To replace? Or not to replace my cam?

[AlexTJ]

OK so I'm rebuilding my failed Titan motor with these specs.

'97 TJ
AX-15 Terminator/Ford8.8/HP Dana30 4.10s 33s 4.5" lift
'93 4.0L block
very close to 0 deck
probably .051 gasket unless the quech achieved with the .043 is worth the added compression
.60 over 3241hcs (enginetech tho) dished to 20ccs (thanks oletshot)
4.2L rods
remanufactured crank (40/40) under
'93 Head chamber enlarged to 60/61 cc if possible
Cloyes "true" roller set.
APN cheapo header
super 44 flowmaster with 2.25 for now, going 2.5 this summer

But here's the kicker. The cam I had before looked ok (until I noticed the distributor gear today) but I was unable to identify it. I measured its lift to be about .448/.448 (so comp 68-201-4) and I called titan and chuck said he used to often use that cam in his strokers. But then again this sucker is totally unmarked.

Then add to the fact that the galley plug behind the cam had funny wear marks and the distributor gear is all messed up. I'm thinking the cam had too much endplay. I have some pics here, is it toast like I think?









IF it is toast, I've been runnign different profiles on the Desktop dyno and I'm liking the Lunati 63502. But I dunno if my OBDII will enjoy it as much as I could.
Here is some pics for the 231-4 and 63502 both compared to the 201-4 (if thats what it REALLY is):

63502/201-4:


231-4/201-4:


Also not sure if I want to go with a comp since they seem tofail so much....but lunatis may be no different

[SilverXJ]

That crank was really cut, huh?

Really, I haven't heard of a lot of Comps failing. In my case, even though 3 different people I didn't cause the failure, I believe to be attributed to turning the engine over with the starter. The cam failed immediately after that. The other recent one had a defect in a lobe before it was even ran.

As for your cam, I don't like the wear on the distributor gears. Looks nasty. But pics are a bit fuzzy. Its not a Comp Cam though, no marking on the end. As for the plug wear, the plug was probably seated too far in.

After running both the comp 68-231-4 and the Isky cam, I favor the Isky cam. It had a lot more top end power. The comp did have a lot of off idle torque, but it basically died after 4000 rpm.

[AlexTJ]

Ok so from my desktop comparison your isky runs almost exactly like a Comp 201-4 or a lunati 63501/63502 all have the exact same curve shape. The relative power (greatest to least) being 63502>63501>201-4>Isky but the difference isnt that great (and this is a theoretical program).

I heard you had a tough time with Iskys customer service. The Lunati's have higher lift and the Comp is potetially what I already have (but needs replaced)

Here's the graphs:

201-4 vs Silver custom isky:


63502 vs Silver custom isky:


Lunati has the most power but it also has the highest lift and lifter acceleration rate. Is it worth it?

Silver did u ever figure out if the reduced diameter of the isky shaft actually did anything?

[SilverXJ]

On your desktop dyno, you show single plane for the manifold type. Shouldn't it be TPI? Isky's customer service was horrible. I did like the grind compared to the 68-231-4. I don't think the reduced diameter did anything negative or positive to the cam. The harmonics was just a theory I had, but I am 90% sure that it was the oil pump pickup sucking in air.

[AlexTJ]

I switched them all to TPI and I'm still liking the 63502 ALOT. But will it be way too much for the stock OBDII computer? I'm planning on a dyno or FTCI/wideband tune this summer but would like it to still be drivable just in case.

Specs:

Lunati 63502: Lift .507/.527
adv IVO 23
IVC 59
EVO 70
EVc 18
.050 IVO 7
IVC 33
EVO 49
EVC -3

[SilverXJ]

Given that it has an LCA of 112 it shouldn't cause an issue with the PCM. It is quite a large cam in terms of lift, not so much in duration. Just make sure your springs can handle it. It also has a rather high lifter accel rate (or hydraulic intensity as Crane calls it). Which means it will me noisy. On the Comp Cam 68-231-4 there was a sound similar to lifter tick, which was probably the valves slamming shut. It was probably also exacerbated by the tube style exhaust header. I am not sure what effect that has on cam shaft and lifter life though. I would bet it has a negative impact.

[AlexTJ]

That's what I thought as far as the pcm goes. My machinist told me I just need to tell him how much lift my cam would have and he would get springs and set up the head for it. As far as the acceleration goes the desktop dyno set a number automatically (given adv and 050 specs) that can be used for comaprison. The lunati is similar to a 231-4 and a 232-4 as far as that rate goes (a little over 3) and gives your cam and my supposed old cam rates at around 2.6/2.7. My buddys titan in his xj has a 231 or 232 in it so that explains the valvetrain noise I heard in that brand new engine.

[AlexTJ]

what springs would I need to run with this cam?

[AlexTJ]

[quote="SilverXJ"]
As for your cam, I don't like the wear on the distributor gears. Looks nasty. But pics are a bit fuzzy. Its not a Comp Cam though, no marking on the end. As for the plug wear, the plug was probably seated too far in.

I just realized.... I don't believe I saw any mechanism for controlling cam walk installed when I took apart the titan. There was no pin or button or anything..... Just a bolt I believe

[cigarluvr]

Not to thread jack, but I am wondering the same thing? What keeps the cam from walking? Since the comp cam isnt machined for the retaining plate...and my rollmaster timing set actually rests against the block...is this the way it is supposed to be? I undersyand that it wont come out the front...because of the pin and spring, but as for the back of the block...things that make me go hmmm!

[SilverXJ]

There is a pin and spring that goes in the cam bolt. The pine makes contact with the timing cover and pushes the cam into the block. I don't remember when that was started though as the earlier engines didn't have that.

[cigarluvr]

I think the first year was in the '00 but don't quote me on that.

Also, I understand that the pin and spring keep the cam from walking forward but what keeps it from walking out the back and scoring the plug like the picture above? Is it the taper of the cam bore or PFM?

[SilverXJ]

No, 00 was the first year for the cam retainer plate, which replaced the pin and spring. AFAIK the cam taper and diff gear should keep the cam in the block just fine.

The cam gear is what keeps the cam from going back too far as it rides against the block. If the cam gear is correct and the cam rides the cam plug, the plug is in too far.

[cigarluvr]

Supa sweet...thats exactly what I was hoping to hear...thanks!

[lafrad]

my '99 XJ had a cam retainer plate. Converted over to the pin and spring style with the aftermarket cam on the stroker build.