Here's my situation...over the winter I took the 460 out of my 74 F250 to change a few things, and now that it's back in, I've got a decent vibration that shakes the truck at all speeds, however it seems more noticeable at idle and low speeds.

Here is what I did to the engine: changed oil pan (along with oil pump, pickup, etc), changed water pump, replaced valve seals, replaced flexplate and starter, replaced distributor. Now, out of what I listed, what would be the most likely cause of the vibration? My initial thought was timing since I didn't do a good job of marking the old distributor before taking it out. I set the #1 cylinder to TDC and installed the dist., then set timing at 14degrees BTC. The truck doesn't hesitate or bog down when driven, just vibrates. So, my other thought it the flexplate I got may not have been balanced just right from the manufacturer. I bought it at Advance Auto, so I'm not sure if there is a real quality difference from retailers.

The engine mounts are tight and they are not missing any rubber. Would an improperly balanced flexplate be the most likely culptit, or could there be anything else causing the vibration based on what I changed over the winter? If I didn't get one of those rods to line up correctly after changing valve seals and putting the rockers back on, could that cause a vibration also?

My next step was to take it to a tranny shop to see if they can determine a bad flexplate before taking it apart, but I was hoping any of you guys would have some ideas first.

Thanks

 

Does it not do it at all if you rev it while it's not moving? If not, that would rule out the flexplate. When you disconnected the driveline did you index the position of the yoke/driveline and reinstall exactly as it was? If you let the truck role a little bit that would put it off possibly. Could there be a cylinder misfire? If you disconnected the driveline maybe that's all an old carrier bearing needed to finally show it's age(if you've got one).

 

It still vibrates if I rev it in park, or if it's idling. When I took the engine out, I left the tranny in place. The carrier bearing was replaced about 3 years ago.

I'm open to the possiblility of a misfire, but not sure how to tell if that's happening. How would I check that?

 

Anyone else have any suggestions on this? I need all the advise I can get.

 

Curious, how did you come out on this? I bought a flex plate from Advance Auto and I have this same issue. Mine seems to aggresive to be a flex plate issue though.

 

Check your engine, early 429/460's 68-70 I think are internally balanced, the 79 460's should be externally balanced. Easy way to check is look/feel behind your harmonic balancer, if it has a counterweight on it(they are fair sized), it probably is externally balanced-if so your flexplate should have a fair sized piece of steel spot welded on it for balance. I could see a mix up at the parts place getting you the incorrect flexplate.
On a stock internally balanced engine, the "spacer" behind the harmonic balancer is just a round spacer
Some rebuilds or overhauls mix and match parts-so have to watch that.
My internal/external balance info is probably a bit off-I would have to look it up. Yet the counterweight behind the balancer check is easy to do.
Hopefully its a bad cap, rotor, wire, or spark plug. If the balance is off from the wrong flexplate it will shake like a bugger, and its not good for it.
Dunno if this info helps, good luck and let us know what you find!

 

I think thunderjet pretty much has it, a 74 should be internally balanced and you may have been sold a flexplate for a 79 or newer engine, check your invoice to compare part numbers but it could still be mispackaged, I too hope its something simpler..

 

Ok, gents.
You have my curiousity. I looked at the balancer (Part Number D2VE-AA) and I looked at the block numbers (BIVE-6015 A2P) or (8IVE-6015 A2P).
I was told the engine was out of a 70's Continental. I asked for a flexplate out of a 70 Continental.
I think I remember the flexplate having the balancing weights welded on it. But I will check this week.
Can someone proove what year of engine this is and if the balancer is right and whether the flexplate should have weights on it or not?

 

This conversation is hugely interesting to me. My '79 (400 cid 6.6L) Ranger shakes pretty badly too. I thought I'd start with a compression check. Just to be clear, is my '79 <i>externally</i> balanced?

 

Not 1979 and newer, midyear 1979 and newer. 1979 and newer is a common mis-conception because no cars in 1979 were available with a 460 engine.

F100/350's and Econolines only. (Because of strict CA emission standards, no 1979 E150's or 1979 F100/150's sold new in CA were available with a 460)

There's no serial number break, so the only way to know for sure which flexplate is required is by the engine bare block casting number.

If the casting number is: D1VE-6015-AB, AB1, AB2 = DISZ6375A .. Flexplate / Fits: 1968/74 429 / 1968 thru midyear 1979 460.

If the casting number is D9TE-6015-B = D9TZ6375A .. Flexplate / Fits: midyear 1979 460 and later.

Both these flexplates are still available from Ford.

 

Okay. My '79 F250 (6.6L 400) does the whole engine shake thing. It stops shaking when I rev the engine but continues when the engine drops back to idle. I don't notice it when I'm in motion but at stop lights it continues.
before I dig in I just thought I'd get an opinion. I'd hate to think it was transmission related.