I had O2 bungs put in my CMI headers and fired it up and pulled the cap and quite a bit of water was coming out. The water dumps out at the tips so the bungs are a good 16" from where the water dumps in. The headers were pressure tested and the volume of water was equal on both sides - enough to soak my hand after a few seconds.

My question is does this kill any chance of an open loop EFI? And secondary, does that seem excessive?

BBC 502 with ZZ502 cam
Excuse the loose rigging as I'm not buttoned up yet.

I had the SAME issue with my Eddie Marine's....
Ran it without anything in the O2 bung and water was flying all over the place in the riser...


Learned that the exhaust leak from pulling out the plug causes reversion. Put my sensor in, haven't have an issue...

Ah, thanks! I've heard about leaky exhaust gaskets causing reversion and now that I've seen it I'm a believer.

Yea you should be ok.

What he said. You should be fine.

run the engine w/ the plugs in,,then,turn engine off and pull plug,,if its dry,your good to go.
also,the exhaust can not have any leaks or it will revert,,found that out first hand.

after dealing with this for years, does not take much water at all to kill a heated 02, we ended up putting a bung in the header tube about 10" from flange, worked fine, understand only reading one cyl, but only way not to kill a $150 sensor..which we did 3 times in mins. also that ZZ502 cam may not be great against revision...

Ran the motor again with the plugs snugged up, checked them after, and they were dry as a bone. If anything they were way too sooty. Stupid carb, lol.

On my Checkmate, I installed a Throttle Position Sensor on my carb and ran an Innovate LM-2 to datalog.. Got that carb DIALED in..

stupid carb ?? what do you think a pig rich merc EFI would look like..