Cam timing - In The Car!
 

For a stupid reason I need to re-do the cam timing on my '86 930.

The engine is in the car and I'd rather not pull it if I have to.

Questions:

1) Can I do the timing without removing all the rockers except the #1 and #4 ones I'm using for the timing? e.g. by backing off the adjusters all the way on the others

2) Can I use the exhaust valves on #1 and #4 instead of intake, since there isn't enough room for my dial gauges to use the intake side?

3) If #2 is yes, what adjustments to I need to make to the procedures and measurements?

1986 930 with Dougherty SC30 cams.

Right now I have a jack stand under the engine and the rear axle stubs with the exhaust, engine carrier, rear sheet metal, and chain covers off.

1) Don't back off any rockers, just verify that the valve lash is 0.004"

2) Never tried it that way, but it's possible if you know the spec. Another option is using a different cylinder on that bank and the corresponding mark on the crank pulley, if that would give you more clearance for the dial indicator on the intake side.

3) Call up John Dougherty and tell him what you're trying to do, he will likely have a spec that you can use.

Using a diff cylinder and mark would work, but its simply that I don't have room to mount my dial gauge on the zblock anywhere inside the engine compartment but loads of room underneath.

I was thinking I'd back the adjusters off to relieve pressure on the valve springs that would otherwise be attempting to rotate the cam in the housing. Maybe my mental picture is off.

FWIW its actually only the RHS I need to do. Replaced the cam sprocket gear.

I checked with John. At TDC overlap, accounting for .1mm clearance on the rocker, I should have 1.0mm valve lift on the exhaust valve.

Since I actually only have to do the right hand side, I can measure the left hand side to validate this number. I know I had 1.831mm lift on the LHS intake at TDC overlap.

Following


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I resealed the chain boxes in a 2.7 this winter with the engine in the car. The owner wanted the rear bumper off the car to repaint it, which once removed, gave me a ton of room to work. Timing was just as straightforward as on a stand. I verified .1mm rocker gap, mounted the z gage and went to work. As for timing off the exhaust side, let us know how that worked out!

That's pretty cool he knew the exhaust valve lift at TDC overlap.

No room on a 930 left side. Engine out unless you're a magician.

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