50jetback Posted June 24, 2018 Share Posted June 24, 2018 This is a query received by our local club - anyone have any suggestions as to what may be happening here? " I am having difficulty with my Buick. The motor in my 55 Century is a Nailhead V8 322 CID. The vehicle had an ignition problem and it will run but struggles under load. My timing light shows that the 4 cylinders on the RHS all spark as should. However the 4 on the LHS show that they break down intermittently or sometimes don’t spark at all. I have replaced the Distributor cap, rotor button, points and condenser, leads and spark plugs. To no avail. However when I changed back to the old rotor button it improved slightly. I have spoken to friends who are mechanics and have tried advancing the timing etc. They both said it is very strange. Any suggestions at this point would be appreciated ." Anyone heard of a similar problem? Link to comment Share on other sites More sharing options...
old-tank Posted June 24, 2018 Share Posted June 24, 2018 compression check; vacuum gauge readings; plug wires resistance? 1 Link to comment Share on other sites More sharing options...
hchris Posted June 24, 2018 Share Posted June 24, 2018 5 hours ago, 50jetback said: This is a query received by our local club - anyone have any suggestions as to what may be happening here? " I am having difficulty with my Buick. The motor in my 55 Century is a Nailhead V8 322 CID. The vehicle had an ignition problem and it will run but struggles under load. My timing light shows that the 4 cylinders on the RHS all spark as should. However the 4 on the LHS show that they break down intermittently or sometimes don’t spark at all. I have replaced the Distributor cap, rotor button, points and condenser, leads and spark plugs. To no avail. However when I changed back to the old rotor button it improved slightly. I have spoken to friends who are mechanics and have tried advancing the timing etc. They both said it is very strange. Any suggestions at this point would be appreciated ." Anyone heard of a similar problem? Not familiar with this engine but, does it have dual point ignition ? Aside from this I can see no reason at all why one side of the engine would fire but not the other, you say it " had an ignition problem" what was the problem ? Link to comment Share on other sites More sharing options...
Fr. Buick Posted June 24, 2018 Share Posted June 24, 2018 Oil leak from the rocker cover that gets into the plug holes? If the cover is bulging out of shape, a common problem, put it in a vice to bend the edges back into a traight line. 1 Link to comment Share on other sites More sharing options...
Aaron65 Posted June 24, 2018 Share Posted June 24, 2018 Is the distributor shaft wobbling in the bushings? Link to comment Share on other sites More sharing options...
195354 Posted June 24, 2018 Share Posted June 24, 2018 Run tests old tank recommends and report results. Also follow recomend routing for the plug wires they could be cross firing. Have you ran the engine in the dark you might see spark jumping around. Please let us know what you find Steve Link to comment Share on other sites More sharing options...
Aaron65 Posted June 24, 2018 Share Posted June 24, 2018 Just to add to my post, it looks like three of the four cylinders on the left side of the engine are fired by the left side (facing the front) of the distributor. If it had a lot of distributor wear, it's possible that the points aren't opening and closing correctly. 1 Link to comment Share on other sites More sharing options...
195354 Posted June 24, 2018 Share Posted June 24, 2018 Another thought l have is check voltage to ballast resistor running also output voltage to coil. I am traveling and cannot check needed input and outputs in a manual. If you have required input voltage unhook it and put a load on the wire. I have seen voltage and no amp capacity. A led test light can and does send you down the wrong road. I have a head light with alligator clips to test a circuit and confirm it will carry a load this might be to large of a load for this circuit. Using a1157 bulb if you test it might be a better option. Link to comment Share on other sites More sharing options...
old-tank Posted June 25, 2018 Share Posted June 25, 2018 Check dwell at all engine speeds. Also be sure the distributor cap is seated. Some of the currently available replacement caps fit tight...so tight that you have to seat with dowel. 2 Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 25, 2018 Share Posted June 25, 2018 On 6/23/2018 at 10:31 PM, old-tank said: compression check; vacuum gauge readings; plug wires resistance? Second compression check on the affected cylinder Link to comment Share on other sites More sharing options...
50jetback Posted June 27, 2018 Author Share Posted June 27, 2018 Thanks for the responses so far. I can't add much more at the moment. The person inquiring is a F.I.F.O ( fly in, fly out worker in our mining industry - many of our mines are in remote areas so workers will be flown to the sites and live in camp conditions working 12 hour shifts for maybe 14 days and then flown back home and have maybe the next 7 days off ) and is at present on site so I haven't had a chance for further discussion as yet. In general terms he has told me he has tried the obvious - new plugs, plug leads, compression test ( all within 5% ) but I will get a more definitive list from him during his next time home. I did ask about distributor wear and he said it was worn on the shaft/bushings. I had thought this wear would have resulted in a more generalised misfire across both cylinder banks but Aaron 65 information indicates it may be more noticeable on the left hand bank and I would be interested in further thoughts re this - Willy?? In the meantime I'll keep compiling the list of your suggestions so Rob ( the inquirer ) can spend some quality time in the garage with his Buick on his next break. Link to comment Share on other sites More sharing options...
Beemon Posted June 27, 2018 Share Posted June 27, 2018 Compression check within 5% of what range? A worn down engine can have equal compression but still not enough to fire off. Link to comment Share on other sites More sharing options...
Aaron65 Posted June 27, 2018 Share Posted June 27, 2018 Quote 7 hours ago, 50jetback said: I did ask about distributor wear and he said it was worn on the shaft/bushings. I had thought this wear would have resulted in a more generalised misfire across both cylinder banks but Aaron 65 information indicates it may be more noticeable on the left hand bank and I would be interested in further thoughts re this - Willy?? My thought on this (and I don't own anything with a Nailhead) is that the points' opening and closing is a game of thousandths of an inch. If the bushings are worn and the shaft wobbles to one side of the distributor based on cam gear load, it's possible that the distributor cam doesn't engage the points as far on the opposite side of the distributor. A good test might be to tighten up the points a few thousandths to see if it gets better (and afterward loosen them, because I suppose the opposite could be true, that they're opening too much on one side). 1 Link to comment Share on other sites More sharing options...
NTX5467 Posted June 28, 2018 Share Posted June 28, 2018 It might be possible that "wobble" of the shaft is an issue, BUT I highly suspect that the spring load of the point's rubbing block on the distributor cam will probably minimize any wobble from bushing wear. Reason I say this is that when examining and electronic ignition distributor, there was very little lateral movement of the rotor, quite less that expected. In comparison to a point-style distributor, there's always a load against the distributor cam by the ignition point's rubbing block. When the lube for the rubbing block goes away, "wear" on the lobes of the distributor cam AND the rubbing block happen, which affects point gap AND ignition timing. If the dwell can be adjusted "in spec", but the point gap is NOT "in spec", or vice versa, you'll most probably find wear on the lobes of the distributor's cam. Once, I had that situation on a distributor. Not pleased with the dwell, I got a dial indicator to set the points with (distributor removed from the engine). As I checked EACH lobe, I found more variations between them than I ever expected! Most cylinders had a unique point gap AND dwell, which also meant each one had different spark plug firing points. I was surprised! NTX5467 1 Link to comment Share on other sites More sharing options...
Aaron65 Posted June 28, 2018 Share Posted June 28, 2018 I picked up an old Sun oscilloscope from a local dealer for $50 a few years ago, and I'm able to check dwell variation pretty easily. My Dart's old distributor had something like 6% dwell variation, compared to 2% for the used Chrysler electronic distributor that came with a used engine I bought. Either way, as mentioned above, a dwell check is also in order as points plates can wear out, distributor cams can wear, etc., etc... 1 Link to comment Share on other sites More sharing options...
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