4.6L Rebuild - 68-231-4 or 68-232-4 ?

[Brandon_K]

I originally built the motor 3 years ago, it died 6 months ago due to what I believe was a failed Sealed Power lifter, which took out #5 intake lobe.

What I'm building;

P5249464 springs,along with MP locks and retainers
Stock valves
Crower Cam Saver lifters
Stock injectors (this may change if need be, ran fine on them for the last 15k miles)

4.2L crank .10/.10
4.2L rods
H825CP pistons (stock dish)
No machine work on the block other than the overbore
VR .043 head gasket
Melling standard flow oil pump
Shittastic quench @ .0645

I currently have a CompCam 68-231-4. It had some surface rust on the bearing surfaces from sitting for the last 3 years, but after some Evaporust (seriously, the stuff is like magic!) and a buffing wheel, it cleaned up beautifully. (The cam was part of the original build in 7/09, but I went with stock after I started putting it together and failed to realize that I needed the old 4.2L timing setup).

I called CC today, he asked about the build and recommended a 68-232-4. He feels that the 231-4 doesn't produce enough vacuum and won't play well with the PCM, causing it to dump to much fuel, especially at idle. I kind of got the feeling that he was going off of the computer and picked the only one that doesn't say "Not for fuel injection". I can't be positive about that, but he wasn't very convincing.

Thoughts? If I need the 232-4, then I need it. If I can run the 231-4, then the $150 savings buys me two cases of Brad Penn oil. Intake duration, lobe separation, this is all still above my full understanding at this point.

For reference, she ran fine before on the same exact build (sans the lifters, those were Sealed Power) on 87 pump gas, I never heard any pinging, even pulling a trailer at 70 during the summer months, even with stock injectors. She sits on 35's, 4.10's and a NV3550 grindbox. SCR is 9.8. With the OEM cam, DCR is 8.47. With the 231-4 DCR is 8.57 and with the 232-4 DCR is 8.42. I would suspect with the 231-4 it might push me into 89/91 octane range, which I'm fine with. Again, thoughts on the cam? Thanks!

[Muad'Dib]

You didnt mention what year or RENIX, OBD1 or OBD2... but it really shouldnt matter.

The 68-231-4 is the better choice. As long as your comfortable with the clean up job then go with it.. Although with all the cam falures i dont know if i would trust a cam i cleaned myself. YMMV.

[Brandon_K]

Wow, I can't believe I left that out. It's a "hybrid" 99 block / head, OBD II. It all came out of a 99, but uses the 98 intake/exhaust gasket.

The story behind the cam is, went to install it 3 years ago, realized I didn't have the right setup (out of all of my research, I never came across the magical bit of info that the performance cams are setup for the old 4.2 timing kit). As I needed to get it back together in the next two days, I slid the stock cam back in. The CompCam was well hosed with assembly lube, except for where it laid to rest in the box. The bottoms of the journals had a bit of surface rust on it from sitting in the box. I was in such a hurry to get it back together (had to leave for work out of town), I didn't properly bag it and wipe it down to prevent rust. The Evaporust removed the polished finish (just the journals were exposed to Evaporust), but still seems to check out. The lobes, still being covered in assembly lube, are spotless and as it came from the factory.

The million dollar question, for me at least, why is the 231-4 better than the 232 (or vice versa)? I realize this might end up being a Cam-101 response, but I'm interested. That is the one thing I haven't fully wrapped my head around.

[Cheromaniac]

The 231 cam will produce more torque at higher rpm than the 232 with a small trade-off at low rpm. Ultimately you'll have a broader torque curve with the 231.

[RayRay]

ive had both cams.2-231-4 & 2-232-4. this all depends on how you are going to use the ride and your driving habbits.the 2-232-4 is my allaround fav.

[CobraMarty]

ive had both cams.2-231-4 & 2-232-4. this all depends on how you are going to use the ride and your driving habbits.the 2-232-4 is my allaround fav.

Can you elaborate? DD, crawling, mpg, rpm range, etc.