Only 258 crank and rods???

[Freyrt]

I have a 1997 xj with the 242 inline six. I have several minor mods arround the engine: No cat and 2,5" all the way with only one cherry bomb vertex, bored TB (60 mm), cold air intake with K&N cone filter.

I have thought alot about a stroker build but have seen so many have some problems with them that I am a bit afraid to put one in my XJ since it's an expedition vehicle and I travel far from home often just on this single jeep without others as backup. To me it seems like the problems often start when modifieing the valvetrain/camshaft but I'm not sure.

My question is this: What about only installing 258 crank and rods and keep everything else original (except the several minor mods I already have)??? Maybe just put in a bit higher flowing injectors with better "mist" instead of the original one hole type???

And also: What do you recommand, higher compression ratio or keep the low original CR and advance the ignition several degrees (by modifieing the crank sensor to move it further to the passenger side)???

Thanks before hand, Freyr Thorsson, Iceland.

Pictures of my Jeep:

[604rail_king]

neat pics!

with using the 4.2 crank and rods, sounds like a poor mans stroker recipe fits best. it may be best to replace your stock 4.0 pistons depending on the condition/milage, but either way you will have to play with the stroker calculator with changing the piston dish cc's as there are several options even though they are all stock replacements (check in the FAQ for the cc info).

also seeing you are using a 97 4.0, you can add a dual adj timing chain which can also change your compression depending on if you adv/ret it.

I personally would go with higher compression (within reason) vs keeping stock compression + adv ignition timing.


http://www.jeep4.0performance.4mg.com/stroker.html


4.6L "poor man's" stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.2L 5.875" rods
Sealed Power 677CP +0.020" bore pistons
9.25:1 CR
Stock 4.0 camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket
0.088" quench height
Ford 24lb/hr injectors for '87-'95 engines, Accel 24lb/hr injectors for '96-'04 engines, '98 Chevy LS1 25.2lb/hr injectors for '05-'06 engines
248hp @ 4900rpm, 306lbft @ 3250rpm ('87-'95 camshaft)
245hp @ 4800rpm, 315lbft @ 3000rpm ('96-'04 camshaft)

[Freyrt]

Since my cherokee is only driven arround 115.000 km (under 100.000 miles) I would probably reuse all parts (timing chain incl.) rather than swapping out parts in perfect condition but thanks for the info....

[Cheromaniac]

The only parts you'll need to change are the 258 crank, 258 rods, rod/main bearings, and 677P pistons. If the roundness and taper of the cylinders in your existing block are within factory tolerances, you could avoid a rebore altogether and use standard bore 677P pistons with new rings for a budget 4.5L stroker.

[Freyrt]

Thanks for the help

For curiousity's sake why not reuse my old pistons and piston bolt? Just put in new rings and hone the cylinders.....

[Cheromaniac]

For curiousity's sake why not reuse my old pistons and piston bolt?

The CR will be a highish ~9.7:1 if you reuse the stock pistons and could cause pinging problems with the stock cam.

[SilverXJ]

Your block is most likely going to need at least a hone. There may be a ridge at the top of the bore as well as ovality of the cylinder. Most likely the old pistons will be damaged when pressed off the rod. its never a good idea to reuse pistons, rings and bore finish when changing stroke, unless the engine has very low miles.

[92tank]

D

For curiousity's sake why not reuse my old pistons and piston bolt?

The CR will be a highish ~9.7:1 if you reuse the stock pistons and could cause pinging problems with the stock cam.

That's how mine is built, I built it before I found this site, and it runs fine just likes the premium fuel. That's not that big of a deal because its only like $5 more per tank, and it gets better mileage. And I have over 40,000 miles and still going!

[I6FAN]

Cool pictures Freyrt! When I first looked a these, I was thinking, "where is this", and then I read Iceland. That is truly a surreal setting!

[str8-6]

D

For curiousity's sake why not reuse my old pistons and piston bolt?

The CR will be a highish ~9.7:1 if you reuse the stock pistons and could cause pinging problems with the stock cam.

That's how mine is built, I built it before I found this site, and it runs fine just likes the premium fuel. That's not that big of a deal because its only like $5 more per tank, and it gets better mileage. And I have over 40,000 miles and still going!

Mine too:stock 4.0 pistons/258 rods/crank,carburated with a Offenhauser manifold 600 Holley vac. stock Renix exhaust-manifold and a Crane cam (272/284 dur .484/512 lift)258 waterpump and ign.-dist.with Pertronix Ignitor 2 and a cheap 36000 volt "dry" coil. No pinging but it's a bit on the warm side on the exhaust "no water-temp problems" 95 "swedish"octane = 92 US I think...

[Retlaw01XJ]

Cool pictures Freyrt! When I first looked a these, I was thinking, "where is this", and then I read Iceland. That is truly a surreal setting!

Take a trip to Iceland if you can, it's an incredible place. Glaciers and volcanoes combine to produce a surreal landscape.