Advice on cam selection

[Tar2001]

Building my second stroker... Blew up a piston in the first engine after around 20k, overheating most probably, will post some pics very soon.
Anyway, im planning the following setup (will reuse some parts from previous engine):
4cw crank
4.0 long rods
Around 9.5- 9.6 scr
Kb944 30 or 40 overbore (i wouldve prefered to find forged pistons with 1.5mm rings using stovk long rods)
Dekcking the block to get near zero
Good porting job (will post some pics)
Cloyes double roller
Melling HV oil pump
Ceramic coated doug thorley headers
62 mm tb


Now the big question is the cam selection:
1- comp cam 68-231-4 (mopar performance springs and retainers)
2- oem pre-96 cam (+4 deg adv using the cloyes gear)
3- oem 96+ cam (+4 deg adv using the cloyes gear)

I have all 3 cams ready (231 comp still looks in good shape from previous strokr)

I would appreciate some expert advice, how would these 3 compare? Any other suggestions on advance / retard?

[Tar2001]

My previous stroker was a short rod with scr> 10 and dcr > 8.6 quench about 0.053 the porting job had a major mistake as the outer edge of the exhaust port was considerably larger than the throat and larger than the headers diameter. It also had a custom 99+ intake manifold with dual tb with adjustable internal diameter. (wil post some pics after finishing the stroker).

I have to mention here that it's a 2001 xj and the stroker continuously threw misfire codes. Dont know if it was due to the 231 cam. I know that there are mixed opinions about its compatibility with fuel injection.

But my major prob with that engine was hesitation just off idle (which was slightly rough) if u floor it quickly. It would kinda choke and i could even see the rpm needle bearly going down before the engine responded like a monster afterwards. This lack of responsivness was only present off-idle. Holding the rpm slightly above 1000 and then flooring it would cause no problem. But i honestly felt the engine lacked the torque that you'd expect in the low rpm range.
While it pulled much quicker than our 5.2 zj, the zj's low end torque was much better. It's just much nicer when ur cruising.

Any advice on the cam? Other things to prevent the same results? I am flexible with suggestions since i haven't ordered any parts yet. I need a nice low end torque at least comparable to a 5.2 zj but i also want some hp between 3000 and 5000 rpm.

[Russ Pottenger]

The 68-231-4 is a good all around cam but with one exception. I'd recommend that cam on a 113 lobe separation.

Another recommendation I highly suggest is to have the camshaft Nitrided. Comp offers this option and will eliminate 95% of all flat tappet camshaft failures.

Fill free to pm me if you have any other questions, or would like to get some more information.


Russ
Bishop-Buehl Racing Engines

[Tar2001]

The 68-231-4 that I have was not nitirded, but it is still in good shape after around 20k miles. Is it still prone to failure?

It actually has a LSA of 111 if im not mistaken, so are you refering to the 68-232-4 in this case? Wouldnt this one have lower peak hp compared to the 231?

What would be the pros / cons of each?

N.B: I am actually thinking of going with 0.060 overbore with the above setup.

How would an increase in displacement affect the same cam.(will peak torque and peak hp still be delivered at the same rpm?)

How can i benefit from the 4 deg advance/retard option that cloyes gear sets offer? I mean in design phase, theoretically this is like multiplying the number of available cam profiles we can choose from by 3??? Isn't it?

[Cheromaniac]

It actually has a LSA of 111 if im not mistaken, so are you refering to the 68-232-4 in this case? Wouldnt this one have lower peak hp compared to the 231?

The answer's yes so go with the 231. With a 111* LSA and a 107* ICA, it already has 4 degrees of advance built into it so you can just install it straight up.

[Tar2001]

Thanks for the advice.

I am just worried that the misfire codes might come back... I had to install back my original 01 engine (almost stock except ported head, pacesetter headers, dual tb) in the meantime and i have no check engine or DTC so now i know i dont have a problem with the cam sensor or any other electric issue. By the way, i also noticed how smoother it runs compared to the stroker specially at high rpm.

So how would you compare the power and torque curves of the 231 compared to the stock cams?
I have to admit the 4.0 with the ported head has a nice power after 4000 rpm and at full throttle the aw4 upshifts to 2nd or 3rd slightly before 5000. Of course, it lacks the low and mid range torque and it not even comparable. Also, i can confirm that the stroker had a better fuel milage while i have a very heavy foot.

Im also not sure whether the hesitation i described before was due to the 231 cam or to something else. It was actually more than that, forgot to mention that it used to stall moslty when in reverse, but also on D sometimes. The engine did not actually turn so freely, my mechanic noticed a huge difference compared to stock 4.0 while trying to adjust the cam sensor. You could also feel the starter suffering when cranking... I dont know whether all strokers behave like this but i felt it was a bit more than it should be.

Dr Dino, allow me to thank you for your efforts... Ive known your website for so many years and i learned and applied many things, i share the same passion you have for the legendary xj and this is my second one, i bought it in 2006. My previous laredo 88 lived with me from 1992 till 2005. During all these years, ive also owned several other cars a 300E an E320 and a 540i, but there was always a jeep in my life .

Is it ok to keep the same lifters, they were new ones and broke in with the comp cam. And if it is better to get new one i guess then no need to do the same cam break in procedure?

[SilverXJ]

The misfires codes were not cam related unless it wasn't degree'd in. Sensor out of whack most likely or something external tot he engine. What you describe sounds like you had other issues(hesitation, stalling, etc). A balanced stroker will run up the RPMs smoother than a stock engine. The idle may be a little choppy based on the cam selection, but nothing like muscle car choppy.

No, on the lifters. New cam, new lifters. If you reuse a good old cam, you can put new lifters on it. And you need to redo the break in.

[Tar2001]

Thanks for the advice, which lifters would you recommend? Where from?

If the hesitation / stalling is external to the engine it should've been present now with the 4.0. Just swaped blocks, all peripherals remained the same, even injectors (using the v8 wj HO red tips). But the cam was not degreed... Frankly, i've read the procedure and planing to do it on this next engine, but i still don't get what to do after getting the numbers and assuming they are or are not as per manufacturer specs?... How do i know that it was the cause for the misfire?

I am surprised to hear that a stroker will run smoother up th rpm range... Well what im refering to is vibration. So if we're talking the same thing, i must have missed something in my build ??? What should i consider?? What would cause vibration at high rpm?

[Tar2001]

If reusing the good old comp cam with new lifters, should i run it first with stock valve springs or is ok to directly install the mopar springs?

[dragginwagon406]

From what I've read, the 231 cam has too much lift for stock springs.

When going to the mopar spring, double check the installed height and verify spring pressure.

[dragginwagon406]

Now the big question is the cam selection:
1- comp cam 68-231-4 (mopar performance springs and retainers)
2- oem pre-96 cam (+4 deg adv using the cloyes gear)
3- oem 96+ cam (+4 deg adv using the cloyes gear)

I have all 3 cams ready (231 comp still looks in good shape from previous strokr)

I would appreciate some expert advice, how would these 3 compare? Any other suggestions on advance / retard?

I am no Jeep expert but I have played with SBC a long time...

I have the 4.6L with oem 96+ cam and I couldn't imagine wanting to advance the cam from stock. Advancing the cam tends to increase low end power at the loss of top end power. After driving mine for a few days now, I would say power tends to nose over after 4200 rpm. I'm not ready to retard the cam, I'll see what a throttle body will pick up first but it is something to keep in mind.

[SilverXJ]

If using the stock cam or a 68-231-4 or 68-232-1 I wouldn't advance it. The Mopar springs are weak enough to not have to use a break in spring. The main culprit in back fires, no start, hesitation is an improperly indexed cam sensor/ distributor. However, something in your engine could have pushed one of the sensors in to a bad area, or is already faulty but works with the current config. If your engine wasn't smooth at high rpm it could have been an imbalanced, misfire (perhaps linked to the hesitation), etc. Some builders just don't take the time to correctly balance an engine. Close enough is often not good enough. Even though it is internally balanced you still should have the harmonic balancer and flexplate balanced. The last two balancers I took to my machinist were off by 9-16 grams. Two different brands, Professional Products and a Powerbond. I wouldn't even touch a Dorman.

[dragginwagon406]

If using the stock cam or a 68-231-4 or 68-232-1 I wouldn't advance it.... Some builders just don't take the time to correctly balance an engine. Close enough is often not good enough. Even though it is internally balanced you still should have the harmonic balancer and flexplate balanced. The last two balancers I took to my machinist were off by 9-16 grams. Two different brands, Professional Products and a Powerbond. I wouldn't even touch a Dorman.

Agree. I took both my balancer, flywheel and bolts to the machine shop for the balance job for that reason.

[Cheromaniac]

So how would you compare the power and torque curves of the 231 compared to the stock cams?

Is it ok to keep the same lifters, they were new ones and broke in with the comp cam. And if it is better to get new one i guess then no need to do the same cam break in procedure?

The 231 will produce stronger torque from about 2300rpm upwards. Below that, the stock cam will produce more torque.

Unfortunately our Jeep engines have a flat tappet cam so if you change the cam, you have to swap in new lifters and go through the cam break-in procedure again. If it was a roller cam you'd be able to reuse the old roller lifters and not have to do a cam break-in.

[Tar2001]

It seems as if the stock cam torque curve is flatter, and the 231 has considerably more mid range hp and torque? But woukd the comp 231 produce more hp where it peaks? And between 4750 and 5200 rpm? How about the diff bet pre 96 and 96+ stock cams?

How about the 505 performance roller cams? Did anyone really test them in a stroker?
And how would you compare their output to a stock cam or to the 231? Dr. Dino you are the expert, so how much additional hp would be gained over a flat tappet cam with same profile?

Sorry for asking so many questions but the cam issue needs a lot info to get the big picture and be able to choose!