| Author |
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eric
| | Posted on Monday, October 07, 2002 - 01:32 am: | 
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Anyone know the valve clearance for a 3.9L? If I get an aftermarket cam, just want to make sure everything works.
The RPI lift is .432 for both. Crane is .416 Int. and .432 Exh. Erson is .437 int. and .448 exh. The stock Rover cam for a 3.9 is .373 for both.
The duration of the Crane and RPI are 260, 268 for the Crane exhaust. Erson is 274 In. and 280 Ex.
Stock duration is 256 for both.
Anyone knowledgeable about cams, your thoughts.
Thanks,
eric |
Jason Vance (Jason)
| | Posted on Tuesday, October 08, 2002 - 02:37 pm: |
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That Erson cam has too much duration for what you have claimed to want, IMO. I don't know if the added lift over the other cams would benefit the engine any (e.g. the stock heads may quit flowing above .420" of lift for all I know...added lift above a certain point doesn't necessarily help).
As far as "valve clearance" goes, I can't find any published values that you want (you are not talking about valve-stem to lifter clearance, which is typical "clearance" states in books/manuals). The cams you mentioned are at most making .070" (.040 - .060" for the Crane and RPI) more lift than stock. I really doubt there is less than .100" before coil bind on the stock head/valves. Unless someone else wants to chime in, you will have plenty of valve travel with the stock heads/valves/springs. You may want to shim the valves to .070-.100" before coil bind at max lift to put more pressure at the seat and over the nose, especially if plan to run the whole RPM range of your engine. |
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