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Opel Key Master
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Discussion Starter #1
I just put in the combination cam and chevy valves in my 1.9 engine. Timing seems correct, but I cannot keep the engine idling without keeping the butterflies to the choke closed. I changed the gasket under the carb, doped the threads on the intake manifold, and still runs rough. Tried to richen up the mixture, but wasn't any better. Could it be caused by the booster? Any ideas?
 

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Super Moderator
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13,583 Posts
What is the rpm the engine is idling at? Above 1200 or so rpms, the main circuit is coming into play, so adjusting the idle mixture does absolutely nothing. What is the ignition timing set at? Stock will not do in most cases with an aftermarket cam. Do you have specs on this "combination" cam? I could suggest an alternate timing curve perhaps. It could be a vacuum leak elsewhere, have you tried a vacuum gauge on it yet? If you drop below 15" @ idle, the power valve will also fluctuate, and that must be modified for correct idle quality and power progression. Just need a little more input in order for me to correctly diagnose it. Out of curiousity, do you have the higher compression pistons in this engine?

Bob
 

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Super Moderator
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I should also have mentioned that if the cam timing is retarded one tooth off, it will have symptoms similar to what you have described.

Bob
 

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Super Moderator
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1,798 Posts
Which carb are you running? If you are using a solex still you may need to change the thick base gasket with all the holes in it. For troubleshooting you may want to remove and plug the brake booster line all together. One more thing to check would be to make sure you didn't swap the 2 vacuum lines from the distributor. I've done all of these things and more, Opels love to be loved.:D
 
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