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chattering issues

839 Views 4 Replies 2 Participants Last post by  squatch4x4
I have an 86 K20 with a 468/400/208 in it. The noise that Iam hearing sounds like a loud spark knock issue. This all startes when I changed the cam and put new motormounts in the truck while still in the truck. Thinking that it was spark knock, I checked and rechecked the timing, was running a Billet HEI, then I went and bought a complete MSD set-up billet dist., 6al, HVC coil, this didnt make any difference, just money spent. Now that the old dist is back in there it seems to be getting louder, and seems to be coming from under the truck, on the drivers side. I might add that I hear it ususlly when I take off, or when the tranny shifts under a load. I have checked to make sure everything was tight, no exhaust leaks, I even checked the flexplate, and it seems to be good condition. Any help is greatly appreciated. :cuss:
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what cam? and what's the static CR? what about the carb? is this on 93 octane? please provide summo' info.

just wondering but how did you go about breaking the cam in?
The cc is just barely 9:1, the cam is a Comp Xtreme grind, Ill need to get the cam card, but it is a street hyd cam. Right now I have a 3310 750 on it, I had an 850dp on it, but all that did was waste gas. I have plenty of fuel pressure..Mallory Comp 140 with reg set @ 7psi. aLL I run init is 93. But like I said, its not all the time that it does this, therefore I dont think its spark knock. Oh and it stays, no matter what the temp outside @ 180
my first guess after reading your reply is that the carb is leaning out when accelerating. I know squat about holleys so hopefully somone else can chime in on that.

edit: weell I got bored so I checked out holley's site and this is a pdf regarding the operation of their carbs. if you already know it then disregard.
Thanks for the input, but like I said before I tried an 850 and that didnt help any. I have also tried different plug heat ranges to. This is why Iam not certain that the noise Iam hearing is detination.
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