CuttyShark

Now that I have EFI... how do I connect the OAI flapper? Right now I have the vacuum going direct to the flapper so that when at idle it is open and at acceleration it is closed. That draws hot air from inside engine compartment. I can even see the difference on my Holley Sniper handheld. At idle I was pulling in 90 degree outside air and on acceleration I was getting 120-130 degree air through the snorkle above the passenger exhaust manifold.

what was the behavior originally with the carb and how do I make the Sniper mimic the way it should work? The TVS is gone in place is the water temp sensor for the EFI.

joe_padavano

The actuator for the flapper is simply connected to manifold vacuum. Any manifold vacuum port works. At idle and part throttle manifold vacuum is high and the actuator holds the flapper closed. At wide open throttle manifold vacuum drops to zero, the actuator no longer has any force, and the flapper drops open from gravity. Are you sure there isn't anything preventing the flapper from dropping open, like an air cleaner stud that is too long?

VC455

That's not right. The flapper should not open until the manifold vacuum drops below about 10 inches. If your cam were so radical that it would give such low idle vacuum, the Holley EFI would not be able to idle correctly.

So check where you have the vacuum line connected. It should connect to full vacuum. If you have it connected to the carb, you may have selected ported vacuum, which would make it operate as you described.

cutlassefi

Absolutely not true. The newer systems have no problem with low idle vacuum when setup correctly, sorry.

VC455

OK, I must have been stuck in a time warp with that old information.

However, Cutty still needs to check the source of vacuum for his OAI adapter.

cutlassefi

Absolutely.