Hi there,

 

Building up a 5K block and have several heads at my disposal, 3K, 4K and 5K. The 5K head needs to be repaired, so as a cheap solution I want to use either the 3K or 4K head on the 5K block.

 

Will a 3K/4K head bolt onto a 5K block without any hassles? I also want to use the 5K hydraulic lifters and rocker gear, so will they work with a 3K/4K head?

 

Also my 5K block has dished pistons. Will that cause any problems when using a head intended for flat tops?

 

Thanks very much.

If you have dished pistons, I think you can only use a dished piston head as the compression will be way down

Also my 5K block has dished pistons. Will that cause any problems when using a head intended for flat tops?

 

 

what coln said, it will be slow as shit and have no power.

Edited August 12, 201016 yr by philbey

Okay, that's odd!

 

I thought a smaller head would give more compression?

 

Guess I'll have to get the 5K head repaired. Also does anyone know where to get replacement 5K dished pistons from? Figured I may aswell do it properly now!

 

Thanks.

you don't have a "smaller" head with a 3k/4k. You have a head with a larger combustion chamber than the 5K, hence you have less compression.

 

Head doesn't define engine capacity.

Edited August 13, 201016 yr by philbey

Less compression = More BOOST!!!!!!!!!!!!!!

Okay...

 

So why is it that when using a 3K head on a 4K block you get more compression? Is it something to do with flat top pistons? I'm getting a little confused!

 

Cheers.

Is it something to do with the fact 5K's have the ignition happen in the cylinder bore itself? Something called a Heron type combustion chamber I think I read somewhere?

 

Don't know alot about this stuff, still trying to get my head around it!

i don't know the K motor specifics,

 

but its all about combustion chamber volume.

 

if you put a 3k head on a 4k block and the compression goes up, then the volume of combustion chamber inside the head must be smaller on the 3k head than on the 4k head.

 

and visa versa, i assume if you were to put a 4k head on a 3k block, the compression ratio would go down, since the 4k head has more volume then the 3k head.

 

and then you got dished vs non dished pistons, the dished ones have more volume than the non dished ones etc.

 

and combinations of all these different things can either provide a higher compression, or a crappy low compression. depends what you use.

take a look in my thread when i was building my 5k, should be some info there

Okay, makes more sense now.

 

I picked up another 5K head today, is in real good nick so I'll just use that. Not worth cheaping out here, would want it to have decent compression.

 

Thanks for the advice guy's. Think I'll have a much gutsier 5K because of it!