I think I fixed it! took carb apart and moved all components from 600 cfm to my 500 cfm (it's only primary venturies, jets and metering rods). I changed my vacuum spring 4 hg/inches. While it was apart I removed the fuel/air bleed screws and gently blew compressed air through the openings. Put everything back together. Got it started, backed off idle just above 900, put it in drive and it dropped to 700 and did not stall. Plus it just idles like a different car, still has the lope but a lot tamer. Remember I have this 4 point manoeuvre to get my car into my garage, it stalled three of four time last night before I got it backed in there. I remove my plugs afterward and the tips were as white as snow...not getting enough fuel to keep it alive. I will dial it in with vacuum gauge tomorrow.
Well Maybe it's not fixed, best I could muster in drive with hand brake on & frt wheels blocked at 760 RPM was 9 HG. It runs stronger with the carb mods I did but not as crisp as I would like. I will go down to the next smaller jet size that I have and see how it runs. My initial timing was only at 2.5*, I increased it to 8-10*. I will try increasing it a couple more degrees. In the end if this is the best I can do with this cam and that my converter does not have the right stall and my gear ratio of 3,23 is not steep enough I may just go to a milder cam when the snow starts to blow. I also have access to a really good carb guy.He is an engineer at Ford and he tunes on weekends. He has people lined up every Saturday. He did a great job last time I used him. Maybe he can get to the root cause if there is one.
Re: The final chapter Well fellas, I did some research and looked at various cams applications on line. If my reground cam truly has 255 duration @50, that definitely explains all of my idle challenges. This engine shakes like a hoola dancer. Even in the most aggressive cam applications I could find NO ONE that makes a cam for a 300 with that type of duration. I will contact ISKY or CROWER next week and have them select a cam for my application. For now I will stick close to home with the Buick and do the cam swap on a rainy day. Cheers.
Re: Miss on #1 plug... (UPDATE) UPDATE: It's been a while since this post. We pulled the cam, replaced the fried cam bearing, put in a milder cam, file fitted new rings then discovered the block was cracked. Car now has a 340, break in went really well, sounds great, but had this issue with idle again, way to similar to issues discussed in this thread. So I removed the air/fuel mixture screws and look what I found. For the life of me, I don't know how I missed that, I had those screws out before, I guess I just never really looked at them!!!!
It looks like the screw was screwed in too far and it broke off. That probably means the pointer on the end of that screw has made the hole bigger in the carb. I would get rid of the carb. You will never get the metering right with that side of the carb.
I agree, i a would not use that carb again! I also agree that it was likely broken last time you turned the screws all the way in then backed them out. The seat area is very easy to damage and once it is the carb will never idle well. You could try a new screw, and see how iot works... No harm in trying. I would just call Ken at Everyday Performance have him build you a Q jet and be done with it. Now that you have 340 CID it would love the Q jet!!!
Hard to tell without them laying side by side. Either the bottom one was so damaged that it doesn't look like its former self, or those aren't the same screws. The taper of the top one looks greater thant he bottom and the head thinner. May just be the angle.
They are not identical. One is broken, the other one is not! It's just the angle. I will still give it a shot and see how much vaccumm I can pull out of it. I think worse case is maybe drivers side only gets one turn vs 2.5 turns on the passenger side.
You can check the diameter of the holes where the idle mixture screws go with a good set of drill bits to see if the one was changed. If it was, you can try to fill it with a small amount of epoxy or JB Weld, then redrill to spec.
