Engine Fresh Rebuild Vibraton/shutter At High Rpm

Discussion in '1994 - 1995 Specific Tech' started by jmil918, May 28, 2014.

  1. I just completed my first rebuild on my 95 Mustang 5.0 everything went pretty smooth and the car started right up and idled great. However, when I push the RPMs up I get a very bad vibration. This happens in neutral as well as driving down the road so that should eliminate anything to do with the drive shaft. After doing some research I think I might have made a rookie mistake......

    Almost all of the parts in the engine are new with the exception of the block, the crank, and the connecting rods. The mistake I believe I made was not having everything balanced together. Everything I purchased was balanced at 50oz, but I've been told that even if they are balanced the same, they still need to be balanced together by a machine shop.

    One additional thing to note, I did NOT have the machine shop line hone the mains/crank (Another no no) and when I got it back from the machine shop the crank was pretty tight, but I used thinner bearings and everything checked out with plastigauge. Can anyone weigh in on if I'm on the right track or a possible solution? I have removed, cleaned, and reinstalled the harmonic balancer and there was no change. Thanks!
  2. Is the HB new and 50 oz and not 28 oz by mistake?
  3. The HB and the flywheel are both new & balanced from 50oz. They were ordered from reputable places (American Muscle & Summit), is there a way to distinguish between 28 & 50oz?
  4. Ugh. Did you have the rods resized?

  5. No, I was told since I was re-using the same rods, crank, mains, and bolts that I wouldn't have to do that. Was I told bad information?
  6. I don't think there is anything that can visually distinguish them. They must also match the flywheel imbalance as well. I would call the source provider and ask if they can confirm the part number for you. All the 302s from the early 80s forward are 50 oz imbalance engines.
  7. Generally whenever you have the bearings changed you do a line hone and a rod resize. I would consult another machinest to see if the first one missed something. It could be something serious or something simple. I have seen engine vibrations that were fixed by swapping around the 6 bolts on the pressure plate.

  8. Did you ever figure this out? I DID have everything balanced and have the exact same problem you describe with my 66 (with 68 302)