Cams

[Faceplant]

Hi Peeps,

Anyone put performance cams in a fiat twinny, does it make much difference?

FP

[dp]

Yes it makes a difference but not in isolation. I've changed just the inlet cam to a Guy Croft CC3A which means engine is still driveable, not too wild like a rally cam. But this is in conjunction with bigger carburettors

Lots of info here:

http://www.guy-croft.com/

[Faceplant]

cool,

im running a gas flowed and ported head by Guy Croft, twin 40's and 4-2-1 exhaust

so your only running an inlet cam?

FP

[dp]

With what you already have the cam(s) will make a difference yes. You'll lose a little bit of pickup but get more power further up the rev range. One or two cams, diminishing returns - inlet cam will give you something, exhaust will give a bit more but not double the power. You will pay double for two performance cams than one though. Maybe ask Guy what you want as your end result and see what he suggests.

I was originally going to fit a supercharger which wouldn't want a hotter exhaust cam but that's also subject to diminishing returns. It starts to get cheaper (especially in fuel consumption) at some point to get an engine that has the power you want rather than tuning more and more out of an 8V Fiat lump.

I'm sure someone on here had a Fiat T/C with both inlet and exhaust and could comment.

Also, if you have a 2 litre engine you could go to twin 45s even with the standard cam - not sure of the power gain though.

[MartinB]

The best road engine I ever had was the turbo 16 valve head on the 131 2 litre block. I ran this on twin 45 dellortos and used the standard turbo cams, pistons were modified flat top 2 litre ones. This was really torquey, did 40 to the gallon but ran out of puff over 7k rpm. I remember if I pulled away gently and then nailed the throttle (i.e. not dumping the clutch) it would spin the wheels at 1500 rpm.
Before that I ran an 8 valve engine with modified cams/head and really that was no way near the 16 valver!