I found a local welder, sent him the video, and he gave it back to me a couple days later. He even already had the bungs in stock.

That’s what I did. I still have the wideband in the port side bank with the EFI in the SB bank and I can keep an eye on them both. On occasion there’s about .5 difference in the AFRs and it’s a redundant way to keep an eye on things.

I had my carb “dialed” in running perfectly, but installed the wideband and in the window of about 500rpms where I cruise the most it leaned out to the high 14s and occasionally the 15s. Would’ve likely toasted the engine. So even with carbs I highly recommend a wideband. I know a lot of the vendors will install them if you send the exhaust bits back to them.

Maybe next year if I make changes.

I’ve read on the forums that you have to do some trial and error stuff to get them to work. A concern was that Holley wouldn’t support these configurations I think it was scaring off some from attempting to get them working. Could very well be the target audience. I don’t think that would be an issues for folks around here.

I’ve got too much invested in these engines to have them burn up and that’s exactly my biggest worry... lean cruise and creeping up on peak torque where real damage can happen without even realizing it. AFR monitoring is cheap insurance in my eyes.

New to the efi world but have bought a Holley sniper system to install on a single engine fountain, the problem we are having is where to run the return fuel line back into the fuel system . What is the best way to get it back in the loop ?

Best way is back to tank. 2nd way is back to an inlet to the fuel filter/water separator.

Is the fuel fill hose nearby ?
See for two fill hose size options:
https://www.cpperformance.com/vsearc...Tank%20Adapter

If you route back to the separator, you could run into heating/vapor lock issues. Merc used the cool fuel system to combat this.

SB’s suggestion of running it back to the fill hose is best. The tank then ends up being the heat sink.

You may have just sold me on it. Gonna contact CMI about some new tail pipes this week.

Love the fill neck adapter, would have been easier than welding a bung to my tank. I run tank to separator, to pump, to carb, back side of carb inlet line to regulator, regulator to tank. Constant circulation of fresh , cool fuel, zero chance of vapor lock or pressure build up. Next time I have the tank out, I would love to go with a set of the in tank pumps and push fuel through the separator/filters. The pumps I have are mounted low (stringers) and thanks to the constant circulation of fuel they dont get warm, but they, like most pumps are better at pushing than pulling.

I'm planning this myself on my 454 mag.... my plan was to pump fuel from the stock pump/filter into to a surge tank setup with built in high pressure pump, then run that to the sniper setup.

Sidebar question.... I currently only run premium mostly to avoid ethanol in the carb and risk it gumming it up over winter. This engine does not need the high octane fuel, especially as cool as they run with only around 8:1-8.5:1 compression.
So, one of the fringe benefits I expect with EFI is to be able to run standard fuel without the problems the carb has with it... 87octane which around here has 10% ethanol. Is that a realistic expectation, or do I still want to stick with premium (over $4 a gallon now into my 88 gallon tank)?

you can run the return to the water separator filter head if you have a port available without issue if done correctly