Mopar purple cam and lifters from summit, new valve springs, am I missing anything el

[blondejoncherokee]

I've been reading more, and it seems like the 28 cam gives more torque and earlier in the RPM range, that seems more attractive to me. Its not a DD, but it does get driven to the trail and sometimes to work while in working out bugs or breaking things in. I just wonder if I can get away swapping in a 28ad cam now and just leave the cam bearings as they are ?

from this thread:

The Mopar cams do improve power over the late model cams even though the duration is less 'cause as I stated earlier, the overlap is less and thus the dynamic compression is more. Compression ratio calculator from Jeepstrokers: http://www.jeepstrokers.com/calculator
The dynamic comp from the renix/obd1(87-95) installed -8* is 6.36:1, installed straight up 0* is 6.82:1. The dynamic comp from the 96-01 cam is 7.47:1. Install the Mopar 28 straight up and it is 7.73:1. Install the Mopar 29 straight up and it's 7.56:1. So with the 28 you have more low-end torque and have it earlier, and it lets more air in with lift at .43" compared to the 87-95's .424" and the 96-01's dual pattern .408in/.414"ex. The downfall with the 28 is that the power drops 500rpm shy of redline(no biggie).

 

[JeepBTDT]

Stock '87-'95 270/270 197/[email protected]" 0.424"/0.424" LSA 112 Overlap 46
Stock '96-'04 253/259 188/[email protected]" 0.408"/0.414" LSA 107.5 Overlap 41.6
Mopar-28 240/240 199/[email protected]" 0.430"/0.430" LSA 108 Overlap 24
Mopar-29 248/248 202/[email protected]" 0.440"/0.440" LSA 108 Overlap 32

I think that the 28 and 29 cams were originally designed for 'stock' 4.0L engines and still be EFI/ECU friendly without a tune and work with stock springs and not bind.
Their specs are 'very mild' for a stroker 4.6L engine.

 

[blondejoncherokee]

Stock '87-'95 270/270 197/[email protected]" 0.424"/0.424" LSA 112 Overlap 46
Stock '96-'04 253/259 188/[email protected]" 0.408"/0.414" LSA 107.5 Overlap 41.6
Mopar-28 240/240 199/[email protected]" 0.430"/0.430" LSA 108 Overlap 24
Mopar-29 248/248 202/[email protected]" 0.440"/0.440" LSA 108 Overlap 32

I think that the 28 and 29 cams were originally designed for 'stock' 4.0L engines and still be EFI/ECU friendly without a tune and work with stock springs and not bind.
Their specs are 'very mild' for a stroker 4.6L engine.

awesome . this is great. ill probably buy replacement stock valve springs just for piece of mind.

 

[torque062]

If you can, run a dual pattern cam. The exhaust ports in the head can only be ported so much but a little more lift and duration on the exhaust lobe can help it breathe better

 

[Johnnie Walker]

Make sure you know how much material has been taken off the head. Especially since you are going to use the MP gasket.
Chris' heep wouldn't run for shit after he put his back together. As there was enough removed from the head and the thinner gasket, his push rods were too long. He ended up using a stock height head gasket.

 

[torque062]

That is a good point. A lot of the 4.7l stroker engines also need to machine the block deck height which would only make that problem worse.

 

[old_man]

Ah ok. I think I am starting to get it. I will do that then. Thanks for the help. this is great information. I was already planning on the performance head gasket.

I've been getting lost in what pistons with what crank. I believe the 12 weight crank is the one that produces more torque and the 4 weight revs up faster?

No difference in torque, only a difference in how fast it will spin up due to rotational mass. I started with the heavy crank when I built the stroker with an AX-15 tranny. I have since converted to AW4.

 

[Alexia]

No difference in torque, only a difference in how fast it will spin up due to rotational mass. I started with the heavy crank when I built the stroker with an AX-15 tranny. I have since converted to AW4.

No mechanical fan with a four weight crankshaft shifts fast with an AW4. I personally have not found a down side to having the four weight version.

 

[Root Moose]

The idea behind more weight on the crank for this type of application is that once it is spinning it is harder to stall out at low revs and/or it makes it easier/smoother to drive in stop and go traffic.

For involved drivers it doesn't really matter IME. On a sports car it helps to rev faster but the few cars I've driven with lightened flywheels (S2000s) it didn't make enough of a difference to make the change specifically. It satisfies the butt dyno but from corner to corner on track, meh. Perhaps if you were starting with a POS setup it would make a bigger difference.

If you've got it apart anyway...

 

[4.whoa]

Make sure you know how much material has been taken off the head. Especially since you are going to use the MP gasket.
Chris' heep wouldn't run for shit after he put his back together. As there was enough removed from the head and the thinner gasket, his push rods were too long. He ended up using a stock height head gasket.

Sorry, but that's just silly. "custom" length pushrods aren't that much and you can get shims for under the rockers very cheap. I used the shims on mine and its been fine for 8yrs.

 

[Talyn]

Sorry, but that's just silly. "custom" length pushrods aren't that much and you can get shims for under the rockers very cheap. I used the shims on mine and its been fine for 8yrs.

Yes, custom pushrods aren't that much. Smith Brothers are relatively inexpensive and quick. And they know their shit. Besides how much has been removed from the head, block and head gasket thickness you need to take into account how much the valve job has effected the preload as well as the cam itself. Best bet is to measure and get the correct pushrods. Math won't always work here. Personally I would start with the stock pushrod and see where it places preload. Being hydraulic lifters you have quite a bit of leway and while .0xx amount of preload may matter in some cases it doesn't in our case.

As far as shims are concerned they can adjust preload, but will also changes the valve to rocker pattern. While it might not mean much in out engines with the little of lift its best practice not to use them unless there is a sweep pattern issue you are trying to correct or the valve job has moved the valve tip height that much.

 

[Johnnie Walker]

Not making excuses, especially since it's not my deal. But, he had the head work done several months before he re-installed it, misplaced the paperwork, got it back together with the MP gasket and it did not run correctly. Getting it back together last minute, and not knowing the specific length pushrods required, it worked out with the stock replacement gasket.