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Gary Wiegand · 06-18-2012, 10:31 AM

Hi Ben,

The reson I had asked if your engine has a carb. spacer plate is because an engine miss I once had behaved strangely like what you're describing. In any case don't overlook a small vacuum leak which can show up more pronounced under load, and may not even be noticable at idle or when reving the engine. My situation involed an "Extreme Poly" 1" spacer plate which became deformed after a number of races one summer evening. (Dyno time heat could possibly cause a similar situation?) I didn't notice the miss until the next weekend at the track when the engine would misfire under load. Seemed like a lean misfire, but plugs were good and I hadn't changed anything in the carb. lately so I initally thought it was electrically related. The plate had apparenly heat soaked possibly from the cast cast iron heads which were on the car at the time. After chasing down every conceivable electrical problem I could think of and finding nothing, I accidentally found that the bottom of the spacer plate had become deformed. It was only after cracking the carb. base plate after having removed the carb. for the third time for cleaning and inspection, that I removed the spacer plate and found the problem. I was curious as to why the carb. plate would crack if it was level on the manifold with normal tightening procedure, and not "strong arming" it. I replaced it with a Moroso unit and haven't had a problem since. Anyway, maybe you have a small vacuum leak somewhere, don't overlook manifold bolt threads and things like that. Just a suggestion - at this point I'd sure like to know what you find out. This sure has been dragging on for a long time. Good luck finding the problem!

06-18-2012, 10:31 AM	#115
Gary Wiegand Junior Member Join Date: Jun 2012 Posts: 8 Likes: 0 Liked 0 Times in 0 Posts	Re: Help!! Engine Miss Hi Ben, The reson I had asked if your engine has a carb. spacer plate is because an engine miss I once had behaved strangely like what you're describing. In any case don't overlook a small vacuum leak which can show up more pronounced under load, and may not even be noticable at idle or when reving the engine. My situation involed an "Extreme Poly" 1" spacer plate which became deformed after a number of races one summer evening. (Dyno time heat could possibly cause a similar situation?) I didn't notice the miss until the next weekend at the track when the engine would misfire under load. Seemed like a lean misfire, but plugs were good and I hadn't changed anything in the carb. lately so I initally thought it was electrically related. The plate had apparenly heat soaked possibly from the cast cast iron heads which were on the car at the time. After chasing down every conceivable electrical problem I could think of and finding nothing, I accidentally found that the bottom of the spacer plate had become deformed. It was only after cracking the carb. base plate after having removed the carb. for the third time for cleaning and inspection, that I removed the spacer plate and found the problem. I was curious as to why the carb. plate would crack if it was level on the manifold with normal tightening procedure, and not "strong arming" it. I replaced it with a Moroso unit and haven't had a problem since. Anyway, maybe you have a small vacuum leak somewhere, don't overlook manifold bolt threads and things like that. Just a suggestion - at this point I'd sure like to know what you find out. This sure has been dragging on for a long time. Good luck finding the problem!