318-360 motor swap ???

I have a '79 Cordoba that had a 318 in it. I rebuilt a '86 truck 360 motor and I now have a vibration coming from the motor/trans. I am using the 904 trans and converter from the 318 with a B&M flexplate (#10239) for a 360 that is suppose to correct the balancing issue. The harmonic balancer is for a manual trans but I have been told there is no difference between the two. Any ideas why it still vibrates? I have installed the original flexplate and it still vibrates. Do I need to install a new converter or look for another problem.  

When does it vibrate, while it's in gear and you're driving, or while it's in park or neutral?  
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Sometimes you just gotta say...

Which balancer are you using? the 318 or 360? You'll need the 360 balancer and converter, or an externally balanced flex plate in lieu of the correct converter.

Did you change anything internally in the engine during the rebuild? Like pistons or connecting rods? Did you have it balanced? If so, that could be the cause of the problem.  

It vibrates at all rpms and it doesn't matter if it's in drive or neutral. No changes to the pistons or rods on the rebuild and the motor was NOT balanced. I have the 360 harmonic balancer on it and the B&M flexplate with the stock 318 converter. The B&M is suppose to balance the converter. I'm going to try a stock 360 flexplate and a 360 converter next. The B&M flexplate might be the problem. I hope.  

Well, a new stock 360 converter and flexplate cured the problem. I don't know if the old converter was bad and thats why the B&M flexplate didn't work or what but I have a B&M flexplate for sale if anyone is interested.  

always good to hear a happy ending. good job bad and rb  

Use the 360 balancer all 360s are externally balanced  

Though there are 2 different balances between old and new[magnum].  
age is no lock on brillance

1 question though,,, somethings funky here, did you use the 6 bolt 10239 6 crank bolt flywheel on the truck 10231 8 bolt flywheel? I think theres more to this story ,as bad stated its one or the other,anything else ya wanna fess up on doba? heh, take care  

whoops flexplates,keep thinking about the 4 speed truck. the truth shall set you free.cya  

council, is it possible your blowing smoke screen up our arses? haha  

Hello

I'm in England, and have the exact same problem you had. I have a '69 Barracuda with its 904 trans. It was a 318 originally, and the previous owner fitted a 360 from a 1978 truck.

The same horrible vibration is there at all rpms. I need a B & M 10239 plate, what would you want to send via airmail asap, I could pay by paypal or direct account transfer.

I have the trans in bits waiting. I am confused though: extensive research showed me NO torque converter is available for a 360 to 904 application, only 360 to 727. So your trans must be a 727, so a 360 external balanced converter and standard flexplate would cure your problem.... or did you have an externally balanced 360 converter specially made to order?  

Barracudaboy:
Hello

I'm in England, and have the exact same problem you had. I have a '69 Barracuda with its 904 trans. It was a 318 originally, and the previous owner fitted a 360 from a 1978 truck.

The same horrible vibration is there at all rpms. I need a B & M 10239 plate, what would you want to send via airmail asap, I could pay by paypal or direct account transfer.

I have the trans in bits waiting. I am confused though: extensive research showed me NO torque converter is available for a 360 to 904 application, only 360 to 727. So your trans must be a 727, so a 360 external balanced converter and standard flexplate would cure your problem.... or did you have an externally balanced 360 converter specially made to order?

hi, i dont think buying doba's flex plate would be wise, just in case it is faulty you'll be stuck with it. a better choice would to buy the weight kit from mopar. comes with instructions to place the weights and just weld them on. as far as the 360/904 combo,it is quite common here and used in many factory applications. the s/s racers also like it because it's lighter, better gear ratio on the later models and works great with a brake.  

Well, all is cured.

Installed the B&M 10239 flexplate, and after a few hours of oily fettling, the Motor/trans is now vibration free. Very big difference and I'm very pleased indeed.

The 360 has only been mated to the 904 for about 2000 miles before the fault was identified and now fixed. I sure hope that isn't enough to wear my engine and gearbox out? Does anyone have any idea?

I just did a compression test and all 8 cylinders are excellent, and within 1-2% of each other. Plugs are excellent, and show no signs of oil being burnt at all. Manifold vacuum @ 850rpm is 19.5 inches. Changed engine and trans oil, both appear to be working very well.

Is there anything else I should look out for, or should I rest easy that the beast is cured and in good shape?

Thanks,

Lee.  

hey guys just wanted to say, Ma mopar put the 360 in front of both 904 and 727.  BTW if you don't want to throw good money after bad away on parts, just have a reputable converter/trans shop balance your 318 converter to a 360. no biggie.  last time I had it done cost $35