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Discussion Starter #1 (Edited)
It's a 347, as follows,

Windsor Jr. heads (used)
Camshaft Innovations (used) 220/231 @ .050, 545" lift, LS 115 degrees
Hyd. roller, roller rocker (double roller)
BG Demon 650, on Air Gap intake
Mallory optical shutter electronic ignition

Symptoms:
Starts and runs with no unusual noise, but needs at least 20 degrees advance to idle.
The left bank is fine. Cylinders 3 and 4 are either not firing or misfiring.
The right bank is "cold" at the exhaust pipe, the left bank is both hot, and MUCH stronger exhaust output. No oil smoke. Normal amount of water at exhaust, none after warm up.

History:

It was running like this (not quite as bad) when I quit driving it last fall and started the build. Was running a Pertronix at that time. Switched back to points system did not help. Changed coil. Assumed I may have jumped timing, but that was not the case when I opened up the engine. It went from running great to dying in traffic in about five minutes........ a couple of misfires, and then nothing....dead. I blamed the Pertronix at the time, but not at all convinced of that now.

I had an "incident" during the build. Put on the right head during the mock-up, got a phone call, came back to the shop, and rolled the engine over to get a better angle to put on the left head. When interrupted, I forgot to put a couple of bolts on the left head, and when I rolled the engine, the right head crashed to the floor.....thank GOD I was working on the opposite side, or that would have been a trip to the ER! It couldn't have landed worse......right on the valve stems. I was sick when I looked at it.
Pulled all the valves and rolled them on a piece a heavy flat stock to check for any obvious damage.....they all looked fine, and buying new heads was out of the question at this point, so I reassembled them and built up the engine.

The engine runs better the higher the RPM....there is no popping through the carb at any rpm (up to about 2700 or so), which tells me that the valves aren't sticking (?).

Compression on the left bank is 172 average, but on the right side, 3 and 4 are only 145, with 156 on 1 and 2. I am POSITIVE that I am on TDC on the compression stroke.
I have tried both the Mallory elctronic ignition, and the old points dizzy, and there is no difference....both produce exactly the same result. The only common thing is the plug wires, which are eight years old, but with less than 1K mile on them.

I'm quite certain that 3 and 4 are not firing because the new exhaust manifold has not discolored on those cylinders, while it has on all the others. The plugs on these two cylinders look like it's in a very lean condition.....just barely discolored (ligh gray). I even pulled out the 1" spacer under the carb, thinking it may have been starving those cylinders somehow.......no difference.

I know that the head incident is suspect, and I may very well end up tearing off the top end and rebuilding that head, but I'm hoping you all might have some ideas before I go to all that trouble, or a way to test, for certain, that that head is the issue here.

BTW, the compression readings were taken after three compression strokes on the gauge.

Sorry for being so long winded, but the background info is germain to you folks troubleshooting this whole deal.

Thanks so much!

Tom
 

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If the header tubes for 3 and 4 are stone cold they are not firing. If they are warm but not as hot as the other tubes then they are misfiring. Do you possibly have the plug wires for 3 and 4 mixed up?

Have you adjusted the idle mixture screws on the carb yet. If the screws are not set the same you can get different air/fuel ratios on the different banks of the engine. Check this along with your valve lash to make sure that they are set correctly.
 

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Discussion Starter #3
Ryan,

Tripple checked the plug wires.....all in the right place.

Those two ports are warm, not stone cold.

The carb/intake are new , right out of the box.....I have not touched any of the adjustments. I should check the manifold vacuum as well.
I am getting some backfiring through the carb during cranking, but again, I'm positive I'm not 180 degrees off.
I've had enough pinishment for one day......I'll check the idle mix and vac tomorrow.

Thanks!

Tom
 
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