pro-x 350 engine vibration?

[kevin wcmo]

i have a 350 (78mm piston) pro-x jug i put on a 86 motor.  the motor seems to have quite a bit of vibration through all rpm.  all of the dots where lined up when the motor was assembled.  i had a machined aluminum balancer cap that i had picked up in a pile of parts somewhere down the line that i put in as well.  the bearings seemed good on both ends.  is there something a guy can do to help, or is this just the nature of the beast with the big bores and heavier than stock pistons. thanks

[Skeans1]

i have a 350 (78mm piston) pro-x jug i put on a 86 motor.  the motor seems to have quite a bit of vibration through all rpm.  all of the dots where lined up when the motor was assembled.  i had a machined aluminum balancer cap that i had picked up in a pile of parts somewhere down the line that i put in as well.  the bearings seemed good on both ends.  is there something a guy can do to help, or is this just the nature of the beast with the big bores and heavier than stock pistons. thanks

Which piston was used when assembled?

[hontrx265r]

They do vibrate a little more then a smaller motor. If its too much to tolerate something is wrong. If its just a little more then normal and your being cautious, it is probably fine.

[kevin wcmo]

wiseco piston

forgot to mention it does also have a very low hour hot rod crank setup the was replaced prior to and ran a few hours on the original cylinder do to excessive bearing play in the stock one

[Victork]

Just throwing it out there in case you didn't notice but the crank has a punch that lined up with the punch on the inside of the gear also, the gear has a inner and outer punch mark so it's not only lining the gear and counter balancer up. Some after market cranks don't have the punch mark on them

[Pumashine]

Just throwing it out there in case you didn't notice but the crank has a punch that lined up with the punch on the inside of the gear also, the gear has a inner and outer punch mark so it's not only lining the gear and counter balancer up. Some after market cranks don't have the punch mark on them

Agreed.This is important cause you have to put the gear on the crank with crank at TDC where the mark on the end of the crank is also TDC. If your off by 1 tooth you will get some vibration. You do not have to balance the crank unless you go over 80mm piston weight. 78mm should not vibrate.

[kevin wcmo]

when i get a chance i will pull both covers of and verify everything, but yes i am aware of the dots on the crank as well, and am 99% sure they are all lined up.  just trying to get a head start when i get it broke down.