pontiacfreak142 Posted July 8, 2009 Report Share Posted July 8, 2009 Basically we put a new cam in my dads 5.0 mustang the other day, because the one that was in it (it was in the car before we bought it), was to big for the setup. With that cam, we shifted the car at 5800 rpm with no problems. Now that put a new cam in, which is smaller, the car starts breaking up really bad at about 5000 rpm. Any idea's? We have tried adjustimg fuel pressure, new spark plugs, and a new coil. the miss kinda feels and seems like something electrical but not sure. Nothing else was changed on the car but the cam. Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted July 8, 2009 Report Share Posted July 8, 2009 valve springs Quote Link to comment Share on other sites More sharing options...
rl Posted July 8, 2009 Report Share Posted July 8, 2009 Did you check PTV clearence? Quote Link to comment Share on other sites More sharing options...
pontiacfreak142 Posted July 8, 2009 Author Report Share Posted July 8, 2009 i thought the springs to, but i dont understand how that could really cause that though. and yep sure did Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted July 8, 2009 Report Share Posted July 8, 2009 even if the cam is smaller,the spring pressure could be very different(higher needs), do to cam angles, etc. thats or it just time for the springs..but hard to tell. Quote Link to comment Share on other sites More sharing options...
pontiacfreak142 Posted July 8, 2009 Author Report Share Posted July 8, 2009 oh ok. i wish i even knew what springs were on it lol. Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted July 8, 2009 Report Share Posted July 8, 2009 check them pressure wise if you can. may not have enough Quote Link to comment Share on other sites More sharing options...
Dave1647545494 Posted July 8, 2009 Report Share Posted July 8, 2009 what did you set the timing at? two marks on the balancer and if you use the wrong one its got about 40 degrees of timing in it Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted July 8, 2009 Report Share Posted July 8, 2009 cam could not be timed correctly also..i was thinking of this earlyer... Quote Link to comment Share on other sites More sharing options...
ruinms Posted July 9, 2009 Report Share Posted July 9, 2009 if you have the dizzy a tooth off it will do this. or you put the cam in a tooth or two off. i got a sbf with no dowl pin in it once and it ran like crap becasue the cam twisted. Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted July 9, 2009 Report Share Posted July 9, 2009 i have had them do this when the pin in the dizzy gear shears off, and moves. Quote Link to comment Share on other sites More sharing options...
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