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measure for yourself !
Posted: Thu Dec 02, 2010 9:28 pm
by vanzen
John Falconer had some excellent pages detailing the squish-band / piston differences year to year.
I can no longer access it, however.
In any event, there will be no substitute for breaking out the tools and measuring.
Talk will be talk, but a micrometer tells no lies.
Re: Earlier Heads on a Later Model? Need info quick!
Posted: Fri Dec 03, 2010 10:21 am
by John Falconer
If the heads have an absolutely flat, i.e., perpendicular to the cylinder axis, periphery then they are "squish band" heads. The later heads taper slightly to join the hemisphere of the rest of the combustion chamber.
If no other modifications have been made you CAN run them with the pistons intended for the post-78 heads but the combustion chamber shape resulting is not very nice (there's a pinched off area all around - I suspect it to be susceptible to pre-ignition).
The site with the piston info will be back up. I'm divorcing my wife but left a number of servers running in the garage of our house, including the one serving up those images. She had a lengthy power failure and I haven't brought that server back up - don't really relish going over there and it isn't set up for remote access except on the local LAN. Sorry!
Re: Earlier Heads on a Later Model? Need info quick!
Posted: Fri Dec 03, 2010 10:25 am
by Garnet
John Falconer wrote:
The site with the piston info will be back up. I'm divorcing my wife but left a number of servers running in the garage of our house, including the one serving up those images. She had a lengthy power failure and I haven't brought that server back up - don't really relish going over there and it isn't set up for remote access except on the local LAN. Sorry!
Don't you just love technoligy!
Re: Earlier Heads on a Later Model? Need info quick!
Posted: Fri Dec 03, 2010 10:27 am
by Garnet
John Falconer wrote:
If no other modifications have been made you CAN run them with the pistons intended for the post-78 heads but the combustion chamber shape resulting is not very nice (there's a pinched off area all around - I suspect it to be susceptible to pre-ignition).
And, I would think, at a loss of power and gas milage.
Re: Earlier Heads on a Later Model? Need info quick!
Posted: Wed Dec 08, 2010 9:06 am
by John Falconer
In case someone is still wanting to see them, the pages I did long ago re pistons are "back on the air" since I went over and reset the server at my ex-wife's home.
They are here:
http://moragafalconers.org/BMW_pistons but I can't promise how long they'll be up.