Jeep Strokers

Hey Jeepers,
Well, my stroker is on the road! I am one of the unfortunate Jeep owners who has to pay to have the work done. No shop, no time, no tools Anyway, I went to the shop where it was being installed, and it was sitting in the parking lot ready to be fired up. Fluids in, everything hooked up. Popped the hood and saw one connection hangin' loose. Ended up being the IAT connection. Found the old sending unit in the back, stuck it in. So...turned the key and...IT FIRED RIGHT UP! NO PROBLEMS. Ran it up to 2000 rpms for 20 mins. and then 500 rpm increases to 3500 for one minute each, then back down to 1000 rpms, 500 at a time for one minute each. That was Lunati's procedure. At the end of the break-in, the temp. had gotten high and it blew off the bottom radiator hose. Tightened the hose back down, filled it back up with coolant and burped the air bubbles. Fired it back up and it settled in to a nice smooth 700-750 rpm idle. NICE. NO LEAKS.

Issues- The oil pressure gauge acted up, flippin' all over the place. Turned out to be the sending unit. Loose or crappin' out. No biggie.

Weird-It runs REALLY COOL. Goin' down the road, it only shows about 125-150 on the gauge. It takes about 20 minute setting in place for it to get up to 180-190. The mechanic used a thermal gun on it yesterday and it indeed showed 175 at one end of the engine and 200 at the other end. It is SOOOOO quite too. My old 4.0 had a cam, header, RR's, T-Body, etc, so it was reasonably strong, but it was NOISY! The lifter had been on it's way for a long time and I just got used to the noise. My stroker is as quite as a stocker, accept for the exhaust note I am using the Hesco H2O pump, Robert Shaw 180 thermostat, Turbo City high flow T-Stat housing, and a new radiator. Is it possible it just VERY efficient? Works great so far.

Driving-Well, like I said my 4.0 was pretty strong , even with the bad lifter. I haven't really stomped the pedal either, since it's so new. But it feels REALLY smooth and it now holds overdrive going up hills that it would have QUICKLY shifted down to be able to climb. It has a resonance that I can feel through the whole vehicle. I'm lookin' forward to gettin' the break-in completed and being able to stretch it out a bit.

Build-
*Original '94 XJ engine
*4 wt. 258 crank, stock 4.0 rods, ARP rod bolts, KB 9.0:1 forged pistons. Crank, rods, pistons, and flex plate balanced.
*Block bored .60 over, zero decked, hot tanked, lined bored, bottom end girdle fitted.
*Head fitted with .160/2.02 valves, Mopar 5.2 springs, extensive porting and bench flow work, flows 247 cfm at .500 intake, 158 cfm at .500 exhaust, combustion chambers reduced to 58 CC's.
*Lunati Voodoo cam, 484/507 lift, Yella Terra RR's, chromo pushrods.
*Hesco oil pump, H2O pump, and fuel pressure reg.
*Cloyes true roller timing set.
* '99 intake conversion, #24 Ford blue top injectors, 62MM Fastman throttle body, K&N cold air.
*Full MSD ignition brain, coil, wires.
*Doug Thorley stainless, ceramic header. NO problems with mine.

The simulator on the site gave me a static comp of about 9.6:1 with around 8.23:1 dynamic. Quench is .040-.045.

I is an expensive build, but so far it RUNS GREAT

Thanks for all you input. Will keep ya' posted. Any thoughts on the cool running?

crust1

Congrats on the successful built-for-you stroker! Which model Lunatti cam did you go with? or is it just called a 4.0 "voodoo" cam?

BTW i think your temp problems are from your thermostat. If it got so hot and built so much pressure to blow the bottom hose off, i'm sure the thermostat is damaged and stuck partially open. I'd suggest replacing it and the gasket with another one, just to be sure. One of the things i enjoy about my stroker is how it comes up to temp quicker on these cold days then my stock engine did....

don't be afraid to accelerate sharply, there are a thousand and one theories on engine break in, but very few of them suggest babying the engine, just don't cruise at a constant RPM and don't maintain high RPM's or high speed for any length of time.

I have several break in instruction sheets from performance engine machine shops and every single one of them strongly suggests sharp acceleration, even WOT blasts. To promote sealing the rings UNDER LOAD one of them even suggest that sealing while idling or low load driving (highway cruising) is a bad thing, and will promote "lazy poor sealing rings under higher load". Don't know if that's an old mechanics tale or not.

Depending somewhat on ring material and preparation, many rings today have coatings or special prep (read, intentional burrs) that are intended to promote ring seal in the first few miles of break in. Supposedly you can't screw those up.

From what KB told me prior to purchasing the pistons is that the rings will basically me seated at the end of the cam break in procedure. That was for their plasma moly rings though and i don't know which ones you went with.

As for the temp.. running cold is probably the t-stat. blowing the hose off could just be a lose hose or a faulty rad cap.

What was your piston clearance set at? Also, let us know what fuel grade it can get away with without pinging.

-Chris

Here's an update-
I just went out for a couple of hours this morn. It's about 36-40 degrees here in Oregon. The XJ is running GREAT!!! I just went on a 90 miles cruise out in the country, 20-70 mph, up some steep hills in swanky estates, long straights, etc... The engine is SOOOO torquey. It seems to get to overdrive quicker and then holds it down to lower rpm's too. Throttle response is INSTANTANEOUS. It look like I got about 16.2 mpg on this loop too. That's better than the old 4.0 for sure. My XJ is a '94, ex-Gov't rig, no power anything, rubber floor matting, column shift, about as light as they come. I run 4:10's, and 31/10.50 Dick Cepeck Mountain Cats, which are like the Mickey Thompson MTZ's. Fairly aggressive tread. The new engine only has "noise" when I'm on the throttle. At idle or cruise it's as quite as stock. FANTASTIC I thought about the T-Stat being stuck, but I went through a Starbucks and after being in line 6-8 minutes, the temp came up to 190-200. As soon as I hit the street it came down about 15-20 degrees. It's not running rich, based on the MPG, but I'll check the plugs to see for sure. It used to run around 220, so I don't think the T-Stat. is bad, but I may need to go back to the 195, maybe.

The Lunati cam is the #63501 with corresponding lifters. It's the #2 of the 4 that are available for the AMC 6's. Operating range is 1200-5400 rpm's , I think. I feel the Luanti's are an EXCELLENT choice. They are profiled for our lifter size and run about the same price as comp, Crane, etc... I messed with the comp. calculator this more and it looks like the static comp is 9.6:1, but only bleeds down to about 9.32:1, based on the intake closing degrees of 34.5 and the 4 degree advance built in to the cam. I'm running premium, always have, since it's only 10-12 cents more and I seem to have always gotten better mileage on it.

What rpm's should I keep the engine under and for how many thousand miles? I have Valveoline 30wt non-detergent and the Comp brake in additive in it for another 250 miles and then I'll run Valveoline 10-30 with additive until 5000 miles, the Brad Penn 10-30 for a couple of oil changes. I'm using earth magnets on the filter and pan bolts to catch the "bits".

So far, so good, SO FUN

crust1~

Hey guys,
I am pondering one quirk that my Jeep has now and also had with the original 4.0. Cold or hot, at around 2000ish rpms or so, if I chop the throttle from a steady cruise, high or low road speed, I experience a slight surging or "bucking". It only lasts a second or two and then it seems fine. I have the AW4. Is this a TPS glitch? Does it happen as a result of a bored TB? It's slightly annoying, but more important if it's a sign of a problem ahead, I want to fix it now.

Thanks,
crust1

It isn't a result of the throttle body. What do you mean by chop? What do the engine RPMs do?

I think he means mash the pedal.

A little better detail that describes exactly what happens, and what the conditions arem may help to reveal the problems

Hey guys,
No I mean when I'm goin' down the road, regardless of road speed, but around 1800 rpm's (approx.) and I let off the throttle all the way, the vehicle "bucks" or surges, for about 2-4 seconds then runs normally. I'll watch it today to see what the rpm's do while it's happening. I have wondered if it's the effect of the Detroit TruTrac locking and unlocking, but it feels more like it's in the engine. Like I said, it did it in the old 4.0 too. What does a bad TPS cause for problems if that may be it?

Thanks,
T~

Possible a bad vehicle speed sensor. The ECU uses that to determine if the vehicle is in a state of "decelleration". Closed throttle plate and loosing land speed = state of decelleration.

Stick or automatic?

It's the AW4 auto.

i'm not sure if its possible to check the pulses from the VSS with a DRB2 scanner. If you know someone with one it might be worth a shot to have it analized.

Hey MG,
Where is the VSS located?

T~

The VSS is in the transfer case for 4wds and the tail part of the tranny for 2wds. Look underneath at about mid body driver side. Congrats.

I've had a similar problem and it was my TPS... which is easily checked.