Cam timing

[ChrisJC]

The Haynes manual for the Range Rover gives the valve timing. I was looking at the supplement chapter (13), and it gives the timing for the carb engine and the EFi engine.

I noticed that the carb cam seemed to be identical to the EFi cam, but for a constant 12degree difference (I forget which one was more advanced than the other).

What difference does that 12degrees make?, and why did they do it?

Chris.

[ChrisJC]

It seems that the plot thickens. Whilst putting my engine back together, before I put the heads on, I thought it was a great opportunity to check the cam timing using a dial test indicator.

I checked that TDC on the crank pulley was right, then looked for a cam lobe that was on max duration at about TDC. I measured no. 3 inlet at being fully open at 15deg after TDC on no. 1.

A few calcs shows (assuming a 280deg cam) that the valve starts to open at 35 before TDC and closes 65 degrees after BDC. These figures match up with the carburettor camshaft settings, but I definitely fitted an EFi cam!!!

According to Mr. Haynes, the carb engine produces 126BHP, and the EFi engine produces 165BHP.

How much difference can I expect this 12 degree error to cause me??? 40BHP?

Ta,

Chris.

[katanaman]

no idea about your cam but 126bhp would be more in line with a P6 engine or possibly some low comp engines. Its definitely too low a figure for any of the later 3.5 engines.