Cylinder Heads

[Rusty's Uncle]

No this head has not been ported and sadly I do not have a spare 652ccs head to hand to compare . I am guessing that the German engine had a 30mms carb hence the inlet port size & valve. Also the passage down to the valve seat looks to have quite good characteristics so I think that it would be quite an easy job to open up the inlet to match the Solex Manifold if I decide to go down that route . So all in all it is an interesting bunch of bits to play with so at the price I paid I think it is OK. It will be interesting getting quotes in for having the big valves fitted to one of the heads I have  [-/

[MaLi]

From what I remember the German spec 126 Bambino had the same carb (28mm) as standard aircooled had. Did the standard head not have 30mm inlet port as well? I am too laisy to go and have a look in the loft for my spare head   :

[Rusty's Uncle]

I was only guessing that the port might be 28 mms on the 126 as the 500 one I have is 26 mms diameter in line with the carb .

[Rusty's Uncle]

The extra big valves from eBay arrived today so dropped them into a head to see how they look. OOOOO ! not a lot more room in there  :

[1973/126]

  Wooo that`s what you call tight.

[MaLi]

Nice. How big is the inlet? 36mm?

[Rusty's Uncle]

  Yes the Inlet Valve is 36mms and Exhaust is 31mms  [-/

[MaLi]

What sort of bhp you want to get?

My college on similar valve sizes, panda head, weber 40 dcoe (me thinks) got this:


http://img155.imageshack.us/img155/1498/maluszek2ka.jpg

Thats just to give you some motivation  [-/

[1973/126]

 So what was the max output? Is it 44bhp? Is this just with a reworked Panda head, carb etc , or any internal mods?

[MaLi]

Yeap 44hp (not bhp) and 59Nm in the best run. The other lines are from different states of tune - I think he was trying different camshafts at that point.

I don't remember exactly what was done but it definately had prety high compression ratio, and some racing camshaft. It could have been also running 77.6mm pistons (so 662 instead of 652cc) but that wouldn't change much.

[Rusty's Uncle]

                  PUMA RACE ENGINES - OPTIMUM EXHAUST VALVE SIZE

If you like technical stuff google the above as it makes very interesting reading about valve sizes  [-/

[Rusty's Uncle]

So I bet all you guys stayed up late reading that article 
Well the main theme of it is that you will only get a minor benefit from increasing exhaust valve size but a much greater potential by increasing the inlet valve size. There are also recomendations for valve size to bore capacity.
I just found the big valves I bought on eBay on the Axel Gerst site 59 euros each  so looks like I got an eBay bargain  [-/
So now exploring a lead to get oversize valves at a more reasonable price 
There have always been loads of tuning options for the aircooled engines & this is one. but the Bis has always been limited. But I would guess that with a slight skim of the head, bigger inlet valves & porting , possible carb upgrade & a sports exhaust you could have an interesting little motor 

[Alfons1972]

that cylinder head definitely is a german one... look down for a complete engine.

I went to the cellar to measure the inlet port of such a german head and it is 30mm too.
It has this shape because of the german regulation for homologation to avoid exhaust gas attain the passenger cabin if the gasket of the cylinder head is damaged.

The carburator of the german 126's has been a 28 IMB. I think, there was no difference to the british ones.


click on that:  http://img7.myimg.de/120320103052a535d.jpg

[Darrell]

Imagine 44hp...
must say my prayers to the god of e-bay that my boat gets sold so I can buy more go-faster bits

[Rusty's Uncle]

Hi Alfons , I see what you are saying  [-/
By taking the hot air across the cylinder head & above the head gasket there is no chance of engine exhaust gasses getting into the interior of the car . I am not sure what to do with this head as I do not have the parts to fit that side of the engine