vibration problems

[devilzombiewolf]

I have a 69 mustang with a 351 C that I am building for the secound time the first time she had 3 speed auto trans and she ran slick but drank a lot of gas so I retrofited a transmission from a 84 LTD crown victoria wich has a tork sinsative mettrick overdrive the car will go into gear but no matter what gear or park I am getting a bad vibration at 800 rpms. I was thinking the tork converter was bad or had sludge built up in it. Any one have an idea?

[bkf77]

Sounds like a balance issue. Was the vibration present before changing the trans?

[mahanja]

Here goes a shot in the dark...You changed the flywheel too didn't you? Have your flywheel balanced with a 351 crank. Should fix your problem. I know. I did it on my 302. Cost me $45 in machining, $120 in flywheel, and a pain in the ass.

[devilzombiewolf]

No the vibration was not there before I changed the transmission. I did how ever change the fly wheel as well the one from the C-4 was to small is there that big a diferance in the ballence in a 302 and a 351 Clev. If so is there a fly wheel for a 351 that would fit a metric transmission from a 1984 5.0 LTD crown victoria, Or do I have to hunt down a good machine shop.

[doug 351]

Older 302's and 351c's both used the same imbalance flywheel (28oz. external imbalance). The problem comes in when you use a later model 302 flywheel. They are 50 oz. external imbalance. If that's the case, you'll definately have an imbalance issue. I don't know what flywheel you need for the application you are running, but it should be a 28oz. imbalance, and shouldn't need to be balanced. There may not be one, but now you know what to look for.

[mahanja]

Great info doug. I couldn't remember the weight.
devilzombiewolf, since you already have the flywheel, it will probably be cheaper to just have it balanced. The machine shop should be able to hook you up. A couple grinds/welds should take care of it. Let us know how it turns out!