Aye its comical. Why they thought of that before having it direct lift i dont know!

Its definetly gonna have to use a different cam, 6mm is unreal.

Newman 284* with 10.6, yes please.

What I was getting at, is that the rocker ratio might not be 1:1, hence the cam lobe lift might seem small - but that could be multiplied at the valve depending on the rocker ratio...

Anyway, update on the HK head!

Damn they're easy to take apart, once you've got the cam out that is...

Comparisson shot between hyrdo and mechanical head;

Some shots of removing the valves;

Also found some more pikey-ing, some people shouldn't be aloud to fuck about with engines...

God knows why they decided to ground half of the fuel pump boss off, test fitted a mecky fuel pump and i can't work out the reasoning.

Anyway, i think i'll be using a facet.

What I was getting at, is that the rocker ratio might not be 1:1, hence the cam lobe lift might seem small - but that could be multiplied at the valve depending on the rocker ratio...

Ah ofcourse! I assumed they were a 1:1

There aren't any markings on the rockers, so i'll try and some figures.

Just did abit of number crunching in solidworks, and did a little schematic of the rocker arm.

applying a linear movement of 6mm (the cams lift), gave the bottom point an ~8mm displacement,

Which gives a ratio of 1.4?

This was with rough measurements of the rocker arm, verniers etc.

Sound about right?

Also found this in the FAQ;

1272cc engine, code HK (54hp, mk2 polo, mk2 golf)

Cam Duration

Inlet 221°

Exhaust 218°

Just quickly assembled one of the valve assemblies...

The cam has a lift of approximately 6.7mm, this is one of the exhaust valves, with a random rocker. I dont know if the inlets and exhaust valves have slightly different rocker dimensions, i will check.

Few shots after another few hours in the bath...

Rockers y0.

Max is this a build thread or a sonic cleaner demonstration article?

EDIT: jus noticed I was a page behind and you've already established the rockers fact lol.

Do you actually do any work at work?

Edited 10 December, 201213 yr by harris.racing

Rockers y0.

Max is this a build thread or a sonic cleaner demonstration article?

EDIT: jus noticed I was a page behind and you've already established the rockers fact lol.

Do you actually do any work at work?

Both :-D

HAHA nick, its fun cleaning stuff in the bath, makes life very easy, and everyone seems to be enjoying the pics. Ill cease now until the heads are complete.

And the work is done on my breaks, i'm a fast worker!

No matter how quickly I seem to do my work I just get given more boo! Never have chance for foreign activities

You have breaks though, do it then!

According to the lift at the valve (~6.7mm) and the displacement of the cam, the rocker ratio is 1:1.1

Anyway, doesn't really matter. Its a shit cam, so its gonna be changed for a much livelier one.

Its a petty no one seems to do different ratio'd rockers!

Is the lift not increased by the rocker arm ratio? IIRC (and its a long time since i looked at one!) the cam doesn't push directly on the lifter/valve stem but rather on an arm.

I may have that all backwards mind!

Yeah simon.

I've measured the resultant valve lift (6.7mm) and the actual cam lobe displacement is 6mm

Giving a 1:1.1 rocker ratio. Gonna see if there was anything on the subject in "the book"

Might aswell research from a decent source ey?

Nah i skipped to the last read post and didn't think to go forward

Head is looking great BTW, love the mechy heads, so cool looking. May have to get min in that bath some time!

Ah right,

Thanks, they're certainly a lot different to the hyrdo heads, they look crazy!

Also, they're unbelievably easy to dis-assemble once the cam has been taken out, which is pretty time consuming actually

I had 8 valves out in like 5 minutes, and that was taking out the spring seats/valve stem seals.

Your more than welcome to send the head up, and i'll drop the casting in the bath over night!

I just messured the exhaust ports on my 38/33mm GK mech. head.

At the transition to the exhaust manifold it reads 35mm high and 35mm wide.

The furthest in i could messure with my tools I got a 31mm reading, approx 12mm inside the port.

I just messured the exhaust ports on my 38/33mm GK mech. head.

At the transition to the exhaust manifold it reads 35mm high and 35mm wide.

The furthest in i could messure with my tools I got a 31mm reading, approx 12mm inside the port.

Ill check that with both my heads here when i can mate thanks

Should hopefully get the HK sent off soon!

Sent off where and for what Maximus?

Sent off where and for what Maximus?

To JMR racing dude. To have then head properly flowed etc.

However hes stacked with work at the moment, so i dont know if it will fit in with my dealine.

I've got a mate whos handy at that sort of thing, so will give him a tap up.

Definetly gonna have to get the camshaft though, the standard component is pretty rubbish for an NA engine.

Do you know what the cam is in your HK head?

I don't have a HK head, the head I will use is a GF

I don't have a HK head, the head I will use is a GF

Ah ok,

I beleive it to be the same apart from the combustion chambers are partly in the head on yours

Really, how come?

Really, how come?

Dont know why VW changed design, but its desireable over the flat faced head of the HK

Thats if the GF does have combustion chambers in the head. I'm 90% sure.

Will this be better or worse for boostings?

Will this be better or worse for boostings?

I cant really comment in regards to FI applications

But in general the flat faced design is thought to be inferior as the pistons have to be bigger to accomodate the combustion space, which adds weight etc

The flat face (heron design) is also said to be the worst flowing design.

^^Thats a gayer as that what I have. The danger with the recessed heads is the lack of availability for off the shelf pistons. With a flat head, assuming deck heights are the same fo mech and hydros, a PY bottom end can be used for cheap boost. Then again, a set of flat topped 1W pistons may work with a recessed head to lower the cr. Would need to be calculated off course

However, what are the bore diameters of the recessed heads? IIRC aren't they smaller than later hydros? If so, that would make mating to a different bottom end more difficult whereas so long as oil/water ways didnt overlap the combustion chamber, flat heads could be bolted to any bottom end. Right or wrong?

Edited 11 December, 201213 yr by prankstar2003

Right, as already said, i wont be able to get the headprofessionally flowed untill february, so looks like i may have to give it abash myself again, as i want the car finished before january.This time i want to go abit further than just removingcasting burs and valve guide purtrusions! (SP)

I'll also have to make do with the standard valve sizes,which according to sources, a circa 350cc cylinder responds best to a 38mminlet valve, and a 30-32mm exhaust valve. These sizes aren't calculated usingforumlea, but have been tried and tested supposedly.

The Standard valves of the HK head measure 34mm and 28mm, inlet and exhaust, so they are pretty dam undersized!

Anyway, some pics of the standard ports, a lot of room for improvement...

Inlet;

As can be seen the guide prodtrudes a good 10mm out of the casting

Exhaust port;

Same thing, guide protrusion, massive stem diameter...

Inlet throat, this is the most important part of the port, plenty of work to be done here! Including enlargement of the venturi and generally improving its shape..

Exhaust throat;

Same problem as inlet. Things that i'm also going to try an improve on include gas swirl into the cylinder, valve shape etc.

Need to do some calcs, research!

Edited 12 December, 201213 yr by MaxGT