Lovely stuff. What head is this from?

Thats the head from a GT dude. That i had new guides/seats fitted too.

I have just spoken to a mate that works at sheffield engine services and he said fitting bigger seats would not be a problem, though id have to go and show him the head so he can see how much bigger they could be. I've got the calcs for the optinum size, so ill measure the valve head from the HK head and go from there.

Which valves did you say have been used before?

This will look aswesome with a the HK!

Edited 5 December, 201213 yr by MaxGT

Either of u two got a spare abd bottom end by chance?

May have some internals at some point, but no time soon.

I think the valves were sierra exhaust valves do inlets. But don't quote me

Cant see anything regarding the sierra valves, but the 2mm oversized exhaust valves are supposedly sourced by Jabba, and are not an OEM valve, meaning they're expensive!

Something like £160 for the 4 (To exchange 4 exhaust valves obviously), then there's getting the new seats fitted into the head, or maybe there's enough meat on the existing seat to re-grind that instead, IDK.

You can go slightly bigger on the inlets too, using inlet valves from some of the bigger OHC engines VW produced for the Golf's etc, but people dont recommend fitting these to fast road cars as the area of material around the spark plug can over hear over pro-longed use, leading to cracks etc.

On that note, if your interested in maximising the HK head, it might be a good idea to fit the same sized valves as the standard 1272 heads.

The seirra exhaust valves are meant to be used as inlets. But that was a long time ago and probably folk lore (though I'm sure it was Will Salter who mentioned it).

May look at fitting 2g valves then. I really need to get it in front of me and have a look.

The seirra exhaust valves are meant to be used as inlets. But that was a long time ago and probably folk lore (though I'm sure it was Will Salter who mentioned it).

May look at fitting 2g valves then. I really need to get it in front of me and have a look.

I guess the seirra ones will be a similar size the golf GTI ones used, which aren't recommeded for the reason already mentioned, for the inlet.

I'll probably get the valves fitted from a hyrdaulic head, but i want to do some calculations on the port/valve size to see if its even worth it.

Also had a read of the cam section in the "the book" last night and it mentioned that some cams aren't suitable for re-grinds as they're not able to re-harden the sufrace to the desired spec,

Then funnily enough, after speaking to david newman, he confirmed this was the case with the camshaft found in the HK type engines. I then asked him for a quote on a "off the shelf" cam and it turns out it would be cheaper to buy a brand new one!, the cost is £150 (plus VAT) for a 284* camshaft, with brand new lifters. So thats what i'll be getting.

Thats dirt cheap! Can they do them to your spec? 284 is pretty road lairy!

I guess so, thats what they quoted me on. I wont be buying one till after christmas anyway, so we've got time, can buy together if you want.

284 wont be too bad, the lift is 9.61mm at the valve.

I won't be in a rush for one I'm afraid. Is that lift measured with valve 1mm from the seat? I'll have to do some investigations and calculations to see what would be best for a turbo app.

I won't be in a rush for one I'm afraid. Is that lift measured with valve 1mm from the seat? I'll have to do some investigations and calculations to see what would be best for a turbo app.

Ah I'm getting mixed up between the cam and head. I mean we could get the heads done at the same time to save a bit of money. But like i said ill do the calcs to see if the head could do with slighly bigger valves, or if the smaller ports of mecky head are suited to the smaller valve.

Ah, I see. The problem is distance though as we're pretty far from eachother. But keep me posted. I'm sure we'll share a few shows so could swap then or whatever.

The valves may well be ok for the ports but what if the ports were enlarged?

It would have to be done properly though, not by someone with a dremmel lol, No good enlarging the port mouth if you start to introduce turbulent flow into the port, you want the turbulent flow in the cylinder as I'm sure your aware.

The best thing to do would be to get in contact with the guy who flowed "Tavs" head off here. He got amazing results, something like 30% improvement in peak CFM.

Really? Thats pretty impressive. I'm not likely to go blazing away with my dremel (i dont even have one!) just yet

All depends what you want the engine for

How do you mean? A better flowing head surely provides an advantage regardless of function?

Surely it's still relevant to power areas and such, like using smaller carbs and such

How do you mean? A better flowing head surely provides an advantage regardless of function?

An efficient port/valve design is desirable whatever the function obviously, your aiming for a decent flow co-efficient. As little pressure drop as possible.

Carbs are a different matter entirely, you match the carburetor size to the displacement and inlet valve surface area,

Its all relative , "smaller carbs" aren't better, its just that 600cc carbs worked out too big for a 1272cc engine, so fitting smaller carbs (400cc) gave an improvement through a higher inlet air speed. As i'm sure your aware, you want to match the maximum diameter of the carbs (the throttle bore) to the inlet port to get the best overall performance, you wont get any more air into the ports by fitting bigger bigger bore carbs, as its still restricted by the port area.

Who's that aimed at Max? Really confused. Looks like Nick made a statement then replied with a question

I dunno I haven't read a book like you two lol I'm just thinking with logic

Well today was another good one. Took the car up to a local 'air field' and did a little testing. Didn't break down once, struggle for fuel or have any of the previous gremlins re-surface. So I'm going to say all is now well! Also bled the brakes again, and now they are rock solid, being able to lock them up which is new! I get brakes at about 1/4 travel rather than about 3/4 as before Still feel shite compare to my On/Off 9n brakes though. So it's MOT time this week, which I'm going to book for firday then tax it and get a bit of use from it over the Xmas period I think.

It's a hoot to drive with power from 2K onwards, though I daredn't fully stretch the legs as it's not run in. Also the tracking is way out and she squirms like buggery, refusing to stay in a straight line, especially under throttle and brakes. The times you really want a straight run! Doesn't smell as rich, which I'm putting down the the larger carbs. Lovely stuff :-D

Well today was another good one. Took the car up to a local 'air field' and did a little testing. Didn't break down once, struggle for fuel or have any of the previous gremlins re-surface. So I'm going to say all is now well! Also bled the brakes again, and now they are rock solid, being able to lock them up which is new! I get brakes at about 1/4 travel rather than about 3/4 as before Still feel shite compare to my On/Off 9n brakes though. So it's MOT time this week, which I'm going to book for firday then tax it and get a bit of use from it over the Xmas period I think.

It's a hoot to drive with power from 2K onwards, though I daredn't fully stretch the legs as it's not run in. Also the tracking is way out and she squirms like buggery, refusing to stay in a straight line, especially under throttle and brakes. The times you really want a straight run! Doesn't smell as rich, which I'm putting down the the larger carbs. Lovely stuff :-D

Wohoo!

Glad your finally enjoying it lol

Should be a nice motor to drive with the GT cam not being too biased.

Feels nice, but it makes such a noise that you think you're doing about 90. A glance at the clock shows 40 though My wheel/tyre combo puts it close to standrard rolling radius too. Being low and bouncy helps with the illusion too. Can't wait to get the tracking done and really test the stage 3 subframe. Just wish I had a stock motor to compare it to as it's been so long since I drove one and the 9n is quite a well handling car compared to a standard mk2

Awesome dude :)

9n brakes are so sharp in my experience lol! You'll love it when it can go in a remotely straight line :)

Any progress si?

Just had a quick flick through the cylinder head section and as i suspected the valves are quite a lot smaller than they want to be in the HK head. Though there is ways to get round this and use it as a small advantage. Ill probably document it in my thread if i can be bothered.

Got a lot of stuff in there about port work too, so might use it to do the work on the HK head myself...