Hi all,

Somedays ago, I got three tuning heads for A7. (Dante, Speedex and Supaloy)

Dante has very high comp. combustion chamber and others have look a like Ruby H/C chamber.
Spark plug is all 14mm so I'd like to change some heads on my nippy.

Which head will you choice? Please advice me.

(top to bottom; Dante,Speedex,Supaloy)



Junichi Sugimoto

Location: JPN

I tried several heads on my Nippy. Ruby High compression, reproduction Nippy and Supaloy.
Of these the Supaloy seemed to be the best.
I haven't tried the other 2 you have.

Location: Melrose, Scottish Borders

It is common for sporty heads to have been repeatedly planed until the c.r. is unrealistically high for normal use. Careful measurement of the volumes is necessary. My guess is the lowest will prove the most tolerable, esp by the crankshaft.

Location: Auckland, NZ

Disregard Mr Culver he's talking about things he knows nothing about. However since he mentions volumes, for a road engine I'd think about head volumes of about 30cc. Racing engines use considerably less, and work ok. The big problem you may encounter is that there's not enough height in the valve chamber to accommodate the lift of a nippy cam. I'd check that most carefully. Of the three, the Dante will have highest compression and it doesn't breathe brilliantly. It will give you good torque at low engine speed but won't rev well. The Speedex is virtually a copy of the 37 head. Nothing much wrong with that, except you'd might as well use an iron 37 head. The Supaloy is a good head too. I used one for years. They breathe quite well compared to the Dante and mine used to rev off the clock.
Difficult choice out of the last two, but I think the Supaloy wins.

I generally agree with Alan, but the Speedex has one great advantage over the '37 head, and that's the plug position. You can run a harder plug in the Speedex without risk of oiling.
I used both Speedex and Supaloy years ago, I'd give the edge to the Supaloy.

Location: Richmond, Texas, USA

I would think anything is better than the repro Nippy head Jun has on the engine ,its one I fitted 35 ago years when I owned his Nippy . I remember I had to relieve the casting as the valves were touching the combustion chamber.

I would be wary of fitting a secondhand alloy head when there is the excellent reproduction Ricardo head available.
I have a brand new Dante head but have never tried it as the combustion chamber is minimal!

I would be wary of any old head some weren't good when new.Alta,for instance were very soft and combustion shape bad.At least if you buy a new one you can send it back if it's no good!
I have been told a Ricardo gives 3bhp over a modified ruby head and up to 10 on a supercharged engine

I have Speedex heads on 2 cars,both are better than Ruby heads as they don't oil plugs.
Dave.

Location: Sheffield

But in reality it's not the head that oils the plug, is it?

Alan,
No,it's tired bores and rings,but because of the position of the plug on the HC Austin head over the junction between bore and piston it oils plugs. My chummy with Austin HC head and rebored/new pistons is fine. I modified an Austin low compression head to have a similar combustion chamber shape as the high compression head, the idea being that the plug is on the centre of the bore and less prone to oiling. I think I had the head surface ground as well but this is about 3o years ago so I can't remember.
I have lent it to a friend as he was having plug oiling problems and as far as I know it is still on his car.
Cheers,
Dave

Location: Sheffield

Hi Dave

You are in good company. NZ racing driver Bruce McLaren filled a low comp head with bronze and reworked to the later shape for success in his first car, a Seven.

The low comp heads with plug central to piston are incredibly resistant to oil consumption, the stock 1936 heads quite the reverse, as notd above. At one stage my car would lay down a screen sufficien to obscure rear view without misfiring!

Location: Auckland, NZ

My bitza engine oiled its late ruby head plugs in less than 15 miles when fitted.

Location: Auckland NZ

Hi Ian

But it does broaden the subject from interest mainly to a small group of racers to the wider Seven ownership. There is a lot more trivial minutae of very limited interest on this forum which does not attract your sarcism.
Presumably AiS's comment falls in the same category as mine.

Location: Auckland, NZ

Location: Auckland NZ

The Ricardo, Ulster and 37heads were designed by the same person. Harry Ricardo - probably the best engine technology expert of the 20s and 30s, possibly the best ever. He designed them in that order, with a lot of research in between. Ricardo was very bad at publishing results of his research, at least in findable form, unless you have access to the IMechE library and loads of time on your hands. Nevertheless, each step represents an improvement, and it's interesting that all the really quick Austins in VSCC at least use either Ulster or modified 37 heads.
Frankly chaps, if your bores are so worn that they won't tolerate a 37 head, you need to fix the bores, not change to an inferior head.

I don't doubt that Ulster and 37 are very good heads Alan, in fact I use both types myself, however are the heads used in VSCC competition not heavily restricted by regulations?.

Location: Auckland NZ

No, not really. You can't use any of the 50s/60s stuff like Speedex and Supaloy, but you can use repro Ricardo and Whatmough Hewitt, if you want. These are both reproduction pre war designs of course.

Interesting Frank, I have never managed to find pictures of SV flame front travel only OHV. I have also seen pictures of grooves cut across the quench area of an OHV head aimed at increasing velocity and turbulence of the ejected mixture. I am imagining that with a side valve design this idea is not quite so necessary but always keen to learn.

Location: Auckland NZ

By 1936 there were so many Ricardo type heads in use by many makes, licensed or not, am surprised Austin involved Ricardo directly.

We have been over this before, but does anyone know when the patent ran out?

He may not have recorded every action but the several editions of his textbook The Internal Combustion Engine, are all a great read. Ditto his auto biography Memories and Machines, also as Engines and Enterprises.

Other makes adopted variants with deeper squish space; whether this was to reduce the rapid harsh combustion or to dodge patents I dunno.

If detonation is not a problem, a long flame path may give a more tolerable rate of pressure rise.

Location: Auckland, NZ

As a first-timer, Stanley Edge didn't do a bad job on his Seven head design. In more recent years he told me he "may have pinched some of Ricardo's ideas without knowing it at the time". Comparing it with contemporary cars of the era, Austin & Edge did a remarkable job with the overall design of the Seven, not just the cylinder head. It's a pity that many judge it by today's standards. (Pardon me, just trying to get the post back onto Austin Sevens, 'cos the comments from the EXPERIENCED USERS have been most interesting & I feel that those are the only ones our Nippy Friend & others would be interested in). Cheers, Bill in Oz

Location: Down Under

Just as a follow on from Bob,s writings above Ricardo are still in business at Shoreham by Sea in Sussex , I had the privilege of being invited to attend the opening of the Vehicle Emission Research Centre last July as I am (apart from my son and grandchildren )the only surviving male direct family member in the UK. My grandfather worked together with Harry (his cousin )and did a lot of the design work but Harry got the credit for it.

Hi Junichi

Please keep us informed of the measured chamber volumes, which head you used, and impressions of.

You did not state the sort of use intended.

A combustion characteristic which may provide max power at 6,000 rpm and more may not necessarily provide the most acceptably smooth running at more usual road rev speeds of 4,500 rpm to 2500 rpm and less. Harsh, high squish, high cr, shortflame travel combustion which may be ideal for the former may not be so for the latter.

When it comes to theorising on flame travel, none have seen inside; most opinions are based on facts read, so EXPERIENCED USERS will not necessarily know exactly what goes on any more than anyone else who has read the subject and compared pre and post 1936 heads.

It is a little surprising that the Ricardo patent style head had not been adopted accidentally prior. But cr was so low on larger engines, typically 4:1 that the channel was of generous size for the rpm without having to save volume over the piston. High rates of burning may not have suited very early engines with bent wire cranks, just as Sevens are smoother with the early heads.

I recall in the autobiography (also published as The Ricardo Story), Austin was one of the firms Ricardo contended with over his patent, but which model and when who knows?

Location: Auckland, NZ

HI BOB, Well you have done it again opened mouth before engaging Brain.

GENERAL MOTORS RESEACH have film showing the flam front taken from the piston and from outside of the cyl to the inside

Location: Tinopai NZ

Combustion in Action!

https://www.youtube.com/watch?v=FDrzyvls7j8

Thanks Ruairidh

That is as good a basic description as will find anywhere. Ricardo still a good read nonetheless.

Photos of ignition have been published for many decades and I think appear in some editions of Ricardo.

Location: Auckland, NZ

Odd, that Bob because I thought you said no one had seen inside a cylinder to observe the flame front. You really should get your facts straight before you come to play with people who know what they are talking about.

Hi Colin and Alan

I was of course referring to EXPERIENCED USERS. Photos appear in many elementary references and I presumed most knew this.

Location: Auckland, NZ

Bob,

"When it comes to theorising on flame travel, none have seen inside; most opinions are based on facts read, so EXPERIENCED USERS will not necessarily know exactly what goes on any more than anyone else who has read the subject and compared pre and post 1936 heads."

I do have trouble reading some posts as seen but what does this mean?

Tony.

Location: Australia

Alan, Bill, Colin, Ian, Tony, et al.
I appreciate the frustration, as I too would vote him off the island,
but surely you can understand that it is an exercise in futility embarking
on a battle of wits with an unarmed man.

Location: too bloody close to B.C. New Zealand

HI JOSS, Will take a deep Breath next time, there are to many very informative post to waste time on BC thanks

Location: Tinopai NZ

Hopefully all Forum users have now viewed the excellent video and have an understanding. It is certainly a painless way to learn compared with books.

For the more curious, in the sv frames at 1.50 the flame front seems to reverse unlike the other shots. Presumably this is due the squish effect of a typical sv head

To complete the picture it is perhaps appropriate to point out that normally a thin layer of static molecules remain adjacent to the metal surfaces and act as an insulator. The pressure waves from persistent detonation strip these way and hence holes burn thru piston crowns etc. The risk is greatest at high power (when often the tell tale noise is obscured by the general din.)

Location: Auckland, NZ

This thread seems to be getting nasty and personal.

The subject is one on which I can't contribute anything useful, but I'm interested to read everyone's opinion, as I have a Speedex head on a car that hasn't yet hit the road.

By all means point out errors in other people's statements, but lay off the personal abuse and insults!

Location: Herefordshire, with an "E", not a "T".

Yes, Martin and Dave are right - let's discuss the ideas and not the personalities. This thread is about tuning heads - let's tune ours to be tolerant of others views.

Disappointed Dave

Martin. I agree. This is supposed to be the Friends Forum. It seems to me that Bob might be poking a stick at his protagonists, and in that regard he's winning hands down!
In the interest of learning and increasing our scope of knowledge we should laud those that make contributions, not ridicule. Age is supposed to mellow us.

Location: New Zealand

Hi Folks,

I have just taken delivery of a Replica Whatmough Hewitt head,which I have been led to believe has better breathing than most other heads.

I am about to polish out the casting marks on the chambers then give it a whirl on my type 65

I have been hitting a brick wall at 5000rpm the engine pulls like a train then seems to run out of puff.

Pigsty trials cam and followers/80 thou bore / alan crank and rods, 1 1/4 downdraft SU on standard manifold / light flywheel and coverplate.

I will let you know how I get on.

Regards Richard

Location: Cornwall

This is all ok, but I think burn pattern is not the most important thing, anyway.
I agree you have to burn the fuel/air mix efficiently, but it's all a waste of time if the cylinder isn't full of the stuff. So, for me, I'd go for improving volumetric efficiency, any day. If it can't breathe, it won't rev. If it won't Rev, you won't get power, at least not in a 750cc engine.

Richard, two questions. What head were you using, and what axle ratio have you. And a supplementary question will it Rev higher than that in third gear?

Hi Alan,
I am running a standard Nippy Head at the moment.
I can hit the same revs in all gears. cars has the correct low axle ratio and close ratio gearbox.
I have tried a VW distributor and found it to be no better than a good manual advance one.
I have also tried different exhaust systems.
I am sure that the engine is running out of breathing hence the Whatmough Hewitt cylinder head.

I have had more revs with a ruby head on the same engine but it oils up the plugs.

Regards Richard

If it revs to 5k in top on 5.625 axle, that's about 70mph which I guess is about right for a nippy. However you are really getting into the zone where bolt on go faster bits aren't enough, and you'll need to give some serious thought to port shapes, manifolding etc to get it to go faster. Frankly, an engine that won't tolerate a 37 head is not the right place to start tuning and I'd be inclined to fix that before anything else. Another thing, it's surprising it pulls the same revs in all gears. If it does 5k in top I'd expect it to go off the clock in 1st, 2nd and 3rd. Are you sure you don't have valve bounce?

Richard,
Is the ignition coil limiting your revs? Have you tried a different/new one?
Dave.

Location: Sheffield

Hi,
I am running 12v with a new coil fitted last year.
I have no sign of any missfiring and my electric revcounter holds steady.

Double valve springs fitted so no valve bounce.

I have just finished die grinding the Whatmough Head to give valve clearance at 8mm lift with no gasket fitted, I have also balanced the chamber volumes.

So apart from finding a set of long reach plugs I am ready to swap the heads over.

Location: Cornwall

Just be a bit careful with long reach plugs. On the Whatmough head I used the valve would hit the bottom of a 3/4in reach plug. You might find you need some spacers to lift them up a little bit.

Hi Richard

I realise I am encroaching on sacred territory, but is that the Pigsty cam documented on the old Speedex site? 22 40 54 13? And if so is it run in that form or retarded? If the former the inlet closing seems conservative for high power at 5000 rpm, altho would not prevent revving at light load. Or is it some more recent version?

Location: Auckland, NZ

Is your rev counter accurate?
Is your can timed correctly?

A friend of mine has a Pigsty trials cam in his Ulster rep trials car, 1 1/4 semi DD SU, proper Ulster exhaust manifold. I know from personal experience that it will rev past 6000rpm (the rev counter only goes to 6k). However, it does not have great low down torque and is quite easy to bog down with it coming "off cam" at anything under 1500rpm.