NineMeister

I'll make this easy for you.

It's a road engine, so keep it simple.

The last thing you need is to have a breakdown in the middle of nowhere and not be able to find a garage to help you put it right. Everyone understands factory systems so leave them be. Get a 1979 non-vacuum advance distributor, have it re-curved to suit the engine (probably 25 degree total advance, 5 at idle and 30 at 6000rpm) and run the stock CDi on single plug.

On the rally engine above I modified small port turbo heads to get the big increase in mid-range torque. 911 Carrera CS intake valves and 930 exhaust valves are the lightest, use stock springs and stock rockers.

theiceman

guys i have been following this thread with great interest , Especially Colin's comments about the timing , which is about the only part that intimidates me a little. I have a couple of questions about it .
1. when you get the engine to TDC is there a special tool that locks the crank in this position ?
2. when you are actually turning the crank and viewing your dial guages on the cam , how is the chain tension set ? as the tensioners will obviously effect the timing , and there is nothing feeding the tensioners while the engine is out. Is the static tension of the tensioners acceptable ? .

and one follow up question ( not related to me ) if you had the old mechnical tensioners ( on say an old 2.4 or something ) . how would you adjust these before doing timing ? as if i follow the same train of thought they will affect timing also .



Thanks Guys

NineMeister

When adjusting the cam timing on any 911 engine you need to use either mechanical or spring pre-load tensioners in place of the hydraulics.

The crankshaft is not locked in position as you need to rotate the engine to find the correct lift. The traditional method is to use a degree wheel on the crankshaft and use a piston stop in a spark plug hole to locate TDC of #1 cylinder. Then with a dial gauge on #1 intake valve retainer you can measure the lift at TDC to set the timing.

The modern method is to use digital rotary and linear sensors to do the same job more accurately.

theiceman

That's good info Colin thanks

When I was practising. With a buddy we put a plstic dowel in cylinder one and rigged up a rudimentary dial so we new we were at tdc. Then set op a dial guage on the cam. The problem came when tightening down the nut. It would always move somehow.
We were using spring loaded testioners. But I thought the older ones were adjustable. If they were I wouldn't know where to start.

NineMeister

Exactly. You set up the cam, you tighten the nut, you measure again. If it's out, you slacken the nut, set it slightly off, tighten again and see if you got it right.....

.... two hours later you do the same for the other side......

.... 4 hours later you have both cams dialled in within 0.03mm of each other.