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| Northstar 6 Speed (Page 13/20) |
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Will
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FEB 16, 10:27 PM
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If the problem's the bore surface finish, then the only way to fix it is to tear the engine back down...
I know it sucks to hear that. I *really* didn't want to pull the car back down after I'd gotten it back together, but the fix requires rehoning the bores correctly.
Once you do that, your piston-bore clearance will be out of spec... There are no oversized pistons available...
It gets to be an expensive spiral quickly.
Northstars are NOT engines that can be torn down for a quick, easy overhaul like Chevies can be...[This message has been edited by Will (edited 02-16-2008).]
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AJxtcman
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FEB 16, 10:44 PM
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Will
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FEB 16, 10:52 PM
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| quote | Originally posted by AJxtcman:
I think GM sells oversize pistons. I know they list that the 93 to 99 engines can be bored .050
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Sure that's not .005, the same as the initial overbore spec for the LS1? Liners don't like being overbored.
Last time I checked (admittedly ~4 years ago), a replacement piston from GM could only be had in kit that included the rings, locks and pin to go with the piston. ONE kit was for ONE cylinder and cost ~$200.
I've had 8 or 10 longblocks that were warranteed because GM would rather warrantee that engine than have dealership techs try to overhaul it. Read the threads on this board about overhauling Northstars and you'll see why...
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AJxtcman
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FEB 16, 11:04 PM
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| quote | Originally posted by Will:
Sure that's not .005, the same as the initial overbore spec for the LS1? Liners don't like being overbored.
Last time I checked (admittedly ~4 years ago), a replacement piston from GM could only be had in kit that included the rings, locks and pin to go with the piston. ONE kit was for ONE cylinder and cost ~$200.
I've had 8 or 10 longblocks that were warranteed because GM would rather warrantee that engine than have dealership techs try to overhaul it. Read the threads on this board about overhauling Northstars and you'll see why... |
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I have installed over 50 sets of pistons in Northstars under warranty. All of them standard, but I know what it will take to bore and hone the 93 to 99. They even have stone specs
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AJxtcman
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FEB 16, 11:07 PM
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| quote | Originally posted by Will:
Last time I checked (admittedly ~4 years ago), a replacement piston from GM could only be had in kit that included the rings, locks and pin to go with the piston. ONE kit was for ONE cylinder and cost ~$200.
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I have never seen a Piston and Ring kit. The 00 to 03 piston upgrade come separately. When I had to replace my single piston I ordered the piston and ring set separately.[This message has been edited by AJxtcman (edited 02-16-2008).]
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AJxtcman
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FEB 16, 11:23 PM
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| quote | Originally posted by Will:
Sure that's not .005. |
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Dam it I did it again. it is in mm not inches
I think .5mm is about .030"
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ALLTRBO
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FEB 17, 08:53 AM
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.5mm is .01968", or just under .020"
Man, as cool as N*s are, they sure do seem impossible to use!
I like how Will has referred to the SBC before... You can rebuild it with bubblegum and sand and it'll run just fine. 
Good luck with your problems, that'll be one SWEET car when the bugs are worked out. It sounds great too!
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AJxtcman
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FEB 17, 11:24 AM
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I think that the Northstar gets cobbled together as well.
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Zac88GT
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FEB 17, 05:35 PM
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I put the intake back on today and ran it for a while with the PCV disconnected and it was still smoking, so i shut it off and pulled the intake again. This time there was definatly a pool of oil on the backs of some of the valves. Probably a teaspoons worth on the backs of the #7 valves. I might still do the leakdown test depending on how i feel but it looks like it's gotta come out again. The real question is: Is it worth it to try and rebuild it again and have it bored and honed with new pistons and whatnot, or should i just buy a new shortblock from the dealer?
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crzyone
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FEB 17, 08:37 PM
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| quote | Originally posted by AJxtcman:
I think that the Northstar gets cobbled together as well. |
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I don't think its the engine, more the owner. The engine needs to redline now and then to get rid of carbon deposits. It doesn't seem to like lumbering along in an old man cadillac. Piston slap can be pretty much solved.
There is no reason the N* can't last 300k miles, but you have to do propper maintinance on it, like changing out the coolant every few years. Keep the anti corosion properties fresh in the coolant and 3/4 of the headgasket problems would go away.
Great motor, a big cadillac is a poor platform for a DOHC V-8. A new N* will probably last longer in a fiero with regular WOT runs than idling along in a cadillac.[This message has been edited by crzyone (edited 02-17-2008).]
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