Sper 55 Problems

[Anonymous-0]

Had engine overhauled and asked for them to balance it. Engine starts and runs great, except, at 1100rpms the vibrations start, at 1400 rpms it is bad and then starts coming out of it and not to bad at 2200.
Question, could he have balanced the flywheel to the crank shaft 180 off and when I mounted it correct this caused the vibration??????
Took it a local shop today and flywheel checked 74.8 grams out, we 0 it and now it still vibrates but comes in now at 950 rpms.
Sure wish I had turned the flywheel 180 degrees before we touched it, oh well more hind site.
Let me know what you all think.
Bob

 

[Bruce Hopf]

Bob-Wyo
Could be that when the fly wheel was installed, didn't have it torqud right, posibly forgot to bend safty tabs aroud bolt heads, to prevent bolts from backing out, and comming lose. sounds like a lose bolt or bolts. I woult check there.

 

[Anonymous-0]

The bolts are offset the flywheel will only go on one way.

 

[Anonymous-0]

One other thing the pto disc can have one side break off and cause vibration evan when not ingaged.

 

[Anonymous-0]

We used to balance engines. Now depending on what type of balancer the shop had if the work is done correctly the engine will be in ballance at 1 RPM. 1000 RPM or 10.000 RPM or somewhere inbetween. Just the laws of physics. Now is this a gas or diesel. How long have you run it after it was assembled?

 

[Anonymous-0]

J Schwiebert , the machine is a Sunnen DCE-750 crankshaft balancer. Only would turn up to 800 rpms when within 17 grams he said.
It is a gas engine- 1955 year and has run a total of 1.2hours by new hour meter and the new over haul.
After the balance job yesterday I ran it with just the flywheel on as I had done the Z split and it was still seperated from the trans, etc., and flywheel run true.
Quote" ballance at 1 RPM. 1000 RPM or 10.000 RPM
Are you saying that it will only be in perfect balance at a certain Rpm and not the full range?
One more question- is the crank internally balanced so then the flywheel can be 0 balanced?
Seems they were trying to ofset the crank balance with the flywheel and some are like that for sure.
Thanks for your time and all the info, this has about done the ole boy in, wished I would have never told them to balance it.
Also I had that flywheel off and had it resurfaced and installed a new clutch and pressure plate about 2 months ago and it was fine then, just a very slight and normal vibration, betting a main bearing causing this as one was in pretty bad shape and rod bearings where showing copper.
Thanks again,
Bob
So is this true it will only go on one way? just seems now they balanced it to the crank 180 off, with the timing marks on the left side instead of the right side.

 

[Anonymous-0]

When the keyway in the front of the crank is pointing strait up, then the timeing mark should be on zero in the hole.If this is wrong someone has done it wrong!

 

[Anonymous-0]

Zero is the TDC mark

 

[Anonymous-0]

No If the assembly (rotating group) is balanced it will be in balance no matter what the RPM is. On the crank you spin the shaft and you may need to remove weight or you may need to add heavy metal to add more weight and in some case you may need to do both. You get the big ends of the rods to all weigh the same and the same is true for the small ends. You get all the pistons to weight the same You also get everything else to be equal as well. Then you make up the Bob weights from all this data and go to to work. Get it in balance the balance the flywheel and clutch sperately.

 

[Anonymous-0]

Thanks for your time and great info, will let you know what we find out is the problem.
Bob

 

[Tramway Guy]

Did you line bore the mains, or at least check them? If they aren't in alignment, you will have problems.