hi all,

i am rebuilding a 4k and was wondering what is the best way to up compression and make more power out of it?

get the head skimmed.

 

:D How to build a tough K motor

3K head. easiest way.

3K head. easiest way.

 

Potentially WAY more expensive.

 

Why not just skim the head you've already got if it is in good overall condition.

 

If you are serious about doing a decent rebuild you should get the head skimmed so you know it is flat. Then you don't have to worry about a blown/leaky head gasket down the track. Costs like $60. Cheap insurance. Do it properly the first time.

 

Sure you could use a 3k bigport head, but then you have you buy one, for say $100. Problem is they are old, have a crap valve stem sealing arrangement, and most likely have worn guides... The later valves/valve guides and valve stem seals can be fitted, but you are then looking at a heap of $$$ for the parts, plus fitment for no real benefit. Also consider that being older they have more chance of water jacket corrosion so factor in some welding before they can be skimmed.

Edited May 17, 200917 yr by Felix

Potentially WAY more expensive.

 

Why not just skim the head you've already got if it is in good overall condition.

 

If you are serious about doing a decent rebuild you should get the head skimmed so you know it is flat. Then you don't have to worry about a blown/leaky head gasket down the track. Costs like $60. Cheap insurance. Do it properly the first time.

 

Sure you could use a 3k bigport head, but then you have you buy one, for say $100. Problem is they are old, have a crap valve stem sealing arrangement, and most likely have worn guides... The later valves/valve guides and valve stem seals can be fitted, but you are then looking at a heap of $$$ for the parts, plus fitment for no real benefit. Also consider that being older they have more chance of water jacket corrosion so factor in some welding before they can be skimmed.

 

 

TOO TRUE.

 

There was someone on here (no names) spent around 150 for a 3K BP head and it was so warped it blew the headgasket in a few days.

did they get it skimmed?

there is absolutely no point putting a head on unless you get it skimmed...

not at all.

 

Get contacted by said person sayin his engines running rough and whats it mean when theres coolant on the plugs.

 

He ended up pulling it off and puting on a 4K head

then it was to be expected the bloody thing would blow a head gasket, have you seen the tolerances?

if you can pull something off after 20 years of service and still expect it to be within what is it, something like 2 thou of flat then your expecting too much.

if he had of skimmed the head, there would not have been an issue.

To get back to Blane's question...

 

You should clean the ports and combustion chambers up first and get them smooth and free-flowing, with the port diameter matched to the size of whatever inlet you are going to use.

 

Then measure the volume of the combustion chambers with a burette and chop out metal until they are equal. Then decide what compression ratio you want and calculate how much to skim off to get that ratio, and take it down to a motor engineer and tell them that.

 

Get a cam cut, fit twin carbs and a freeflow exhaust and away you go... faster and poorer by several thousand dollars!

and you would spend several thousand dollars on a K motor to still go like a K motor why?

^^^ Because there are some people out there that want to keep the k motor instead of putting a 4 motor in ^^^^

but why waste so much money on the piece of puss?

More to keep the original style to the car.

The 4age's that I used to compete against were not that quick. I'm talking seconds slower over a 2km lap than my old 5k.

 

Remember kiddies, its not how much power you make, its where you make it and over how many revs.

Edited June 1, 200917 yr by coln72

Some people waste all their money on pieces of puss ke70's :bash: :P

 

Let him spend his money.

 

Get your head skimmed like they said. Do some research, do some maths, decide the compression ratio you're after and calculate the amount you need to skim and soon you'll be able to talk the same language as the guy doing the work for you.

Edited June 2, 200917 yr by philbey