1bigoldman

I have a LR4 long block I picked up just because I thought it was a good deal. It has the 706 casting heads on it.

My neighbor just gave me two complete rotating assemblies. One is a 50k LQ4 with no noticeable wear on it. The other is a LQ9 with unknown milage and I have not seen it. He is also giving me two sets of 317 heads from the same motors.

Can I bore my block that far and have it live?
How big of valves can I stuff in the 706 heads?
What kind of compression ratio will I be looking at with the 706 heads?
I really want the motor to externally still appear to be a 4.8L.

I will probably stuff this motor in my Sonoma and DD it.

1964SS

iTrader: (1)

Externally it's pretty damn hard to tell the difference between any of them anyway. With the accessories on the motor you can't see the stamp on the front of the block very well. I would use one of the 6.0L short blocks over the 4.8 any day.

Regarding your question.
They can be bored from the stock 5.3L/4.8L 3.779 (96mm) to Factory LS1 3.898 (99mm) bore in some cases up to 3.905. It is however recomended that you have the block sonic checked First before trying to go that far. Some blocks may have casting flaws or core shift issues that may not allow that much of an over bore...

Now in some very early cases there were 5.3/4.8 blocks that were cast with a large 6.0 above the 5.3/4.8 These blocks are few and far between but can be bored to the stock 6.0L 4.00 bore (101mm). There is not a whole lot of info out there on them as they seem to be hard to find.

1bigoldman

Thanks for the reply.
That is what I thought. My buddy that gave me the parts says that they did a 4.8 to 6.0 for the Engine Masters. He figured well if they can do it so can I.
I will get the block sonic tested and see what I can do with it. Maybe I'll bore it to LS1 and put in a 4" crank.

crmd37

Anything ever happen with this? I just picked up the LR4 also in hopes that I could possibly buy an LQ4 short block and swap the 4.8L with the 6.0L shortblock. Got such a good deal on the motor and van that I couldn't pass it up.

My question is plainly is that possible? I know people say you can hardly tell the difference between "smaller" motors and "bigger" motors. Anybody ever done this before? Worth it?

Lsxford

iTrader: (6)

You can swap the shortblocks with no issues. Swapping rotating assemblies however is a different animal.

Afaik all the heads will bolt up to all the shortblocks. The LSX components are different in that they have 6 bolts per cylinder heads where production LSx only have 5 bolts per cyl heads