Cylinder head off, seeking advantageous executions.

[David McHugh]

Hello to All,

 

While I have the cylinder head off, I am looking for ideas/suggestions for what I can do to it that will be beneficial, I thought of either putting new valves in or grinding in the existing, incase there are any signs of carbon build-up, however I don't know if this is worthwhile or not.

Your thoughts and comments on the above and on other things that I can or should do that is beneficial, will be greatly appreciated.

Many thanks in advance.

 

Kind regards

David

 

Spitfire IV '73 1300cc French Blue

[Clive]

I would pull the cam followers and check for damage, and see how the cam lobes are.

As to decarboning a wirebruch in a drill works and doesn't damage the valve seats. If the head is not converted to unleaded then check for valve seat recession on the exhaust valves, if non best not to grind in at all as it will expose.fresh soft head that is more likely to suffer recession. Or get the head converted. Or a better cam or whatever you wish to achieve, but the short answer is good a,few checks unless you want to start tuning...

[Guest]

David.

 

Does your Spitfire have the cooling pipe under the manifold - usually made of mild steel and moved at your peril ?? !! If it does I would replace & upgrade it.

 

My Mk2 Vitesse had one and I replaced it with Canley's stainless steel version; whilst doing an unleaded head conversion - well worth doing and not expensive. With the head off etc it gives you the best access opportunity to do so.

 

Regards.

 

Richard.

[Pete Lewis]

Agree if now is the time to add hard inserts to the exhaust seats while its off

I have ground valves in to clean up the seating without any long term effect on the lead memory the castings take in over years of leaded petrol usage.

 

cutting the seat will remove the memory.

 

check your engine number as after fd25000 the mk IV has much bigger inlet valves if it has the original head.

 

if you dont want any complications stick with the triumph specification does what itnsays on the tin

 

if you like twiddling then there, s lots available, but many modifications can breed hassle

 

dont add pankace filters , keep the orig with a cold air supply

 

Electronic points can take some work out of the service times and makes for smoother running

 

pete

[David McHugh]

Thank you for your replies.

 

The head has been converted to unleaded, I put in new cam followers when I did a partial rebuild at the same time I upgraded the cooling pipe that Richard referred to with stainless steel and Pete, I did change the filters but once I get some flexible hosing I will put the original back. I have also purchased the radiator and engine side panels.

Going back to the head, I was wandering if it is worth replacing valves and springs those sort of things? I have no intention of tweaking as Pete said it can lead to problems.

 

Kind regards

David

[Clive]

If you can find some nos or genuine jag valve springs it may not hurt otherwise don't change them.however, well worth checking those followers. I managed under 15k on a reground cam and new followers. Properly looked after too. One lobe was almost round and the follower disintegrating.

[JohnD]

I was going g to suggest flowing the head, ducts and chambers, and a skim to raise the CR. But you don't want that? Just a skim then, Sir? Will have a lesser effect but simply and safely done, if you calculate how much, not go by a magic number.

 

John

[Pete Lewis]

air duct hose for the twin inlets on the twin carb air boxes      for nice smooth internal bores I used simple waste pipe , which may need some mitred corners to dodge

round the edge of the radiator  and a hot air gun to blend a flare on the end 

 

2nd choice for smooth and cheap is simple  black convoluted ( outside) water tubing for pond pumps  and that does go round corners 

 

Pete

[Pete Lewis]

unless they have got pitted beyond a reface then theres' no mileage in replacing valves ,  springs do age ,  I dont have the unfitted spring rates as i dont have a MkIV

manual

 

you can get more  valve lift with roller rockers but they cost a lot and some were notably  good at demounting the rollers or fracturing ..

 

 

stick to basics and 97+ ron fuel and  it does what you want ,

as john says upping the compression a little is best £ per HP without trouble and strife   but not too much

 

Pete

[David McHugh]

 

 

I was going g to suggest flowing the head, ducts and chambers, and a skim to raise the CR. But you don't want that? Just a skim then, Sir? Will have a lesser effect but simply and safely done, if you calculate how much, not go by a magic number.
John

John
I do actually like the sound of increasing the compression, while I understand skimming the head, I don't understand what you mean by "flowing the head, ducts and chambers," I would be greatfull if you would elaborate.

Kind regards
David

[Pete Lewis]

Basicly this is removing sharp corners in the casting, by light grinding and much polishing to

ease the flow though the manifold and ports in the head to the valves, there are defined and documented areas that could benefit from a bit of fettling

 

pete

[JohnD]

Thank you, Pete.

David, as you have the head off and perhaps the valves out, try sticking a finger through the valve seat and into the duct. You'll find the surface is rough and lumpy. Flowing will remove such impediments to flow and when really clever adjusts the diameter of the duct to promote flow. The idea is to optimise the "volumetric efficiency", to get more air/fuel mixture. A typical non-turbo engine's VE, the ratio of air pumped per cycle over tbe theoretical stroke, may be about 75%.

 

Lots of advice about on how and what to do, for very little, or people to do it for you for quite a !ot.

John

[Pete Lewis]

i see a dremmel on the easter wish list

 

Pete

[Colin Lindsay]

i see a dremmel on the easter wish list

 

Pete

 

....and a new head after inexperienced use of a Dremel....

It's been done!

[JohnD]

Don't even think of flowing a head with a Dremel.    It would take forever.

 

A die grinder, and not with stones, with burrs.

A selection, but a burr will outlast a stone by years, and take a tenth the time to do the same job.

 

David Vizard did more professional work on TRiumphs than most, and his book on engines more than 1300cc is online. http://auskellian.com/paul/links_files/David%20Vizard-Tuning%20Standard%20Triumph.pdf

Doesn't deal with Spitfire engines but the ideas are there.

His "Theory & Practice of Cylinder Head Modification" does deal with four cylinder Triumphs, along with a lot else, but it's out of print and selling 2nd hand for silly prices: http://www.amazon.co.uk/Theory-Practice-Cylinder-Modification-speedsport/dp/0851130666

 

John

[Pete Lewis]

didnt say it would work  just  a good idea for easter    

 

what you need is an old head to play experiment  with first before you wreck anything,    

 

guess to make a good job of this idea you need to be a cross between dentist and gynaecologist  !!!

 

Pete

[David McHugh]

John and Pete, wow so much information. Thank you guys for your time spent on providing me with some great possibilities. Due to the complexity of fettling a head I have ordered a book,

How to Build, Modify & Power Tune Cylinder Heads by Peter Burgess & David Gullane. I do actually have a spare engine, so have a head to play around with, I think this is a job that is going to take me some time so ha email put my head back on the car so that I can use it.

 

Using the other head and the book when it arrives I will have a go at tuning òver the coming couple of months and will let you both know how I get on.

 

Kind regards

David.

[JohnD]

Good book!  Only includes specific advice for 1500 engine.

 

When I photocopied my copy of Vizard's T&P , I didn't bother with the pages specificly about four cylinder Triumphs, so I can't send you a cutting plan.

 

This book is long out of print, but is on sale at prices from £37 to £132 (!!!!)   

Surely the TSSC should spend some of our funds, buy a copy and scan it, making copies available to members only, like a library.

Who could complain?

 

John