Cherry picking the best parts for a 4.6 build

[TheDarkSideofWill]

I'm new here and interested in building a stroker for my '85 AMC Eagle wagon 5 speed.

I've gotten some cursory information from other sources, but this place seems like it's pretty much the source for stroker info, so I'd like to get down to brass tacks here.

What I'm currently looking at:

Block: '98-'99 NVH block
Crank: <'80 fully counterweighted 258 crankshaft
Rods: 4.0 or drop in aftermarket replacements (Eagle H-beams for instance)
Pistons: Keith Black
Head: 91-95 7120 casting
Intake manifold: '98+
EFI: Hybrid distributor and fuel injection using GM parts. This eliminates the need for the Jeep crank sensor.

Undecided:
Headers: Is there anything that fits and Eagle or will I have to massage anything I get? Are there any real equal length long tube headers available for the 4.0 in any chassis?
Coil pack ignition: I only recently found out that the 4.0 was upgraded to a coil pack ignition in 2000. I'd like to know more about this system. Is there a good article anyone can point me to?
Head Gasket: What are my options? Are metal shim gaskets available for the 4.0?
Head porting: Who does a good job (in terms of power, not necessarily raw flow numbers)? What are the common tricks? Substitute valves, etc? Anyone do CNC porting?
Flywheels: Are there any lightweight flywheels available? I know that a heavy flywheel is preferred for off-roading, but I'd like to make that concession to on-road performance.

I saw a thread in the main forum about the 7120 head vs. the 0331, so I'll go read that. I see that there are also some threads about KB vs. Diamond pistons...

Thanks!

[TheDarkSideofWill]

I also ran across this thread about an aluminum head: http://www.jeepstrokers.com/forum/viewt ... f=5&t=1321

Where can I learn more? I didn't know there were aluminum heads for these engines.

[John]

The aluminum head is from Hesco here is a link http://www.hesco.us/shop.asp?action=cat&catID=7735. More info available in their open forum. To answer another of your questions, they also have CNC ported cast heads.
Tell me about the GM EFI you are considering.
John

[SilverXJ]

Crank: <'80 fully counterweighted 258 crankshaft

I assume you are talking about the 12 wt crank? If so, why did you choose that one?

Rods: 4.0 or drop in aftermarket replacements (Eagle H-beams for instance)

Eagle rods won't work with the KB944/945 pistons. If you want to use the eagle rods you will have to go with custom pistons. If you are dead set on the eagle rods 505 performance sells them along with matching pistons.

Coil pack ignition: I only recently found out that the 4.0 was upgraded to a coil pack ignition in 2000. I'd like to know more about this system. Is there a good article anyone can point me to?

Waste of time. There is no gain in using the coil packs. It doesn't produce a more powerful spark over any other Jeep system. It also makes shorting the plugs out for diagnosing a pain and it is a pain to take on and off when you have heater hoses and other various cables in the way.

Head Gasket: What are my options? Are metal shim gaskets available for the 4.0?

There is the Mopar performance/VR MLS gasket which compresses to .044". Search on here for 'mls compressed gasket thickness'. I have a post that lists the 3 part numbers for the gasket.

Head porting: Who does a good job (in terms of power, not necessarily raw flow numbers)? What are the common tricks? Substitute valves, etc? Anyone do CNC porting?

Just do a clean up home port and polish job. IIRC someone did a cnc ported head. Maybe its was accurate power or patriot performance. I know I mentioned it in one of the threads on here, so search for that. As for valves, the general consensus is that there are very little if any gains from using a larger valve.

[gradon]

What he said. If you're going with the "fully counterweighted crank", aka 12-weight, then why do you want a ltw flywheel? I say go for the 20# lighter 4 weight 3727 for a serpentine setup or the 3235477 for a v-belt setup(what yours has currently, right?) Hesco does have a ltw flywheel that you need a starter ring for for $345:
http://www.hesco.us/shop.asp?action=det ... catId=7848
Oh yeah, that intake mani is 99+.

[Plechtan]

I am interisted in the GM efI Conversion. A while back i was talking to someone who makes a HEI distributor for the AMC6, and asked if they would Make one without the Vacuum ans centrinfigul advance, they said they would but wanted about $350.00 for it.

Here is somthing interisting for a HEI distributor conversion http://www.davessmallbodyheis.com/

Are you talking about TBI or port injection?

The system that Painless sells id pretty cheap ( about $1500) also DFI makes.

Don't waste your money on rods, use the 4.0 rods with KB944 pistons. Seem to be the best bang for the buck. Sixpak is running stock (258) rods in his sand drag cj for the last 20 years, never had a problem. I agree with not doing a bunch of head work unless you are building a very high performance engine.

[TheDarkSideofWill]

Thanks for the links and info, everyone!

What he said. If you're going with the "fully counterweighted crank", aka 12-weight, then why do you want a ltw flywheel? I say go for the 20# lighter 4 weight 3727 for a serpentine setup or the 3235477 for a v-belt setup(what yours has currently, right?) Hesco does have a ltw flywheel that you need a starter ring for for $345:
http://www.hesco.us/shop.asp?action=det ... catId=7848
Oh yeah, that intake mani is 99+.

I've heard that the 12 weight crank is tougher and more durable than the lighter cranks. Is this not the case? I didn't know that there were multiple versions of the lighter crank. Was the 258 ever built with a serpentine drive?

From a rudimentary perspective, for a given bobweight, the heavier crankshaft will have a lower moment of inertia and will spin up more quickly than a lighter crankshaft. This is because the multiple smaller counterweights *should* have a smaller radius than the two larger counterweights.

22# aluminum flywheel? In *addition* to the flexplate? Is that a joke?

I'd rather convert to serpentine than keep the multi-V arrangement. What are the differences in crank snouts? Is the serpentine drive adaptible to the older crank snout?

[John]

The serpentine drive works for any of the cranks,light crank vs heavier 12 wt. crank. I still think the 12 wt. is the stronger crank. Other than the snout length variations (short or long) I use spacers machined from old harmonic balancers, some cut the snout length down. Look in our FAQ section for cranks for more info.
John

[TheDarkSideofWill]

Eagle rods won't work with the KB944/945 pistons. If you want to use the eagle rods you will have to go with custom pistons. If you are dead set on the eagle rods 505 performance sells them along with matching pistons.

I just ran across reference to the Eagle rods being 6.150", which is baffling. I'll stick with the 4.0 rods. After just building an engine with custom pistons, I'd rather stick with shelf slugs this time.
I read things about Diamond pistons. How do the KB's and Diamonds compare?

Just do a clean up home port and polish job. IIRC someone did a cnc ported head. Maybe its was accurate power or patriot performance. I know I mentioned it in one of the threads on here, so search for that. As for valves, the general consensus is that there are very little if any gains from using a larger valve.

Hesco has a CNC iron head as well, but no flow numbers. Patriot's 2V 4.6 V8 Mustang heads suck.

[TheDarkSideofWill]

The serpentine drive works for any of the cranks,light crank vs heavier 12 wt. crank. I still think the 12 wt. is the stronger crank. Other than the snout length variations (short or long) I use spacers machined from old harmonic balancers, some cut the snout length down. Look in our FAQ section for cranks for more info.
John

Cool. I'll check the FAQ for the details. Is the serpentine snout longer or shorter than the V-belt snout? I almost grew up in a machine shop, so cutting the long one down would not be an issue, but I've never seen a "put it back on" attachment for a lathe, so the other way is harder.

[John]

You won't have to worry about "reverse machining" to get extra material, They are slightly long or just right for the serpentine belt arraignment, the difference is 10mm in length. The longer end was for the v belt pulleys. Cut the 64mm down to 54mm or add a 1 cm spacer between the pulley and the bolt/washer.
John

[TheDarkSideofWill]

The thread on the 7120 vs 0331 head was interesting... the 0331 exhaust port is much smaller but flows the same... much more efficient port. Maybe I'll have to use one of those heads.

Is there some serious info about the coil pack ignition around? I've been told it's not worth horsepower, but I'm interested in higher technology where feasible. I'm curious about it.

[SilverXJ]

Is there some serious info about the coil pack ignition around? I've been told it's not worth horsepower, but I'm interested in higher technology where feasible. I'm curious about it.

What serious info do you want? Its a waste spark system that fires two plugs at once, using 3 coils. Its a serious waste of time installing it aftermarket. Its cumbersome to get in and out, you can't diagnose the engine by simply pulling a plug wire, there no upgrades for it unlike the distributor system, and to install it in a vehicle that came with out it you would need to install the PCM, associated sensors that are different from the current sensors, plus a whole bunch of emissions equipment, etc... Along with the wiring harness from the original vehicle to get it to work and then you would have do something about the gauges.

[TheDarkSideofWill]

to install it in a vehicle that came with out it you would need to install the PCM, associated sensors that are different from the current sensors, plus a whole bunch of emissions equipment, etc... Along with the wiring harness from the original vehicle to get it to work and then you would have do something about the gauges.

Fuel injection is NOT a black box.

For example, the GM coil pack is almost the same as a distributor from an interface standpoint. The same ECM was used to control distributor and DIS engines. The only difference was the chip.

I was wondering if there was a diagram of the signal interfaces between the coil pack and the ECM. In the GM system, the analog crank sensor signal goes to the DIS where it is converted to a 0-5V square wave to go to the ECM in place of the reluctor signal from the distributor. The ECM sends back exactly the same timing signal it would use to fire a single coil distributor setup, but the DIS picks which coil to charge and which to fire (the two are different).

The 60 degree V6's retained the distributor port in the block and used a plug to drive the oil pump. How does the 4.0 deal with not having a distributor? Plug in the hole? Hole not there?

[TheDarkSideofWill]

I am interisted in the GM efI Conversion. A while back i was talking to someone who makes a HEI distributor for the AMC6, and asked if they would Make one without the Vacuum ans centrinfigul advance, they said they would but wanted about $350.00 for it.

Here is somthing interisting for a HEI distributor conversion http://www.davessmallbodyheis.com/

Are you talking about TBI or port injection?

The system that Painless sells id pretty cheap ( about $1500) also DFI makes.

I'll have to review the parts selection, but I thought there was a combo that would bolt together. It may be necessary to modify the non-EFI HEI base from the GM blue flame 6 to accept the later EFI module. I'd also have to snag the reluctor & pickup coil from an even-fire 4.3 or 3.4 and adapt them. I should be able to put the entire system together for just a couple hundred dollars, depending on what injectors I decide to use.