Balancing a 360

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Zbojnik

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Hello everyone.

I have taken to restoring a 1973 Scamp that I bought while I was awaiting medical retirement in the Marine Corps. It's been quite a learning experience and curve balls keep being thrown in my direction. I have had the vehicle running and all seems well at the moment, however I've been reading up on the 360 and how it is externally balanced and I seem to have a lot of vibration in my engine. As this is the first engine old school V8 I have built, I'm not sure if this vibration is simply the motor doing its thing, or a symptom if engine imbalance. I used an OEM replacment cast crank from Eagle that is externally balanced, along with the stock rods and aftermarket Speed Pro dish pistons. I used the OEM balancer and flexplate. Is there a certain way for the flexplate and balancer to go on? Also, would it be worth my while to have this engine pulled and taken to a machine shop to have it internally balanced? I'm going to be driving this vehicle back to Chicago from San Diego in the upcoming week or two and want to make sure everything is in tip top shape for the trip. Don't really want to do any side of the road repairs.

Thank you very much for the help in advance.
 
Did you have everything balanced together before you put it back together? If you start adding new parts you should always have the balance checked!
 
the balancer has a key way...only goes on one way...

flexplate has six bolts and only bolts on one way...

what is important is the flexplate and torque converter...mopar oem flexplate back then do not have weights on them for the external balance...the weight is on torque converter..
 
The Eagle 360 cast crank is nuetral balanced because they are used for the old LA block and the new magnum which is nuetral balanced. If you are using your stock converter and balancer you are shaking things up pretty good inside, also you should always have your rotating assembly rebalanced anytime you add any new parts.
 
I am using the OEM torque converter as well, and I can see that it has weights on it. How would I go about getting this engine internally balanced? I would have to get an neutral balance torque converter, balancer and flexplate? And no Robzilla, I didn't have everything balanced. I was just learning and honestly had no idea that you had to have it balanced.
 
Sorry if I came off blunt, yes to properly balance your set up you will need a nuetral balance converter and balancer. Unless you have an aftermarket flexplate specifically for using an offset balanced 360 and a nuetrtal converter your flexpalte will work on your set-up. Trust me you are not the first guy who has done this and won't be the last especially with the ease of access to Eagle cranks. Good Luck
p.s. Thanks for your service, I am a 19 year Air Force member.
 
Thanks for the help Robzilla. I know its hard to tell but do you think any damage was done to the engine. It hasn't been driven yet only idled. Also, would it be a horrible idea to attempt the trip back to Chicago like this? I'd like to get back home already and get on with my life instead of prolonging my stay here in San Diego. Also, I looked up the cast 360 crank from Eagle and it says it is externally balanced. And with the torque converter and balancer, when it says Internal Balance, thats the same as Neutral correct?
Glad to see another service member here. Are you retired or still active duty? And no, you didn't come out blunt at all.
 
Yes internal means neutral. I will do some double checking for you on the crank. I am retiring next Summer!
 
Well part # EAG-103603580 on Summit website says that it is externally balanced, but I definately would have it balanced with a new crank and pistons to go with the rest of your stock stuff. If you are using a stock balancer, many times the rubber shock absorber ring can deteriorate and the outer piece will slip a bit, which wouldn't be good on a exernally balanced motor. Good luck with this, Rob
 
I checked on both the Summit and Eagle website and it seems that the cast 360 crank is in fact externally balanced. Seeing as I am using the OEM flexplate, torque converter and balancer, the vibration that the engine is giving is normal? I did switch out the pistons but they are nearly identical to the stock ones in terms of size and weight. Seeing as this is my first carburetor powered V8, this vibration may just be normal engine operation that I am misidentifying? Would there be any other telltale signs that I am missing?
 
LA 360 and Magnum 360 are both externally balanced....

the amount of external weight differs because of the lighter pistons in the Magnum engine...
 
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