4.0L build advice

[brimstone]

Hello all, I need some help with my engine build plans. 2000 TJ 4.0L 5-speed. 175k miles. Original 0331 head, thankfully not cracked yet. First let me say I do not plan to stroke it. I'm asking here though because this community seems to have the most knowledge about internal engine work. Here's what I'm trying to accomplish:

1. Increase overall efficiency and durability
2. Increase low- to mid-range power and torque (I don't want to move power higher up the rpm range)
3. Prepare for future supercharger install

Here's what I'm looking at so far. I've purchased a used 0331 TUPY head (has valves and springs, but no rockers). As I said my factory head has not cracked yet, but since I plan to eventually S/C it, I wanted to swap it for the improved head before I do. Having the extra head also gives me time to port/polish and do any other machine work I want before swapping it in. Since I have to buy rockers for it (I don't plan on re-using the 175k mile ones from my stock head), I was planning to put roller rockers in it (more considerations on that idea later). I will also probably buy new pushrods at a minimum. I also bought an extra horseshoe-style manifold, so I can do port matching work to it before it goes into the Jeep. My Jeep has the 2-piece exhaust manifolds but no pre-cats. Right now I'm looking at a Pacesetter 70-1129 header (says its for '99 or before, but since I don't have pre-cats it should work fine for me).

I also have an Eaton gen 3 M90 supercharger off of a GM L67 3.8L V6, as well as the fuel injectors from a supercharged 3.8 and a Unichip piggyback controller. My plan is to build a custom setup similar to the Avenger (with the blower mounted directly to the manifold). My goal is to produce only a few pounds of boost. I'm not building a drag racer, I really want to gain just a bit more power when I need it, and overcome the affects of altitude (currently live in Colorado and driving in the mountains takes its toll).

So, my goal is to increase airflow through the head, first to maximize power and efficiency of the 4.0L at stock displacement. And secondly to increase airflow and durability to stand up to the eventual S/C install. I was originally just going to port/polish and buy a set of roller rockers. However, after much research here are some of the factors that I am now considering:

1. Porting/polising:
(a) I understand that you don't want to do a full "port match" or "gasket match" on the head. It is OK to have a "step" to a larger diameter on the downstream side of the flow, and a step in the exhaust can help reduce reversion. Just remove casting flaws on the intake, and mirror polish the chamber and exhaust ports.
(b) The exhaust ports on the 0331 head are intentionally smaller than previous heads, which increases exhaust velocity. Also the raised floor is a more efficient design. Some places claim that higher exhaust velocity is better for low-end torque. Dino's site claims the smaller ports were intended to warm up the pre-cats faster.
(c) Since I don't have the pre-cats and want to improve airflow, should I open up the exhaust ports a bit? Or would that actually hurt low-end torque?

2. Valves
(a) I'm considering putting in a nice set of stainless valves, to increase durability with the future forced induction.
(b) Since I should take the used head to a shop to be checked anyway, I'm also considering having a multi-angle valve job done to improve flow.
(c) If I'm buying valves and paying for a valve job, that opens up the possibility of putting in larger valves at the same time (more on this option later).

3. Rockers
(a) I was planning on buying a set of roller rockers. However, I don't need adjustable ones, and reading the post in the FAQ makes me think now I won't actually see much benefit from them. And I'm worried about durability with aluminum rockers, particularly if I go with higher lift or see higher chamber pressure after the supercharger install
(b) I may go with rollers for a 1.7 ratio rocker (more on that later)
(c) I like the idea of the Crower steel rollers, however I understand that will require machining. If I stay with 1.6 ratio I'm considering the Hesco high performance stamped ones

4. Cam
(a) I wasn't planning on replacing the cam. However, at 175k miles I think it may be good to replace it anyway. And after some research, I'm thinking a different cam might be needed, both for my N/A plans and to get the most out of F/I.
(b) I like the idea of a roller cam, with the lower friction and faster ramp rates. I was considering dropping the $1200 on 505's least aggressive cam kit, until I started reading on here about the quality and longevity issues.
(c) I've also been reading that for a S/C, you want a cam with shorter intake, longer exhaust, and less overlap.

5. Compression ratio
(a) I don't want to increase compression ratio. I know some F/I setups actually use a lower SCR than their N/A counterparts. However, since I only plan to run a few pounds of boost, and I don't want to lower power before I get the S/C installed, I plan to keep the ratio the same.

6. Timing chain
(a) I was looking at replacing my timing chain (175k miles on my stock one). I wanted to go with a double roller setup, but I understand that my '00 cam won't work with them, unless I replace the cam.
(b) I read a few threads on here that seemed to suggest the OEM chain setup was just as good as a double roller?

Right now I'm trying to decide what the best course is to increase performance for a N/A and later F/I 4.0:

Option A (mostly stock valvetrain)
-stock cam (If I keep my stock cam, would it be a good idea to at least put in new lifters?)
-stock size stainless valves with multi-angle valve job
-1.6 rockers (stock or roller)

Option B (more lift)
-Stock size stainless valves with multi-angle valve job
-Stock cam
-1.7 rockers (roller required)
-New valve springs required?

Option C (larger valves)
-Larger stainless valves (valve job required)
-Stock cam
-1.6 rockers (stock or roller)
-Stock springs? (upgrade better?)

Option D (more lift and duration)
-New cam
-Stock size stainless valves with multi-angle valve job
-1.6 rockers (stock or roller)

Or some combination of the above? Without the increased displacement of a stroker I don't think I need the combined effects of a cam, larger valves, and 1.7 rockers. But what is the most efficient way to get more air through a 4.0 both N/A and F/I? Are there other factors I'm not considering.

Thanks in advance for your input.

[Cheromaniac]

I think you'll need to pick Russ Pottenger's brain for this one but I'd suggest the following:

1. TUPY 0331 head ported by Russ Pottenger with larger SS valves and 3-angle grind.
2. Custom cam (Russ can advise on specs).
3. New OEM timing set or Rollermaster dual roller depending on cam used (Russ can advise there also).
4. Harland Sharp 1.6 ratio non-adjustable roller rockers.
5. Crower chromemoly pushrods.

[brimstone]

Thanks for the input. Basically what I'm trying to find out is just how extreme I need to go, if I'm not increasing displacement. I'd like to make the 4.0L breathe better as is, but with the understanding that with a future F/I setup, the head/valves do not need to flow as well as, say, N/A stroker, because the blower pressure will overcome a more restrictive head.

There are (in my understanding) three ways to increase flow: larger valves, higher lift (on the cam or higher ratio lifters), or more duration. Or some combination of the three. I'm trying to decide what is the best combination to accomplish my goals?

[jeepxj3]

Are you trying to do this on the cheap or money is no object?
You can't go much away from stock to keep your ECU happy and run well

-stock or bigger valves if you can afford them
-new stock valve springs, cheap on rockauto
-reuse your stock cam, lifters and pushrods
-new '00+ timing chain
-port and polish, head and intake
-1.7 roller rockers
-Victor Reinz MLS head gasket
-new Victor Reinz or equivalent head bolts

[brimstone]

Another question. Trying to determine whether to stick with the stock cam, or install an aftermarket, and which might lend itself more to supercharging. I can't seem to figure out the stock cam numbers.

There are a few different threads around where I saw Dino post up the following numbers (here is one such thread over on JU):

4.0L I6 '96-'05:

Duration advertised: 256*/260*
Duration @ 0.050" lift I/E: 188*/192*
Valve lift I/E: 0.408"/0.414"
Valve overlap: 43*
LSA: 107.5*, ICA: 100*, ECA: 115*
IVO: 6*ATDC (0.050" lift)
IVC: 14*ABDC
EVO: 30*BBDC
EVC: 18*BTDC

However, on Dino's 4.0performance site it give the following numbers:

Advertised duration int./exh.: 253/259 deg
Duration @ 0.050" lift int./exh.: 188/192 deg
Valve lift int./exh.: 0.408"/0.414"
Lobe separation angle: 107 deg
Intake centerline angle: 114 deg
Valve overlap (advertised): 43 deg
IVO: 20 deg ATDC (0.050" lift)
IVC: 28 deg ABDC
EVO: 16 deg BBDC
EVC: 4 deg BTDC

And finally, on the hosted spreadsheet that is linked directly from that page, it gives yet different numbers:

Advertised duration int./exh.: 253.3/259
Duration @ 0.050" lift int./exh.: 188/190
Valve lift int./exh.: 0.408"/0.414"
Lobe separation angle: 107.5
Intake centerline angle: 110
Valve overlap (advertised): 41.6
IVO: -16 BTDC (0.050" lift)
IVC: 24 ABDC
EVO: 20 BBDC
EVC: -10 ATDC

So which of these three different sets of numbers is correct?

[Cheromaniac]

Thanks for pointing out the discrepancy. The numbers on my spreadsheet are the correct ones so I'll need to update the numbers on my performance site.

[jeepxj3]

For your 2000, Cam you have 2 options-
-Comp 232 and use 'old' style pin and spring and double roller timing chain
-Jones Cam with similar specs ground on a 99+ cam and reuse the 'newer' style cam retention pate and stock timing chain

Comp 232 250/256 206/[email protected]" 1.6:1-0.460"/0.476" LSA 113 Overlap 27 *
Jones Cam 256/260 200/[email protected]" 1.6:1-0.462"/0.472" 1.7:1-0.491"/0.502"
Jones Cam 260/264 204/[email protected]" 1.6:1-0.472"/0.478" 1.7:1-0.502"/0.508"
Jones Cam 260/272 204/[email protected]" 1.6:1-0.472"/0.488" 1.7:1-0.502"/0.519"

[brimstone]

For your 2000, Cam you have 2 options-
-Comp 232 and use 'old' style pin and spring and double roller timing chain
-Jones Cam with similar specs ground on a 99+ cam and reuse the 'newer' style cam retention pate and stock timing chain

Comp 232 250/256 206/[email protected]" 1.6:1-0.460"/0.476" LSA 113 Overlap 27 *
Jones Cam 256/260 200/[email protected]" 1.6:1-0.462"/0.472" 1.7:1-0.491"/0.502"
Jones Cam 260/264 204/[email protected]" 1.6:1-0.472"/0.478" 1.7:1-0.502"/0.508"
Jones Cam 260/272 204/[email protected]" 1.6:1-0.472"/0.488" 1.7:1-0.502"/0.519"

Do you know what the LSA and overlap on the Jones cams are? And if they are the newer cam do they also have the wider lobe profile?

Here is what I am thinking now:

Option A) Reuse my stock cam, possibly new OEM timing chain and lifters (benefit being lower cost, and I don't have to pull my radiator to replace the cam)
Question: I've never replaced a cam before, how much wear can I expect on a 175k mile stock cam? Can it reasonably be expected to hold up to possible 1.7 lifters or forced induction (either of which will increase pressure and wear on the cam)?

Option B) Replace the cam with a Melling factory replacement (benefit being factory timing, 99+ style retention and wide-lobe cam)
-or-
Option C) Replace with the Melling pre-99 cam (benefit being the same factory timing, wide-lobes, and the ability to use a double roller chain)
Question: Is there a significant performance benefit between using a OEM vs. double roller chain, enough that it should influence my build decision?

Option D) Comp 232 cam (can use double roller chain, and the wider LSA, less overlap, and more lift/timing are better suited for the future supercharger)
Question: I've seen comments that the Comp cam quality is questionable, and the narrower lobe profile may be an issue. Should this be a factor?

Option E) Jones 204/216 (The numbers are a little higher than the Comp 232, but I think would still lend themselves to supercharging as long as it has similar LSA and overlap)
Question: Does anyone know the LSA and overlap for the Jones cam?

[jeepxj3]

I think 113*LSA and 40*overlap.

[Cheromaniac]

how much wear can I expect on a 175k mile stock cam? Can it reasonably be expected to hold up to possible 1.7 lifters or forced induction (either of which will increase pressure and wear on the cam)?

My original stock '92 cam had 174k miles and 12 years of use on it when I recycled it in my stroker for a mini-rebuild (Crane cam & lifters went tits up after 34k miles in stroker), and I've put another 49k miles on it since then so I think yours will be just fine. My Jeep now has 257k miles under its belt.
A set of 1.7 roller rockers will only raise the valve lift to 0.433"/0.440" so you can still use stock valve springs, and forced induction has no effect on the camshaft.
Just use new lifters and perform the same break-in procedure as you would for a new cam.

[jeepxj3]

Jones cams are wide lobe.

[jsawduste]

Jones cams are wide lobe.

Which means nothing.

[brimstone]

Jones cams are wide lobe.

Which means nothing.

Are the wide-lobe cams not more durable? I have seen several mentions around the forum that the quality of aftermarket cams is declining (see Dino's post above as just one example).

Thanks for all the input so far. So I will probably leave my stock cam in for now (I may put in a Comp 232 when I get the supercharger on, the wider LSA and lower overlap on the Comp cam should perform much better with the supercharger). So I need some recommendations on the following:

If I put in slightly oversized stainless valves, what are the best ones to use?
I've seen some stainless valves that are single-groove, I believe mine should be three-groove? What does it take to convert over?
New lifters? (Are OEM best? Where is the best place to purchase them?)
New pushrods? (Same question)
New springs? (Are new OEM the best choice, even if I go with 1.7 roller rockers? Or would a performance spring require machining the spring seats?)

[Russ Pottenger]

A few thoughts,
Many will disagree with me on this forum, but I don't quite understand obsession some have with having to run a wide lobe cam.
My understanding on how a mechanical flat tappet functions along with input from the cam manufacturers, lessons my concerns that lobe width has anything to do with camshaft failure.

If you look down the lifter bore you'll notice that the lobe is off-center in the bore. Because of the Lobe is off set,and taper is ground into the lobe, along with a slight crown on the bottom of the lifter, the lifter will turn or rotate as it travels up and down in its motion in the lifter bore. If it didn't even for a minute the camshaft would go flat instantly.

In all of my engines I install Chevy LS valves, springs and retainers. It will require honing the guides and machining down the spring seats approximately .050

A combination that I use a lot and works well is running the Comp 68-232-4 cam with a 1.65 roller rocker that Harland Sharp builds for me.

Engines that turn 4000 to 5000 RPM will require a .080 wall 5/16 chrome Molly pushrod. 5500 and above you'll need to step up to a 3/8 pushrod.

Feel free to contact me. I have wide variety of custom stroker kits along with specialty engine components.

Russ Pottenger
Bishop-Buehl Racing Engines
(626) 673- 2204
Email/PayPal: [email protected]

[jsawduste]

Listen to Russ, buy from Russ, do as Russ recommends. = Happy engine/happy customer.