more power from 258?

[bigchief79]

What is a reasonably cheap and reasonably easy way to get more power from a 258?

[64Trvlr]

Why not do a compression test and see what you have to work with? Then maybe a major tune up would in line to help make some more power and improve your mileage.
:cool:

[Archie]

I've heard that using a MC2100 carb with a 2bbl to 4bbl adaptor and a Cliford Intake will give you the best HP gains. Keep the stock manifold and run a 2" exhaust (to keep the power band down in the low RPM's). The TFI upgrade helped my power somewhat.

[joe]

I'm with 64trvlr on this...first get everything to spec and see what you're dealing with. No sense bolting a $1000 worth of stuff to a worn out or out of tune motor.
These are tractor motors and more designed to work at the bottom end rather than be a freeway flier. They can be hopped up(with money) but if speed is a big issue swap in a V8. Someone once said "Power costs money, how fast you wanna go?"

[Oracle]

Going with Trav on this also. Get a good baseline. In the meantime get on the phone to Clifford. In my book they know more about inline sixes than anyone in the world. Whether bottom or top end power, they can advise. Had a dog of a chevy six in a full length panel van once. New Carb and intake from Clifford, plus their advice on timing and spark gap made an AMAZING difference. You would not have believed it was the same motor.

[J10Truken]

I have a 258 6 cyl in my 82 j-10. I am or should I say have gone thru the gamut of available performance parts for this engine. First let me tell you that there are no cheap parts unless you find them used somewhere. Second the best place I found for parts that are truely made for this engine are at Clifford Performance.com. Good Luck and if you find some cheap ones let me know.

[KivaKid]

I find it strange that I have more lack of power in the low end than the high end. I can speed with the best of them on the highway. It seems opposite of what I normally hear. Maybe go for the GM HEI ignition upgrade. It supposed to be around $100-$150 for this. I'm planning it soon myself. There are several good articles on it. Here's one:

http://www.geocities.com/jeeperaz/hei.htm

[joe]

<blockquote>quote:</font><hr>Originally posted by KivaKid:
I find it strange that I have more lack of power in the low end than the high end. I can speed with the best of them on the highway. It seems opposite of what I normally hear. <hr></blockquote>

In an 80 up rig it is abnormal. What you hear about the grunt/tree climb ability etc of the 258 refers to the pre-80 rigs with decent gearing. 80+ rigs ran rediculous high stock gears 2.73/3.31's which sort of negate(is that a word?) the bottom end power a 258 was built for.
The 2.73 gears make it less desirable for botom end power but with patience will fly on the freeway ;)
Drop some 4.09's in your six banger Wag and the next time ya need to do some roof repairs on your house just drive up...no ladders req'd :D
Even with a good low rpm motor though ya still need comparable gears to make it all work.
Gears are more important than HP if "you really have to get up there"

[bigchief79]

Thanks guys. I'll have to check out Clifford. Last time I checked, 'bout a year ago, comperssion was 120 pounds all around. The motor is in fairly good shape, regular tune ups, bosch plugs and accel super stock coil went in last time. It definately has no problem on the trail, it lacks hill climbing power in the urban jungle. :( just can't hold speed up those darn freeway hills!

[RustyCJ8]

Bigchief-You described the 258 in my CJ-8...I have the 2.72 gears :( BUT the high gear helps me get a little better mpg,what 9mpg or so :eek:
I blame most of it to the crapper-I mean carter carb tongue.gif

[J10Truken]

Ineed to up-date my last reply about cheap parts for your 258. I have found an offenhauser intake that is less money than the clifford set-up as with clifford you have to buy the adapter plates. Also, hedman, makes a good exhaust header cheaper than clifford. By the way I just put 410's in mine and it goes up the hills at 65 without going into second gear now. WOW......what a difference. I am running 31x10.50 15's and this thing pulls now. Good Luck.

[LRRH]

can't belive i'm the first to say it, but "6=8"

two things:

the stock carter bbd carb is crap. if you haven't had to rebuild it yet, i'm sure you will soon. ;) i'm pretty sure adapter plates are fairly cheap($20).

also, the stock distributor is junk. it's such a small cap. when your reach higher RPMs the sparks will start interfere with each other causing less than peak spark. the HEI upgrade is fairly simple, and gives a much more reliable spark in the top end beacause there is greater distance between terminals, even compared to a stock distributor and an acccel coil.

if you find a used HEI at a junk yard you can pay less than $40 for it. there is a simple modification involving flattening the output gear, but not too hard. add a new cap&rotor for and you're still under $100. this is the biggest single difference I have noticied on a 258.

parts from Clifford or Offenhouser will be expensive, but good quality. Choose your own poison i guess :D