I built a 351-w for my 90 Lx, I just put it in the other day, But @ around 3,000 RPM it will just about shake you out of the car & the oil pressure starts jumpin around... Heres my engine build up, 1990 351-w, Stock crank, turned 10/10, Eagle rods, Kb dome pistons, Cam,Intake with GT-40 heads. I used an 351-w flywheel out of an 1995 Cobra R Mustang. But used my 90 351-w damper... Could some one plz help.
Hey, When you say 3000rpm... Are you revving it in standing still in Neutral/Park when you get vibration? Or are you cruising and get vibration around 3000rpm. If it's while you're cruising than it could be u-joints, driveshaft (bent or out of ballance) etc... But the vibration would occur at different rpm's depending on what gear you are in. If it happens at 3g's standing still, than you have a possible rotating assembly ballance problem. Also, wear the mains and main bearings installed in correct order, direction and with proper clearances? Good luck! Indy
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'69 357W in '79 Fox Mustang .030" Flat-Tops, 11:1 Compression. '86 T5, 8.8" Posi w/ 3.73 FRPP gears.
Holley 750HP/DP and Fuel Pump, RPM Intake, RPM Heads (2.02"/1.60"), Comp Magnum Rockers, Comp Pushrods, Lunati Voodo Cam, BBK Long Tubes
Same here on the vibration problem.Driveline could be pinion angle and many other things.If its when you are sitting there revving the motor,You got a balance issue most likely.Did the COMPLETE rotating assembly get balanced,Which would include the flywheel and damper you used.Ford likes to change up the damper and flywheel balacing every couple of model years it seems.Might need to get that checked out before you break something with that imbalance.
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If you don't kick the hornet's nest,You won't get stung!
The balancers and flywheels should be the same, 28oz. so that should be OK.
Is it an rpm issue? Or a speed issue? What year is the stock crank? When you installed the clutch, did you use the dowel pins for the pressure plate? Did you have the rotating assembly balanced for the new pistons and rods? Are all the header tubes about the same temp?
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351-w Viberation @ 3000 Rpm up. - 
