My 4.6 Project engine

[wjtom]

you just went from buying kb pistons to a 328 dollar engine kit from rock auto?Thats a leap.

[akadeutsch]

yep. Ive been wifed. The cost of those pistons was just too high. Perhaps some day ill build her for a blower but that day is far off. And I returned that kit from rock auto. I read it was made with cheap Taiwan parts. They had good customer service, but Summit racing was way cheaper. I will piece my kit together using clevite 77 bearings. Sealed Power Pistons, moly rings, Fell Pro Gaskets, and a Melling oil pump.
Not only was I wifed but I also talked to a mechanic who has built a number of these strokers for customers, and he said the best combo was simple SP Pistons with the short rods. For around 800 bucks I can build this thing with the best parts there is. Plus.... I'm at 6000 feet and with this recipe I dont think I will ever see compression that would require forged pistons. At this point I just want to put this thing back together.

[akadeutsch]

Just got my set of H802CP - Sealed Power Pistons +.030 over. They were 101.00 bucks from Summit Racing. Now all I have to do is get them to the machine shop so they can bore my block.

[akadeutsch]

Waiting and more waiting for the machinists to finish the block and crank work. Good news is that I found a good ARMY buddy working at Mile high Crankshafts in Denver and they said they were going to grind my crank for FREE. Can you believe it. Thanks Falicia and Dave. MILE HIGH CRANKSHAFTS IS THE PLACE TO GO IN DENVER.
So I took my valve springs to the machine shop to have them tested yesterday. Spec says 71-79 lbs @1.640". Mine tested a little low @ 68lbs. With a .030 shim they are at 73lbs. For a few bucks I think that I will just replace them.

[akadeutsch]

The 4.6L "poor man's" stroker recipe calls for the stock cam but I want to change that up. I want to be able to hear that there is an aftermarket cam in it while it is at idle; I like the sound and I want to notice it.
Also, I went with H802CP Pistons instead of the 677 that were in the recipe. Is this a problem? Can anyone recommend a cam? preferably one that works with stock springs or Mopar performance springs.

[akadeutsch]

Found this info on another site and I found it to be very useful when picking a camshaft

"There are 3 numbers that are important:

1. Lift
2. Duration
3. Lobe Separation Angle

By buying a cam with certain measurements, you can tailor your engine to specific rpm ranges, torque curves, and even throttle response. With each, comes a price. Lift is simple... its how far the valves are opened verses their seated position. More lift equals more air intake, and with the proper fuel trim, more power. more lift also creates more wear and tear on the valve train. Your asking the valve to react very violently when adding a ton of lift and then giving it the beans. Unless you have a serious head on that engine, it's not recommended to venture too far over stock as far as lift goes.

Duration is also very simple... its the length of time (in degrees of rotation) that it take the valve to open from the seated position, reach its max lift height, and then close back to the seated position. The longer the duration, the longer the valve is open and the more you're promoting high rpm usage. Duration has a HUGE effect on where in the rpm range will the power be useful. In an engine like the 4.0, I cant see anything over about 230-240deg @ .050 lift, being useful because we stay around 5500rpm MAX, have no power adders, and are looking for off the line torque verses top end horsepower.

Lobe Separation Angles make things quite a bit more complicated... and if you don't plan on running a hot motor, stick with the factory cam spec on that. It is basically fiddling with the timing of the intake and exhaust valves verses each other... its adding or removing overlap... has a lot to do with extending burn time, cycling unburnt fuel out, lowering static compression to a more usable dynamic compression, blah blah blah. It's really something people only mess with if they know what kind of fire they are dealing with... so just leave that one alone.

Out of the 5, the cam that will least change the stock characteristics yet yield a gain in daily driving would be the Mopar Performance Purple Cam. It has a short overlap, just like stock, .430 lift which is more than enough, and a 240deg duration that will keep the power band low to spin those big tires a bit easier off the line."

[akadeutsch]

I have been changing my recipe around quite a bit so I thought I would share where I'm currently at
2000 WJ 4.0 Block #53020569 Free
1988 XJ 4.2 Crank #53005535 4 counterweights, 46lb, 54mm nose, ground .010 and .010 50.00
1988 XJ 4.2 Rods 50.00
Piston H802CP - Sealed Power, 1.592 pin ht, 15.5cc 101.00
Sealed power Moly rings 78.99
Clevite 77 main bearings 86.97
Clevite 77 rod bearings 41.76
Clevite cam bearings 23.79
Fell Pro head Gasket kit 92.97
Fell Pro conversion gasket kit 27.97
Clegg stage 1 cam/timing/valve train kit 327.00
injectors 249.99
64mm TB 100.00

[akadeutsch]

I have decided on the Clegg stage one cam. Here is the spec sheet. It has a little more lift and a little more duration than the stock cam. Will this move my RPM range too high?
The big difference is in the LSA. Stock = 107.5 Clegg = 114. I understand this to mean it will have more overlap and a more aggressive idle.

[jeepxj3]

I wish they gave you the 0.050" duration numbers.
I though that the wider LSA will give you smoother idle and more idle vacuum for the MAP sensor and ecu.
IDK if " LSA=114, I understand this to mean it will have more overlap and a more aggressive idle" is correct? I thought it was just the opposite.

[wjtom]

You are 100 percent wrong about lobe seperation.wider gives a smoother idle if the duration stayed the same.wider lobe seperation typically has less overlap thats why most race cams have tight lobe centers usually 108 and lower but again not always.Lobe seperation is very important when choosing a cam just as important as duration.If you want to read some good articles on the subject google david vizard.The cam you are looking at will not have any sound to it like you are looking for.Mine is 218 and 228 at .050 on 110 and still idles at 650 in gear.You can tell its not stock but its far from lumpy.But you wont be able to do what i did with the compression you have without loosing alot of bottom end.Im at 10.3 to 1 compression.hope this helps.

[FlyinRyan]

You could have gone way bigger and about 6 degrees tighter . Bullet makes a good cam but you will find yourself in the same trap all these other builds find themselves in (lacking on power)

[akadeutsch]

Thanks guys. It sounds like this is not the one for me. Plus, I am open to the idea of mopar performance springs as well. If it will open up more doors. I'll keep looking..get ready for more questions.

[jeepxj3]

You could have gone way bigger and about 6 degrees tighter . Bullet makes a good cam but you will find yourself in the same trap all these other builds find themselves in (lacking on power)

Ryan,
What are your favorite cam recommendations with regards to duration, lift, sobe separation and overlap?
Before you came along with the ability to tune the ecu, cams were picked that would work with the stock ecu tune and not necessarily best running or power.
You have opened the doors to picking a cam that is best for the engine and adjust the ecu accordingly.

[akadeutsch]

I think Tom is on the right track. Tom how tall is your cam? Is that a custom grind? Where did you get it? I did not buy that clegg cam. After talking to some intelligent people I want to find something with Lift around .450, Duration around 220 @.050 on 107 LSA. I'm looking for a bit of a rough idle but I don't need power beyond 5 grand.

[akadeutsch]

Mopar # P4529229 is pretty close but I'd like a little more duration. P4529229 is at 202/202, lift .440/.440 on 108.