Box Stock

Box Stock Rod Clearance

T

TedD

New member
Getting ready to go through my Box Stock clone for the first time. What should the rod clearance be on the big end?
 
.0025 to .0035. Never tighter than .002. Key is to be sure crank AND rod journal are round. Absolutely round. Smoother the better. Those building large numbers of engines may have more precise info. This is just my opinion. Good luck.
 
They come from the factory with .001-.0014 clearance. The rod is nice and round within .0002 usually but the cranks usually need some attention. Like jsstump, I like to see from .002-.003.
 
Once you get the clearance you want, next step is to PROPERLY torque the rod. Very often folks give a little "extra" when tightening down the bolt on the rod, head and side cover. Any extra on the rod will surely distort the rod so that it will no longer be round. Been tested many times. Over tighten the rod and then measure it with good precision equipment. These cheap rods are easily distorted in this manner. Over tightening these not so high quality bolts can also result in unwanted excessive stretch. Now your over tightened fastener is holding it less, not more. If you can replace the bolts in any part of the engine legally with quality fasteners, do so. I have found Honda bolts to be of much higher quality with much better repeatable holding ability. As a general rule, studs are typically better than bolts and fine thread better than course. Good luck.
 
It is a general rule not to reuse connecting rod bolts. I know most do but it's not a good practice. Even ARC rod bolts should be replaced if reusing the rod.
 
I would be more concerned with the threads in the rod than the bolts used in these rods. The rule regarding new bolts or studs would be applicable to a steel rod.
 
Would it be legal to get some 5/16 threaded rod or whatever the stock thread pitch is for the stock side cover bolts, and use that to make some studs for the sidecover, as a cheap sidecover stud kit? We have done this with motorcycle and quad engines on the case covers but not tried it on these engines before
 
Weddle Racing said:
Would it be legal to get some 5/16 threaded rod or whatever the stock thread pitch is for the stock side cover bolts, and use that to make some studs for the sidecover, as a cheap sidecover stud kit? We have done this with motorcycle and quad engines on the case covers but not tried it on these engines before
Click to expand...

That should be legal, according to the way I read the rules. But, you can get a stud kit from Dover for $8.50 (but I see they are out of stock right now). I used them on my modified engines with no problems. http://www.doverpoweronlinestore.com/catalog/item/8251221/9871620.htm
 
Some disagree but I use red locktite comes in a tube like Chapstick but I've been a tech for 30 years never had a rod come loose
 
Most all of my new engines have been .002 clearance
Some very fine sand paper and diamond polish and smooth the surfaces up and they have been good to go
 
You must log in or register to reply here.
Back
Top