Help!! Engine Miss

[Ben Kallies]

Joe,

Thanks for your thoughts. My distributor gear looks great. I've actually had 3 different distributors (all new) in the car since the problem began, so I think it's safe to rule out a bad distributor.

-Ben

[buzzinhalfdozen]

Ben, hate to hear you're still chasing this problem. After reading all the posts here, looks like every avenue has been explored. The post about the carb. being set up for W.O.T. seems like it could have some merit, that would be easy to check, simply install a "normal" carb and test, sure it's not a race set up but under no real load it should quickly tell you if that's the issue.Broken valve springs could be an issue however I'd expect you would only encounter the misfire at a higher RPM range, unless of course they're "really" bad. When the engine starts to "break up" does it have smoke out the headers?Black or dark grey smoke would indicate 1 of 2 things, insufficient ignition events or being overly fueled.AS I've posted before, borrow or buy an MSD ign. tester ( this is an invaluable tool) put the spark tester on the coil and spin the system up to redline, paying close attention to the "look" of the spark.IF you can trigger the system to redline with no loss of spark you know your box and coil are up to the task.I don't believe I've been to a race in the last 4-5 years that I haven't had my MSD tester on my own or someone elses car. A leak down or at least a compression test would be in order, a cheap valve spring pressure tester would be nice to verify at least that all springs are close.Moroso makes an inexpensive one , not sure how accurate it is but it would show a weak spring I'm sure. Flat lobe on cam should be easy to recognize with valve covers off, spinning engine while observing each rocker 1 at a time. While this problem does seem to be very odd, the only SURE way of resolving it is with proper inspection and testing, of course we can always hope to stumble upon the answer, but that requires much more time and effort. Please consider some of the pinpoint tests provided as I've found them to be invaluable tools in diagnosing issues such as the one you're experiencing. Joe 1 other thing that caught my eye, you posted your batt. neg. cable goes to the frame near the batt. and your engine is grounded near the front on the frame, this is correct? Using the frame as ground is not advisable, Running a dedicated ground cable for all your electronics, electrical loads is far better to insure proper function. I've got a #4 ground run from the battery neg. postto the front of my car going to a buss strip, you can ground everything to this strip knowing it's all directly grounded to the battery.Thought of 1 other thing, have you ever had a timing lite on the engine and reved engine to the issue RPM range? If so what happens, does the timing move, do you notice the lite starts to quit flashing?

[Ben Kallies]

Joe B,

Thanks for taking the time to jot down all of your thoughts. I too have been thinking more and more about Bill's comment about his carb being set up for WOT. If my leakdown test this weekend shows no issues with the engine, I believe that I'll be turning my attention back to the fuel system.

While your thoughts on the MSD ignition tester are well received, I believe that I've eliminated the MSD box as a possible problem when I tested with the HEI distributor. Your comments on using the frame as a ground are also noteworthy, and something that I'll consider.

I recently had a racer suggest that my valves are set too tight for the Smith lifters, and/or the lifters are not operating properly, and are hanging the valves open. While I've got the valves set the same as on the dyno, I assume that the leakdown test should verify where I stand with this. I'll share the leakdown results this weekend. Thanks again.

-Ben

[Mike Taylor 3601]

Is your miss @ idle or higher RPM or ?
Mike Taylor3601

[Ben Kallies]

Mike,

The miss is there from idle on up. Under load at part throttle (like when driving around the block) it seems to hit a wall around 3,000 rpm. On the other hand, when I simply blip the throttle in nuetral, it seems to rev cleanly. I haven't brought the car to the track, or had the opportunity to really put my foot in it to see how it responds. (I live in a busy Milwaukee neighborhood where dropping the hammer would be neither safe, nor recommended. Just firing the car up typically garners a lot of attention, along with a small crowd)

-Ben

[MEXJOE]

How about the neutral safety switch?

[Monte Howard]

Does your carb have one to one linkage, sounds like it to me.
One to one linkage carbs will do that during normal driving, especially if you run the carb one to one and no front metering rods

[tony wood]

Ben unplug the tach. Will probably fix your miss. Good luck.

[larrylomascolo]

Ben is any of the factory wire being used in the car or relays ,regulators,check for the green corrosion,im just thinking here ,hope you get this fixed

[Terry Cain]

Originally Posted by tony wood

Ben unplug the tach. Will probably fix your miss. Good luck.

You might have something there. I remember yrs back a car I was working on did the same thing and the tach was the problem.