ToxicWS6

so i have a 346 that had dished forged pistons, H-beam rods and stock crank, i ended up spinning rod bearings, so i need new rods and a new crank, the pistons are still good

i recently picked up a 6.0L lq4 im not sure what i want to do with, thought a out buying a 408 stroker engine with it but i have the above ls1 also and would like to use my pistons

thoughts where to keep the lq4 put 243 heads on it with a cam and put it in my truck for an ls swap then turb my 347 into a 383 with buying a 4.0 crank instead of a factory one and then figuring rods out

question is, is there a negitive to having a 383 as a turbo motor?

can i just get a 4.0 stroke crank and throw it in, like will it fit and all?

RezinTexas

you cant use pistons from a 346 in a 383. They will be too tall. See the graphic below, all components need to be sized to achieve the correct height.

ToxicWS6

ah ok, what would be an option then if i had the 347 with pistons? like what could i do with it

am i stuck with stock crank size and all or can i get shorter rods to make up for the longer crank?

conan

iTrader: (5)

What is the length of your rods ? If they are 6.125" you can reuse them and buy new pistons for a 4" stroke.

RezinTexas

the pistons are matched to the stroke. There is some variability in the rod length, but this is minor.

You cant use those pistons with a 4" stroke for at least 3 reasons:

1. The Rod/Stroke ratio would be lower than recommended minimum of 1.5.
2. The piston will come out too far at BDC and cause excessive wear.
3. The counterweights on the 4" crankshaft will clash with the pistons before BDC, and it will never turn over.

Here is an image to show the issue for #3 above. The crank counterweights are roughly 0.100" from hitting the piston skirt. With your current pistons, there would be a major clash here.



Basically, if you want to use a 4" crank, you MUST get new pistons also.

I've heard decent things about Probe pistons, and they are a lot cheaper than Wiseco.

ToxicWS6

ight thanks guys!

and the pistons i have are the only things that are still good so it was basically what can i do with my forged pistons and 347 block, i need ot buy new rods and a crank

so basically i can ether sell the pistons and go that route or just be stuck with buyin new rods and a stock stroke crank?