Camshaft Question

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HotRodPC

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davbell22602

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So if the kit you're buying comes with new pistons, get the oversize and have it bored. You're looking at likley $100 or so more for the added machine work. Consider it insurance, and your build will last at least twice as long as a rering job.

Will a machine shop just bore it that extra 5 thousandths to 40 over or will I have to bore to 60 over? I was told I could bore it myself with a hone to get a 40 over bore.
 

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Will a machine shop just bore it that extra 5 thousandths to 40 over or will I have to bore to 60 over? I was told I could bore it myself with a hone to get a 40 over bore.

If it's 5 thousandths out of spec, they can bore it .030 over. You normally want to bore it least as possbile unless you're just trying to squeeze every cubic inch out of it. IF you go .030 now, then when it needs built again, should be able to .040 or .060. Now if you have a deep gouge in a clylinder, it might need to go .060 to clean up good and if it needs to go .060 to clean up, then go .060. Provided your block can take it. Small Block 400's for example can only be bored .030, some might make it .040, but none will go .060.
 

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If it's 5 thousandths out of spec, they can bore it .030 over. You normally want to bore it least as possbile unless you're just trying to squeeze every cubic inch out of it. IF you go .030 now, then when it needs built again, should be able to .040 or .060. Now if you have a deep gouge in a clylinder, it might need to go .060 to clean up good and if it needs to go .060 to clean up, then go .060. Provided your block can take it. Small Block 400's for example can only be bored .030, some might make it .040, but none will go .060.

Its already bored to 30 over.
 

HotRodPC

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Its already bored to 30 over.

Ok, so then now it can go .040 or .060 over. Be sure 390's can go .060 over, I'm about certain they can, and also need to make sure the pistons come in .040 over. Normally .030 and .060 over are the common ones. .040 became common when a block woudln't clean up at .030 and couldn't be taken to .060. Now days you can even get .010 pistons.
 

bucket

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Just for pleasure driving. No towing and hauling. Tagged antique with the yellow tags.

I'm getting my engine kit from here.

http://www.apmengineparts.com/ford-6-4-390-v8-1968-1973-engine-kit.html

I don't think "pleasure driving" and "Furd" is a possible combination.

If it's 5 thousandths out of spec, they can bore it .030 over. You normally want to bore it least as possbile unless you're just trying to squeeze every cubic inch out of it. IF you go .030 now, then when it needs built again, should be able to .040 or .060. Now if you have a deep gouge in a clylinder, it might need to go .060 to clean up good and if it needs to go .060 to clean up, then go .060. Provided your block can take it. Small Block 400's for example can only be bored .030, some might make it .040, but none will go .060.

Didn't guys used to go .060 over on 400's all the time? I thought that's how they got a 406. Or is that a 400 that's .040 over?
 

HotRodPC

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I don't think "pleasure driving" and "Furd" is a possible combination.



Didn't guys used to go .060 over on 400's all the time? I thought that's how they got a 406. Or is that a 400 that's .040 over?

Don't make go getting into all that math to find out. I sure wouldn't do it without sonic testing the block. The books I read way back in the day said NO, NO and NO on more than .030 over and .040 pistons were available for 350's I know for sure. Technology has changed alot now so it could be possible for certain.
 

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Ok, so then now it can go .040 or .060 over. Be sure 390's can go .060 over, I'm about certain they can, and also need to make sure the pistons come in .040 over. Normally .030 and .060 over are the common ones. .040 became common when a block woudln't clean up at .030 and couldn't be taken to .060. Now days you can even get .010 pistons.

Yea I can get 30 , 40 and 60 over engine kits from that link I posted earlier. There's even 80 over pistons available for the 390 too.
 

davbell22602

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Called Napa Machine Shop, $160/$20 per hole plus $65 for cleaning the block. He said if I'm already 5 thousandths out then I have to 60 over because that 5 thousandths out is really 5 on each side of the cylinder so it really 10 out.

Called Gants in WV and its the same price @ $20 per hole. Carquest wants $160, $65 for cleaning, $45 for magnaflexing, and $45 for cambearing installation.
 

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They're crazy if they think it needs to go 0.060" because your measurement is 0.005" larger than what the bore is supposed to be. That would be 0.0025" on both sides. Keep looking for a machine shop that really knows their ass from their hat.
 

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Reguardless of what machine shop I go with they said they need the pistons bore it to the piston diameter size.
 

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What C4 is saying, is it doesn't need bored. And I'd tend to agree, but if your kit you're buying comes with new pistons, then yes, I'd go ahead and go over bore. That .005 you're talking about it probably needed, or are you talking out of spec? See I have problmes understanding you at time. Here is an example, If you are not .030 over, so lets say you have X.030 pistons. If you have X.035 as a measurement, then for god sakes, call it brand new with a rering motor cuz you will not get a X.030 piston to move in a X.030 cylinder. That would be to tight and you'd likley break your ring groove landings off the pistons. Another good way to measure a block cylinder is to use your rings. Put the original rings in the bore. Push them down square with a piston top to make sure they are square in the cylinder. Then measure the gap. That will give you a clue of how much the rings and cylinder wore. If it's not much, rering the bitch and be done. And don't waste money on new pistons either. Also when measuring this way with rings, only go down about 1/2 inch in the cylinder. That is where you get most of the wear. That is called the Ridge.
 

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Its .035 all together. I'll still have to hone to get the ridge out at the top. I get .0015 when measuring piston to wall gap with a piston feeler gauge at the top where the ridge is. The tightest piston to wall can be is .0015 and loosest can .0023.

I have to replace the pistons. One has crack in it. Other than that they have surface markings.
 
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HotRodPC

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Now that makes no sense. It's .035 over all together which tells me, that is almost a new bore, but yet it has a ridge?? :shrug: Am I the only one not following here?
 

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