Balancing an Inline Six
- Thread starter Lazy JW
- Start date
A
Anonymous
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I think it was Thad, a few years ago, who said they had checked half a dozen 300 cranks in his shop and found that the factory balance was quite good for all of them. That right, Thad?
Personally, though, having built a couple of engines in the past that vibrated more than I liked, I have not and would never build another without sending the parts off to the balancer man (I can end-for-end balance the rods myself, first). Even if I am only changing a clutch and getting the flywheel faced, those parts go to the balancer if the car is a keeper.
Personally, though, having built a couple of engines in the past that vibrated more than I liked, I have not and would never build another without sending the parts off to the balancer man (I can end-for-end balance the rods myself, first). Even if I am only changing a clutch and getting the flywheel faced, those parts go to the balancer if the car is a keeper.
Ever 300 crank we spun on the balancer was balanced better than what is needed for street.
Couple were so close to zero, checked and checked, still right at zero.
You can buy a matched set of pistons. For rods use a digital scale and a pivot. Find the lightest big end then make all the big ends match. Find the lighest small end, make them all match. Now the rods all weigh the same, the pistons weigh the same. The difference in bearings or rings is nil.
The beauty of a straight six crank you do not need bob weights to balance, just have the crank balanced to zero or what value you want.
Couple were so close to zero, checked and checked, still right at zero.
You can buy a matched set of pistons. For rods use a digital scale and a pivot. Find the lightest big end then make all the big ends match. Find the lighest small end, make them all match. Now the rods all weigh the same, the pistons weigh the same. The difference in bearings or rings is nil.
The beauty of a straight six crank you do not need bob weights to balance, just have the crank balanced to zero or what value you want.
A
Anonymous
Guest
I'll still get stuff checked. One of the engines that vibrated after I rebuilt it without balancing was the 240 in my old van. It wasn't bad, just annoying. I never did anything about it, though it was probably just the reground flywheel and/or new clutch.
A
Anonymous
Guest
Thats what I'm saying, that based on your findings, my vibration probably was not due to the crank. I did rebuild with a set of new Silvolite pistons, but I'd bet the imbalance was in the flywheel/clutch. I'll never know, the van is gone.
Thad:
You said: "You can buy a matched set of pistons. For rods use a digital scale and a pivot. Find the lightest big end then make all the big ends match. Find the lighest small end, make them all match."
I have heard about balancing the ends of the rods seperately that seems to agree with what you are saying but I am still missing something (I learn better visually). Is the other end of the rod supported in a holding fixture next to the scale? Any pictures of this process?
Second question - to what resolution? I have a digital scale that reads down to 5 gram - is that accurate enough?
You said: "You can buy a matched set of pistons. For rods use a digital scale and a pivot. Find the lightest big end then make all the big ends match. Find the lighest small end, make them all match."
I have heard about balancing the ends of the rods seperately that seems to agree with what you are saying but I am still missing something (I learn better visually). Is the other end of the rod supported in a holding fixture next to the scale? Any pictures of this process?
Second question - to what resolution? I have a digital scale that reads down to 5 gram - is that accurate enough?
