If it was an eagle kit, call eagle and give them the rod balance weight figures and they can send you a rod that is real close to that. I dont know if they would sell you a single piston but they have got a ton of them sitting around the shop if it was one of thier kits. If they will sell you one they can get it very close to the weight you give them off the balance card before you start. It will be easier that way than taking your chances on what comes out of the box.

 

Uh I think we are talking in circles now. Funny how that happens. I was merely pointing out the fact that he can't just replace a new rod and piston and throw it in there. Don't know or think that it was quite put like that just wanted to be sure he didn't understand it like that.

I certainly understand that a set of rods are sent out closely matched, but closely matched doesn't equate to a perfect match or balance. Furthermore they are matched in stocks, or lots of thousands, chances that he will get a rod or piston from the same lot are slim at best. The total weight of the rings, wrist pin, little end and big end and piston should be the same in all of the assembly. As I said before, if he has the original balance card it is fine, if he does not he needs to have the ENTIRE assembly rebalanced. That can probably be done with one of the other assemblies but in essence it is bringing the new within the same tolerances. What happens if the new pieces are actually lighter than the rest, chances are it will be heavier. It is a moot point as I think we are all on the same page, just wanted to be clear about it, as not all have the same ability to read and comprehend.

 

Lighter up to a suprising amount of grams you wont even notice, the case to worry about is underbalanced. Overbalance is desired to a small extent. In fact balancing is not as exact a science as most believe it is, there are factors for oil and other things at are just a best guess that has been found to work ok experimentally. There is a laundry list of things that can cause the calculated values to be off which is why we have to spin it up in the machine and test it out at all.

 

No need to rebalance.

Rich

 

thats good to know, save me a little money on not having to reballance the whole asembly again. I already ordered the new rod (waiting to really inspect the combustion chamber before I order the piston, may need to go with .040" over and bore another .010") So calling eagle and giving them the data on the ballance card is out of the question. besides I got the rod for $35 by shopping around. I also found where I can buy one piston for $22. Im going to have to buy a full set of rings, mains, and rod bearings - wich does not bother me to much.

I pulled a lazy move today and didnt get out to the shop to check anything out. I forgot it was sunday and my machine shop is closed anyway. I will get back into it tomorow


I guess lack of piston explains this:




EDIT:

Looking threw some pics of my build. I found a readable picture of the ballance sheet, just incase I cant find it. lol

 

Torquing the bolts to 40lbs in one step didn't cause this. As WS6TERROR said, you probably forgot to torque that one at all.

 

damn.. I guess I could have.. thats a stupid mistake eh!.. I cant believe I made it 37 miles before it starting ticking, it must have been hand tightned only. well, that will not happen again. I will be mark them this time.


Also, got my new rod today. its one gram heavier than mine. thats good. machine shop should have no problems with that.

 

If youre going to do it yourself get a yellow paint pen and mark each rod bolt AFTER you torque it to spec, also put a feeler gauge of the propper size between the rods (at the journal) as you torque them down. when tightening them before the torque do a criss cross on that rod so that it applys evenly.
Oil head of bolt (I prefer ARP molylube on threads and head).

I would as well just have the block and crank checked and replace one piston and rod. a few grams here and there will mean nothing !!!

Unless youre spinning the thing way past 7000 rpm a few grams are not going to mean squat.

If youre in doubt get a digital scales and measure it all.

I built a cheap rod balancing fixture with a 1 foot peice of 2x4 (with a notch on one side inthe middle) and a propper sides pipe for the big and little end.

Wow I balanced my rods myself for free...lol

 

Most important part.

 

my machine shop is going to match the weight on the new rod and piston for $25. I just gave him the ballance sheet, and the new rod, piston, and rings. said he will get to it tommrow. nice.

 

$25 to balance, that is extremely cheap.

 

well hes not doing the whole thing, just rod and piston, and hes just matching it to the ballance card.. wont take but 10 mins

 

Ahhhh... I was about to say!

 

Too cheap. Something aint right there.

 

WELL. I jumped the gun a bit, after full disasembly of the engine down the the block I notice some imperfection in cylinder number 7. and its a hair to much to hone out, so it look like I am going to order a set of .040" over speedpros and I will take the block in to get bored and cleaned good. who knows where the thousands of metal peices went in that engine. so a good cleanig will ensure no problems down the road. I am also going to give him the heads to look at. I may need some new valves and a valve job. So I have a complete set (7 used with 37 miles on them) and one new speedpro .030 over pistons for sale. (the weight of the new one was matched to the 37 miles pistons)

atleast I didnt waste much money, I needed to get the rod weight correct anyway. and when I get the new pistons I will just have my machine shop be sure they weight the same of very close to my ballance card for the original pistons so as to not throw off the ballance there.