Roller Cam and Lifters

[Don H Jr]

Silver/all: the 505 ad said good for 75-100K. How long you think a stressed stroker is going to run anyhow? How many miles?Don Jr

[SilverXJ]

not sure how long they will last, but I'm hoping more than 100,000 miles. How do you mean stressed? The components in the basic stroker (4.5-4.7L) aren't stressed that much unless someone is constantly beating on it.

[lafrad]

I would expect a stroker to have similar durability as a 4.2L... the increase in stroke means it will run with a piston speed of a 4.2L at "the same" driving speeds/rpm... Other than that, cam, head, etc, all will be the same as ANY AMC I6

[Don H Jr]

Ia, I'm game. But I figure when we cam the engine up and add all that extra horsepower and torque and it likes to run hot, that's heat from stress and extra compression most the time also in there somewhere. WIth the shorty rod program I can't help imagining rod ratio and stressing of the the pistons in the bore adding to the deal.
Hey I can learn, and I am. Thanks to you folks and others like you. Thanks.

Don Jr

[Don H Jr]

CNC Cam site was way too over my head. It's a world of it's own, but I think I took away something from the immersion.

Don't try to shortcut camology.

Don Jr

[SilverXJ]

A cooling system in good condition is usually sufficient to cool a stroker. An upgraded radiator may/may not be necessary. Make your AFR ratios are correct, watch out for pinging, and it should be good. As for the short rod, it could possibly add more stress to the piston skirt. I don't think the little bit of extra compression is an issue either. By most other engine build standards (SBC, etc) it would be considered low compression... lol

[old_man]

I've been running a 4.7L stroker for 6 years and have 100k+ on it with no problems. It has had a bit of piston slap since the first time I started it. Cooling at slow speeds at 10k ft+ is close. Adding a switch to the electric fan handled it fine.

[Don H Jr]

Good to hear of a stroker over 100K, I wonder if it will get to 2 or 250K? Seems like it should/will make it. So many solutions on these sites, but I have to remind myself to look elsewhere now and then not just on Jeep sites to plan my build and solve problems/ many of them are not new at all to hot rodding/\but the I6 isn't a well engineered, tested design like Chevs or others. It is what it is. A noisy, low/mid rpm truck motor full of design flaws that show up right away when they are hotrodded to get more power. The engine only has about so much to give before it starts showing its weaknesses.
All the talk about the high rpm stuff.
Most of us dont give a rat's behind about anything above 5K. When you have a Square engine, bore and stroke the same, and you have dyno charts showing torque line always higher than HP line, never crossing like most engines: what you have is a workhorse.
Let the few experiment with the busting edge of this design, that's cool by me. But I'm interested in finding an affordable Roller Cam build on a tough cast cam core. I read there are two types of cast cores and the harder one is the one to use for street rollers. Soon I hope we figure out how do to this mod to our engines. It opens up lots of possibilities and less stress, so less heat buildup...which means more power.

Don H Jr

[SilverXJ]

dyno charts showing torque line always higher than HP line, never crossing like most engines:

A true dyno graph will ALWAYS have the torque and HP crossing at 5252. If they don't then it has been tampered with as HP is a a function of torque and RPM (HP = (TQ * RPM)/5252).

[Don H Jr]

Sliver, i had read that somewhere too. Hows the rule work when the engine tops out at 5K?

[SilverXJ]

Lol.. if the engine tops out at 5k they don't cross... the reason is because they don't kit 5252.

never crossing like most engines:

Never actually pushing that high. Rev it to 5252 and it will cross.

[lafrad]

I'm pretty sure the intent of "not crossing" was more along the lines of: "Its difficult to get it to make more HP than torque, without seriously affecting the torque output, and stressing the engine unnecessarily"


I know that I'm lovin the small-ish Crower cam (setup straight up, NOT advanced) with 10:1 CR and 91 octane. the Jeep jumps off the line, still gets 18-20 freeway MPG, and it REALLY can put a lot of twist on the tires when goin slow. Perfect for what it is.

PS: If I could have afforded the roller swap, I would have.

[amcinstaller]

It is what it is. A noisy, low/mid rpm truck motor full of design flaws

um, i think the 4.0 evolved from the amc 258 or 232. and until the 4.0 hit jeeps, the design wasnt in many trucks, mostly small cars as a more economic choice than the amc v8s of the day. i could be wrong though.

[Don H Jr]

I stand corrected on the Truck engine statement. It is our truck engine, though. We are stuck with it's good flat torque curve and long milage longivity numbers, which are huge plusses. I have a 400 Chev smallblock PU outside on it's third motor, and I have my 94' Cherokee I6 that is closing in on 300K and still doesn't burn oil.
But after we poke-n-stroke, and cam and port the ole 4.0, I'm not sure we can expect numbers like these (above) anylonger, as we stuff the underhood with Ford injectors, adjustable MAP sensors; trick the temp sensor/air sensor temps and computers.
I'm hoping for decent milage after the mods, as mine sucks these days bad. I dont' even check it anymore since it was around 12 or less the last few times I did. Pushing around the 31s with 3.55s and a high milage engine and worn out brake parts and universal joints that have never been changed or lubed, a D35c with a bent tube, worn pinion bearing, leaky seals... I guess I can't expect any more of this rig than I am willing to put back into it as far as maint goes.
Truth is, I could never find a place to lube the univ joints, all these years, lol. I know all engine mounts, including tranny mount are shot and I have new Daystars in a box for past 6 years but not installed, which would explain things. Since I put the B and M Trick Shift syn fluid in the AW4 a few years ago it has really shifted great, but might explain all the light oil sprayed around under the Jeep I never understood till lately. I meant to check the VENT on the tranny for years, which I think is the culprit; pluse the O ring in the speedo sensor is probably a clulprit too. When you have a steady leak and nothing is losing fluid it keeps you thinking. I keep the tranny slightly over full, so it's probably comeing from there and I simply don't notice.
Oh, well...my ADHD is sure kicking in today, all over the place....lol.
I just got my new, rebuilt, used little D35c Posi for cheap yesterday to replace my munched one, to last me till I change both pumpkins over to lower geared, stronger units in another dream.

Oh, yeah: The TQ curve wasn't a joke. The HP thing isn't an issue with me. WInding engines for HP is best done for me in my BB Chev PU with the built SS Chevelle engine...or in my wife's 3 series BMW convertible, dual overhead cammed (with variable cam timing); not with my Cherokee, power-sliding, Dick Cepek tire-spinning Jeep.

Don H Jr

[jeepxj3]

Any more on this hydraulic roller lifters and cam?