Join Date: Sep 1999
Location: San Diego, CA
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Re: 4.0 BLOCK and HEAD / 258 CRANK ???
I have talked to guys at HESCO about the differences. All of the 4.0 strokers are very similar in design. The basic idea is a 4.0 block (the 4.0 engines have a wider bore) with the 4.2 crank (longer stroke).
There are other things that will either increase it's characteristic as a stroker or increase it's top end ability. Here are a couple I know of:
* If you use the 4.2 rods they are shorter and heavier than the 4.0 rods. You can use the 4.2 rods with stock 4.0 pistons. The 4.0 rods are longer and considered better for torque, but require custom pistons (which I think Hesco and accurate power sell). My pistons are being made by a local speed shop for about the same $$ as Hesco's. So, the comment about the homemade kits being revving is slightly true depending on rods.
* The early 4.2s (I think prior to '80) had a heavier crank. This is better for torque. The lighter 4.2 cranks are better to rev.
* The crank grind can be offset to either increase or decrease stroke and compression. Again, we're talking very small differences.
* Cam choice will obviously allow the engine to perform better at lower RPMs with good torque or High RPM HP.
* Intake/Exhaust set-ups. I know Hesco sells a CNC machined throttle body that inreases flow. Also, the exhaust header type can affect torque v. hp. I chose the Cherokee header partly because it should help in torque dept (also, it was only $100 at a junk yard).
The basic stroker is a common platform. It uses the wider 4.0 bore, but increases stroke by about 1/2". That's the most significant increase alone. All the other things will enhance the basic set-up.
258 4.0 Head/MPI,NV4500,D300,4.10's,HS9500