Re: [AMC-list] camshafts

[Frank Swygert <farna@xxxxxxxxxxx>]

Date: Sat, 9 Nov 2013 09:10:09 -0500 (EST)
From:tnmorrison@xxxxxxxxxxxxx

come spring, I plan to have the engine(258) rebuilt in my '82 SX/4. My
mechanic informed me that was a one year only style camshaft? I heard that
year had soft cam issues, but one year only? Really?
==================================================================

I'm not sure of the specs either, but I wouldn't use a factory replacement cam. Instead use a torque cam (sometimes called an "RV" cam). You want something with a peak torque range from about 1500-3500 rpm. I prefer the Isky Mile-A-Mor for best economy and good power (1000-3800 rpm range) or the 256 Supercam for a bit more power (1500-4800 rpm range). Either will be a great street cam. I wouldn't use one of their "bigger" cams for a street engine that's in a daily driver/cruiser. If you want a more aggressive engine by all means try a "bigger" cam! Comp makes some good cams, but I stay away from the Xtreme cams. They could be considered better in that they have split lobe centers (intake and exhaust duration isn't the same), but the lift is "extreme". Comp will custom grind one of their Xtreme cams with less lift (I'd only go 0.450"). That will decrease the high rpm power, but won't hurt low and mid range -- which is mostly what you want for a street engine.

By all means DO NOT use Comp valve springs! They are primarily racing springs and are too stiff for a mild engine. You can use stock springs up to 0.470" lift. If you want slightly stiffer springs use Crane or (best) Mopar Performance springs for a 4.0L. They fit, and are just a bit stiffer than stock. The Crane springs are right on the edge of what I'd use in a stock motor. You want the cam to survive on regular oil with no additives.

With the stiff Comp springs you'll lose a slight bit of gas mileage (not really enough to worry about -- about 0.25 MPG or less), and the added pressure on the cam will cause premature wear. If you don't use a ZDDP replacement additive all the time (a break-in additive) a cam lobe or two will get wiped off in a hurry -- usually less than 1000 miles.

--
Frank Swygert
Editor - American Motors Cars Magazine
www.amc-mag.com


_______________________________________________
AMC-list mailing list
AMC-list@xxxxxxxxxxxxxxxxx
http://list.amc-list.com/listinfo.cgi/amc-list-amc-list.com