jays55

Posting this for anyone who has done a Pertronix distibutor conversion to replace their original point/condenser...... On a recent start up. my '70 454SS had a distinct miss. I removed the spark plugs and the #4 plug was wet. I checked the #4 plug wire and was getting no fire at the plug. I removed the #4 wire at the distributor and there was no spark from the distributor. I replaced the distributor cap and rotor. Still no spark at #4 cylinder. Not knowing were to go next (and after posting on the forum), I contacted Pertronix to see if they had any idea what could cause this miss at a single cylinder. The tech immediately suspected the Pertronix magnetic ring of having damage, or a thrown magnet. Without hesitation, he offered to send me a replacement magnetic ring. When I received the replacement magnetic ring, I removed the distributor and, sure enough, the insulating material below the #4 magnet was torn. I replaced the ring and the car runs like new! For anyone else who has done this upgrade and is experiencing a non-firing cylinder before the distributor cap, here is the likely problem. This would be difficult to diagnose without this info. Below is a pic of the old magnetic ring (left) and the replacement (right). Also a link to the youtube video on converting the distributor..... Installing PerTronix 1181 Ignitor or 91181 Ignitor II into standard Delco Remy Distributor - YouTube

Replacement ring arrived from Pertronix. Pulled the distributor and the ring had a rub/tear in the material below the #4 magnet! Replaced the ring and now car is running great again! This is "must-know" info for anyone running a Pertronix electronic conversion. I will create another post about this fix, so it will show up better in searches. Thanks everyone for your help.........

OK, I just called Pertronix and did get through to tech help this time. He said the kit's ring that goes under the rotor has 8 magnets. He seemed sure one of the magnets flew off. Without hesitation, he is sending me a replacement ring, so I can fix it when I pull the distributor. On hold until that part arrives, but very hopeful. I will update, as this would be great info for anyone having a Pertronix unit to know.........

Thanks for the great input. I am a long-time "shade tree" mechanic, so I keep hoping I'm overlooking something obvious! Pulled the #4 plug wire and attached a new plug outside the cylinder. Engine running, there is no spark at that plug when held to a grounding surface. There is no spark at the distributor cap, when the #4 wire is pulled from the cap. The other cylinders have a spark when the wires are pulled from the distributor cap. Seems to me that rules out the rotor, cap, wires and plugs (all of which have been replaced since it started missing). How would a broken valve spring, or bent valve effect the spark at the distributor, if the cam is turning the distributor (7 cylinders have spark and engine runs, but with a miss)? I will probably pull the valve cover and check for a broken spring, though I would be confused how that could cause a miss-fire. I don't understand how this can be a problem with the Pertronix unit, but I did contact them and haven't heard anything back, yet.

odd .... for sure! Cap is aligned, spark on firing cylinders was white (if I remember correctly, will check again). One day is was running smoothly, the next day missing. Replaced cap, rotor, wires, spark plugs .... no improvement/change from prior. I am baffled!

Didn't check them all. At the distributor cap, I pulled #4 first, since the plug was wet (other plugs looked normal). I pulled 3-4 more wires at the cap to check them and all had spark flying. Didn't check the shaft for play, but don't know what would be normal. The only thing I did differently before it began missing, was I had the car idling for a while as I charged the A/C and the temp went up to 225-230 degrees (185 is normal). Was running smooth when I shut it down. At next startup, the miss was there. Thanks

Hi Gang, Looking for some diagnostic help with a non-firing cylinder; 1970 SS454 stock motor, updated with Pertronix electronic points replacement kit and coil in 2016 (no points/condenser). Recently began to "miss". Pulled the plugs and #4 was "wet". Pulled the plug wires at the distributor and there is no spark jumping at #4. I went ahead and replaced plugs, wires, distributor cap and rotor. #4 still not sparking at the cap/wire connection..... That's about as far as I know to go with diagnostics. Maybe a problem with the Pertronix unit? I contacted Pertronix, but haven't heard anything back. I would like to know what I'm looking for, before I start pulling the distributor, etc. Anyone have experience with one cylinder not firing and not a rotor/cap/ware/plug issue? Thanks for you input......

Valve spring replaced and problem solved! I used the "rope trick" to keep the valve in place. No other valve/rocker/push rod wear noted. Thanks for all the advice/assistance here. Interesting side note; when the #6 exhaust spring was removed, it was actually broken in two places! For as long as I've owned the car, it has had a slight noise on that side and always felt like it wasn't tuned properly. I've re-tuned it multiple times and checked for exhaust leaks over the years, but never felt it was completely "right". I suspect one of the breaks has been there awhile and the second crack finally gave it away. Car is now running smoother than ever and noises are gone. On to the FGMCC Western on Thursday, with a smile!

Back from vacation..... Pulled the passenger side valve cover and the #6 exhaust valve spring is broken. Good News, for sure! Relatively easy fix. Never had a broken spring without a significant tick, so I was suspecting much worse. Should be ready for B.C. Meet

All of the plugs on the pass. side looked the same, that has me stumped! The driver side plugs were also consistent, but slightly cleaner......

Thanks for the insights. A little more sleuthing today, based on feedback here. I put in a new set of spark plugs and checked the wires. Started the engine. As the stock exhaust manifolds heated up, the #8 cylinder remained touchable, as the others got too hot to touch. Pulled the #8 plug wire and confirmed fire to the cylinder. Looks like I probably have a dead #8 cylinder. UGH! Leaving on vacation shortly and returning with only a couple of weeks before the FGMCC Western Meet. I will pull the valve cover and hopefully find something obvious. If I have to pull the head, not likely I'll have it back together in time for the trip ...... Fingers crossed! Any other insights will be appreciated ...... thanks!

Any ideas about whether the differing exhaust temps (at the tailpipe) on the passenger side (cool) vs the drivers side (hot) means anything?

Thanks for the great feedback! I will pick up a vacuum gauge to have on hand. Since I disconnected and plugged all of the vacuum lines and there was no change, I felt an external component failure could be ruled out. The "bent valve" suggestion is interesting. I have always felt a slight miss at idle, but it never felt significant. I just did a drive around the block and I do feel a more pronounced miss/flat cylinder. The issue seems confined to the carb, or engine. But, I don't want to overlook something simple, before going into the engine....... Thanks for any suggestions!

Semi-skilled mechanic looking for some help! Stock 1970 SS454, except for Holley 650cfm carb (#80555-1). I came back from a drive and, pulling into the driveway, noticed the power brakes were hard and the engine was idling rough. Didn't notice anything while driving at speed. Vacuum Leak, right? Went under the hood and checked all vacuum lines to the carb (dist. advance, choke, PCV) and intake manifold (brakes, trans, canister, all attached behind carb). Pulled each hose off and plugged it (1 at a time) and saw no change. Noted that there was vacuum to the brake booster. Also, the PCV valve is pulsating, rather than being pulled open. Low vacuum at idle, right? Sprayed some carb cleaner around the carb and intake manifold, noticed no change. I am hearing a hissing sound from the carb (with the air cleaner off), but don't know if that's normal. A couple of other observations; I pulled the plugs and they all look even. However, I noticed the passenger side exhaust at the tailpipe is cool, while the driver side in hot. There is a heat riser on the pass side, which is functioning. That's about as far as I know to go. I don't have a vacuum gauge, but seems obvious there is low vacuum. Any ideas would be appreciated. Your help is appreciated, in advance......

Last Name: Marsh First Name: Jay Screen Name: jays55 Name Of Others In Your Party: Total Number In Your Party: 1 Home City & State/Province: Bend, OR Arrival Date: Fri, 8/10 Depart Date: Mon, 8/13 Are you attending the Friday cruise (starts at 10AM): yes Are you attending the FGMCC banquet (Sunday 4:30-6:30): yes Driving or trailering your Monte Carlo: trailer Car Year: 1970 Car Color: black Vinyl Top Color (if any): black Stock/Street/Modified/unrestored: Hotel: yes, host Email Address: jays55@earthlink.net