I should do a piston to valve check to be sure but just thought someone would know off the top of their head. Engine has stock pistons and unmilled heads that have mildly ported and polished and stiffer springs installed(not sure which ones). Thank you.
OK, I just looked at the cam card. Its a Crane Cam and has .311 cam lift and .498 at the valve. 282 avertised duration. So correct me if i'm wrong, but that should be roughly .529 with the 1.7s. Can anyone tell me if this is going to be too much lift. I know I should do a piston to valve check to be sure but just thought someone would know off the top of their head. Engine has stock pistons and unmilled heads that have mildly ported and polished and stiffer springs installed(not sure which ones). Thank you.
01-19-2008, 05:08 PM
#7
5th Gear Member
Join Date: Jan 2006
Location: Puerto Rico
Posts: 3,926
RE: cam
ORIGINAL: sec
OK, I just looked at the cam card. Its a Crane Cam and has .311 cam lift and .498 at the valve. 282 avertised duration. So correct me if i'm wrong, but that should be roughly .529 with the 1.7s. Can anyone tell me if this is going to be too much lift. I know I should do a piston to valve check to be sure but just thought someone would know off the top of their head. Engine has stock pistons and unmilled heads that have mildly ported and polished and stiffer springs installed(not sure which ones). Thank you.
OK, I just looked at the cam card. Its a Crane Cam and has .311 cam lift and .498 at the valve. 282 avertised duration. So correct me if i'm wrong, but that should be roughly .529 with the 1.7s. Can anyone tell me if this is going to be too much lift. I know I should do a piston to valve check to be sure but just thought someone would know off the top of their head. Engine has stock pistons and unmilled heads that have mildly ported and polished and stiffer springs installed(not sure which ones). Thank you.
01-19-2008, 05:58 PM
#8
3rd Gear Member
Join Date: Sep 2007
Location:
Posts: 798
RE: cam
Your math is right. Remember, the lift is not going to cause the issue with piston to valve clearance.
Read over this link for the clay method.
Read over this link for the clay method.
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