69 250 390 C/6 flexplate type /size install help

[SoCal250]

My aplogees if this is in the forum index and I didn't find it my truck is back on the road finally I bought a heavy duty flywheel with a bunch of parts from jegs it has a vibration I did see a kinda negative review on this flywheel it was a pioneer I think but the heavy duty one it didn't seem to fit exact the holes did not fit perfect and the holes for the convertor as well it vibrates especially if you rev it and on the decel it shakes the dash you can feel it also on take off it feels choppy .
The motor runs strong although only 200 miles or so on the 390 rebuild I think it's best that I pull the trans again take the flexplate out since I had fitment problems with it I'm sure it is that . I had to shim my starter to keep the teeth from hitting the flywheel that was what the other guy had to do as well I do have a cam 265 dual energy comp cam what wieght should I look for and size I seen a 184 tooth with 15.55 size no wieght ? Or should I choose a certain wieght ? Or no wieght better ? Thanks

[cep62]

You shouldn't have to shim a Ford starter " IF" you have the spacer plate between the block and trans.
I had a improperly balanced flywheel once (400) , and I definitely made a vibration.
One more thing to look at is the harmonic balancer , make sure its the correct one.

I've heard about people using a 390 flywheel on a 429/460 conversion.
And there are different balances on the 460 , IIRC.

[SoCal250]

I think this flex plate was more for a 460 it said 360/390/460 it was thick and the starter was a tuff stuff starter from jegs the guy that made the review stated he had to shim his starter that should had flagged me there . As far as the balancer it was a part of the rebuild kit the shop used I installed it engine tech was the brand it's straight A's a arrow I just don't know what wieght balance to choose there are some with no wieght .....

[SoCal250]

I can see the flexplate moving a little at idle seems like it didn't sit flush at the crank a guy told me at a trans shop on the phone that you should see the welded on wieght facing you ? I don't see it looked 360 also the dished section of the flexplate is supposed to face the engine ? It's not flat is is dished slightly right at the crank he said the bowl side the term he used of the dish is supposed to face the motor ? Is that right ?

[cep62]

I think this flex plate was more for a 460

If I remember later 460s where internally balanced and wouldn't have a weight.

Another thing , does your torque converter have the proper size pilot to fit the crank shaft.

[SoCal250]

That was my next question I was shopping for a lighter duty flexplate and it said internally balanced ?is a 390 internally balanced ? Other wise they showed a wieght of 28/29 ounces hard to find one with a wieght for under 150 ...

[SoCal250]

I think this flex plate was more for a 460

If I remember later 460s where internally balanced and wouldn't have a weight.

Another thing , does your torque converter have the proper size pilot to fit the crank shaft.

Flip I didn't even look I had the trans rebuilt and they gave me a rebuilt torque converter as far as pushing it up against the crank first to see if it fits no ...your talking about the nipple like thing that fits in the hole of the crank shaft ? Something is off what I did notice is the pilot for the flexplate was not a good fit it seemed like it did not want to go on and I had to keep spinning it to find a good match on the pattern you would think it is the same all around I see it's not it really only will go on a certain way . I'm going to need to pull it out to see what is what or take it to them to do the job I hate to take my work to someone since I did 99percent of the work ....it runs like a raped ape with the 500 cfm Holly on there comp 265 dual energy cam I don't need a 4bbl .

[cep62]

what I did notice is the pilot for the flexplate was not a good fit it seemed like it did not want to go on and I had to keep spinning it to find a good match on the pattern you would think it is the same all around I see it's not it really only will go on a certain way

If you're talking about bolting the flexplate to the crank , they only go on one way. (to keep them in balance)

...your talking about the nipple like thing that fits in the hole of the crank shaft ?

Yes different applications have different sizes (two)
Although I don't think you could put them together if they're wrong.

[SoCal250]

I appreciate your responses I did a little online search today this is a common problem all over not just in truck but cars with the FE engine the cheaper flex plates seems like the pilot hole in the center is too small also the studs for the TC ate not drilled right the threads get caught going through the holes so the TQ won't push through correctly well I had that problem but I put it on anyway know I need to deal with it . Also they were saying 66 and earlier FE had a different tooth spacing than 66 up and 66 below used a long shaft starter I think this is why I had to shim my starter 66 up used a short shaft starter and flex plate is 184 tooth I know I have the right flexplate it just didn't fit right on the crank and I bought a Tuff Stuff starter 120 bucks with a long shaft should had been short shaft and ........they were saying all FE engines are internally balanced by the crankshaft so you don't need a counter wieght on the flex it has holes as a final balance just what I read in the online search it was from the Ford truck forums Google search ...here's a link to what they said ...

https://www.google.com/url?q=https://ww ... c_wdC14p-h
Forums
https://www.google.com/url?q=https://ww ... tLeuvMRopI

[SoCal250]

Update !!!! I Hated to do it since I installed everything but I took it to the trans shop they did it I less than a day the Flexplate had a huge wieght on the backside were the torque converter goes in they shaved down the new one a little to pilot on the crank that wieght was big long I think even if I forced it on like I said if that wieght wasn't there it would had been ok at least they did a great Job after I painted everything under there I could never tell they took it out 360/390 flexplate should not have a wieght welded to the flexplate .....