gprimm Posted August 21, 2012 Share Posted August 21, 2012 Ok guys, here's a mystery. Monte has been running fine after the winter redo. On Friday night I was driving and hear what sounded like a tire pop. Sitting at a stop light, heard it again. It was me!! Idling or driving it will "pop" every once in a while and is now about every 20 seconds. As if there is fuel loading in the muffler and then igniting. Changed the distributor to a new MSD and it is still doing it, but used the (existing) new wire "correction" cap with the old coil. Will try the new MSD in-cap coil tomorrow. I am thinking maybe a plug wire is bad and not igniting all the fuel and it is causing raw fuel to eventually ignite. On the left side. Thoughts? Quote Link to comment Share on other sites More sharing options...
TrunkMatt Posted August 21, 2012 Share Posted August 21, 2012 Pop in exhaust = rich, pop in carb = lean You are loading fuel up from somewhere... if you haven't messed with idle / carb than check your spark plugs and find the one that looks fouled and troubleshoot from there... the plug on the responsible cylinder will definitely show it. This website will ID issues based on how your plugs look: http://autopartsinfo.blogspot.com/2012/04/bad-spark-plug-symptoms.html Quote Link to comment Share on other sites More sharing options...
gprimm Posted August 21, 2012 Author Share Posted August 21, 2012 It was running fine as tuned for weeks. It was fine until I stopped at one light and then it started. Yes, checked the plugs and will again. I will double check the rich/lean but the exhaust smelled right. Something simple, just amazing how it was running fine and then blam, it is Chitty Chitty Bang Bang!!! Quote Link to comment Share on other sites More sharing options...
71monteme Posted August 21, 2012 Share Posted August 21, 2012 check the float level in the carb. might be stuck. just a thought. thanh Quote Link to comment Share on other sites More sharing options...
FASTSS454 Posted August 21, 2012 Share Posted August 21, 2012 I hate to mention this but check for a cam wiping a lobe, pull both covers and watch each rocker arm for equal movement. Quote Link to comment Share on other sites More sharing options...
gprimm Posted August 21, 2012 Author Share Posted August 21, 2012 O, I hope not. I even add Risoline Zinc additive just for that purpose. Quote Link to comment Share on other sites More sharing options...
Monteman1971 Posted August 21, 2012 Share Posted August 21, 2012 Maybe a valve sticking...... or I'm with FastSS on this.... but it's not constant so I wouldn't think the worst. Steve Quote Link to comment Share on other sites More sharing options...
black07ss Posted August 22, 2012 Share Posted August 22, 2012 I have no comment but I do have that chitty chitty bang bang song stuck in my head now Quote Link to comment Share on other sites More sharing options...
gprimm Posted August 22, 2012 Author Share Posted August 22, 2012 Love the "stuck in my head comment". I am going to begin looking tomorrow night. The heads are brand new Edelbrock RPMs, it idles fine so I don't think the cam is messed up (has about 4,000 miles on it over the last few years). It is so weird that it runs and "bangs". Will try wires, check the plugs, compression, coil and will call my carb guy and an engine builder. Can't wait to let you know. Quote Link to comment Share on other sites More sharing options...
Andy's Auto Posted August 22, 2012 Share Posted August 22, 2012 I hear a pop in my carb, I have the valve covers off before I post anything. My 496 in my 71 did this two months ago. Wiped the cam. After over a hundred track passes and 7500 street miles in three years. Remember, a NO answer is just as good as a yes answer when dignosing any issue. And if you are going to arbitrarily replace stuff, can I have the old stuff? Quote Link to comment Share on other sites More sharing options...
gprimm Posted August 23, 2012 Author Share Posted August 23, 2012 UPdate: it is the #3 cylinder. Took the valve cover off and all the rockers seem to be working but tomorrow night going to put on the instrument to measure lift. Ran air pressure into the cylinder and the valves hold the air, so they are good (good news on new Eddy heads). Observation: When running it will do what it does but as soon as I disconnect the plug wire on #3 it runs fine. Very interesting. Anxious to measure the lift. Quote Link to comment Share on other sites More sharing options...
wallaby Posted August 23, 2012 Share Posted August 23, 2012 Give a close look to the valve springs. If one is broken, it will behave as you describe. I have had several break in the lifespan of my car; they don't break in the center as you might expect, but break very close to one end. It's just enough to make the spring weak, but hard to see unless you look closely. Quote Link to comment Share on other sites More sharing options...
gprimm Posted August 24, 2012 Author Share Posted August 24, 2012 FIX: Distributor cap. Brand new ACCEL cap that separates the plug wires on each side for a clean look. No crossing from side to side. Also replaced the wires too. Runs like a monster. Did a burn out that wouldn't stop. Idles great and no hesitation. WHEWWWW, nice. Quote Link to comment Share on other sites More sharing options...
Mo's70MCs Posted August 24, 2012 Share Posted August 24, 2012 FIX: Distributor cap. Brand new ACCEL cap that separates the plug wires on each side for a clean look. No crossing from side to side. Also replaced the wires too. Runs like a monster. Did a burn out that wouldn't stop. Idles great and no hesitation. WHEWWWW, nice. Oh you pretty Chitty Bang Bang, Chitty Chitty Bang Bang We love you. Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted August 24, 2012 Share Posted August 24, 2012 Sometimes you just got to get back to basics, glad you got it fixed that easy. Quote Link to comment Share on other sites More sharing options...
gprimm Posted August 24, 2012 Author Share Posted August 24, 2012 $50 ACCEL cap was junk. Live and learn. Quote Link to comment Share on other sites More sharing options...
FASTSS454 Posted August 31, 2012 Share Posted August 31, 2012 Cool, that sure beats a bad cam. I tend to shy away from Accel parts, never had a whole lot of luck with them. Quote Link to comment Share on other sites More sharing options...
stangeba Posted August 31, 2012 Share Posted August 31, 2012 So the "bad" cap was an Accel with the internal wiring to keep the wires on the same side or that's what you just got to replace a standard cap? Have a friend with the cross over cap go bad last year. I got a HD tan cap from NAPPA for a truck with copper tips inside that works great, but I still have the stock points system. Bruce Quote Link to comment Share on other sites More sharing options...
gprimm Posted September 2, 2012 Author Share Posted September 2, 2012 Bruce, it was the ACCEL cap that went bad. Probably 2 hours running time. Put the MSD cap on and runs great. All my friends notice the rubber on the rear lower chrome strips behind the rear wheels. NICE. Quote Link to comment Share on other sites More sharing options...
CKZ03 Posted March 30, 2013 Share Posted March 30, 2013 Just experienced this same problem myself. Some reason I never saw this post, didnt matter I bought my cap quite a while ago and has been mounted on my engine ever since. Just now dialing my engine & everything in & with probably less than an hours run time this GM corrected cap failed on me too. Would strongly recommend not buying one of these. Looks pretty, but JUNK. Intermittent spark at #3 cylinder, causing terrible exhaust backfire. Changed to a standard cap, problem fixed, runs great. http://accel-ignition.com/ignition-elect...gm-hei-red.html Quote Link to comment Share on other sites More sharing options...
Mo's70MCs Posted March 30, 2013 Share Posted March 30, 2013 Chinese made crap.. I hate that junk! Quote Link to comment Share on other sites More sharing options...
stangeba Posted March 30, 2013 Share Posted March 30, 2013 I know someone that had a cap like that did the same thing. Stay away from that style for sure. Quote Link to comment Share on other sites More sharing options...
footballubet Posted March 30, 2013 Share Posted March 30, 2013 I have heard of the same problem with these caps. Too bad because it sure does look good. Quote Link to comment Share on other sites More sharing options...
gprimm Posted March 30, 2013 Author Share Posted March 30, 2013 Exactly; mine was #3 also. $50 mistake. Quote Link to comment Share on other sites More sharing options...
wallaby Posted March 30, 2013 Share Posted March 30, 2013 That's good to know. I guess I can live with messy wires if the engine runs right. I stayed away from those caps just on design theory: You want to keep the seperate conductors as far apart as possible. When they switched to high energy ignitions, they used a larger diameter cap just to get everything spread out to eliminate cross firing. Ford kept the small distributor, but used a 2-piece cap with a large diameter lid to get the terminals away from each other. Then along comes this solution that has conductors cris-crossing in the cap...there isn't much room to keep them seperated as one must pass over the other within the confines of the plastic above the rotor. It just sounded like a bad idea electrically. Quote Link to comment Share on other sites More sharing options...
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