Hi

I'll soon be putting an order in to VDL and was thinking about adding bigger valves and a copper head gasket to the list, but thought I'd check in to make sure this is advisable, particularly if I am keeping the 28 carb (for now..) and not doing anything else to the head.

I was thinking thinking of 34/28 8mm values (so within the advised 78-82% ratio), largely as I can't find a 35 value and so that I don't have to change the existing guides.

Thanks as ever
Steve

http://www.fiat500sport.com/engine-assembly.html

is where I bought mine from....

sheylings said:

I was thinking thinking of 34/28 8mm values (so within the advised 78-82% ratio), largely as I can't find a 35 value and so that I don't have to change the existing guides.

Click to expand...

Hi Steve,

I did this when I built my 695cc engine - I also had the inlet tract opened up.
34mm is about as big as you can go without some significant surgery.
On advice I also fitted a 29mm exhaust valve more for heat transfer than aperture size. All the valves had 8mm stems.

The copper gasket is also a good idea - it raises the CR quite a bit.

I've attached a photo of my 'big valve' 34/29 head.

Chris

Steve - I now have some spare new unused valves, 36 in 29 out - are you interested?

If you are going to the trouble of fitting larger valves, I would suggest that in order to benefit from there fitment you 'flow' the head. By using the relevant gaskets, open up the exhaust ports (and the exhaust elbows) to match the gaskets and also reduce (and smooth round) the ridge just inside the inlet ports (just behind the valve seat). These simple mods will allow the head to breath much better. You will probably have to up a couple of sizes on both the main and slow-running jets

Bambino said:

Hi Steve,

I did this when I built my 695cc engine - I also had the inlet tract opened up.
34mm is about as big as you can go without some significant surgery.
On advice I also fitted a 29mm exhaust valve more for heat transfer than aperture size. All the valves had 8mm stems.

The copper gasket is also a good idea - it raises the CR quite a bit.

I've attached a photo of my 'big valve' 34/29 head.

Chris

Click to expand...

Hi Chris

Is a copper gasket worth doing on all engines?

cheers, Steve

Hi Andrew. I've since souced some 34s but I'm certainly intersted in the 29 ex valves - let me know how much you want and I'll PM my address. Thank you
Steve

they are at the machine shop at the mo...
I'm back there tuesday..........once I've got them in my hand I'll let you know

Greetings, can anyone let me know the best sizes for the panda 30 head with the appropriate amount of gas flow work done too?? Thanks.

Ian.

I bought a set of valves that were said to be the largest you could fit without setting the valves at an angle. From memory the inlet was 36mms, not sure about the exhaust. Anyway I had work dome on a number of heads by two different specialists and they both refused to fit the bigger valves because of the interference needed on the valve seats. However the guy from the club126uk forum who has developed a 100+ hp turbo charged 700ccs engine told me that the trick is to fit the larger inlet valve seat first then cut the exhaust seat on the overlap. Seems to make sense and he has had no problems in that department but he has bent and snapped a couple of crankshafts with the power he is getting.