It could also be you have a '68-up engine (big crank hub hole) and an earlier torque converter, so they are not centered. Common problem with Slant engine swaps...

Lou

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Home of Slant6-powered fun machines since 1988

yeah, I agree with Lou. 1968 and newer slants must be used with a torque converter that has a matching "nub" to fit inside of the rear recess of the crankshaft. With an incorrect matchup, the convertor moves around and causes vibration. If the head is a late model head, I'll bet the motor is newer too. [just a hunch] Try to find the numbers on the block and someone on here can decode them. If the block is a later block [68+] you got a few choices: The easiest; have an adapter made to fill the gap.

I like the Idea of the adapter. Does anybody know if someone makes them??

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1979 W150 Shortbox
225, NP435, 9 1/4, Dana 44

The Good Life.

Reluctant Dodger,

Something to consider.....

After I rebuilt my engine and replaced the mounts I had a heck of a vibration for the first 20,000 miles. After that the rubber softened up and the vibration is gone. My old mounts were super soft and spongy. The new Anchor brand mounts were rock hard.

My engine was internally balanced and looked smooth but I still felt things shaking in the car until the mounts softened up.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Well I'm sure fond of Ted's solution; It'll fix itself. Unfortunately the mismatch theory would seem to make sense. I'm fairly certain the tranny is original to the car (1963) and the probibility that the engine is 68 or later would seem likely (It was a rebuild). I took it for a test drive this morning and these were my impressions: The vibration is at it's worst from about 0 to 20. It is present beyond that but diminished slightly. It was negligble going up a long grade at about 45mph, almost unnoticeble.
So my next questions are: Is driving it damaging something if we assume that there is a mismatch? Is there an adapter available? How much work is involved installing an adapter? (I'm not much of a transmission guy, especially automatic) And do the symtoms I've described on the test drive seem consistent with the mismatch theory or are the mounts still a suspect?
Again I thank you for your insight and assistance

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Reluctant Dodger

There are adapters available from Wildcat wrecking and from torqueflite patty (Pat Blais). Search this site for contact info. They may even be up on Ebay.

If it smooths out it could be a broken/loose motor mount too, but the hub problem is likely it. You can look at the block front right corner boss behind the alternator for build date and that will tell you. Or, if it's a 5 freeze plug block then it's 1968-up.

Lou

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Home of Slant6-powered fun machines since 1988

One other possible cause of a shake is the ball & trunion front u-joint.
Worn units are known to shake bad, right when you start-off, in the 0 to 10 mph speed and will "settle down" as speeds increase.
This would not be the cause if the engine vibrates when reved-up in neutral.
DD

I checked the block and there is indeed 5 freeze plugs. The date I was never able to make out, but I got out a magnifying glass and a bright light and just before the 225 there is a 9 and with the magnifying glass it appears there is a 6 in front of that, which I assume means 1969.
I guess my next move would be to order the adapter. I'm hoping this is the final chapter. Thanks again for everyone's help.

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Reluctant Dodger

I have the adaptor rings, $22.50 each. That price includes shipping to any lower 48 - USA location.
Send me a PM if interested.
DD

I can't tell you how thankful I am for everyone's input. The final correct answer was indeed the mismatch crankshaft hole with the earlier tranny. When I got the part I started to be a little skeptical because the size differential seemed so little but the change was beyond remarkable. Before the idle seemed fairly smooth, now the engine is rock solid. Driving it is unbelievable...it's rock steady in gear stopped, and everthing you'd hope for with a new engine...great throttle response, smooth power, yes it's all there. The other good news is my wife was able to return the book she ordered on the internet: "How To Stage an Accident", it came complete with plastic explosives. So thanks to your help and insight another Dart will be plying the highways. Now it just needs a paint job so the outside can be as beautiful as the inside.

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Reluctant Dodger