ssdungeon

iTrader: (24)

For iron block lq4 or lq9
TSP and others have kits.
has anyone had any experience with the 421 kit?

I understand it will cause probably increased heat because of the long stroke.

definitely not good for boost or massive nitrous hits..

For NA revving no hogher than 6500 rpm every now and then ...
would it last ok?

Please share your insight.

bortous

What block?
LS3?

ssdungeon

iTrader: (24)

lq4 or lq9 iron

bortous

Can you overbore this block to 4.060 being iron?
The gen 4 LS2 can only go up to 4.030.

KCS

iTrader: (20)

Yes, you can, but he’s probably talking about a 4.030” x 4.125” rotating assembly.

bortous

Ok cool.
Let's see what stroke and bore the OP is planning on using.

ssdungeon

iTrader: (24)

that's correct.
The bore 030 is fine for the iron 6.0 im sure of that.. 7plus years i had that with a 350 shot revving to 7000 rpm sold it runnimg.

The longer stroke is the main question area I think. There mY be other things to consider so if anyone has insight let me know before I pull the trigger.

DavidBoren

How much of the piston is still in the cylinder at BDC? Don't the iron blocks have notoriously short cylinders?

64post

iTrader: (5)

I did a 425 ci using a LQ block 4.065x4.100 only because I had the 4.100 crank laying around. I would suggest no more stroke than 4.00 If you still have a choice. The skirt of the piston on a 4.100 stroke hangs out a lot abdc.

BigDaddy97

I ran a LQ4 based 421 stroker with 821 heads in my drag truck for a couple years. Ran 10.20's shifting at 7200.

ssdungeon

iTrader: (24)

when it failed was it from a piston dropping too far?

BigDaddy97

No sir. I had a shop change my heads and cam, and they didn't verify valve to piston clearance so a valve kissed the piston and destroyed it.

Jimbo1367

WTF? lol. I hope you went after them. They should of known to check. With that said, I would of made sure they knew they had to check it.

DavidBoren

What shop worth its salt changes the heads AND cam without checking PTV clearance? Seriously, who-the-f!ck does that?

PTV clearance should be checked even if you only change the heads OR the cam... definitely if you change both. Measure for pushrods. Check the rockers contact patch and geometry.

Half-assed nonsense, somebody deserves to stub their toe every day for the rest of their pathetic natural life...

KCS

iTrader: (20)

I have a 4.250" crank in my 6.0L iron block so I wouldn't even hesitate to run a 4.030" x 4.125" combo.