Inlet Valve Timing - Alfa Romeo Forum
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(Post Link) post #1 of 3 Old 24-10-01 Thread Starter
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Join Date: Mar 2001
Location: Scotland, UK
Posts: 39

Member car:

155 1.8 16V

Inlet Valve Timing

Hi Guys,

Does anybody know what the inlet valve timing should be for a 1.8 16V? I found details on the 2.0l which are:-


Retarded timing

- opens 3 BTDC

- closes 51 ABDC

Is the 1.8 the same?
The reason I'm asking is that I recently changed the cam belt and variator and was surprised to find the intake cam wheel mounted on slots i.e. completely adjustable. I did mark the cam before I started but although the car runs fine and pulls like a train (now that the variator is working) it doesn't sound right at high revs, especially on a trailing throttle.

Any help with the numbers would be greatly appreciated.


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Simon Atkinson
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Hi, The figures for the 1.8 16v out of the manual are:

Intake: Opens -3 deg before TDC (with the variator engaged 22 deg before TDC). Closes 51 deg after BDC(26 deg before BDC with variato engaged).

Exhaust: Opens 47 deg before TDc and closes 4 deg after BDC.

These are the same as the ones you found for the 2 litre. However, according to my manual the figures for the 2 litre are:

Intake: Opens 0 deg before TDC (25 deg before TDC with variator engaged). Closes 55 deg after BDC (30 deg before BDC with variator engaged).

Exhaust: Opens 50 deg before TDC. Closes 8 deg after BDC.

All the figures are from the TS 16v supplement.

Hope this helps,

(Post Link) post #3 of 3 Old 25-10-01 Thread Starter
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AO Member
Join Date: Mar 2001
Location: Scotland, UK
Posts: 39

Member car:

155 1.8 16V

Thanks Simon,

Interesting the differences in the numbers for the 2.0l. It seems the Alfa website and Alfa manuals do not agree, surprise, surprise. Although the website also states that cam drive is by chain so maybe those numbers are for the old twin cams by mistake.

I noticed that you had a "-" before the 3 degrees for inlet opening in your post. Does this mean "minus" i.e. inlet opens 3 deg AFTER TDC? This may sound strange but also on the website it states that the variator swings by 25 degrees so if full tilt is 22 deg before then no tilt would be 3 deg AFTER. Usually inlets open before TDC but when I was timing up my engine the inlet was still closed at TDC. This I thought was strange and hence the reason for the post in the first place but if we add up all the clues it would seem to be correct - inlet opens 3 deg AFTER TDC.

Many thanks for your help, looks like it's set up correctly after all.

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