My first 302 rebuild new everything crank, cam, heads done at machine shop etc.. After about 3500 miles motor developed a bottom end knock. I thought that I did everything perfectly. Torqued everything to spec, made sure work area was clean. Anyway, I'm getting ready to attempt another 302 rebuild. Any tips or possible causes for the last failed rebuild? How true are the $20 torque wrenches? I dont know what happened last time (haven't taken that motor apart yet) but I dont want to have a bad rebuild again. Please, all helpful tips are much appreciated.

 

if you haven't pulled motor yet, check the flywheel mounting bolts. they might be loose, causing a knocking sound. no matter what, it's a pain trying to diagnose and repair accurately.
as for 20.00 wrench, they make great pry bars.

 

Actually the $20 torque wrench makes a better de-icer than a pry bar. I broke mine using it as a prybar, the socket tip just twisted right off.

If you want to save a buck on a torque wrench get a Craftsman pointer type (non-rachet) they don't cost that much and are dead accurate. The pointer types are harder to use but you don't have to spend big bucks for a accurate one.

I had a knock last summer with my new 428. I bought a complete rebuild kit from PAW and had a local machine shop do the machine work. I've built engines before and took a great amount of time on this one. Ends up the big ends of the rods were not round, they were not sized properly. I paid a shop to check the whole thing out and that's what they said the problem was.

I would tear yours down and inspect it, you should see some wear marks on the rods, bearings ...

I also took mine to several experts to find the problem when the engine was running. Based on the sound and timming of the sound, they properly determined the problem to be in the rods / bearing...

 

You didn't forget to put assembly lube on the Main & Rod Bearings
did you?.
pull pan and check bearings before tearing into the engine.

 

Thanks for responces, I haven't pulled the motor yet, so I will check the flywheel mounting bolts first. I was thinking that I didn't get accurate enought with the $20 torque wrench. I guess I will be buying a new wrench. Anyway thanks again. Ray

 

Cut your oil filter apart, look for anything that may be in there. You should be able to get a good idea of the problem by what you find. Scott Hartford WI

 

great idea about cutting the oil filter up. you can even check the oil itself ffor nice silver and copper metallic residue. this is how i found a problem was occurring in a 302 i had.

 

 

First, I would get an auto stethescope to pinpoint the knock. Also, rods and mains make different noises. Mains usually make a double knock. If you can't afford the stethescope, use a long screw driver with a wooden handle. Place the handle against your ear and the noise will transmit to the handle. The oil filter idea is an excelent idea. If you pull the pan, check out the contents in the bottom. You may be able to learn something by draining the oil and seeing what is in it.
When you rebuilt your block, did you clean out all oil passages with brushes? Especially clean out the crankshaft holes if the crank has been turned. At the very least clean it in solvent and blow out the holes after doing so. Some of the shops don't do a good job on this and its left up to the machanic to make sure that it is done.
About the torque wrench, I believe that no torque wrench is better than a cheap one. However, doing without one is a matter of experience. Usually, one came by learning the hard way by breaking the bolt or stud off. One thing is for certain, you need to find out what exactly went wrong, before you try again.
Don't give up on what you have already done till you know it's not fixable. One word of advice on not using a torque wrench, if while tightening it suddenly gets easier to turn. Stop and either take the bolt back out and check it to see if the bolt has stretched or don't mess with it if you think it is tight. You can usually see where a bolt has stretched , it will have a hour glass shape somewhere, usually on the threads.
Good Luck,
Rich