#1 cylinder not firing

[trent_tweeter]

1977 Johny, 175 V6. Compression 95 #1, 100 all others. Usually runs on 5 of 6. #1 plug wet, all other plugs look good. New plugs(surface gap type), had conventional plugs when purchased and problem existed. Switched #1 plug , coil, and lead, from powerpac to # 2 cylinder and all # 2 cylinder stuff,from powerpak on, to #1. Still # 1 cylinder missing or not firing whatsoever. After a long run 15 min. switched #1 plug with #2 plug. Ran better but still misses. Are the left and right powerpaks interchangable? Is it possible that the powerpak is to blame? Seems that primary to # 1 is weak or nonexistant. Is compression difference an issue? Motor runs great other than this problem. Just added a teltale to the top of #1 cylinder. Any suggestions would be appreciated.
Regards,
Peter

 

[emdsapmgr]

Re: #1 cylinder not firing

Yes the powerpacks are interchangeable on this engine. It is a good way to troubleshoot the ignition system between the two heads. Your compression is only slightly low, from new-but certainly your compression is ok and the engine should run fine. The 5# variance between #1 and the others should not an issue. If your #1 reading is with some oil addded, it will affect the true compression reading somewhat. Adding oil to a cylinder during the compression test can influence your numbers higher. As soon as some fuel enters the engine, it will wash out that excess oil and the compression will return to it's "normal" reading. You should base your engine findings on a "normal" reading.

 

[trent_tweeter]

Re: #1 cylinder not firing

Thanks,
Tomorrow I will swap powerpaks and see if problem moves to other bank of three. Compression was done on cold engine with no oil added.

 

[trent_tweeter]

Re: #1 cylinder not firing

Compression #s were achieved on cold engine with no oil added. Swapped left and right power packs. Problem is less noticable and seems to clear up after running up the revs. Is it possible that a power pack may have only one flakey output to a coil? How good are the Sierra packs? They are certainly less expensive than the omc brand.