Guide: How to build a K series motor

**Hurricane** · 04-06-2006, 10:03 PM

yeah nice work there man, just at the right time to cos im stratin to build a rolla engine some

might be a 5k or a 7k though, not to sore?

**Billzilla** · 04-06-2006, 10:38 PM

Originally Posted by oldcorollas

the different blocks are K, 3K, 4K, 5K and 7K.

FWIW I have a 2K sitting downstairs. It's out of the KP-60 Starlet I have, and it's a one litre thing of about 45hp I think.

There's also a lot to be done to make the oil pump work properly - We ended up having to spend a lot of time on the one we had in the 3K full-race engine we ran for a few years.
They're pretty crappy standard, and so what we did to make the oil system work better was to put the pump body in the lathe and machine three grooves in the shaft that runs from the pump body up to the cam gear drive. The grooves were for o-rings, and they kept the oil pressure from squirting out into the gap around that long shaft top & bottom and so losing pressure.
The small hole up near the top that squirts oil out onto the drive gear also needs to be drilled out a little to improve the flow onto the gear, as with a big cam and lots of revs they wear out quickly.
We also fiddled with the profiles of the internal passeges a fair bit inside the pump body to improve the flow.
The big nut that holds the pressure relief valve in place also can sometimes come undone, leaving you with a maximum of about 20 - 30psi at any revs. We had that happen so they always got lock-wired in place after that.

**Billzilla** · 04-06-2006, 10:55 PM

Originally Posted by oldcorollas

--- 4K crank is IDENTICAL to 5K crank. 5K block is same deck height as 4K, but bigger bores. Apparently 3K and 4K blocks can be bored by 3-4mm, but you may be taking your chances due to core movement during casting.
Rods are not too bad. DEFINITELY have them checked for balance, they may be a long way out. Replace rod bolts with either new toyota ones, or something a bit more heavy duty. check balance end to end, and also total weight.t

More now that I think about it -
The 3/4K blocks are good for a 4mm over-bore, but the 3K block is a lot stronger, the 4K's crack along the camshaft welsh plug line when getting up around 140hp & lots of revs.

The rods are easy - You need Datsun 180B (L18 engine) rod bolts. They need to be linished down by 0.007" to fit, but they're a LOT better than the weak K bolts. But they're a lot bigger than the K bolts and so you need to put four bumps in the sump on the side for them to clear.

We also used to remove the springs in the rocker shaft and replace them with solid alloy tubes, to stop the rockers from walking around at high revs.

**myne** · 04-06-2006, 10:59 PM

140hp from a 1.3L pushrod?
It's almost embarassing to own a supercharged 1.6 twinky with a mere ~160hp

**Billzilla** · 04-06-2006, 11:05 PM

Originally Posted by myne

140hp from a 1.3L pushrod?
It's almost embarassing to own a supercharged 1.6 twinky with a mere ~160hp

With roller-rockers and lots of other trick & expensive gear, it's possible to get a bit over 150hp from them. They also last about three hours between rebuilds.

**SL666** · 05-06-2006, 07:34 AM

I've got a mostly complete 5k (comes with a free brand new headgasket) that ive never run thats supposed to be in good condition, would probably suit someone that wanted to pull it down and put it back together, a K head, and a couple of boxes of bits... valvtrain, carbs etc.

In canberra, make an offer..

great article oldrolla

**oldcorollas** · 05-06-2006, 12:56 PM

it's just a starting point for those beginning to play with motors.
you can do so much more with them toi get more power... and shorten life... as people like Bill know much more than i do

**SL666** · 05-06-2006, 05:47 PM

i know how to shorten the life of engines.. making them go harder bit is a mystery..

**Hurricane** · 05-06-2006, 09:18 PM

hay PL666 would you post it to VIC 3240?

OH any one know what would be bettin in the ke20, a 5K or a 7K? ive got two 5K's at home pulled apart, so a 7K would have to be bort. but one of the guys at work was thinkin the 5k would be better cos of the shorter stroke, becose of the revs.

Also was thinkin of runnin twin 40mm solexs on it cos ive got some, a cam, balance the bottom end, port the head, run higher comprestion, and maybe bigger valves?

Any ideas are tips?

Cheers, DAN

**SL666** · 05-06-2006, 10:57 PM

i wouldn't want to post the whole engine.. its probably not worth it.. but if you just want the head PM me an offer..

**Hokey** · 05-06-2006, 11:34 PM

Dan,
There is no substitue for cubic inches

don't you just love the low down of the 2F in our forties

**oldcorollas** · 05-06-2006, 11:43 PM

get hold of Mal McKiggan in adelaide.
he was playing with 7K's. was having issues with cams last i heard tho...

5K is easy. 5K with 7K EFI is easy

7K will have more torque, but the stroke is getting pretty long... then again, a major weakpoint of the K series are the heads anyway (valvetrain etc) so you can't really rev the ring out of them for long.. so 7K with grunter cam would be great

**Hokey** · 06-06-2006, 12:10 AM

Couple of guys on rollaclub.com playing with 7K's aswell

**SL666** · 06-06-2006, 01:21 PM

ooo 7k.. big block.

**ToDa30/4** · 06-06-2006, 07:36 PM

what would the cc's be on a 4K block 40 thou o/s ,& with the 260/265 cam ,CB4/CB4A springs,.extactors & carb upgrade & 3K head would around 40 rwkw @ 6500 rpm be a reasonable outcome but with much better torque or am i dreaming