• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Skim 1500 head

Share this page

Morris

Morris

Yoda
Offline
I finally got my head off to a GOOD machine shop! I really like the guy who is going to be doing the work. A couple of Hemisfair heads he had in the shop made me feel even better!

Anyway, I would like to shoot for a roughly 9.5:1 compression ratio on a 79 1500 with flat top pistons and stock head. Any idea how much I need to skim the head to acheive this?
 
The machine shop guy should be able to tell you rather quickly.
 
Morris, flat tops and stock head thickness give you 9:1. I'd just guess at .040"~.050" or so to kick it up an extra 1/2 point.
One thing about the 1500 head, is that there is a ton of material available for removal. I took .265" off the last race head!
Jeff
 
I was told by a Triumph guy that the 9:1 cars had a smaller combustion chamber and that the most I could expect with an unskimmed head is 8.5:1. Is that contrary to your experience Jeff?
 
My 1500 has AE flat-top, 9:1 pistons.
I took about 0.110" off the head. After, cc-ing the head, it calculates to about 10.25:1 compression ratio.
At this level, I'm using Sunoco GT 100 (unleaded) just to be safe, but it's $6.00+ a gallon.
If I were running a street car, I wouldn't take more than about 0.050" off if I wanted to run street fuel with a decent amount of total ignition advance.
 
Back
Top