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MaxGT

Early type - Mechanical lifter/rocker engines

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v dub polo shaun
Yeah the same overal spec camshaft in the hyrdo head will work in the mechanical head the same way,

But bare in mind that because the mechanical head uses rockers with a lift ratio, the linear displacement of the camshaft, is not the overal valve lift.

The cam lift is 6mm on the HK, but the valve lift is 6.8 (approx) which gives a rocker ratio of around 1:1.1

Contact JMR Racing regarding the headwork, they quoted me £450 for the port work and a total rebuild, new guides etc, with the results found from Tav's head on here, its well worth the money.

Also, regarding the distributor, either the cam or the dizzy will need to be modified. The hyrdo dizzy's are not compatible, drive wise.

I'll be machining a little housing to covert between the two.

If you read up abit my mate owes me a large favor for some mini parts i gave him in a rush to get his car finished so hes doing alot of the work for me.

Ahh, i may be in contact for a conversion setup myself then mate. I dont want to run standalone yet, my daily (fiesta) will donate its parts in 12 months time for standalone when the polo is done so i will worry about that then.

Drop me a whatsapp regards the adapter :-)

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Phataz1
Also, regarding the distributor, either the cam or the dizzy will need to be modified. The hyrdo dizzy's are not compatible, drive wise.

What management are you using again? Will you need vac advance?

Cos I ran a mk2 Golf KR distributor on my engine with the 3F injection. Didn't have any problems!

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MaxGT

Just a mk2 ignition set-up at the minute, may send the dizzy off to H&H for it to be re-profiled.

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harris.racing

You running mechy boosted or NA?

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Winston
How much were they winston! I hate you...

I've got just over £400 in both of them. Can't wait for the other to turn up. :ninja:

Wow this threads got technical this afternoon. You making me want to get my head modified. fml :lol:

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MaxGT
How much were they winston! I hate you...

I've got just over £400 in both of them. Can't wait for the other to turn up. :ninja:

Wow this threads got technical this afternoon. You making me want to get my head modified. fml :lol:

Jesus! Didnt think theyd be that much!

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prankstar2003

Why do you need to use a later dizzy then max? What's wrong with the standard one?

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v dub polo shaun

Worth every penny 8-)

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MaxGT
Worth every penny 8-)

Has anyone got any NA power figures for mechanic headed engines?

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MikeyMK

You only really need to open up the inlet, if you can get a bigger inlet valve by leaving the exhaust stock then that'd be a better route because the inlet is everything.

I've ran a 16v in the MK2 with one exhaust valve stuck shut (no rocker) and it ran fine, some G40s have got over 250bhp and their exhaust valves weren't three times the size..

Exhaust valve size isn't a priority on a n/a short block.

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TurboPolo

Regarding valves: my 38/33mm BVH mech. head has covered more than 18k miles and have no mechanical problems. That being said the engine does not like low revs over long period of times, if that is due to ignition or fueling I am not sure of.

If it gets driven hard as f*ck then it runs smoother and cooler than when its just on a cruise.

Below you see a HH 38/32 BVH head, where the chaimbers have been smothened out. This is from a KWL engine with approx 140BHP@8krpm...

brennraum.jpg

Regarding igntion: I know of people using complete dizzy + loom etc from a VW Passat 32b, said to have a slightly different ignition curve in the high revs, EP engine code AFAIK. On the GK engine there is also elec. igintion, and not the "mechanical" ones that HK aso. have.

On my GK engine I have GK dizzy with Weber-Aplha mapable ignition.

Edited by TurboPolo

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MaxGT

Fantastic work!

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harris.racing

Valvein'el

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MaxGT

What's the neck diameter on them valves "turbopolo"

By the way, the "Danger" of the material between the valve seats fracturing etc was regarding FI engines, with higher cylinder temps etc

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PeteG40

not always the case - apparently KR 16v golf heads crack all the time - and its rumoured they do it on start up from factory! IMO its about distance as well as temps.

That said many g40 heads do have cracks, esp big valve ones. - between the seats and to the spark plug hole too.

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harris.racing

Books can only share a certain amount of experience, real world experience of our specific engines ftw

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MaxGT

That wasn't from any book, thats from "Jabba" themselves.

Literature + experience is better than just experience.

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harris.racing

Wider range of experience - a KR isn't boosted but said to break from cold start - no high cylinder temps or boost there.

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MaxGT
Wider range of experience - a KR isn't boosted but said to break from cold start - no high cylinder temps or boost there.

Thats obviously a manufacturing flaw though :? totally different.

Were talking about the supposed failure of the surrounding material when using enlarged valves.

Some companies don't reccomend bigger than 1mm oversize, some say its OK. "Turbopolo" head proves the former companies wrong!

No book can tell you if your head is gonna crack :-)

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harris.racing

It can if you hit it with a hammer mate, could recommend there's a strong chance of that happening. I'm gonna write that book :D

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MaxGT

Anyway, back on topic...

@ "turbopolo" , what are them valves taken from?

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G40NUT

some pics of my hydro head from Knobloch

topp3833008.jpg

topp3833021.jpg

topp3833020.jpg

topp3833019.jpg

topp3833018.jpg

topp3833011.jpg

topp3833010.jpg

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MaxGT

Wow they're pretty big in comparison to the standard ones,

Cant remember the original port sizes though, nice work!

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TurboPolo
Anyway, back on topic...

@ "turbopolo" , what are them valves taken from?

I do not know the origin of the valves, but i dont think they are fancy racing valves.

KWL Motorsport offers 4 in and 4ex valves with 38/32mm for 288 euros.

And they charge from 1250 euros for work to make a 38/32 head, incl valves.

If you like something more exotic maybye custom titanium valves from Ferrea would be a good deal :)

http://www.ferrea.com/custom_valves.php

There is also a option to take a hydro head, and make it machanical with new lifters and mount 39/33 valves.

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MaxGT

I think i may have a go at building such a head in the future.

But for my current project, i haven't got the time.

The valves may possibly be taken from a big block GTi engine....

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