anyone got experience of fitting modified camshafts?

[muppo]

Trying to get hold of someone (possibly Neil/flying farmer) who has experience of fitting modified camshafts to the Triumph lump.
I have contacted various cam suppliers/grinders who all say there has never been any call for Stag parts!

[stagmuffin]

istbc but im sure Faversham's supply and fit fast road cams ,worth checking them out with a call perhaps .

[V Mad]

Maybe theres a good reason few fit hotter cams

[flying farmer]

Faversham Classics supplied the cams I use, and they have worked very well but they need to be fitted to a modified engine to stand any chance of working.

As a minimum you would need tubular manifolds, straight through exhausts and ported heads before even thinking of fitting them, and they work better with larger primary pipes on the exhaust manifolds than the commercially available exhaust manifolds, hence the reason I build my own manifolds.

The greatest restriction to power on the Stag engine is the inlet manifold, regardless of the type of carb or even efi using the original manifold.

If you are hoping for a quick power boost by fitting cams to a standard engine you will be disappointed. Talking to Tony Hart a few years ago he reckoned the best way to improve the power output of a fast road cammed stag would be to replace the standard cams!

Neil

[mjheathcote]

I have Holbay Tornado fast road camshafts fitted to mine, now Coltec Racing.

http://www.coltecracing.com/camshafts.html#various

But not camshafts alone, ported heads, tubular manifolds, engine balanced with HC pistons, Holley carb.

[thebadleys]

Hi,

Not related to camshafts, but Neil says "The greatest restriction to power on the Stag engine is the inlet manifold, regardless of the type of carb or even efi using the original manifold" with which is a basic principle of a internal combustion engine, more air, bigger bang.

So why does the standard air cleaner have a restriction in the base of the filter where it attaches to the manifold elbow ? if this were removed would there be any benefit?

IMG_2402.jpg

[Ian Durrant]

I understand Tony Hart tested removing that restriction and found it made no difference. There are two theories for its existence, one that it promotes tumble in the airflow which better distributes the fuel inside the carb venturi. Another that it helps the air turn the bend of the aluminium elbow before it enters the carb.

[tractorjames]

Faversham Classics supplied the cams I use, and they have worked very well but they need to be fitted to a modified engine to stand any chance of working.

As a minimum you would need tubular manifolds, straight through exhausts and ported heads before even thinking of fitting them, and they work better with larger primary pipes on the exhaust manifolds than the commercially available exhaust manifolds, hence the reason I build my own manifolds.

The greatest restriction to power on the Stag engine is the inlet manifold, regardless of the type of carb or even efi using the original manifold.

If you are hoping for a quick power boost by fitting cams to a standard engine you will be disappointed. Talking to Tony Hart a few years ago he reckoned the best way to improve the power output of a fast road cammed stag would be to replace the standard cams!

Neil

Do I recall you previously mentioning piston/valve clearance issues when using modified cams with HC pistons?

James

[flying farmer]

Do I recall you previously mentioning piston/valve clearance issues when using modified cams with HC pistons?

James

I was told they should fit without piston modifications. They probably would with county pistons (slightly lower deck height than the mk2 HC items) and relatively unskimmed heads and thick gaskets.
My engines have skimmed blocks, heads skimmed so the valves are close to the head face, HC pistons and thin gaskets so piston cut outs are definitely required.

Neil

[Guest]

Replying to the baddleys re the obstruction in the air filter system.I looked at them and worked on the principle the more air in without obstruction would be beneficial to engine running etc. I did it about 3 years ago but really can't say I notice a big difference.On an economy run I got nearly 30 mpg and on the open road at 100 kph (60mph) I get 26 mpg.
Anthony

[thebadleys]

Anthony,
Thanks for the response, I am glad someone else has queried this, i think I will cut it away, because it still seems illogical to restrict the potential volume of air by approx. 30%, even to add turbulence, i'm not sure about helping it to turn the bend.
I don't expect I will be able to realise any change as I haven't driven it much, any stunning changes I will start at new thread.

Nigel

[stagmuffin]

the tiniest of changes can affect air velocity and in turn fuel and air mixture and the way it detonates and burns ,so by actually removing the offending article you could be reducing the air velocity and having a detrimental effect on the fuel burn speed resulting in poor economy or loss of power or both probably you may not immediately notice it ,im guessing the boys at triumph had a pretty good knowledge as to the flow characteristics of the manifold and its attachments .they did do a few dyno runs before they sold the motors ...

[KOY 23]

Very true, I think we underestimate their skills and replace their designs with parts that are untested and unproven, then try and justify the £xxx spent. I know, I've been guilty in the past.

[Staggard]

I think you will find the restriction creates velocity, I has been discussed on here before. In my experience manufactures don't stick bits on that are totally unnecessary. Only people thinking they know better taking off bits that are

[thebadleys]

Can't argue that the boys at Triumph should have had the knowledge greater than mine regarding to air flow, etc. But isn't air velocity determined by the vacuum created by the "suck" in the suck push bang blow cycle? I suppose that by reducing the aperture size this could create a reduction in pressure below the flange, our friend in New Zealand didn't appear to have any adverse effect of removing it.

The dyno runs certainly must have benefited the development of the vehicle, but there were still a few "Gremlins" got through!!

looks like a new thread, don't want to hijack the camshaft issue