Re: Chasing Rough idle...compression?

Posted by Mike On 2011/5/25 21:04:03

I've missed a lot while being gone!

I have a baby coming in literally 2-3 weeks, so my time to try your suggestions is thin, but i do read and appreciate them.

Looking at the straight eight wire setup, they're just going to touch. Easy enough to test though, i'll run the coil wire through a small run of rubber heater hose and spread the rest apart with clothes pins. I'll give that idea 1 2% chance of working but since it'll take 10 minutes and no money to test, i'll try it.

Let's address the other ideas:

Timing - damn near perfect but i have to adjust dwell yet so that could change, and is still suspect then

Advances - both distributors ran great in my 288. Engine ran without a hitch. Seems to advance correctly with timing light, not likely.

Point gap and condition - points new but i installed, still suspect

Plugs - all brand new, 2 new sets, triple checked gap.

Ignition wires - brand new set of yellow braided solid core spark plug wires from kanter. If they're bad fred i'll let you know :)

Coil weak - unlikely, umpteen coils later, no issues


Carb linkage adjusted wrong - possible, but for rough idle? I'd think idle mixture wrong more likely? It's idling at the right RPM, not like the idle screw is too low. Just roughly at the right RPM.


low compression - perhaps but you guys weren't feeling that with the numbers i turned in.

MY ADDITIONS:
Choke not opening - starts RIGHT up cold, when engine warmed up choke blade is vertical.

Manifold butterfly stuck closed - actually held with spring so that it's not warming up the intake when car is cold. Parts to fix to factory were missing, don't feel it's contributing to the issue and should help if anything.


Restriction in mufler/exhaust system - car ran great before engine swap at damn good speed, and i have a small exhaust leak at muffler but doubt it's contributing.

Air cleaner dirty/restricted - just remaned. Clean as a whistle and free flowing and pretty.

Not to keep two threads going (with the removing hot spot), i'll report back here and not there:

I'm going to install new bushings in both distributors.

I'm going to quadruple check point gap, and then dwell, and then timing.

If that doesn't fix, i'll try spreading the wires and protecting coil wire just to try it.

I'll check to make sure advance is working again.

If that doesn't fix it i'll stop working until after the 4 bbl is on it and start focusing on fuel/mixture/adjustments to see where that gets me.

Re carb:

"One possible source of a rough engine idle is carburetor jetting. Not sure if this particular carb has a removeable jet for idle circuit or not but if it does that mite be one source of the rough idle problem.

Since there was some evidence of high speed 'breathing' problem it could also be that any high speed circuit jets of the carb need to be larger."

Yes BUT the 288 and 327 are so close that, on the idle circuit, they should be using the same settings and running smooth at a warm sitting idle.

The high speed breathing is likely, however, because i'm using a 288 jetted carb and 288 intake manifold for the moment. If jetting or the carb is the issue, the 4bbl wcfb will likely solve it.