race cam shaft question

[Guest nateoneel]

I heard from a guy at colt cams that you could take the valve springs out of a roadster and put them in an L20b so you can run a race cam. He said the roadster used the same size valve springs but there lbs rating is higher.

Can anyone tell me this is true or offer valve spring options for running a big cam?

[Jason]

It's true, however, you will need to run the springs that are meant for the "B" grind cam for the Solex 44's. More lift (about .507 I think) , more overlap and duration than the "A" grind with SU's.

[datzenmike]

Hmmm that's interesting Jason. Should work on a Z engine then too. They are a bit weak and the valves are a tad longer and heavier.

[Jason]

Neat eh :)? The "A" grind cam on the U20 had a .492 lift.

[datzenmike]

The .492 would be more than I would need. Still same stiffness or close?

[Jason]

According to Jeff B at Colt, if you aren't going to rev out the engine the .492 lift cam will be usable with stock springs. However, if you do plan to rev out the engine then the roadster springs are a better choice. I thinking that the springs may be the same for the 2 grinds now that I've looked over the section. There are stiffer roadster springs that where available through NISMO at one point also.

 

http://www.datsunroadster.com/SUB_SECTION_DIRECTORIES/head_2000.htm