Im overhauling my 258 and need some tips

[stan]

I am going to be rebuilding the engine in my 84 renegade in a few weeks and I was wondering if anyone had any info about a high performance overhaul kit, or a good quality kit that covers everything ill need to fix up my sweetheart. Any info would be appreciated Thanks, stan.

 

[jay79cj7]

One thing you might want to consider is a 4.0 head swap if you are looking for performance on the 258. Do a search for that and you will come up with many write-ups. Supposedly gains you many horses.

 

[Junkpile]

Clifford four barrel intake and a 390cfm Holley 4barrel carb. Split/dual outlet header with 2.0"-2.25" dual exhaust. HEI ignition conversion. Comp cams X4254H camshaft. Port and polish the exhaust side/ open up the intake ports of the factory head a little and match them to the ports in the intake manifold. Some bigger valves would be nice and a set of roller-rockers along with as lightweight valvetrain components as you can find will free up more power than you think. During the rebuild, take steps to raise compression to 9.2-9.5:1 to take advantage of more aggressive valve timing. This engine will produce a broad torque curve and would run best with slightly "tall" gearing. It will maintain the great low-end grunt of the 258 and allow it to pull HARD all the way up to 5,500rpm with the head work and 5,000rpm without.

The H.O. 4.0 head will make 30hp by itself and make the above mods so much sweeter, but it's expensive and unless the engine is being built for maximum power it's not really needed.......just better.

 

[WV77CJ5]

Just to throw this out there, will the 4.0 head bolt right in and also will it give you better gas mileage??

 

[Snitty]

it will BOLT right in.. but you do need to modify it... and it will help your economy quite well

 

[WV77CJ5]

what kind of mods are we talkin here?

 

[jay79cj7]

There are quite a few write ups out there on the head swap. Do a search for 4.0 head swap and look around a bit. You will find the answers to your questions before you think of them.