Valve train question
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Mountain Pass
Joined: May 2003
Posts: 232
Likes: 16
From: Milwaukee USA
Valve train question
I have a stock '73 head - D20E - BA Stock Iron heads other than enlarged valves 1.9/1.6 with hardened seats. Stock pressed in studs. I know I could have all the machining done to remove the pressed in and go to a threaded stud which might save me some headache here but for now, I can't(won't). Maybe at a later time.
My question is valve springs - there are so many specs out there that will make your head spin. The stock springs are about 1.4 O.D. - I have no idea on seat and open pressure for the stock stuff but I'm not using it so it probably doesn't matter.
Does any one have a recommendation on the correct spring to buy - my cam is hyd fairly mild at .480 lift, rockers probably will be roller tip but stock type because I'm not doing all the machining. I'm guessing I need to stay real close to my 1.4 OD and I've been reading that seat pressure needs to be about 100-125 and open somewhere between 260 - 300 but not over 300 with the pressed in studs - sound right?
Second question - do I need a spring with a damper or not.
My question is valve springs - there are so many specs out there that will make your head spin. The stock springs are about 1.4 O.D. - I have no idea on seat and open pressure for the stock stuff but I'm not using it so it probably doesn't matter.
Does any one have a recommendation on the correct spring to buy - my cam is hyd fairly mild at .480 lift, rockers probably will be roller tip but stock type because I'm not doing all the machining. I'm guessing I need to stay real close to my 1.4 OD and I've been reading that seat pressure needs to be about 100-125 and open somewhere between 260 - 300 but not over 300 with the pressed in studs - sound right?
Second question - do I need a spring with a damper or not.
Senior User
Joined: Mar 2004
Posts: 274
Likes: 0
From: MI
Stock closed valve hyd seat pressure ...
installed spring pressure 70-87 depending on year eng.
open pressure up to 200 depending on year eng.
Hi po engines ... had factory screw in studs
installed spring pressure 90.
open pressure 260.
The seated and open pressures you are planning to run could pull a pressed in stud out. I have two sugestions.
1. Pin the studs
2. Pull the studs .. drill and tap 7/16 corase ... use 7/16 3/8 studs no
guide plates but you have to run the Ford rail rocker arms. I have used this set up before even with solid lifters as long as the cam uses a lash of .020 or less. Lash can be adjusted with feeler gages used to set points in a distributor.
installed spring pressure 70-87 depending on year eng.
open pressure up to 200 depending on year eng.
Hi po engines ... had factory screw in studs
installed spring pressure 90.
open pressure 260.
The seated and open pressures you are planning to run could pull a pressed in stud out. I have two sugestions.
1. Pin the studs
2. Pull the studs .. drill and tap 7/16 corase ... use 7/16 3/8 studs no
guide plates but you have to run the Ford rail rocker arms. I have used this set up before even with solid lifters as long as the cam uses a lash of .020 or less. Lash can be adjusted with feeler gages used to set points in a distributor.
Senior User
Joined: Mar 2004
Posts: 274
Likes: 0
From: MI
The springs may not be advertizing the the installed height you are looking at the Crane catalog has a formula to approximate differances in pressure using a installed/open height other than advertized its not 100% accurate but good enough.
Senior User
Joined: Feb 2005
Posts: 139
Likes: 0
From: Noth Georgia
As for the springs, ask the cam manufacturer, they have recommended springs, which must be used for the warranty. They may be available in a kit; Cam, Lifters, Springs, Retainers, and Assembly Lube
Not too sure about the heads, do they have valve spring pockets. If not, the new spring size (OD) doesn't matter, as long as you get matching retainers.
Check on machine work+springs/retainers, Performance Automotive Wholesale-PAW has complete remanufactured heads $500/pr - no exchange. Max Lift: .500, Pick chamber size, cannot remember if you pay S&H or not.
Hope this helps
Not too sure about the heads, do they have valve spring pockets. If not, the new spring size (OD) doesn't matter, as long as you get matching retainers.
Check on machine work+springs/retainers, Performance Automotive Wholesale-PAW has complete remanufactured heads $500/pr - no exchange. Max Lift: .500, Pick chamber size, cannot remember if you pay S&H or not.
Hope this helps
