Question about buying Carter BBD for my 318 (unless I should look at something else)
Engine warm, choke fully open, all vacuum ports plugged. idle speed set at spec, idle mixture screws set to smooth idle (or maximum vacuum). It probably won't get any better than that. What's your base timing set at with everything I mentioned correct? Things that may cause poor idle that you can't adjust to make it better, loose timing chain, Worn cam lobes and lifter faces, valves not seating (worn guides, valve margins and seats), intake vacuum leaks, Power brake booster vacuum leaks, the list can go on and on.
Cold compression test gives 150 - 160 PSI.
Engine warm, choke fully open, carb is on low speed cam screw. I can get 17 inches vac at 500 rpm but it's a not a smooth even idle, needle fluctuates about 1 inch (so maybe 17 to 18 bouncing vac reading). I can get 22 inches at about 1200 - 1400 rpm.
I'm measuring vac by disconnecting big line to the brake booster and using adapter to go straight to the guage. Only 2 other vac ports (distributor and choke) and they don't leak.
You're going to frown when I say I haven't timed it (timing gun not handy) but I would have set it ages ago to the best timing, probably 10 before TDC. If I advance it from where it is now, even just a little, rpm's go up a little, vac goes up to 18, but I get lots of pinging when driving. This is 87 octane stuff, probably some ethanol in there, maybe 10%.
Plugs are new (RN14YC) but are now sooty / black and only have about 15, 20 miles on them.
Have changed the coil (another old coil, but it meters out to spec) put in new points / condensor, new ballast resistor. Have measured the dwell, it's right on spec at 28 - 30 degrees. Wires are silicone 500 ohms/ft 20+ years old. I have swapped in a new set of wires (NGK 53420 also 500 ohms/ft) and a new cap (blue streak, brass contacts). None of that has evened out the idle, no perceptible change.
Does dual-plane intake make carb idle performance more critical? Idle performance of both barrels must be better matched to give smooth idle - and more importantly, no plug fouling?
>I wouldn't buy one of those carbs. I would rebuild the old one.
>If you aren't comfortable doing it yourself have someone do it that does.
Easier said than done. I doubt there's anyone within 200 miles of me that would take a crack at these carbs. And even if there was, how would I find them?
