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New guy here... both to this forum as well as to Mustangs. Always enjoyed them and have a chance now to work on one for a friend of mine.
It was born with a 250/3-Speed in it and his dad found a 289 to put in it. I know it's not the correct motor for that year, and the motor vibrates. It's a fairly rhythmic vibration and balances out at various RPM levels then returns at others.
I read on one forum that a guy suggested a need to replace his flex plate or he'd have vibration issues. Was wondering if there was a chance this 289 doesn't match up with the flywheel of this 3-Speed so well and possibly causing the vibration issues.
Motor mounts are good... his dad says it ran well when he put it in... The motor seems to run well, just has a pretty bad vibrational issue.
Any thoughts would be greatly appreciated!
Thanks!
Int1m1d8r
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Thanks for the quick reply. He was sure he had the optional 250. I also double-checked the VIN to confirm it as well. Engine code is "L".
Could be a real long shot (the mismatch of the flywheel w/ the motor)... just was interesting that I read a post about it causing vibrational issues and that we can't pinpoint the issue on this car. We suspect it will turn out to be something odd. While we're not professional mechanics, we can get a few steps beyond the basics.
Stepman, thanks! I'll ask that question tomorrow. It would be nice to learn that it is something like that. The motor seems to run fine (barring the vibration of course)... no odd sounds or otherwise discouraging behavior.
Turns out the flywheel was indeed bought from a junkyard, so the possibility that it is incorrect is certainly there. Now I'll have to read up on identifying the flywheel type and ensuring it matches the motor...
There are different balances or rather inbalances to flywheels. 0oz, 28oz, and 50oz are popular on Ford small blocks. Depending on what others before you have done, a 302 based small block may need any of the three. This also goes for the harmonic balancer. The only way to tell what you need for sure is to have the crank checked.
I put a 50oz flywheel on a 351W that needed a 28oz on accident year ago. The engine ran like a big cam motor without the getup and go...just the shaking.
Does the motor vibrate just reving it up standing still or could this shaking be tied to speed or movement?
How do you motor mounts look?
Is the car missing at all or is is running correctly?
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"Yeah, were runnin a little bit hot tonight. I can barely see the road from the heat comin' off of it." Van Halen
289 needs both the 28oz flywheel AND balancer. Stock 50oz flywheels used a 34oz balancer. Make sure they're both correct for the engine. Keep in mind that the balance is to prevent harmonics from causing the crankshaft to break, so don't drive it.
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Who cares how much horsepower it has, all that matters is how fast it goes!
13.20's with 2.25-2.30 60's, 40+ year old suspension sucks!
Best trap 107.11mph, we'll see what the new intake/carb setup does.
12.80 at 110.5mph NHRA DA corrected
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69 Coupe w/ vibrating 289...
