Since aquiring a very low kms 5k motor
I was quite surprised on the height of
the ports of this late head which powers
the factory 73mm stroke and 80.5mm bores.

There is also a 1.8 liter named 7K with
88mm stroke and 80.5mm bores

Both engines can be taken to 83mm bores max.

Just for interests sake here is a 5k head

Attach file:

---

  5k head.jpg.JPG (188.71 KB)

never see such 'big port' K. is it stock? the zorst port looks rectangular, as far as i remember, zorst port for K's are square.

and what about the valves? can you measure them for me? would really appreciate that!

not sure bakat that pic I posted was a for sale one.
Mine is in a 76,000klm liteace but would guess the
valves are smaller than a H89.

the heads are high port (albeit still more or less round port) - not the least of which is bvecause they can 'get away with it' since the motor isn't 'upright' it's tilted over at a slant, so the ports end up being horizontal - paralell with the road, but they are semi downdraught versus the cylinders (which is actually an advantage)

The 'pick' of the K series heads is the early 3k - tends to have the most potential stock, and the most after porting. Basically it's a bit like the toyota equivalent of the gx head. It's easy to identify - instead of a big hole, 4 tiny threads which bolts a plate to the 'rear' of the head, with a heater hose pipe coming out of it, this 'good' big port head has a welsch plug in that location.

I've been there done that with the toyotas, and I can say with a fair degree of confidence that the datsun heads have better flow/power potential. People were able to get around 180bhp out of a toyota K series engine, NA, but the blocks didn't last long in that guise. Datsuns of the same sort of 'full race' spec have gone into the 200s and with a bit more reliability (though no 'full race' engine will last a particularly long time)

The 5k and 7k are 80.5mm and can apparently
go to 83mm for max bore size allowing good
valve sizing. The biggest issue I thought
for the bottom end supposedly is the piston
is so darn tall and heavy.
Been speaking to a 7k works owner who on
toyota track days and sprints gives 4age a
hiding in all states of tunes in ke70 bodies.
Hes not in Oz atm so cant tell me the valve
sizes he went for but will tell me in a month
when he gets back. Its interesting though that
few people straighten the engine upright to
get more flow advantages.
Rolla guys also use datsun pushrods as they are
supposedly lighter also :)