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-   -   Cam timing hypothetical (http://forums.pelicanparts.com/911-engine-rebuilding-forum/325038-cam-timing-hypothetical.html)

dfink 01-15-2007 02:53 PM

Cam timing hypothetical
 
While first timing my cams I had both #1 and #4 cylinder opening on the same revolution. I realized my mistake and corrected. My question is however would the engine run this way though very poorly.

dtw 01-15-2007 03:59 PM

If you're not banging valves on the right bank, the engine will more or less run on the left bank. It'll sound terrible and the car won't get out of its own way, though.

Eagledriver 01-15-2007 05:26 PM

It will not bang valves as long as the overlap setting was correct. It will however only run on 3 cylinders unless you can get a dizzy that fires 2 cylinders at the same time.

-Andy

Walt Fricke 01-15-2007 09:21 PM

Easy - any waste spark system would do that.

Instead of three pulses per revolution you'd have what - 1 for one rev, and 2 for the next?

But would this really work? Generations of us have differentiated cams by the L shape and the rabbit ears.

Not that I'm going to try.

2.7RACER 01-16-2007 08:28 PM

You will have a three cylinder motor. Either the right side will work or the left side will work. Rotate the distributor rotor 180 degrees and you'll get the opposite 3 cylinders to fire.
There is a post from several months ago where a guy bought a poorly running 911 and discovered the cams were not timed 360 crank degrees apart. He rotated one of the cams 180 and had a great running 911 for a fixer upper price.

dfink 01-17-2007 06:28 AM

So in theory (and believe me I am not going to do this) it is only for discussion purposes. If you had a dual plug dual dizzy system you could re-route the wires and have a dual three cylinder system. What would this do to the torque of the engine having two cylinders pushing at the same time.

2.7RACER 01-17-2007 06:42 AM

Probably break the crankshaft.

john walker's workshop 01-17-2007 07:09 AM

so that's what the problem was, eh?

dfink 01-17-2007 08:37 AM

I wish I had a twin plug twin dizzy to screw up no such luck. I did almost make this mistake while timing but corrected it before ever putting in the additional rockers so I don't even know if it would have turned over with everything connected. It would turn 360 with only the #1 and #4 intakes.
Again this is just one of those things that when you almost screw up you wonder what would have happened. It sounds like it would run this way.

Walt Fricke 01-17-2007 11:50 AM

Might sound like a Harley?


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