91 f150
91 f150
Lead Driver
Joined: Nov 2002
Posts: 9,557
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From: Concord, NC
I don't believe that the cam being roller or flat tappet would make a whole lot of difference on the stock computer calibration. The lift and duration characteristics would be the key factor, not to mention the additional 45 cubic inches. A custom tune of the stock computer or possibly a 351 truck computer would really be needed to make sure it runs with a safe mixture. I'm sure someone else can chime in with their favorite cam suggestion.
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
'91 truck should have been a roller block, the casting number will tell you for sure. You can put a roller cam in that motor and you don't need the expensive retrofit cam and lifters, the regular production lifters and retainer assembly will bolt right in. As Eric stated it's the cam profile that determines suitability for EFI or not, but if you don't have a mass air truck then this motor won't work very well with the existing computer at all.. doesn't matter what cam.
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FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
Well that's not an absolute, if the cam isn't to far from a stock grind, heads are stock or ported, then it will run on a 5.8 computer. But if you have aftermarket heads and a healthy cam you need mass air.
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Brett Foote
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Joined: Jun 2006
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From: Ottawa, Ontario
Ouch!!! With those heads I think you're gonna need MAF cause even with a small cam the motor will move lots more air than a stock 5.8. You'll probably need it tuned as well to get emissions down to stock figures at idle and cruise.
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daddyslilmechanic
Explorer, Sport Trac, Mountaineer & Aviator
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Sep 11, 2011 04:56 PM
