Trying to finalize plan

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Brianj5600
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Stroker Displacement: 4.7
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Trying to finalize plan

Post by Brianj5600 »

I have spent a lot of time over the last few weeks reading all I can find on stroking a 4.0L. There are a couple things I'm not too sure on. I have a 2004 TJ and the 4.0 is not going to do what I want with out modification. I have Syked tuning software that has helped some, but not enough. It does okay empty, but I want to pull a 1200-1500 lbs trailer. Where I live and parts of Tennessee I like to travel can have some pretty long climbs. I also plan a trip out west which I think will really test even a 4.6L. I really don't want the complexity of a power adder if I can help it.

It seems like there are not too many recent builds and most of the older builds seem to use 4.2 cranks. I'm a little confused on accessory drive using the short 4.2 crank and later 4.0 front dress. I am also not clear on the fitment on the Scat crank either. Which is the most cost effective route for crankshaft? Would a Scat crank have fewer things to trip you up?

Connecting rods seem straight forward. I plan on using my stock 4.0 rods, but do they really need any machine work if they come out and the bearings look good? Or is it padding the bill at the machine shop?

Is cutting the block the most cost effective way of zero decking or even out of the hole? How close can you run the pistons to the head?
Brianj5600
I think I'll order a "tab"
I think I'll order a "tab"
Posts: 43
Joined: August 23rd, 2019, 10:49 am
Stroker Displacement: 4.7
Vehicle Year: 2004
Vehicle Make: Jeep
Vehicle Model: Wrangler

Re: Trying to finalize plan

Post by Brianj5600 »

I want it to run on 87 octane which seems to be fairly easy with the right, tight combustion chamber. The last couple V8 I built had .035"-.037" quench which is what I'm shooting for with a 4.6L. What CR with the Comp 206/212 duration @ .050", .435"/.448" lift and cut on a 113 lsa?

Does polishing the combustion chambers have much affect in suppressing detonation? Do the long electrode spark plugs contribute to detonation in an N/A 4.6?

I talked to Clegg and Plan to talk to Russ in the near future. I will probably wait until the dead of winter to build it.
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Cheromaniac
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Re: Trying to finalize plan

Post by Cheromaniac »

The Scat crank is a brand new version of the '87-'90 4.2 crank. Any 4.2 crank from '72+ can be used to build a stroker. Regardless of which 4.2 crank you use, you'll be mounting a stock 4.0 harmonic balancer on its nose.
If you're going to reuse your stock 4.0 rods, the big and small ends will need to be checked for ovality and resized if necessary. It's also a good idea to use new ARP rod bolts #112-6001.
With the cam that you mentioned, you could aim for a static CR of 9.5:1. Combined with a tight quench, you could run the engine on 87 octane. Polishing the combustion chambers and piston dishes definitely helps to fight off detonation. Russ can provide you with the correct spec pistons that won't require any milling of the block deck.
1992 XJ 4.6 I6 - 5MT - Stroker build-up, Stroker "recipes" Sold
1995 Mustang GT - 4AT - Modded Sold
2006 Mustang GT - 5MT - Modded Midlife Crisis Car :mrgreen:
Brianj5600
I think I'll order a "tab"
I think I'll order a "tab"
Posts: 43
Joined: August 23rd, 2019, 10:49 am
Stroker Displacement: 4.7
Vehicle Year: 2004
Vehicle Make: Jeep
Vehicle Model: Wrangler

Re: Trying to finalize plan

Post by Brianj5600 »

So if I use a late 258 or Scat crank and my 4.0 damper, the front accessories will all line up. Meaning the 4.0 and 258 are the same except for the stroke?
Notaracetruck
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Re: Trying to finalize plan

Post by Notaracetruck »

Not an expert by far but I believe the nose is a little longer which requires a 10mm spacer under the bolt.
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Cheromaniac
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Re: Trying to finalize plan

Post by Cheromaniac »

Yes, the 4.0 harmonic balancer will line up perfectly with the other pulleys if you use an '87-'90 258 crank or a brand new Scat crank.
Russ Pottenger
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Re: Trying to finalize plan

Post by Russ Pottenger »

Dino is correct.

If you happen to have the longer 2.500 snout found on the early
232 and 258 Cranks I can provide you with a machined spacer cut for a Keyway that will allow you to slide it over the crank snout.
Easy Peezy.
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