• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

1500, 7.5:1 to 9.0:1

Share this page

M

maddy

Senior Member
Offline
I'm pulling the engine this winter and plan to change to 9.0:1 compression ratio. The questions I have... I've noticed that in catalogs that some of the 1500's originally had 9:1 ratios, but was the cam grind the same? If not, for Cal smog purposes I assume, where can I get one. Would it be ridiculous to think I can find a good used one? What about good used 9:1 pistons?
 
I think they're the same for 7.5 and 9:1. Moss only lists one.

I think the Euro-twin carb cam is different.
 
The 7.5:1s are a dished top piston and the 9:1's are flat top on the 1500. I couldn't find my cam data but its here somewhere!


Bruce
 
Somebody correct me here, but I beleive that going with 9:1 pistons doesn't actually give you 9:1 compression. It appears the cylinder head for the European cars are different and that is what gets you all the way to 9:1. I had to have my head cut (.050 I believe) to get me to 9:1 (in my 1500 Spitfire).
 
Back
Top