I was taking to an eng builder and we started talking about what crank i was going to use of my rebuilt (stock) and he said what he dose is take the crank and turn it into a 3.50 stroke from the 3.48 OE stroke...

What are the Pro's and Con's of this
What affect on the rods/length will this have
Are piston changed here as well.

thx

 

Not exactly advanced tech.

It will make a difference of 1.85 cubic inches. Not enough to make any difference. You get more of an increase from a normal rebuild, in which the cylinders are bored 0.030" more than stock (4.030" bore). That results in an increase of 5 cc, to give a 355 ci engine.

Maybe what he was talking about was a 3.75" stroke, which would be a 383? Now that's worth the trouble.

BRAD

 

The .020 longer stroke gives you about 2 more cubic inches, but it also raises the piston .010 in the bore. If the block hasn't been decked, and the pistons are down in the hole, it should be ok and you'll get some slight compression increase, so power will be up a little. You shouldn't have to change rods and stock replacement pistons should be ok unless the block is decked a lot. If the rebuilder has done many he knows (or should know) the things to watch for.

As long as you have to grind the crank undersize anyway, there's not a lot of downside, except perhaps a slightly higher octane requrement if you are now boderline. Around here 2 octane points cost $.10 per gallon.

Would I pay extra to have it done? Probably not.

My $.02

 

On a positive note, the slight increase in compression will also give a slight increase in fuel economy

 

It is a good idea, he sounds like a good eng builder that knows what the hell he is doing. It will give you a more optimum quench distance, which is all around good.