• 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

MGB Lowering Compression ratio in MGB

Share this page

A

al1978

Freshman Member
Offline
How can I lower my compression ratio from 9.5:1 to 8.0-1 easily. Can I use a spacer of some sort to lift the head? Or can I use 2 or 3 head gaskets? Has anyone done this? If so how much would I need to raise the head roughly?
 
Just find a late 18GV engine. IIRC they'd been emasculated well by then: 8 or 8.5:1... No way would you be able to "double gasket" it and machining a spacer would cost near as much as just buying LC pistons for it.

Is this a turbo project?
 
"double-gasketing" is never a good idea but some of us have done it (along with fitting short-thread "VW" L88 plugs) in our Mini's back in the '80's when the octane ratings first dropped and it worked well for years, but I was always surprised!
Bill
 
How was your compression raised to that amount in the first place? If the head was skimmed, you can always just replace it. They aren't that expensive, especially when you sell your old one to someone wanting a performance boost.
 
's why I asked about turbo. Seems "odd".
 
Back
Top