swingingdart
Well-Known Member
I have a 318 with a 340 crank in it.Since the 340 crank is internally balanced, would a 318 harmonic balancer work? Or is that a bad idea?
Okay, second question.Neutral balance is neutral balance. So yes, the same harmonic balancer will work on a 318 or 340.
It is a 340 crank shaft in a 318 with all 318 rods and pistons.Did you put the 340 crank into your 318 or are you just going off the casting numbers on the crankshaft. A 340 has heavier rods and pistons than a 318 so it is balanced different even though it is neutral balanced.
It is a 340 crank shaft in a 318 with all 318 rods and pistons.
However they all spent time in an engine builder's shop together and he did his magic to make sure they would all work together.
I thought the harmonic balancer off the 318 was fine (thanks for verifying what I was hoping) but at some point with checking the timing I realized it spun on the rubber. And driving it i feel a vibration, its hard to describe, but it starts small then vibrates up harder, then drops small and vibrates up harder, over and over and over and the instances increase with RPMs.
Caused by bad harmonic balancer?
I bought it off another member on this site years ago. It is definitely a forged crank and he said it was out of a 340.The reason I asked about the casting number is the 318 and the 340 use the same casting numbers even though they were balanced internally different.
I'll try this, but if memory serves we had the timing mark to start with, then it went away. LolAre you sure the damper has slipped and isn't just marked for a different timing tab location? My experience is if they have slipped they will continue to slip. Mark the balancer from outer ring to inner hub. In a safe place rev the motor aggressively several times then check your marks.
Yes. And if you keep on running it, the damper will eventually just come apart. Not good.Okay, second question.
If the harmonic balancer spun on the rubber, is it junk?
Will do, I fell victim to the Headman header sales pitch. lolIf it's not vibrating with the car stationary and engine revving, it's not likely an engine balance problem. Check the drivetrain items already mentioned, and also how the exhaust system is mounted and the clearance around all it's components. Solid mounts anywhere can cause a vibration.
I sold my early 340 manifolds for enough to buy a set of TTI's.Will do, I fell victim to the Headman header sales pitch. lol
So some parts have 1/16" clearance that could close with engine torque. (Ugh)
I'm considering the 340 manifolds and ditching the headers. But those are pricy....