slap929

Anyone have any clue? Odd question I know.

Jfrahm

It really depends on the ripeness of the melon.

slap929

the humor is lost on me, lol. Anyone else? jokes are appreciated as is the information on the cam positioning.

schip43

Not really clear on what the question is?

slap929

Sorry, bad explanation . Was wondering how many teeth off of the TDC reference mark does the cam tower pulley need to be before it goes from retarding the engine to bending valves.

schip43

Hmm sounds like your prepping for disaster? I'd say the timing marks need to be exact, crank, at it's mark, oh I think the mark is on the fly wheel! #1 piston TDC, distributor ,pointing to #1 on cap.

Anyway others will know more but that's the essence. Been awhile since I've done that job.

Beware of the markings on the balance shaft pulley's , they are not very clear, they have some marks on them that are not really the alignment marks! I had mine 180 out because I used the wrong marks.

ehall

This is a good question. Also, how many teeth can it be advanced without bending valves?

lee101315

I once serviced a 951 at work that wouldnt run right, and everything had already been changed. The cam timing was retarded 3 teeth! No valves were bent, but it ran awful.

If youre going to experiment, Set the timing to where ever you want, and turn the engine by hand. If the engine turns without touching the valves, youll be ok.

theedge

From what I remember, each tooth is about 9 degrees advance or retard. Which is a massive amount. Do it properly and get an adjustable cam gear, CEP makes nice ones.

ehall

I'm not asking about this as a way to screw around with my timing. When I did the belts, I think the cam timing got set a tooth or two retarded.. I'm SUPER rich and boost doesn't hit hard until 4k. Everything else has been checked.

savvas944

i think it should be measured in degrees and not in teeth.
and only with cam vernier pulley,where it will show the max either side.
Depends also how much you shaved the block/head and piston protrusion in side head gasket volume.
There are 3 different head heights used as std in the 951 model.
Unless this is done you can look forward to disaster.
Hope it help

Chris White

You would have to be off by a lot of teeth before the valves made contact. The 951 is an interference engine – but not by much! Typically it takes a complete belt failure to bend the valves, not just a couple of teeth off on the timing mark.

Tedro951

If this is something one really wants to try, it would be easy to set #1 at tdc, then slowly rotate the cam gear and count the teeth in each direction until it makes contact.

We also could have someone remove one quart of oil at a time, to see how low it can get before it knocks....

ehall

Thanks Chris. That's what I wanted to know.

MM951

I can personally attest to the fact is you are 270* off due a failed timing belt, you will have 8 bent valves!