5K Head On 3K?? Trouble... Pics..

[springersrolla]

hey lads whats going down.

 

sitting back with my new little ke11 and have a set of 40mm twin webers. Sold the 5k, now the ke11 has a 3k in it. head forged number 19

 

 

 

 

Years ago i bought the 40mm webers to put on my 5k with twin manifold, i also gained a worked head, and had it reconditioned to slap on the 5k with the webers.

 

My sentence structure doesnt make sense to me yet so hopefully if your reading your on my level.

 

 

 

Took the 3k carb and manifold off today and picked up a bigport extractor gasket to bolt the webers on. Port size of the existing head is roughly 25mm intake and 21/26mm exhaust.

 

 

Extractor gasket is huge to suit big port head, but it actually matches my weber manifold and my extractors.

 

Ive just unwrapped my 5k head, or so i was told... it never came with rocker posts so i don't know if it actually was,. but it does have the 2 lugs under 1 and 4 and has 13 forged number which corollawiki says is a 4k head...

 

The port sizes are 32mm intake, and 29/25 h/w exhaust running 28.5mm exhaust ports and 38mm intake.

 

ive just measured the combustion chamber and the measurement is 80mm over diameter, now knowing it must be a 5k head to suit 80.5mm bore,.

 

 

I'm just curious after practically just measuing that combustion chamber (Doh), there would be no chance i could bolt this on to my 3k... is there anything else I'm better doing or should i chase up another head to suit my 3k??

 

i don't really wanna stuff rags in the head and diegrind 5 mm out of the 3k and funnel the webers in, or should i chase a 5k bottom end....

who fricken knowsss I'm over k motors but keep creeping back on to them

 

cheers

[GJM85]

Dished piston head. Small combustion chambers needs dished pistons. You can keep the 3k and put 4k dished pistons in it. Pushrods length would be your next challenge. Could be easier to cut your losses and start again with a 4k.

[altezzaclub]

My sentence structure doesnt make sense to me yet so hopefully if your reading your on my level

nope- but maybe I can figure out if you even have a problem.

 

the ke11 has a 3k in it.

Ok, got that-

 

now knowing it must be a 5k head to suit 80.5mm bore,.

So that is the head for the 3K??

 

there would be no chance i could bolt this on to my 3k

Why not?? That's the bit that is missing here.

 

I don't see a problem- the head gasket for the 5K and the studs all fit don't they? The ports can easily be cut out to match the inlet manifold, that's what I did on my 4K to match the SUs inlet manifold.

 

What is missing is your measurement of the head's combustion chamber volume. That will give you the compression ratio. Did you measure it with a pippette or burette?

 

Is the combustion chamber 80mm across, or the valve to valve edge? So long as the valves fit down the bore OK then it should be fine. I don't know if they actually stick down into the bore or not, I can't remember what mine looked like.

 

take a look in here-

http://www.rollaclub...the-girls-ke70/

[altezzaclub]

Thankyou Gav, that explains it all. I was busy writing that reply!

 

What sort of compression ratio would it give on a 3K?? Will the valves stick out??

[GJM85]

The capacity of a single 3k cylinder estimated at 291cc & the combustion chamber of a dished piston 5k head at 16cc. That would give an estimated compression ratio of 18:1. Even with that combo your going to have pushrod issues.

 

[springersrolla]

Thanks for the responses lads. Ive just got myself a bigport head too keep myself out of trouble. the 5k head runs 11cc so compression would be even higher. should i have any problems bolting a bigport to 3k with no rocker gear or is it needed??

 

[springersrolla]

i mean retaining my original 3k rocker gear if the big port doesnt have rockers

[GJM85]

Yeah, you shouldn't have a problem with the big port head and original rocker gear.

Edited December 27, 2012 by GJM85