Building A 4k And What To Expect

[Felix]

I suppose we are talking K series motors here, sort of torquely challenged lol.

 

Depends on how you build them. A lot of people tend to go for big cams and kill off all their low end torque. (big cams need close ratio gearsets to get the most from them)

 

With the 5k in my ke15 if you feel lazy you can just leave it in fifth around town, pulls away nicely out of roundabouts and what would normally be a 2nd gear corners. I could drive up Mt Nebo in 5th with the family and a bootload of shopping and still get held up by slower cars. Overtaking on country roads is easily done in 5th from 80 kays. Could do 3rd gear hillstarts on my 30degree driveway when i had the 4.5 in it. :) Helps to have a 700 odd kg car to start with.

 

1 1/2" SU's start getting restrictive on a worked 4k. A decent sized downdraft will flow more. Remember only one cylinder at a time pretty much draws on the available induction that it can see. Running twin carbs does NOT equal twice the airflow. Look up the port from the inlet valves point of view.

[rob83ke70]

I'd beg to differ about the twin su's versus a single downdraught on a k motor. The su's have a much nicer design manifold for better air flow and they definitely feel much much much less restrictive than my weber DHSA2 (28/36)

 

lightened flywheel is not an increase in power as such it just makes your engine spin up faster. Could be nice in the right applications...

 

Robert.

[wrench]

I'm still waiting to hear about this whole Blue 202 valve springs into a 4k idea??? There would be machining involved??? Which collets and retainers do you use???

Yeah i'm still up in the air as to wether to go twin SU or weber 32/36 DGV, deal is i can get a weber for VERY cheap if not free if i winge at my escort mate enough lol. Twin su's i'd have to find first, got a bloke who will knock up pretty much any manifold i want out of alloy so thats sweet. He did me a XF throttle body mouthed rb30 front intake manifold for me for like $100 ( i supplied the NA rb30 manifold and he converted it all over for me including repositioning the throttle body and welding it all up, neat job too.)

By the way, can never find extractors for 3 or 4k on ebay, where do you guys usually buy them and what they worth roughly???

[Redwarf]

202 springs are marganally larger than KE springs. by the look of the head, minor machining was done. The thing is, you will still need to match the spring to the cam. These were an aftermarket set for a blue motor, that happened to match quite well a cam with around .460 (IIRC) lift. They may not suit your purpose.

[Felix]

The head on my 5k has double valve springs (and K-line guides), got it off a mate who ran the head on his ke20 clubcar.

 

I was told they are aftermarket holden items (202 blue?) but unsure of what they are exactly. Couldn't tell you what machining was done as it was 4-5 years ago now. All I can say is the valvetrain is good for 8500+ with converted hydraulic lifters.

 

I've had the springs out when I self ported the head using guidelines from books from David Vizard and A. Graham Bell, but can't remember any obvious machining for the springs... Still runs the orig toyota Valve retainers and collets... The head and retainers could have been machined, but having played with K series motors for many years, nothing stands out from the ordinary from memory.

 

Sorry I can't be of more help. The thing to keep in mind is if you do as much of the work yourself (ie. disassembly, cleaning, reassembly), machining is not overly expensive to get done.

[Felix]

Hey Rob, my head came from Peter Moll. Did you have anything to do with the springs? I know he said you supplied him the cam or something, that he ran with it at the time.

[Felix]

I'd beg to differ about the twin su's versus a single downdraught on a k motor. The su's have a much nicer design manifold for better air flow and they definitely feel much much much less restrictive than my weber DHSA2 (28/36)

 

SU manifolds have a nasty 45 degree turn just before the start of the ports.

 

A downdraft manifold may have a 90 degree turn just below the carb, but the airflow has a chance to straighten out before entering the head ports.

 

"Flow happens mostly on the outside of a turn. This being the case, if a turn exists just prior to the port in the cylinder head, then the intake port in the head is not totally utilized. In other words the flow has not straightened out to fill and utilize the whole port in an even fashion." Quote: David Vizard.

 

Unfortunately these things lay over at a 30 degree angle so unless you stand them up, any sort of manifold is a compromise.

Edited October 4, 2009 by Felix

[Redwarf]

I know he definitely used my lumpstick (I think Xany has it now....) and the head may have been one of mine, but it wasn't my grunter head though. Being doubles I don't know what they were off, but my Holden ones are definitely a single spring.

[coln72]

I was told they are aftermarket holden items (202 blue?) but unsure of what they are exactly. Couldn't tell you what machining was done as it was 4-5 years ago now. All I can say is the valvetrain is good for 8500+ with converted hydraulic lifters.

 

Pfft. My standard valve springed 5k with hydraulic lifters would pull 8000+rpm (ran out of tacho) with a hell of a lot less stuffing around.

Edited October 4, 2009 by coln72

[wrench]

I can never seem to find anything for 5ks, and i never find a complete engine so using anything 5k is sort of out of the question. My first car ( back in 1999 ) was a ke30 4 doors sedan, i searched high and low for a 5k and never with any luck. None of our local wreckers could ever source them or anything for them. So i think that Tamworth must be a 5K freezone or something. Anywho, if i was going to yank the motor out of the car for the sake of another i would probably butcher a 18R or 2T into it, if i could be bothered.

Anywho, i think the weber may be the " less screwing around " option for the 4k, so with the weber ( 32/36 DGV ) correctly jetted, blue 202 valve springs and extractors and exhaust which cam would be best for me? It will be street driven, but like 1 day a week if that, registered so on and so forth.

Just chasing more grunt really, coz stock is real painfully slow.

[Felix]

If you are after more grunt a Tighe 113 is a great choice. It is a 270 degree cam (advertised duration) with a very broad powerband and decent topend. Made best power between 3000-7500 in my old 4k with around 10:1 compression and a ported head.

 

You can get a 104 which is basically the same cam with more lift. The beauty of the 113 though is you can shim the valve springs for more preload without running into coilbind. This will give you more revs before valve float, and save the expense of fitting aftermarket valve springs.

 

Something I've experienced is that a cam that makes max power at say 7500 in a 4k, will make max power at around 500-1000 rpm lower in the rev range in a larger capacity 5k. Just something to keep in mind when people with 5k's give you their thoughts on cam selection.

 

Coln; There was Zero stuffing around on my part. Pete did the hard yards working it out using bits from old K motors he had laying around. Zero cost, zero effort, dropped straight in. Been good for 50,000 kays or so. Motor owes me under $500 all up. :)

[B-Rad]

I currently run a 4K with mild cam, twin sprinter carbies and extractors. I got 40kw (54hp) at the wheels which is aprox 57kw (77hp) at the flywheel.

Edited October 12, 2009 by B-Rad