350 -> 383 stroker.

[Mamby]

My mud truck i have needs an engine rebuild and its gonna be my first engine that i build, pretty exited about it. I want to bore it 40 over (which would make it a 383 right?) Whats done to make it a stroker motor? Shortened rods or is it done on the crank? Any helpful tips would be appreciated too

[TexasRed]

It's built using a 3.75" stroke crankshaft instead of the 3.48" stroke that originally comes with a 350. It's the same stroke that came with the 400ci engines. Depending on how you go, the shorter rods that came in the 400 or 5.7" or 6" rods, you're going to need new pistons to fit that rod and new bore (.040).

[Lt.Del]

a 383 is bored .30 over and uses a 400 ci crank and balancer and flexplate/flywheel

www.delbridge.net/install

[Mamby]

Alright so if I am understanding this correctly:

Crank with a 3.75" stroke and use 5.7" rods.
Bore 0.040 over (pretty much want it bored when ever you do a rebuild correct?)

[Lt.Del]

i wouldn't bore it .40 unless i really had to.  You may thin the cylinder walls so much to cause overheating issues.  .40 will not allow a future safe bore later down the road.

a 350 with a 400 crank  and bored .40 is like a 387 or something close to that.   .30 is a 383

[Captkaos]

Personally I would only bore out a cylinder as much as required to clean up the cylinders.  The amount of displacement difference isn't enough justification in my opinion to bore a motor that just needs a hone job or .020 pistons.

[Jay2D2]

So if somone were to just bore out out what was necessary say .020 over and were to use the 400 crank and the correct length rods, what would be gained? Would it be worth the extra capital and time required for the upgraded parts?

[Captkaos]

You are gaining 1.897 cubic inches with a .030 bore over a .020 bore, and possibly making it the LAST bore the block will ever have.  Keep in mind "383" is basically a term to describe a stroked 350.  In my opinion the extra 5.67 cubes you gain
over a stock block 350 isn't worth it unless it has to be bored.

It is the same thought process around a 350 you need to rebuild.  If it only needed to be honed, would you go ahead and bore it out?  I doubt anyone would think I can get more cubes if I bore it to XXX and it is basically the same gain as the 383..

This is the breakdown of the bore size to cubic nch.

4.000 bore = 376.991
4.010 bore = 378.878
4.020 bore = 380.770
4.030 bore = 382.667
4.040 bore = 384.568

[Jay2D2]

The block I am working with is only in need of being honed.  It has never been bored.  So would there be any benefit of installing a 400 crank in a stock bore 350 block? Now if there is any benefit is enough of one to make it worthwhile in doing?

[Captkaos]

If you want good bottom end torque the 400 crank will get you there.

[Lt.Del]

If you want good bottom end torque the 400 crank will get you there.

Amen!

[Mamby]

Oh ok. I thought boring and honing were the same thing for some reason. So if i were to get it bored I should only go .030 over?

[malibu795]

Oh ok. I thought boring and honing were the same thing for some reason. So if i were to get it bored I should only go .030 over?

std bore and hone is .030 on a block that has never been bored.

also when haveing them machine the block.

might make as sticky thread for this..

get then block decks... std virgin deck is 9.025" on avg then pitons is stil ~.025-.015" (or legnth 9.0-9.1").in then hole at TDC or below the deck.

have then block Decked.. all this does is true up then head gasket surface..  GM specs is ~.003-.005" per 6" of leniar distances IIRC... decking will put you ~.001-.002" across then deck surface.

"square decking" some shope this is in wiht normal decking others it is not.
the way this is done. then block is place in a Jig through the mains. then the deck is shaved/machined squared to the crankshaft axis. allowing htne head to be 90* perpendicuar to then pistons..
my shop does all this for 75.00 a bank on a BBC 150.00 tottal..

another thing you can have done is line honing then main caps.... this ensures then the bore is straight and true and has then least amount of binding on the crankshaft. usually 200-250.00 for this job. something i would look at if you plan on spinging 6,000+ for extended periods of operation.. less likely to sping a bearing.

[Mamby]

Ah thanks, i was wondering what it was calling when they shaved off a bit from where the head goes to make it perfectly flat.

[Lt.Del]

read the post from Chris again....you shouldn't go .30 if you don't need to.

Personally I would only bore out a cylinder as much as required to clean up the cylinders.  The amount of displacement difference isn't enough justification in my opinion to bore a motor that just needs a hone job or .020 pistons.

You can hone the cylinder walls yourself no problem with the three-bladed hone set you can buy or rent that attaches to a drill.  If you are sending in your block in to a machine shop to get it magnafluxed (which I recommend) to ensure no cracks, etc... then you might as well have the shop hone it.  But, depending on the condition, it may have to be bored some, which would negate any honing.

Is your head spinning yet?