Hi

Would like to know the difference between the Standard cams, RS turbo, XR3i MFI/EFI etc.
Are the any difference or are they all the same.

 

i always thought they were all the same.

 

no they're not

 

From Haynes manual.....
VALVES:
1.3 and 1.4cvh:-
inlet valve opens ... ... 13*btdc
inlet valve closes ... ... 28*abdc
exhaust valve opens ... 30*bbdc
exhaust valve closes ... 15*atdc
Valve lift:
inlet ... ... 9.56mm
exhaust ... 9.52mm
Valve spring free length:
47.2mm

1.6cvh and XR but not RS:-
inlet valve opens ... ... 8*btdc
inlet valve closes ... ... 36*abdc
exhaust valve opens ... 34*bbdc
exhaust valve closes ... 6*atdc
Valve lift:
inlet ... ... 10.09mm
exhaust ... 10.06mm
Valve spring free length:
47.2mm

The XR head was revised with three angle valve seats, slightly better flowing ports, and a better shape combustion chamber with pistons to match, and different carb, thus the power hike, but the camshaft was the same as the other 1.6's.
The shafts are all interchangeable prividing you have enough clearance on the pistons and valves, but you cannot put a 1.8 one in; like trying to push a pound of cheese through your letterbox, it wont fit; different kettle a fish camshaft, and a different shaped head and pistons to go with it.
The RS1600 i dont have data for, it could be different as it was designed to rev a bit more, with less valve bounce, due to solid cam followers. Can someone confirm the camshaft data for this?
RST camshaft will be cast like the others (ignoring the 1.8) and will fit but the cam lobes are positioned for forced induction and i dont have the data for that either, sorry. More citation needed.

 

I think, but dont know for sure, that the EFI cam was the same too but the fuel management was better

 

Thank you for that that cleared it up for me.

 

Efi xr3i cam is the best standard cvh cam that ford did and worth between 3 and 5 bhp over the xr3i mfi cam.

Xr3i mfi cam is different to carb cam, less duration and sharper ramp angles.

Rs turbo cam is the same as xr3i mfi but with a different pulley as it has different timing requirements.

Efi cvh also had wasted valve stems to give extra power.

Not seen the different valve seats in all the heads i have looked at, maybe that was the rs1600i only?

Xr3i stayed hemi whilst the carb engine went lean burn. Hemi head flowed better and therefore helped give the extra 15bhp, well 10bhp, over the carb engine.

A lot of power was lost on the xr3i by retarding the ignition timing to 8degrees from the 12, this allowed it to run on normal unleaded without detonation. I run mine at12 and super unleaded as it feels flat as a fart otherwise.