Not Mopar, but need HELP!

[highspeeddirt]

I know its not Mopar, but I'm sure someone here could help me out.  (I hope) Ok, what I've got is a stock 454 w/ 600 eddy carb and headers.  HEI ignition.  The problem is a "miss" between 1800 and 3000 rpm.  Its not really like your common "miss"  It has the feel of more like a flat spot in the carb.  It only does it under acceleration, and very slightly at an even cruise speed.  It doesn't do it at all when you let off the throttle in the same rpm range.  (as in downshifting)  You can watch the tach jump around wildly when it does it too.  From idle to about 1800 rpm its smooth, and once you hit 3000 rpm it smooths out again.  I've changed the vaccum advance canister, cap, rotor, wires, and the advance sling weights and springs.  Timing adjustments advance or retard make no change to the problem.  Does anyone have any suggestions?  I wouldn't think it would be the coil or the module in the distributor since it is only in the specific rpm range, but anyone think thats a possibility?  I'm kinda at a brick wall of ideas aside of swapping out distributors.  Any help ya'll could give would greatly be appreciated! 

                         HSD

Oh, and I know the ultimate resolution to the problem would be sell the chebby, and get a Dodge.    Thats in the works, but I want to get the chebby running right, before I sell it!

[MEK-Dangerfield]

I think if your tach. jumps around during this, then it's electrical. I had a coil go bad once where it would do that if I went over 35MPH.

  Mike

[JCWCuda]

I'd check the Coil and Control Module ,However i wonder if it's possible you have a Weak lifter that is partialy collapsing on you

[highspeeddirt]

Well, I thought I'd update on the problem.....
   I decided I'll just go the whole enchilada and I changed the coil, pick-up coil, and the module.  So, now everything on the distributor is new except for the condenser.  I know this doesn't pin point what the problem was, but I didn't feel like taking it apart more than once.   It made a TON of difference.  The problem is gone.  It still has a very slight miss every once in a while I can't seem to get rid of, but I'm thinking along the lines of JCWCuda.  I do have one lifter that is a little weak that I know of.  Every once in a while you can hear it tick at idle.  I adjusted the rockers a few months ago and you could barely push the plunger down with your hand and couldn't all the others.  If I wasn't thinking about selling it, I'd just rip it apart, and put a whole new cam kit in it.  But I would rather put that money into something more worthy than a chebby!

      Thanks for ya'lls help!

                                                HSD

P.S.  Anyone want to buy an 82 GMC crew cab dually w/454, 700r4 automatic??        

[tactransman]

Are you sure it is not a 400 THM? I have never seen a 700R4 in a Dually.

[highspeeddirt]

Are you sure it is not a 400 THM? I have never seen a 700R4 in a Dually.

Positive.  I did the conversion on it.  My TH400 went south, and with 4.10 gears it wasn't very pleasant at 60 mph or more anyway, so I went with the overdrive.  Much better now only about 2400 rpm around 70mph now.