Hey guys just got a quick question.

 

If i have a 5k block and go about putting a 4k head on it, will that work?

or could it not becuase the 4k head has solid lifter rockers ect, will i have to change to solid lifter for a 4k head to work?

I have reaserched but couldn't find the specific answer i was looking for.

 

Cheers Sam

yes you will need to change to solid lifters

 

by putting the 4k head on it you will infact Lower the compression by a fair bit, making it suitable for Forced induction,

the reason it will lower the compression is because in 5k's they have dished pistons so the combustion chamger is mostly in the top of the piston, while in a 3k/4k the combustion chamber is in head,

therfore haveing dished pistons and a head that has combustion chambers surrounding the valves = alot lower compression.

 

if forced induction is not the plan, then don't do it,

 

unless of course you are changeing pistons to non dished style ones... but thats another world i don't know about

 

hope this was helpful

Edited October 30, 200817 yr by Shizotimang

yeah that helps heaps and answered my question. Thanks for that.

 

Cheers Sam

Just cleaning up my 5K and noticed the pistons are very dished.. Was wondering if this was standard.

 

Wonder answered! :)

Yep. My new ACLs have nowhere near as much dish....

Aftermarket 5k piston on the left (ACL etc), original toyota one on the right.

Most of the aftermarket pistons have around 6cc of dish, where as the toyota ones are 22cc. So even if using a 4k head on the 5k you really want the deep dish pistons for low comp.......

 

 

|blink|

No need to change the lifters, they're in the block. Hydraulics are good for 8000rpm and don't need adjustment Just run the 5K rocker gear that have a couple of mm (height difference between 5K and 4K head) machined off the rocker posts.

 

 

yes you will need to change to solid lifters

 

by putting the 4k head on it you will infact Lower the compression by a fair bit, making it suitable for Forced induction,

the reason it will lower the compression is because in 5k's they have dished pistons so the combustion chamger is mostly in the top of the piston, while in a 3k/4k the combustion chamber is in head,

therfore haveing dished pistons and a head that has combustion chambers surrounding the valves = alot lower compression.

 

if forced induction is not the plan, then don't do it,

 

unless of course you are changeing pistons to non dished style ones... but thats another world i don't know about

 

hope this was helpful

ahh, you learn something new every day |blink|

I was looking at the 4k head on me 5k block today and the measurement in mm that I came up with was 6mm shaved off the rocker post to allow for pre-load on the lifters, any advances on that, as I learning to.

What pre load are you intent on running?