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Discussion Starter · #1 ·
I need peoples opinion on what header I should buy for my 87 YJ 258. Should it go into single or dual exhaust? What kind of power increase will I notice? Will it sound more powerful? I would appreciate it if you could specify weather its in Canadian or American dollars for any price approximations. Thank you

1987 YJ Laredo
Rylan D.
 
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Discussion Starter · #2 ·
I'm gonna give you my opinion on this two ways. I'm sure it's more than you want, but that's never stoped me before.... Here goes...
1. Borla Header. approx $280 (US), Stainless steel, Million mile warranty. No one else can come close.
2. Replace your head with a newer style 4.0L head from '93-'95 4.0. You will see a huge increase in power, both low and high end, as well as fuel economy. The reason I point this out is that if you're gonna buy a new header anyway, do this at the same time. The oem exhaust, as well as the headers designed for the 258 will NOT fit the 4.0L head. Your 258 intake will fit just fine. If you buy a new header now, and deside to upgrade to the 4.0 head later, you'll have to buy yet another header. Spend some now to save some in the long run. You're obviously interested in getting the most out of your engine, so.... Get a 4.0L head and a Borla header designed for that application. The head won't cost much if you pick one up at a parts yard, or if $$ isn't a concern (yeah, right...) you can get one from Hesco or Clifford Performance. Either way, with the new head and the Borla header, you'll see a huge improvement all around, and for a lot less $$ than you'd think. Total project, including head, head gasket, header, various other gaskets, etc, should come in at or under $500. Nothing else you can do to your jeep for $500 would give you the same kind of improvement. Now, just start saving up (gotta get that lottery ticket...) to add the Mopar MPI kit! Hope this helped. Happy Jeepin'!

-Spyder
 
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Discussion Starter · #3 ·
Hey Spyder...

Does that 4.0L head mean a "fully loaded" head with the valves, rockers, springs, etc for the 4.0L or should the 4.2L valve train be switched over to the 4.0L head? What about timing and/or camshaft conflicts? I was just curious....

CJ8George
o[[[[o
85 CJ8,258,Weber32/36,4" BDS lift,4.10,35"tires,f/r lockers
 
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Discussion Starter · #4 ·
Complete head - Valves, springs, etc. I believe the 258 push rods are retained, but I don't remember for sure. If memory serves, its a matter of unbolt the head from the 4.0, bolt it down to the 258. The head bolts are the same size for the '87 258, but the older blocks have a different (smaller?) size bolt. Ideally, you would take the head to a shop and have it checked, new valve job, maybe new valves and springs, and mill the mating surface to ensure a good even seal, but you could still get some nice performance gains just by swapping in a "junk-yard" head, assuming it is in good shape and has no warpage, cracks, etc.

-Spyder
 
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