panda 30 head skimming

[126dave]

hi guys,im gona freshin up my 650 in the new year,at the mo my panda 30 head is standard,im thinking of skimming a bit off to up the compression,nanni recommended a ratio of 10.5 to 1 for the cam they supplied 40-80-40.......now,any ideas on the amount i should be looking at to remove?

engine spec at the mo is,cam as mentioned,652cc, panda head,40dcoe weber carb and sport exhaust..........

any thoughts would be usefull.........i guess normal 652 head skimming amounts would do?...the panda head just different in the porting etc?? ::

i should mention i use super unleaded with lead/octane boost additive

[126dave]

just checked the blitz site...they reckon on 1.4mm to 1.6mm.........anyfeed back would be welcome from members or surfers.......

[MaLi]

I would think that camshaft with 40/80 (300deg opened valves) would need quite a high compression. 10.5:1 seems to be quite right. I am not sure if the camber in Panda  head is the same as in 650E but I would think that 1.6mm will not be enough for this camshaft.

I had  ~1.5mm skimmed head on the standard camshaft and it was working quite well (95 octans and 13deg ingnition). Later I got it to 2.5mm and with standard camshaft it had "pinking" problems. With 98 octans it was just right.

But: Last setup for my engine included 282deg camshaft and 4.5mm skimmed head. On the 95 octans it was possible to set it so it would not detonate but with rally setup ("racing" exhaust and 99 octan) it was mad.

I would suggest to take the head of and measure camber volume (with oil/petrol) and then you will know everything. It is always better to cut the head less then too much.


other tips:
1. f you cut more then 2.5-3.0 mm and/or have camshaft with greater valve lift check if valves will not hit the pistons (I had to do 2mm pockets for my inlet valves)
2. try fitting a copper gasket - it will lower the temprature of the head and they are usually thinner then standard ones.
3. with skim: ~3.0mm and more you might not be able to set the valve/rocker gap properly - have to shorten pushrods (not so complicated as you may think)
4. the "pipes" containing pushrods will need shortening as well (only 650 - as panda ones should adjust by themselfs)


hope I didn't make too many mistakes   :roll:

If you have any questions just ask.

[126dave]

fantastic,this is just the sort of info ive been searching for..........im not starting any of this till next year,im gna fit a bis box in at the same time as the freshen up.........i've spent a lot of time getting the carb mounts etc right,now is the time to pull the motor out and do all the details,i will be asking you for more info later im sure,thanks again  :cool:

im using 650 push rod tubes at the mo,what is the difference with the panda ones?.is it worth me changing to them when i skim the head?

[MaLi]

Panda ones are shorter and they have sth like this at both ends (don't know how would you call it):
<     >
<     >
<     >
<     >

So they can be "squized"

Panda (second picture from the top):
http://motonews.pl/sh_forum.php?op=fvt&t=12052&c=0&f=25&start=20

650/600:
http://img337.imageshack.us/my.php?image=p10100233zs.jpg


Similar project to yours:

http://www.fiat-furious.pl/html/artykuly/krowa.htm

I know it is in polish but it might be interesting for you.

[126dave]

thanks,i think you mean 'concertina'........i will try and find some

[126dave]

also,thank you for the link to fiat and furious........that carb support looks doomed to failure tho!........i've tried so many..the one i have now seems ok

[hudsonhenry]

Dave

This is the head I had on my car, you can see how much I had taken off, some of the racers run without head gaskets or have thin copper ones made up as well.

Having all the engine internals ballanced would have helped reduce the vibration thats breaking your carb mounts. It never goes away I had to replace the rubber bobbins that formed part of the mounting of my twin choke carb every six months, when I replaced it with a single choke FZD I ended up with more power throughout the rev range and because it is smaller and lighter than a twin choke it did not need any extra support – no good for you though, my head was a single port not a twin port.

[126dave]

i see,almost down to the first cooling fin!.......a local guy has an engine from poland,the head is so skimmed he couldnt get the engine mount under the elbow.............im told

no balencing localy...(cant even get those dodgy dutch discs skimmed here)and sending the motor away stripped would be a shot in the dark,i dont have any contacts in the uk for that kind of thing

the vibes are still there,but my latest set is dampning them ok so far

once ive worked out whats what,im gna have to send the head away to be done.............the few firms here are crap really..........

times like this id like to be in the UK

[bis13]

i am going down to see a vw tuning guy i know he wants to look at doing my engine , lightenning and balancing , polishing and porting etc . copper gasket made up. if it sounds good i shall go for it . i will keep you posted on what comes out of it.

[126dave]

you can save a lot of head work if you just go for the twin port panda head.......but then you need a dellorto /weber carb and decent cam................ :roll:

[bis13]

to be honest i dont want a really big carb to eat all my petyrol . i want to try and keep it a little bit ecconomical but more fun. plus my wife would throw a fit she wont notice too much of a change in the carb dept!

[126dave]

perfectly sensible approach......will save ££s on panda 30 head etc

then stick a bis box in mick,you'll grab a few more mpgs from that on your runs to work

[hudsonhenry]

Dave

If you need some details of engine ballancing companies over here who know 126 engines then please let me know.

Did you get the flywheel lightened last time you had the car apart?

nigel

[126dave]

thanks nigel,no i didnt lighten the fly wheel but going too this time,and also gna try the bis clutch idea.
any info on good companys/how much to remove from f/wheel etc welcomed!