Another stroker up and running.

So far about 600 miles on it so I'm still in the "break-in" period. I setup happens to be quite similar to Dino's "DR. DYNO" on this forum, minus a few items.

1989 4.0L block bored .030" over.
1989 Head milled 0.010" and reconditioned.
1987 "short snout" 258 Crank and rods
1989 fuel injection system with knock sensor and EGR system.
24# Accel fuel injectors...fuel pressure the stock 39 psi "effective".
Comp Cams 68-231-4
Mopar Performance valve springs, retainers, and keepers
Sealed Power 677CP pistons...the ones with graphite coated skirts
Fel-Pro standard gaskets

Estimated compression about 9.6:1
Estimated Displacement a tad under 4.6L

Initially I ran it for a few miles with the stock 19# injectors and found some pinging at any throttle over about 1/8. The 24# units seem to have done the trick as I have no pre-ignition although I am still running high octane gas for the break in. I'll soon start lowering my octane to see how low I can go. I'd love to run 87 but I'm hoping for 89.

The low end power is wonderful and the engine seems to be developing a nice feel as it breaks in. The shop I had do the work set the tolerances up fairly tight so the engine has been "loosening" up quite a bit as it breaks in.

The idle is very smooth...same as stock.
I do hear a little more valve train noise compared to stock which I partly attribute to the higher cam lifts and valve spring rates. I'm keeping an eye on this just in case.

I'm noticing a huge difference at highway speeds where I can pull hard up a hill in 5th gear where I previously would have to downshift. The driveability is quite nice as it is not jerky off the start but has good power from about 800 rpm and up. I don't really need to go over 1800 rpm driving around in the city and I accelerate the same if not more than the average motorist.

I haven't let this thing hang loose yet...waiting for about 1000 miles before I go WOT.

The entire cost into this project including the donor 4.0L..all 258 parts, injectors, machine work, etc...$1695 USD. Really there isn't much cost over a regular rebuild...just a little more for the cam, springs, and you need new injectors.

I'm a happy camper so far.

Good to know its working great for you, BTW where did you get the sealed power pistons from, i have only seen them at rockauto.com and they have them for 240 something, it seems high as dino(aka Dr Dyno) got his for $90.

Thanks;
ravi

I actually had an engine shop do all the machine work, assembly work, and source all the parts that I specified. The shop generally buys from Federal Mogul who is a Sealed Power distributor. Those pistons are Sealed Power's stock replacements for the 4.0L..nothing fancy so their price is pretty good.

Glad it's worked out for you Bender. That's proof that my 4.6L low buck stroker option 1 recipe really does work. I hope my own stroker also proves to be a success. I'm using plain vanilla 677P pistons (not graphite-coated).

Summit racing has the sealed power pistons for around $125 - the 97+ type with the narrow metric rings. (which is the replacement piston for the "Piston slap TSB".

Goo deal!...I haven't stopped by the strokers group at yahoo lately but it seems as though more strokers are getting built...nice going!

rsalemi said:

Summit racing has the sealed power pistons for around $125 - the 97+ type with the narrow metric rings. (which is the replacement piston for the "Piston slap TSB".

Click to expand...

Now that i have got my forged eagle rods on the way i will be getting the venolia forged pistons using crash's specs, really appreciate your reply though.

Thanks;
Ravi

Well, I've played around with various octane ratings and so far the verdict is this....

87 Octane I ran with no trouble until trying a long grade on the highway in high gear...I got a couple noticeable "ping's". Other than that it seems fine.

89 Octane I don't hear any pinging at all.

I'll have to see how it does in the summer when the temp rises. I'm guessing I'll be able to run 89 normally and perhaps 91 when I'll be doing some hard wheeling or towing.

The valve train noise I have attributed to the higher compression, higher cam lift, stiffer springs, and the rate at which the cam lift is reached. The valve train is louder than stock but after talking to a few people to have built higher compression race motors my noises are well within acceptable...I'm just a very picky bastard!

As for power...with 4.56 gears and 35's I have to change gears so ofter it's hard to tell how it would really pull. I don't have to gear down on the highway anymore...it will pull at 2200 rpm doing 70 mph in 5th gear better than my old engine would in 4th gear. It's not a speed motor at all but you can definetely feel the torque in there.

Over all I'm a happy camper.

Bender said:

The valve train noise I have attributed to the higher compression, higher cam lift, stiffer springs, and the rate at which the cam lift is reached. The valve train is louder than stock but after talking to a few people to have built higher compression race motors my noises are well within acceptable...I'm just a very picky bastard!

Click to expand...

I think you've hit the nail on the head. Your CompCams cam has a much faster valve opening and closing ramp than the stocker so that would explain why there's more valvetrain noise. Shouldn't be a problem though because you have some heavy duty springs and retainers to handle the extra valve lift.