Just got a coolhead for christmas, and she got me the 22cc domes. I want the most comp. I can have without detonation on 92 oct. gas. what are you all using?

 

Depends on your altitude, probably the most you can go is 19 or 20cc domes. But first check out your altitude then post it on here and someone will be able to tell you.

 

As a reference point I am at 5500' above sea level and I run 19cc domes with pump gas. At my elevation I could probably even go another size down...

 

Here is a chart that someone pointed me to one time. I can't say if it is correct or not though.
http://network54.com/Hide/Forum/mess...geid=972683868

Also here is Pro-Designs phone number
714-534-0620

Adam Biossat

 

i live in ohio and i am running 21 cc domes on 93 octane gas and i was told when i bought it that the 21's was the lowest i could go with out running it on raceing fuel

 

I have 20cc domes and run 92 octane at sea level (glamis). I was told I could not do this by a local shop - shows how much they knew...

I was told by CT that smaller domes than 20cc's at sea level will slow a stock ported motor down.

Static compression at 1100 feet elevation is about 145 psi. I get about 155 psi at sea level.

Don't believe that pro-design compression chart. The sea level numbers are off, but all the rest seem to be right.

Also, stock head volume is 23.2 cc's - FYI

 

Well, I had my girlfriend take back the 22's and get me 20cc domes, (I went riding!!) By the way, I am at sea level, stock engine with fmf pipes, stock reeds, 290 main, 30 pilot, needle in the stock position. So by going with the 20's, is it going to add a lot more power than the stock head?
Later.