VinceNJ Posted March 29, 2023 Share Posted March 29, 2023 New member here. I've been following this forum for some time and enjoy it immensely. Reading this thread remined me of a problem I figured out years ago so I thought I'd join and offer a suggestion. I had a 1970 Dodge Challenger RT that would start to breakup (miss) at about 3000 RPM. It ran perfectly at lower RPM's. After going through plugs, points, distributor cap, carb, etc. with no change I finally figured it out. The bearings (or bushings) in the distributor were shot causing play in the distributor shaft. Try this: Remove the distributor cap, grab the rotor and try to wiggle it. You are not checking rotational play, you are checking it by rocking it side to side. Any slop or movement is bad and will cause a miss at higher RPM's. If you can move it at all you need to replace or rebuild the distributor. I can't comment on the noise in the engine without hearing it. Hope this helps. Vince 2 Link to comment Share on other sites More sharing options...
dodge28 Posted March 30, 2023 Share Posted March 30, 2023 In late 1989 or so a friend bought 8 brand new spark plugs from a automotive store where his wife works. She got them as employees discount. The car was a 8 cylinder Olds. He kept complaining at highway speeds the engine miss fires. At up to about 3500 rpm there was no miss fire, He took it to a shop where it was hook up to some kind of machine and sure enough a brand new plug was miss firing at high speed. Link to comment Share on other sites More sharing options...
edinmass Posted March 30, 2023 Share Posted March 30, 2023 On 3/28/2023 at 9:10 PM, VinceNJ said: New member here. I've been following this forum for some time and enjoy it immensely. Reading this thread remined me of a problem I figured out years ago so I thought I'd join and offer a suggestion. I had a 1970 Dodge Challenger RT that would start to breakup (miss) at about 3000 RPM. It ran perfectly at lower RPM's. After going through plugs, points, distributor cap, carb, etc. with no change I finally figured it out. The bearings (or bushings) in the distributor were shot causing play in the distributor shaft. Try this: Remove the distributor cap, grab the rotor and try to wiggle it. You are not checking rotational play, you are checking it by rocking it side to side. Any slop or movement is bad and will cause a miss at higher RPM's. If you can move it at all you need to replace or rebuild the distributor. I can't comment on the noise in the engine without hearing it. Hope this helps. Vince Vince, you are correct as that being a common issue. Link to comment Share on other sites More sharing options...
60FlatTop Posted March 30, 2023 Share Posted March 30, 2023 (edited) There is a lot of information in this pattern and it is getting less expensive to produce at home all the time. Reading it does not fix the problem. It diagnoses a number of potential problems quickly. Here is an art deco 1930s Sun some whipper snapper who would be in the 90-100 age range now may have used. He might still remember being scorned by his peers for his choice of science over supernatural diagnostics. Even today I see the open palm double tap to the fender as an abbreviated "laying of the hands". Edited March 30, 2023 by 60FlatTop (see edit history) 1 Link to comment Share on other sites More sharing options...
Grimy Posted March 30, 2023 Share Posted March 30, 2023 5 minutes ago, 60FlatTop said: There is a lot of information in this pattern and it is getting less expensive to produce at home all the time. Reading it does not fix the problem. It diagnoses a number of potential problems quickly. Here is an art deco 1930s Sun some whipper snapper who would be in the 90-100 age range now may have used. He might still remember being scorned by his peers for his choice of science over supernatural diagnostics. Even today I see the open palm double tap to the fender as an abbreviated "laying of the hands". I have a Sun 820 like the one to the right of the monster unit, and love it.... 1 Link to comment Share on other sites More sharing options...
TerryB Posted March 30, 2023 Share Posted March 30, 2023 I spoke with the original poster of this thread over the last few days. He is hoping a local guy to him who builds engines will be able to look at the car soon. Car runs well enough to drive but has the issues mentioned in the post. I’ll be anxious to hear what the engine builder guy finds. Link to comment Share on other sites More sharing options...
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