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258 Rebuild: RV Cam and high comp. head/pistons upgrades 258 Rebuild: RV Cam and high comp. head/pistons upgrades
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Old 05-14-2008, 09:52 PM   #1
DirtEater
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1982 CJ7 
 
Join Date: May 2007
Location: Okie City, OK
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258 Rebuild: RV Cam and high comp. head/pistons upgrades
Close to rebuilding the 258 and was thinking while it's being rebuilt, might as well go for a little more power, because these 258's don't have much to begin with.

How much extra power can you expect from an rv cam and higher compression head/pistons? I already have a Borla header and catback system and plan on getting the Howell CA kit as well. Is 30-40 hp a reasonable expectation?
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1982 CJ7 4.2L ~ T-999 ~ Dana 300 ~ SOA Conversion
Dana 30/AMC 20 with Truetrac - one piece axle - 4.10's
33" Toyo M/T's on Pro Comp Xtreme Series 1069
Borla header and Catback Exhaust System
Jeeperman bumper w/ Ramsey Patriot 8000 - Jeeperman tire carrier/bumper
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Old 05-15-2008, 04:42 AM   #2
GPER
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Are you doing the 4.0 head swap????
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Old 05-15-2008, 11:06 AM   #3
DirtEater
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Location: Okie City, OK
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I had thought about it, but it might be easier to keep the 4.2 head. I already have a Borla header and don't want to buy another one to fit the 4.0. Not sure about the 4.2 intake working either. Trying to stay smog legal.
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Terry ~ USN Ret. 30Sep07 : )
1982 CJ7 4.2L ~ T-999 ~ Dana 300 ~ SOA Conversion
Dana 30/AMC 20 with Truetrac - one piece axle - 4.10's
33" Toyo M/T's on Pro Comp Xtreme Series 1069
Borla header and Catback Exhaust System
Jeeperman bumper w/ Ramsey Patriot 8000 - Jeeperman tire carrier/bumper
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Old 05-15-2008, 12:23 PM   #4
jeepwhore
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The only thing I would think about is only bumping the comp. up moderatley. With the price of gas, do you really want to have to run premium?
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Old 05-15-2008, 01:39 PM   #5
DirtEater
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Location: Okie City, OK
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No, I'd rather not buy premium, but since it's only been a weekend driver so far, it wouldn't be that bad, if I could get noticeable performance gains from it. I think stock comp. is 8:1 so I thought bumping it up to 9.5:1 might do some good.
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Terry ~ USN Ret. 30Sep07 : )
1982 CJ7 4.2L ~ T-999 ~ Dana 300 ~ SOA Conversion
Dana 30/AMC 20 with Truetrac - one piece axle - 4.10's
33" Toyo M/T's on Pro Comp Xtreme Series 1069
Borla header and Catback Exhaust System
Jeeperman bumper w/ Ramsey Patriot 8000 - Jeeperman tire carrier/bumper
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Old 05-15-2008, 01:44 PM   #6
supraman1990
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You can make the 4.2 intake fit the 4.0 head. Trust me, if your going for power, do the head swap. It's like night and day.
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Old 05-15-2008, 04:19 PM   #7
DirtEater
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Location: Okie City, OK
Posts: 298
Will the Howell CA kit for the 4.2 work with the 4.0 head swap?
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Terry ~ USN Ret. 30Sep07 : )
1982 CJ7 4.2L ~ T-999 ~ Dana 300 ~ SOA Conversion
Dana 30/AMC 20 with Truetrac - one piece axle - 4.10's
33" Toyo M/T's on Pro Comp Xtreme Series 1069
Borla header and Catback Exhaust System
Jeeperman bumper w/ Ramsey Patriot 8000 - Jeeperman tire carrier/bumper
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Old 05-15-2008, 07:51 PM   #8
supraman1990
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Don't see why not. It doesn't do anything with the block or anything else.
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80 CJ5 in the process of a frame up resto
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The little stuff will kill me.
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