I will preface this with I’m not an engine expert. However my first few thoughts are, factory spec is 18° BTDC as you mentioned. That said, these cars rolled off the assembly line and idled just fine. Something has to be amiss to cause your high idle. Second, obviously idle can change depending on ignition timing but I feel like you’ll be chasing yourself in circles and putting a bandaid on a bleeder if you’re attempting to set idle by altering timing.
That said, I know you’ve been through this before but refresh my memory, have you eliminated all vacuum components to test your idle? That may give you a good starting point if not. Pictures and video are worth a thousand words sometimes. I seem to recall you, or someone else, questioning your timing mark. Ever verify it is correct?
Random thought, you’ve attempted to adjust via the idle screw but have you checked how tight the throttle cable is? Ever try disconnecting it to see if your throttle closes further? Just trying to brainstorm. And I don’t pretend to be smtarter than Cliff, or a lot of people. He’s far more knowledgeable than I am with these engines with personal experience driving that knowledge. You should remember though, with the exception of modern gasoline being of different quality than 1977, there’s no reason why a stock setup engine shouldn’t run with factory settings. Just some thoughts to start things off. Not everyone may agree with me and that’s ok.
I should say the car runs absolutely perfect and idles great I just have a small hesitation when it comes to coming on and off accelerator notably when trying to smoothly shift or coming to a stop, WOT banging gears it runs perfect, which I assume is cause my throttle is set to completely close, closing off transfer slots, very small issue. Through research I found squaring the transfer slot is what people say to do to get the best performance, I am wondering what stock configuration was off the assembly line, cause technically it does hit stock specs but this is with throttle blades completely closed.
Yes, that was me questioning my timing mark, I checked and it is accurate, harmonic seems to be good. Although, I will verify mech adv is working properly, and verify total timing now that I know how.
I checked almost everything in terms of a vacuum leak, the only symptom of a vacuum leak I have is a slightly high idle compared to where the throttle is +50-150 rpm. All the lines seems to be sound, closing choke blade will kill the engine pretty quick, I never checked things like the TVS, EFS, EFS check valve, unsure of a safe way to check, I assume the carb wouldn't run the same with everything removed. In terms of throttle cable/blades, I had them re-bushed and rebuilt by Cliff, so I assume they are as close to good as they can get. Throttle physically can't shut anymore, throttle cable has enough slack to not pull and the return springs are still pretty tight. Only issue there is my blades are deteriorated and letting too much air through, I would assume Cliff would tell me this though.
Any input is good input, I know the least of anyone here so anything is helpful. 2 out of the 19 years of my life have been dedicated to this car so far, accumulating what ever I can find online.
After a few hours of research I think I am going to abandon the idea of changing the timing, low end would most likely take a hit due to low compression, 18 degrees is needed to make it feel snappy off rip. Although, I am still willing to hear what people have to say.
