1986 LG4 camshaft specs???
06-19-2007, 01:23 AM
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Car: Iroc
Engine: 350 4-bolt
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Axle/Gears: 3.27 Open
1986 LG4 camshaft specs???
what is the stock camshaft specs for a 1986 LG4 M5? Duration? lift? Does anyone know
06-19-2007, 08:08 AM
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Re: 1986 LG4 camshaft specs???
https://www.thirdgen.org/mods3
All the way down at the bottom; it's the same as any other LG4 cam, including the one listed as "87 " etc. etc. with the part # ending in 155.
Read em and weep.
All the way down at the bottom; it's the same as any other LG4 cam, including the one listed as "87 " etc. etc. with the part # ending in 155.
Read em and weep.
06-19-2007, 06:37 PM
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Car: Iroc
Engine: 350 4-bolt
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Axle/Gears: 3.27 Open
Re: 1986 LG4 camshaft specs???
wow thats a disgrace. Thanks though. what do u think about the Comp Cam XE256?
06-19-2007, 08:18 PM
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Re: 1986 LG4 camshaft specs???
As a replacement for stock it's a fire-breather by comparison. More than 30* more .050 duration over the stock LG4 cam. Yet still "mild" by performance standards.
06-19-2007, 09:41 PM
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Re: 1986 LG4 camshaft specs???
ok yeah thats what i need then. And now i know your supposed to replace the valve springs but what am i looking for?
06-19-2007, 10:11 PM
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Re: 1986 LG4 camshaft specs???
wow that's REALLY small, the stock cam I mean. Had no idea it was THAT small.
As far as springs go, it probably has recommendations on comp's site, however I'd HIGHLY RECOMMEND AGAINST using the "918 Beehives." Many, many, many people have been experiencing the exact same failures with them recently, look for my previous threads for more info.
As far as springs go, it probably has recommendations on comp's site, however I'd HIGHLY RECOMMEND AGAINST using the "918 Beehives." Many, many, many people have been experiencing the exact same failures with them recently, look for my previous threads for more info.
Last edited by urbanhunter44; 06-19-2007 at 10:14 PM.
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06-20-2007, 08:47 AM
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Re: 1986 LG4 camshaft specs???
The springs are what holds the valves closed, and keeps the whole valve train secure and tight against the cam lobe.
See those LG4 cam specs?
The stock valve springs are just as weenie.
No aftermarket cam will work right if the valve motion doesn't follow the cam profile. ESPECIALLY not one with modern aggressive ramps, like the Comp XE cams. Which by the way, the XE256 is one of the cams known to work the best in an otherwise stock LG4.
See those LG4 cam specs?
The stock valve springs are just as weenie.
No aftermarket cam will work right if the valve motion doesn't follow the cam profile. ESPECIALLY not one with modern aggressive ramps, like the Comp XE cams. Which by the way, the XE256 is one of the cams known to work the best in an otherwise stock LG4.
06-20-2007, 10:55 AM
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Re: 1986 LG4 camshaft specs???
what is the difference between the Computer Controlled XE256H and the regular XE256H???
06-20-2007, 12:30 PM
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Re: 1986 LG4 camshaft specs???
The "regular" is the one you want. The other is set up more for fuel injection.
I think you need about 3 lbs of springs; maybe another ½ lb or so of the retainers and all. Although they don't sell them by the lb, more often by a count (16 in a pkg usually). Visit Comp's web site for the part #s you need, they're all right there in the catalog.
I think you need about 3 lbs of springs; maybe another ½ lb or so of the retainers and all. Although they don't sell them by the lb, more often by a count (16 in a pkg usually). Visit Comp's web site for the part #s you need, they're all right there in the catalog.
06-21-2007, 07:40 PM
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Re: 1986 LG4 camshaft specs???
Comp 981-16 springs will work just fine with that cam (they are the recommended springs, after all) and they are drop-in replacements for stock. No machining required at all. Reuse your stock retainers and locks.
06-22-2007, 12:04 PM
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Car: 82 Berlinetta/57 Bel Air
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I believe you'd at least want to replace the exhaust retainers and eliminate those heavy, useless rotators.
06-23-2007, 06:23 AM
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Re: 1986 LG4 camshaft specs???
If you do you're going to have to shim the exhausts to make up the difference with the thinner (non-rotating) retainer. The factory machines the ehxuast spring pockets deeper to make up for the difference in retainer thicknes with the rotators. It's about .060", by the way.
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