this is something i should've worked out a while ago.. when the head was off.. so i know this'll be a guess.

i do not know how much my head was skimmed. it was taken to the same level as my old GSR SPI head - i don't know who has that now.

it has been skimmed to the max markers on the head, does anyone know how much material that equates to - and so the resulting CR on a 1242?

Im not sure arc,

but my head has been skimmed to max marks and i am running the metal headgasket which has a thickness of 0.42mm and it runs fine if this is what you are asking. The person i asked was Balidey i think he knows alot about compression ratios etc.

He suggested my compression ratio on a 1108cc engine with thin headgasket and skimmed to max would be closer to 11:1 possibly even 12:1. Although my car dont like anything less than BP Ultimate but thats a small price to pay for the extra performance.

With a standard gasket and a skimmed head to max marks, i believe he estimated it would be 10.5:1 CR? Give him a pm he replied to me very quickly.

Many thanks
Matt

thanks for the reply.

i'm running a spesso gasket, and skimmed to the max. i'm just trying to deciede how much i should retard the 9.8:1 ignition table by that i have!

will give Balidey a pm.

you may be able to help me arc.


You say about retarding the ignition timing.

I believe my valve timing is out by 6 degrees. I have the vernier pulley im just waiting on other parts from the Fiat Cinquecento Sporting as i have the MPI cam gear setup on my seicento (i know completely random). As of yet there is no vernier pulley for an MPI so therefore i need the water pump and crank pulley from a cinq.

How and what have you set your valuve timing too. Did you set max lift to a certain degrees? (just for example max lift should be at 119 degress ADTC).

Can anyone else help. Id like to set my valve timing correct before i drive it any more.

Thanks
Matt

i've not altered the cam/valve timing yet. its set to stock. the engine does not run yet..

.. i need a starting point (spark timing) before i start to play with the valve timing. so i'm not much help i'm affraid.

Cool, I got a skimmed head too, no idea by how much but I can feel it slightly more powerfull...