2270 build, 2270 compression question Options

[Alapone]

Hey guys,

I am having a 2270 built, 78mmx96mm. We are using the 163/86b webcam and 2.0l heads. Dellorto 45s and msds headers.

I am trying to decide on the right compression. The build is aimed at aggresive street use. I want to have as much power as possible and not have to run an external oil cooler or have any problems with detonation on 93/4 octane gas.

I have heard anything from 8.5:1 to 9.5:1. Please let me know your thoughts.

Thanks,

Andrew

[Mark Henry]

Bump it up that cam needs at least 8.8 to 9.0CR the one caveat is your jetting and timing needs to be bang on. You definitely need a wide band O2 meter and a head temp sensor under the #3 plug.
I'd start with an AFR of 12.5, keep it on the rich side with timing no more than 28* total. Running rich the fuel charge actually cools the heads a fair bit.

I have the same cam on my 2.6 with 9.3CR, but I have nickies and running a hybrid DTM (copy)/joe cali cooling system in a 400lbs lighter '67 bug. No over heating issues, no extra cooler. I can run extra CR because of the nickies.

As long as your head temps are no more than 325* cruise, 350* (maybe a hair more) pulling a hill and recovers every time on the downhill side you're OK.
Never lug the engine with this combo, 3k rpm minimum, even in trafic or downhill.