Converted 7A Heads

[S2central.net]

Back to plan A here - mcandmar privately reminded me of the noise of that pesky gear arrangement and echoed the alignment issues that Corey mentioned - these give rise to ignition 'scatter' which is kak.

@Doug - I'll have to follow up with you on pricing for a 7A to ABY head conversion - I'm reckoning on a new set of valves as I have no clue if they are sodium filled or not - is there a trick to finding out ?

Also out of interest - is there any benefit from judicious material removal on the inlet or exhaust ports of the head during this conversion ?

I've never compared the two heads side by side so dunno how similar they are... I'm reluctant to dive in with a Dremel myself without knowing how much is too much !

Just trying to get a feel for this - I must dig up the old posts from MarkH when he wrote up his head work.

Paul

[audiman]

There is a great way to test the valves. You get a hacksaw and a bucket of water. Cut the valves open and throw them in the bucket. If they fizz they have sodium in them (BTW thats the correct way of disposing of old valves that are filled with sodium)

[S2central.net]

Neat idea - reminiscent of chemistry classes - only more fun. GUess I'll have to sacrifice a valve or two to find out. Thanks Tom !

Any thoughts on head mod porting - is there much meat to remove, or just a finishing job to get them matched to the manifolds and the exhaust side nicely polished ?


Paul

[audiman]

Honestly im not sure, i have always left that to a machine shop.

[4WheelDrifter]

Neat idea - reminiscent of chemistry classes - only more fun. GUess I'll have to sacrifice a valve or two to find out. Thanks Tom !

Any thoughts on head mod porting - is there much meat to remove, or just a finishing job to get them matched to the manifolds and the exhaust side nicely polished ?


Paul

I've had a go at porting my own cylinder head. I basically just smoothed the ports out a bit, and didn't go too mad with material removal. Some of the original casting is a little rough so some improvement can be made there. I also matched the inlet ports to the gasket and polished up the combustion chambers.

I'm looking at making a template for the water manifold modification. I've also got a block of alloy to make a mount for the hall sender. Thanks to Jamo for the old hall sender. I've bought a new ABY pulley and have measured up ready for machining. I just need to get some time on the Bridgeport.

I've also got both sets of vlaves here, 3B and 7A. Doug's suggestion was to weigh them to see if they are different. At a guess sodium filled valves should be lighter than standard valves.

[S2central.net]

@Stu - that gives me some confidence - I'm just looking at something mild on the head for now as you describe. Nothing too risky with regards material removal as you say... There are perhaps some decent gains to be had on a more extreme engine build, but for me with ~RS2 setup then things like air temperature will be more critical.

What do you recommend in terms of dremel bits/attachments to safely remove material and get a nice finish on these alloy heads ?

I'm gonna get the head flowbench tested first of all to establish a baseline, then see what gains are to be had (from any) of such mild tweaks. Actually, the same place might be able to flowbench a MAF and/or airbox or two... Going off topic here - sorry.

Paul

[terrybullwon]

Paul,

I brought one of these from the US

Porting kit

I will pair it with a standard dremel and have a bash

Cheers James

[GazzaG60]

take a look at cncheads.co.uk

look at the VW 16v to get an idea of what can be done.

[Jon441cc]

It truly is a labour of love when polishing a head with those things well worth it in the end though.

[4WheelDrifter]

@Stu - that gives me some confidence - I'm just looking at something mild on the head for now as you describe. Nothing too risky with regards material removal as you say... There are perhaps some decent gains to be had on a more extreme engine build, but for me with ~RS2 setup then things like air temperature will be more critical.

What do you recommend in terms of dremel bits/attachments to safely remove material and get a nice finish on these alloy heads ?

I'm gonna get the head flowbench tested first of all to establish a baseline, then see what gains are to be had (from any) of such mild tweaks. Actually, the same place might be able to flowbench a MAF and/or airbox or two... Going off topic here - sorry.

Paul

I'm aware that you can do more harm than good by taking material away from the wrong places. I think just before the exhaust ports meet was the most restrictive part, so it took a little metal away there creating more of a knife edge. Other than that I just smoothed out the rough casting with grinding stones, gradually used finer grades of cartridge rolls lubricating with WD-40, and finally polished up with a Scotch pad. I did all the ports at the same time at each stage to try to keep them all the same.
I'm not really looking for big gains from cylinder head porting, so I wasn't intending to do anything too radical.

I just used a porting kit from Merlin Abrasives with a normal electric drill. They also have a Ebay shop here for example.

It was a very time consuming job, although I was doing a little bit at a time. If I did another I could do it a lot quicker.

[S2central.net]

Hey thanks lads - this is good info - cheers for the tips and the linkies. I promise to record the progress of my brave attempts at cleaning up this head for my long awaited engine build project and share as much as I can.

Paul

[S2central.net]

That company cncheads looks clued in - quite some investment they have made. I'm no 16V Golf expert, but surely that head has a LOT of similarity with the S2 except that its one cylinder smaller - right ?

[mcandmar]

Correct, the company i sent you the link for westward engineering are the guys to talk to for all things VW in this country. I found out about them through an Irish GTi forum

[S2central.net]

Cool - I'll get the stock 7A flowbenched at Westward, then we can compare those figures with the 16V VW data at cncheads for another data point.

[4WheelDrifter]

Golf 2 16V heads do look the same as our 20V heads, just with the 5th chamber added to the back of the head IIRC. Most of the valves and related components seem to be interchangable too.

I think it was a guy from cncheads that myself and VolcanoRS spoke to at the Autosport show some time ago. We got some useful information from him.
I was taking photos from all angles of any ported Golf 16V heads I could find. A guy on one of the stands didn't seem to like that much, and told me I wasn't allowed to copy them. As if.

I wasn't sure about port matching the valve guides. I guess this will improve flow a lot, but could compromise valve guide life. I'll probably just bullet the valve guide tips. I know Mr VolcanoRS has done this before, and I've seem a few ported heads with this feature.

Go for it Paul. It's a very satisfying job once you have finished. Untill you decided to do a just little bit more to it.