Hi all. im just after some advice for a cam for my A15.

ive found a nz site which seem reasonably priced
http://www.aucklandcams.co.nz/cam_lis ... NISSAN%20DATSUN%20A12-A15

now i plan on putting twin side draft webers on a standard A15 block. head will be port matched with double valves springs. what cam does everyone recommend. the ute wont be a daily, just weekends and some spirited squirts around the street.

thanks

Double valve springs are for RPMs in excess of 6,000 RPM. How high will you be revving the engine? Is it a standard A15 head or A15 round-port head?

oval port h89 head. no idea how high i'll be revving it until i start driving it. from what ive read on here double valve springs are the norm for some slight head work and decent carbs.

Actually, slight head work and decent carbs do not require double-valve springs. The stock springs are perfectly fine for 6,000 RPM and some runs them to 6400 RPM. They start floating about here, so you'd need upgraded springs to rev higher

Some guys refuse to rev their engine over 5,000 RPM, which is why I asked. If you like to rev and are willing it gives you much more choice and potentially more power

then i will say yes i will be revving over 6000rpm.

in saying that having double valves springs and not revving that high does that affect performance in any way?

Yes, exactly. Upgraded springs are only for revving higher or for heavier valves. They will still work with standard-RPM engines however so no worries

ok now back to my original q's, what cam?

Go with an 8000 RPM cam and springs, easily make 100 rwhp. This will need ported H89 head. If you fit larger valves maybe 120 rwhp? For 100 rear-wheel HP, go with Weber 40s and start the jetting with 32mm chokes.

The H89 head with port matching makes maximum HP at what, 6000-6400 RPM? Rev it any higher and it goes slower -- regardless of the cam. So with this head and if you like to rev to the limit, recommend a GX-spec cam but doubt if it will return 100rwhp

ok youve confused me, you have stated having 8000rpm cam with springs with ported head and webers will make 100rwhp

then you said a ported h89 will make max power at 6000-6400 regardless of cam and with a gx spec cam youd be lucky to make 100rwhp.

so then is there any point in having a 8000rpm cam if max power is made at 6000-6400 with a h89?

sorry for the q's im still learning

actually I said:
Quote:Which is very different from a ported head. Port matching only cleans up the gasket junction area. Porting means shaping the head passageways/runners for more airflow. With the H89 they port the runners + reshape the bowl under the valves + port-match to the intake manifold. Takes a lot of time or money to make big power from mere 1.5 liters!