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Discussion Starter #1
So I have a 1980 chevy 350, standard 4.0" bore. I am putting in new rings and honing the cylinders. Before honing the cylinders I put a new ring inthe cylinder and squared it up with a piston. Using a feeler gauge I measured the end gap, it was at .030. I know it is supposed to Be closer to .016, my question is: will .030 be too much and rob me Of compression? Or will I be ok? Oh I'm also putting a new cam, timing gears and chain, and had a valve job done.
 

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I may be wrong, but the two compression rings are a different spec for each one the upper is like .0010"-0.0020", and lower is .0018"-0.0026"... those are production specs. Rebuilt/service limit is around .010"

You might PM Grumpy Old Fart and ask him to be sure, but I believe that's right.
 

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Discussion Starter #3
I believe that is right also. That was the top compression ring that I measured. That is why I am concerned. All of my new top compression rings are different sizes also. I assumed that they would all be the same.
 

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I believe that is right also. That was the top compression ring that I measured. That is why I am concerned. All of my new top compression rings are different sizes also. I assumed that they would all be the same.
Yeah if service limit is .010" and your at .030" it sounds like it may be time to donate to the machine shop
 

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Or just oversized rings, and file the ends down to get to the proper clearance. Is the ring end gap consistent through the whole cylinder? What is the ovality of the cylinder?
 

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proper spec is .004 per inch of bore for end gap for the top ring, unless using nitrous or a supercharger. Second ring should be close to that as well, .005 per inch.
 

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The good news is it will run. gas mileage will be shitty and hp will be down. If it gets you wheeling while you put a good engine together then run it. Otherwise don't waste your time.:grinpimp:
 

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Discussion Starter #8
thanks for the input guys. I Think I only have two options: 1. bore it .030 over and get bigger pistons and rings. 2. try to get oversized rings and file them down.
And yes the gap is consistent throughout the cylinder. Does anybody have a rough estimate as to how much a machine shop would charge to bore it out? I can do all the teardown and rebuild all they would be doing is machining.
 

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Guess they don't like making money in your neck of teh woods :confused:

Why don't you actually, you know, measure the bores and see what you have? Since you obviously don't have the tools to do this yourself, take the block to a shop and have them check the cylinders with a dial-bore gauge. Then you won't be guessing.
 

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Discussion Starter #11 (Edited)
Guess they don't like making money in your neck of teh woods :confused:

Why don't you actually, you know, measure the bores and see what you have? Since you obviously don't have the tools to do this yourself, take the block to a shop and have them check the cylinders with a dial-bore gauge. Then you won't be guessing.
Well the reason I dont do this is because I have not taken the motor out of the vehicle. I cant take it out without pulling the trans with it and that is a real pain in the ass! If it comes down to it I will, but if I dont have to, I dont want to. I did measure the the bore with a set of calipers and got 4.0''
 

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Well the reason I dont do this is because I have not taken the motor out of the vehicle. I cant take it out without pulling the trans with it and that is a real pain in the ass! If it comes down to it I will, but if I dont have to, I dont want to. I did measure the the bore with a set of calipers and got 4.0''
You measured the top of the bore where there is no wear. You need a dial bore to check where the rings actually ride in the bore and cause wear.
 

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few things. gassers dont get rebuilt in the cradle, only big rigs do, pull the damn motor!!! second of all, like said above, you measured at the TOP of the cylinder where there is no wear, you need to check the cylinder, all 4 corners, top to bottom, make sure it doesnt look like this ( ). lastly, your using calipers. when doing this kind of work, you need to be measuring in .0001's, not .000's. given your last few posts, pull the motor, gather all the parts you have removed from the motor, put them in a box, and bring it to a machine shop, your clearly over your head
 

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few things. gassers dont get rebuilt in the cradle, only big rigs do, pull the damn motor!!! second of all, like said above, you measured at the TOP of the cylinder where there is no wear, you need to check the cylinder, all 4 corners, top to bottom, make sure it doesnt look like this ( ). lastly, your using calipers. when doing this kind of work, you need to be measuring in .0001's, not .000's. given your last few posts, pull the motor, gather all the parts you have removed from the motor, put them in a box, and bring it to a machine shop, your clearly over your head
well said.
 

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Discussion Starter #15
Over my head? Maybe a little but just because I'm out of money at this point. I wasn't planning on completely rebuilding the motor but it's
Looking like I may have to. You are correct about the measuring though.
 
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