Help me find the MISS!!!!

Old 07-21-2008, 04:50 PM
  #1  
duswill
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Default Help me find the MISS!!!!

We just rebuilt our short block due to a destroyed piston and scarred cylinder. The only change to the engine was boring the block and putting in a 14.2 to 1 set of pistons from a 12.9 to 1 set. Compression is good in all cylinders. Everything else is the same. At idle it sounds like it is hitting on about 5 or 6 of the 8 cylinders. When you bring the revs up it sounds fine. We have checked the plug wires all test good, replaced the dist cap and rotor, 2 different sets of plugs, double checked our valve settings and we don't know where to go next. The ignition is a Msd Digital 6 with an HVC coil and a locked out pro billet dist. Any suggestions on where to look next would be appreciated.
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Old 07-21-2008, 05:02 PM
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fla1976
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Default Noise

Could be a vacuum leak. You could try spraying some WD40 around the intake and listen for a change in the idle. If it changes temporarily , you have found the leak. It's a little messy but safer than starting fluid.
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Old 07-21-2008, 05:25 PM
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duswill
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Already tried that, no leaks. Thanks
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Old 07-21-2008, 05:52 PM
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hammertime
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Default Re: Help me find the MISS!!!!

Originally Posted by duswill
We just rebuilt our short block due to a destroyed piston and scarred cylinder. The only change to the engine was boring the block and putting in a 14.2 to 1 set of pistons from a 12.9 to 1 set. Compression is good in all cylinders. Everything else is the same. At idle it sounds like it is hitting on about 5 or 6 of the 8 cylinders. When you bring the revs up it sounds fine. We have checked the plug wires all test good, replaced the dist cap and rotor, 2 different sets of plugs, double checked our valve settings and we don't know where to go next. The ignition is a Msd Digital 6 with an HVC coil and a locked out pro billet dist. Any suggestions on where to look next would be appreciated.
Are all the plug firing ? Have you changed plugs out for another set ? Timing isnt way off is it ?
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Old 07-21-2008, 08:09 PM
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johnracer
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Maybe you have a 4/7 swap cam but have it wired with standard firing order....
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Old 07-21-2008, 08:16 PM
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olds48
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Like Hammertime said,I'd put a timing light on all 8 wires and see if they are firing.Any chance of a broken valve spring or that the timing set is off a tooth?I got a chain off one tooth one time in a hurry and it sounded like that
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