crank work ?

[montess408]

i was reading a older post the other day (can remember the name ) about grinding a crank in a 3400 with a offset and geting a bit more displacement is it possible to do the same with a 3.1 crank ??

[bszopi]

The 3100 and 3400 cranks are the same. What you are referring to is offset grinding a 3500 crank and using it in a 3100/3400 block.

[montess408]

ah ok so it cant be done in a gen 2 block right ? and is ther a diffrence in stroke in a 3400 and 3500 ?

[El_Diablo]

anything can be done... its all on how much money you have and what you would like to achieve... if you grind an already small 31/400 crank journal your gonna have to figure out something for rods and also if your weakening the crank enough to worry

[montess408]

ok say that i use a 3500 crank in a 3400 and i off set grind it what would be my displacement gain ?

[El_Diablo]

depends on how much you grind it, its a bit more work than that either way and you'll need to atleast notch the block and oil pan.... if you can get past that then you'll need to figure out a crank trigger, easiest is to use the stores triggger kit

oh and we cant forget that when your offset grind the crank you change the orientation of the rods and pistons as they sit in the bore so unless you want ultra low compression (in the 8's) you'll need to have some custom pistons made... now you could use the 3400's rods but why when you've spent all the money already? might aswell upgrade to a SBC small journal rod which will also need narrowed..... this is the whole reason im going with the 3500 block

[montess408]

is a 3900 block basicly the same as a 3500 ? that would give me the displacement i want would everything from a 3400 or 3500 bolt to the 3900 ?

[Superdave]

is a 3900 block basicly the same as a 3500 ? that would give me the displacement i want would everything from a 3400 or 3500 bolt to the 3900 ?

http://60degreev6.com/Family_Tree

read through that, it will answer your question.

[montess408]

it says nothing about the 3900 that i see
but form what i see the newer 3500 is all new and nothing fits so i am guessing the 3900 is the same ?

[El_Diablo]

yup.... and good luck with the wiring and vvt...

[montess408]

well thats what i am trying to get around of is the is the VVT some how

[Joseph Upson]

VVT is cake, you only need to lock the cam phaser in the full retard position for max performance. The non VVT 3500 block is different from the 3900 block although many parts are interchangeable, the heads and intake are not among them. Go here for a reference to offset grinding the crank;

http://www.flatlanderracing.com/crankshaft_services.html#weldedstrokers

Contrary to what one member mentioned earlier, if you offset grind the 3500 crank for example it will not lower your compression it will do just the opposite to the tune of pushing the piston above the deck, it will also pull it further down the bore. Since the 3500 crank pins are 2.25" you can offset grind to a stroke increase of about .120. If you really want to push the envelope you can pay an additional fee and have metal added to increase the stroke more.

[montess408]

hey jo thanks for the link ! can you offset grind the 3400 crank or does it have to be a 3500 ? and can i 3400 block be safelly be bored to .060 over ?
and can any good machine shop do the offset grind or does it have to be a specialty shop ?

[bszopi]

In order to use normal sized rods and keep rod strength, you need to use a 3500 crank. This is because the journals on the 3500 crank are 2.25" versus the 2.00" journals on the previous 3x00 cranks. Therefore, you offset grind the crank down to the standard 3x00 crank journal diameter.

As far as boring the block to 60-over, yeah it can be done. But you give yourself no room for cleanup if you ever rebuild the engine again.

[montess408]

will the block have to be clearenced any to do this ? or will the outside or the connecting rods be grinded a bit ?