What would you do?

[Zmanco]

I have a chance to pick up an E31 head with a "lopy" cam in it. The guy selling it doesn't know anything else about it, except to say the guy before him rebuilt the L24 and that it pulls strong. He's selling it because he's parting out the entire car.

 

My current engine is as follows:

- recently rebuilt N42 block w/flat top pistons .030 over and moly rings.

- 6:1 header

- Weber DCOE 40 mm carbs

- N42 hear recently refreshed to stock except for mild cam (.441 lift, 260 duration).

 

Engine pulls strong to 6k, but falls off fast after that. I figure the next steps for me for more power are a more agressive cam and maybe some head work.

 

I figure I have 3 options:

 

A) buy the E31 head and use it as-is on my block.

 

buy the E31 head and move the valve train over to my N42 head to take advantage of bigger valves and the new valve seals.

 

C) pass on this head and wait until I can buy a new cam/valve train which will likely cost me at least 4 times this head/cam.

 

FWIW, my current setup does not ping with 36 degrees total advance. LEngine says that my current CR is 10.2:1 and that with the E31 it would rise to 10.6:1.

 

I'm curious if anyone has any experience comparing the slightly larger valves of the N42 to the slightly higher CR of the E31? Since I drive mostly around 6000 feet elevation I'm not too worried about the higher CR, especially with a longer duration cam.

 

So what would you do?

[Zmanco]

I'm curious if anyone has any experience comparing the slightly larger valves of the N42 to the slightly higher CR of the E31? Since I drive mostly around 6000 feet elevation I'm not too worried about the higher CR, especially with a longer duration cam.

Any thoughts on the benefits of larger valves vs. a higher CR?