Diy Heads

[ncoll]

before and after, standard head and DIY plus head

 

neil

 

 

 

 

[lordleonusa]

FWIW, here's mine, done back in 1987 by an elderly gent as one of his very last jobs.

 

L

 

I am considering increasing the CR a bit, and having the valve seats re-cut with 3 angles, not so commonly done in 1987.

 

 

[lordleonusa]

and a better picture?

 

 

[ncoll]

FWIW, here's mine, done back in 1987 by an elderly gent as one of his very last jobs.

 

Yeah, this is probably this old mans last cast iron head as well. The photos were put on as Bruce asked for, before and after shots of the short side radius.

 

neil

 

 

[DaveNotSoSideways]

Good stuff, Ta.

[Mother Teresa]

Thanks Neil. I'm tempted to have a go myself!!!!!!!! ;D

[GT6Steve]

Bruce,

It's a satisfying job and a bit relaxing in a strange way but as I'm sure Neil will testify, the charm is gone by the sixth or twellfth hole.  Getting all six the same is the trick.  

[flatter4]

 

I've done one with an electric drill attachment - and many many hours.

If you don't have time to spare you really need a big compressor with a die grinder (it gets really boring waiting for a little 1.5 Hp compressor to catch up)

 

Great tips - thanks, I will go and check how equal mine are......

[Nick Jones]

Thanks for that Neil - good pictures!

 

On the modified one it looks like the deepest cut section is biased towards the chamber wall - it that the case or is it an optical illusion?

 

Also I note that you've taken a fair bit out the exhaust side as well which suggests it works - most I've read about this suggest to leave that part alone......

 

I've done a couple of these these now (well, one is about 2/3 done if we're being honest) with a fairly big Dremmel copy and some carbides.  When you are as talentless as I, something that cuts slow could be considered an advantage as it stops you getting through to the water without serious effort  .  The novelty does indeed wear off pretty quick - 6 cylinders is at least 3 too many!  You also need either plenty of practice of a template (template best I'd say) to get them even.  You also need some kind of dust extraction and a mask if you want to make old bones.

 

Cheers

 

Nick

[ncoll]

Hi Nick

I have took many photos and i just cannot get it to show exactly how it is, but,  Yes the deepest cut is biased towards the chamber wall. The exhaust side goes straight down from the  valve seat but slightly laid back, (its really difficult to describe something like this as  i do this so naturally) If you look at the photo on this thread (reply 62) and No 1 of the short side  radius drawing (reply 63) this is the short side radius exhaust side. ( I can't explain it any more than that) Basically don't try and spend time getting them all exactly the same because of the core shift, you never will. At the end of the day, the difference with the ports is only going to be 2 or 3 cfm at the most.

 

I would like to just add that, this is not the short side radius of the full race head, it is the best flowing short side radius i found without doing any chamber mods.

 

neil

[DaveNotSoSideways]

I put about 80hrs into my K head and thats made of alloy!

[steve knight]

Mr Ncoll – this is one of the most interesting series I have read – well done.  I was encouraged to visit this S/S site for the first time by gt6...  and it is certainly more of what I want, rather than … ” what car did you see today ” or bees.   It is also the easiest site to navigate and nothing gets lost.  I’ve spent the last 6 months winding up you and the TR site, so I know you do not like an alternative point of view, but here goes anyway.   My own DIY tuning ( Darryl calls it scrap-yard tuning ) hasn’t got the benefit of flow benches, graphs and seat cutters. ( who has ? ),  so it appears I will take a different angle – starting with three angle – seats ( and valves )  These are designed for long life, not really in the equation of race engines.   My opinion is, a smooth radius gives far better flow into the chamber, and any ridges upset this, and the flame front inside the chamber itself.  It is obvious that any humps do nothing to help, it was just the way the factory machined the head. Also proven for other heads is to grind out ( or fill in ) that dip where the inlet valve protrudes.  The Triumph 6 is a rubbish engine to tune – nothing seems to work very well until you tackle the exhaust tract. The standard ports are too small,  so open them up – why not round? … probably the only way to make them bigger. This gives the biggest improvement ( apart from the cam ) to the six cylinder  - I know it does.  I modify my own manifold gasket.

[GT6Steve]

Hey Steve, Welcome to the Forum,

 

It's OK to identify me, I sent him here during correspondence about his book.  All input is worthy of consideration.

 

Before Neil responds, let me say your thinking on exhaust parallels thoughts I've long pondered although it flies in the face of convention.  My thinking has been that the valve shouldn't know where the exhaust flange sits and the divergant tract should start at the throat.

 

Having said that, I'm an idiot with very little actual data.  A lot of smart fellers have been massaging the ports for years to maximize performance without hogging out the exhaust.  We had a smart feller here for a long time that insisted the exhaust was everything.  He also insisted that most of the published data was for big V-8 engines and to take the "rules" with a grain of salt.

 

If you don't know GT already you should.  I think he'd like your approach even as he tore it apart... ;D

 

Steve

[Mother Teresa]

Hi Steve- welcome aboard. Are you the geezer who put together the recent 'tuning bible'? I'd be interested to see any detail on your suggestions .

[ncoll]

The mods described by Mr Knight, are irrelevant to anyone modifying a fast road head on a DIY basis at home.

But, looking at the manifold gasket, even the hole for the inlet port appears to be enlarged!!!, even for the full race heads i have done, i have never had to modify the gasket in anyway whatsoever.

 

Its funny what people will do to sell a book. i've seen it all done before, but just can't remember where.   ;)

 

 

neil

 

 

 

[steve knight]

Fair comment about the inlet ports.  I did this at least 10 years ago, hoping someone could taper bore my inlets and I would fit bigger butterflies - they couldn't, so it went no further.     I was experimenting with my ideas, that's what I do,  now 10 years on I probably wouldn't go so far,   But the exhaust stays.

[spitNL]

Hi Neil,

 

Got one question, the diy mods in reply 18, what valve size where they done with?

If I'm correct the TR6 had a 1.443"/36.65mm inlet valve, is this the size you used?

 

Cheers,

 

Frederick

[ncoll]

hi frederick

valve head diameter is 36.54, valve throat just below the seat 32.94

 

neil

[spitNL]

Excellent!

 

Thanks for the the throat diameter as well, that's really helpful.

 

Cheers,

 

Frederick

 

[DaveNotSoSideways]

TLD opens up the inlet ports at the manifold face, his heads produce NO torque and NO power.

 

Agreed the exhaust port must hold some of the keys

[GT6Steve]

All fair points above, everyone studies the inlet tract and there are certainly expert data points available.  No argument.

 

I'm intrigued with the exhaust, probably GT's influence, but I've long felt the exhaust was not treated right.  I have my ideas of how to exploit the factory head for expansion but Steve's hogged out port returns us to the question.  How does the valve know where the venturi is?  Hot gases expelled form the head will slow when cooled and acclerate when constricted.

 

I hardly imagine a rectangular port dumping into a round extractor pipe is the optimum.  So does Steve have something valid in opening up the exhaust port into a conic to help the expanding gases.  Why is the head sacred ground not to be disturbed and then expect a magic extrctor to do all the work?

 

 

[thebrookster]

I am assuming the head is supposed to be working as the venturi, wide at the valve and narrower at the port, however I have no idea if this is the case on these cars, having never seen a stripped cylinder head. If that is the case, the so long there are no sharp corners to mess the flow up along the way (maybe ovalled rather then left square) the overall shape will not make that much difference?? what is confusing me is how does the head and exhaust work?? I mean, do they each do their own distinct job, with one complementing the other, as a kinda step by step basis, or are the 'irretrievably' linked, in that the exhaust is a smooth continuation of the same job from the head??

 

I do hope that makes some sort of sense to you guys, at least I know what what I am trying to say, however putting into words ain't that easy it seems!! I am happy to admit I have no real hand experience of this at all, however I am trying at least to understand it from the point of view of Gas Laws/Thermofluids/Physics, which at least I do vaguely understand!!

[spitNL]

How does the valve know where the venturi is?

It doesn't, but it does "see" the effects of the venturi; the gas speed at the valve.

A venturi drops pressure and increases gas speed, and what you are looking for is the optimum gas speed at the valve.

 

Here's in interesting article on ports.

http://www.gofastnews.com/board/technical-articles/1247-porting-school-8-optimal-port-areas.html

and

http://www.gofastnews.com/board/technical-articles/1302-porting-school-10-pushrod-pinch-point-power-issues.html

 

Cheers,

 

Frederick

[Nick Jones]

Great link Frederick!  I've got some reading to do  

 

Nick

[spitNL]

The other articles on there are also good.

 

Frederick