One really nice thing about these older engines is that, if they are left relatively stock, they are very easy to diagnose for difficulties.
Changing multiple items (aftermarket carbs, aftermarket manifolds, aftermarket ignition, etc.) opens up several degrees of uncertainty.
I realize you probably have done much of the following, but still a good idea to do in order rather than just throwing additional parts (read money) at the issue.
(1) compression test - absolutely nothing you do to the ignition or carburetion on an engine with low compression is going to help. Eliminate this unknown first!
(2) ignition TEST!!! If the ignition is STOCK, very easy to test the entire ignition system by hooking it up to a good diagnostic oscilloscope. ABSOLUTELY NO NEED TO GUESS! THE 'SCOPE WILL TELL YOU IF ANYTHING IS WRONG AND WHAT IT MIGHT BE! You have/had a pertronix (note the small "p"). The very first question we ALWAYS ask if a new customer calls with a "carburetor" issue is: "Have you installed a pertronix?". If the answer is yes, we highly suggest putting the ignition BACK TO STOCK at least for testing. THREE OUT OF FIVE CALL BACK THAT THIS FIXED THE PROBLEM! We have found that upgrading to an alternator (more stable voltage) seems to help with the pertronix problems.
(3) Idle vacuum test. Once the ignition system is found to function normally in all facets, checking for idle vacuum (if the engine runs) can be a clue to issues.
(4) Fuel delivery system test. Doesn't sound like this is your issue, but I learned to do tests in order, and that way you can eliminate issues as you go.
(5) Carburetor. I won't say anything bad about the CW carbs (I won't say anything good about them either!). But for testing purposes, should you still have an original manifold and original carb; installing for a test will tell you if the carbs you are currently using are faulty, or if it might be something else.
An engine not functioning normally can be a very frustrating experience (IF YOU LET IT). But use a systematic approach to the problem with TESTING instead of replacing parts, and you WILL find the answer.
And one other comment about installing "new" parts: JUST BECAUSE A PART IS NEW DOES NOT MEAN IT IS NOT FAULTY!!!!! This is especially true of todays offshore parts, even if they are in a recognizable box! Run the tests!
Jon.
