Jeep Strokers

Hi all, just finished my swap over the weekend- bought a used longblock off ebay in january, tore it down, had my machine shop machine the block, install bigger valves, and install the rotating assembly... I finished the rest- pulled the old engine friday, installed the new stroker on saturday, and fired it up, broke in the cam, took it for several test drives yesterday. Runs like a beast!!!

Anyway, my specs-
98 4.0L block/head, block bored 0.060 over
New Scat 258 crank
4.0 rods
KB 944 pistons, mahle rings
Bullet cam
Dodge Magnum SS valves, oversize, deshrouded CC
Mopar Roller rockers (ordered HS ones, but distributor was out of them so just gave me the mopars for free- same s*it, just different color/repackaged)
Crower camsaver lifters
Chevy valve springs
Ford 24# injectors- EV1 top-feed, 16ohm, part # F5DE-B5A- (These work GREAT, for anyone looking for injectors)
Banks header
Cloyes Double-roller timing set
Ram Clutch (needing a new clutch was the motivation to build a new engine to begin with- stocker had 186,000 miles)
New OEM distributor

Anyway, on to the pictures...
https://picasaweb.google.com/1168611645 ... ngineBuild

Enjoy!!

-Chris

Some pics so you don't have to follow the link-

Engine ready for it's covers and accessories:


Old engine coming out-





New engine going in:





Done!!!

Ok, apparently despite the fact that I can swap an engine by myself in a day and have a BS in Computer Science, I can't get the "["img"]" tag to display my images correctly. Sorry for wasting space with junk posts.

I fixed it for you. You have to copy the image location, you were trying to display the whole webpage.

I'm surprised more people don't use the Magnum valves as they are nearly drop in and can be had in stainless swirl polished.

Yeah the magnum valves worked well, just had to open up the seats to fit them as they were larger.

Re: the photos- thanks for trying, but maybe you can't link off of picasa or something, they just refuse to work.

Photos work fine for me on two different machines. Both IE and firefox.

what sizes of valves did you run? how much? more info on valve train please, looks good!

Valve info-

In- P5249877 Stainless swirl polished 1.97 $16 ea
Ex- P5249876 Stainless swirl polished 1.625 $14.50 ea

Update-

Engine backfired hard and started knocking really loudly last saturday- as I was pulling out of my neighborhood- limped it the 1/2 mile home, immediately shut her down and did a compression test, came back fine.

Pulled the valve cover, noticed cyl 3 had NO PUSHROD on the exhaust valve.

Pulled the motor in my driveway.

Pulled the head- broken pushrod as stated above- Lifter and cam lobe wiped, cam bearings destroyed due to metal flowing through the bottom end. Engine is now at the machine shop.


I did everything right- broke the cam in properly and ran Amsoil ZRod 10w30 oil for the flat tappet cam. Oil checked and changed regularly, engine tuned and ran perfectly.

What gives?! Is there ANY way to prevent these motors from wiping cam lobes?

Any idea what your valve spring pressures were? Bummer.

6TIME wrote:Any idea what your valve spring pressures were? Bummer.

I can find out when I get home and pull up all of my build sheets, but I specifically remember going over this with the machine shop when we put the first motor together- the cam was from Bullet Cams, who is the supplier for one of the major pre-built stroker suppliers (I believe Titan), the lifters were Crower cam-savers, the preload was properly set on each valve- used the Harland Sharp pedestal-mount roller rockers, Dodge Charger stainless steel valves, and chevy springs. The springs were appropriately selected according to the lift advertised by the cam-

Upon looking at the head, it appears that the #3 (and a couple of others) exhaust valve suffered significant valve seat recession, which of course would have messed up the valvetrain geometry and certainly made the pushrod effectively too long-

What might cause valve seat recession? The engine never once knocked and was not running lean according to a wideband.

Im starting to also wonder if this is spring pressure related... since i just built a stroker using stock valve springs and its working fantastic.

Did the valve seats sink down or did the valve itself take the damage?

Changing valve material could easily have changed how the exhaust valve and head interact with eachother... add to that a significantly stronger valve spring and things can get weird.

Did you set preload/lash? maybe there was too much play on the valves initially and it was slamming the valves shut...

The valve seats themselves degraded- valves looked fine.

The machine shop set up the valvetrain, measuring for pushrod length/preload.

Cyl 1's exhaust valve had also started to recede, but not as bad as cyl 3-

doublins wrote: Bullet Cams, who is the supplier for one of the major pre-built stroker suppliers (I believe Titan),

Nope, maybe ATK.


I'd like to know your spring pressures as well and what springs were used.