Can it be done? Just getting some options.

 

well anything could be engineered if you have the $$$ but ive never heard of one that doesnt mean it doesnt exist, but on a EFI motor you also have to consider the fuel needs the ecu would have to be remapped to adjust injector pulse (i would think) as well as any number of other adjustments and changes in the ecu for timing and emissions, you want it to pass an inspection i assume, but hell i havent been a real mechanic for some time so somebody else may know better than myself

 

There is already a stroker kit out, pricey, though. Check Summit or Jegs and you should find it.

 

well thats coolness what kind of displacement will that put you up to, do you know?

 

well i found it check this out thats high dollar tho http://www.speedomotive.com/ps-502-8...crank-kit.aspx

can that really be, just bolt on, theres gotta be some ecm changes. am i not right or am i way off base on this

 

$1500 for 10 cubic inches. I can do a 350 swap for way less and get something way more reliable I bet.

 

Mechanics, correct me if I am wrong. I am just an enthusiast.

The 4.3L is identical to the 5.7L when it comes to bore and stroke. I took an automotive tech class and the instructor had done this multiple times. This issue is finding a crankshaft.

That being said, my instructor used to buy 350 stroker kits and only use 3/4 of the parts. So he would use six pistons, etc etc.

Like I said, not sure if a new stock crankshaft would work. I wouldn't see why not, but I have never done this before.

But, if you bore out the cylinders as if it were a 350 and use a 350 stroker kit, everything should fit. You would then have to program your ECM for the new fuel mixture.

And as I said, mechanics, correct me if I am wrong. My instructor did this back when the engines were carbed, not fuel injected.

 

The main things that make a stroker a stroker is the crankshaft. A 383 is nothing more than a standard bore 350 block but they use the 400 crank. Most 4.3s I've seen use reground factory cranks to try to build a stroker (why for the small amount of gain).

The only reason he prolly got v8 parts kits is for some reason they tend to be cheaper than v6 kits.

 

One thing to note about grinding down a stock 4.3L crank is that these cranks are split journal cranks because the rod journals are split by 30 degrees of rotation from each other (splay angle), not shared like they are in v8's.

Here's an image showing the split journals:


And a standard v8 crank for comparison:


Offset grinding is accomplished by reducing the diameter of the journal while moving the center line of the journal further out away from the center line of the crank, thereby increasing stroke. Here is a picture I put together quite some time ago to illustrate what is happening:


Offset grinding a split journal crank down will weaken it. How much is hard to quantify. It all depends on how far you go, the material and what processing it undertook during manufacturing.

This article - 3/4 350 should shed some light on some things that can be done.