3k/4k/5kheads, Pre Pollution?

[Suziefox73]

Hey, just wanted to start this thread for people to thrash out the possiblities for the K series block head combo's! I know that the 3K pre 75(pre pollution) head is a good swap to the 4K block and that the 3K/4K/4KB short has a double row timing chain and the 4KC has a single! But as alloy heads have the habit of getting brittle over time and the fact that the last 3K/4K pre pollution heads came out in 75 to my knowledge means that they are getting rare! Has anyone fitted a 4KC head to a pre 75 3K short and turbo/supercharged the combo? what would the compression ratio be? What k series short motor is the strongest and what are the best combo's to build a project on shoestring budget and where is each state capital do you track down cheap and/or hard to find parts! Example: Gemini G161 motor, I know it's not a Rolla but stay with me! stock G161 short motor, bored 80thou oversize, stock G181 40thou over pistons, stock pre 75 G161 head shaved 10thou, 28/68 reground cam, stock Nikki carb from a early Datto 180B with weaker vac secondary spring, extractors and 2 inch exhaust, stock 2lt Rodeo 4WD clutch, 4sp box and early van diff! Seen that combo run low 16's down willowbank's quarter and you'd be pushing to spend $25 a week for fuel! I think the 4cly/rotary scene has to get back to it's roots a little and remember the days when you could build a fun ride for less than half the price of a 8cly dinosaur and run them down in the twisties and shoot past them on the brakes! Good to see the big budget builds hey, but getting too far from reality for the average guy/girl! Long live the AE86!!!!!!

[philbey]

Haha I live this dude's (?? real name Rob?) enthusiasm...!

 

So you want some more specifics on head-block combo's? I don't think you'll get too much, everyone looks for the coveted 40 year old 3K big port heads but personally I wouldn't waste my time. I run a 5K so I needed a dish piston head, but for 150 bucks I got it planed and had the ports matched to my manifold which pushed the port size out larger than a Bigport head anyway.

[Taz_Rx]

Haha I live this dude's (?? real name Rob?) enthusiasm...!

 

Agreed. ;)

 

Are you in Launy or Hobart?

 

Ever seen my car about?.....

 

 

 

Yeah I know it doesn't look all that flash on the outside, thats sort of how I like it. Most people don't expect that the engine bay looks like this.....

 

 

 

If you're in Launy maybe you should come round for a look and a chat. :D

[Suziefox73]

Yep Launy, fitter/machinist by trade! That's Tarmac drag strip ain't it where the photo was from and that's 5K turbo?

[camerondownunder88]

There are HEAP of different head to K motor combos that can be done.

 

First up Use a late model head. I own old 196X K motor heads to new ish 5K heads out of vans toa TRD made head.

 

Early heads I feel the casting quality is poor lots of dags etc everywhere. As for late-model heads on dished piston motors less dags from external on the head to even in the ports. So a later model head no mods has better ports.

 

Now speaking about ports. Grab a stock 4K-C, 3k-c,k-B what ever head. Run your finger along the top of the exhaust port WOW did u feel that step. Now notice outside on the corner of the head above all exhaust ports is a large flat section. This is where in some countries they drilled holes and installed air injection. So inside the port has a casting hole to allow for this. This kills flow.

 

Now run your finger along the top of a dished piston motor head.....umm flat smooth also notice outside the head no angled flat sections. These heads never had air injection again ports are better because of that.

 

Now. valve sizes a few different valve sizes were use. K heads, 2K heads some early 3K heads have SMALLER valves. Again use a later head larger valves. And some of those small valve heads were big ports. SO they flow crap steer clear.

 

Also for added strength on the bottom of the cylinder head the water holes/slots they have near the cylinder TRD weld these up and drilled a hole 6mm diameter. This then allowed the combustion chamber to be ground out to de shroud valves more. And control water flow better and add strength so can recommend doing this.

 

Now back to valves. All JDM/dished piston heads have nitride valves in them. Other 3k-c, 4k-C heads have shit repco made mild steel valves. They break have had one let go sitting on high way in 5th gear once. So I take exhaust valves out of dished piston heads into other heads stronger take more heat etc. You can tell if valve is nitride their brown from valve to about half way up the stem.

 

Also valve stem on 3k-C, 4k-C valves stem is straight. Dished piston heads valve stem tapers a bit again more flow area. So yeah use these valves in other heads. But now for the catch these heads hard to find..LOL Well there on say all 5K's but if they have ever had valves changed etc prob got crap aussie made repco valves.

 

Now for valve stem seals old heads have nothing..so if you do use an early head whack in later valve guides and seals.

 

Also rocker posts. Early heads use aluminium. Expands fast throws your tappet clearance out. Stick in late-model steel rocket posts. expand less and keep clearances better.

 

So there are lots of small hidden stuff in these heads to look for mix match. Quite a nice head can be made but starting on a dished piston head using a mix up of other heads.

 

But if you wanna build a head with larger valves. YOu can grab a 4k head pull out exhaust valve get it to fit in the intake. Now for the exhaust valve use a gemmini valve. Will require you to bore out the block as new exhaust valve will hit if you don't but this can be done and huge valves using stock valves so there like $6 each for a valve at repco and will increase flow heaps.

 

Also a stock KE15/17 sprinter did the 1/4 mile in 17 seconds stock. So with head mods alone I can't see why a KE1X car can't go it in the mid 16 second mark CHEAP.

 

Cheers

Cameron

Edited September 7, 2010 by camerondownunder88