[Dominick]

Today I was borescoping down my intake runners was trying to see the spray pattern of the injectors.
I noticed that the injectors where firing at the bottom of the runners where the lower intake meets the head.
Is this right? I thought the injectors fired at the intake valve.
Combo is holley systemax 2 intake on AFR heads.

Could this be why I seem to have an incurable misfire at idle and and one hell of a time dialing in idle/ low load low RPM fuel?

[cgrey8]

If you were doing this procedure with no air flow, then yeah any spray probably would land directly on the bottom of the head port. However in a running engine, there's anywhere from a fair to HEAVY airflow through those runners that is picking the fuel up. At idle and very light throttle, some fuel probably does land on the port walls. But during loaded airflow conditions, far more of the fuel is whisked away in the air flow.

For a somewhat gross comparison, sit in the seat of your car and spit out the window. Do the same thing while driving down the road.

[LeadHead]

At idle there's hardly any air going into each individual cylinder. I bet you are getting some pooling at idle. Most OEM injectors I've seen are aimed towards the intake valves.

[Dominick]

I'll have to re-seat them. They don't look like there at the correct angle
And the rails seem to make them float there.

[decipha]

increasing fuel pressure will give you a tad better atomization, its no secret, thats why ford kicked it up the 65psi in the late 90s, better emissions, fuel economy, etc... you'll see i recommend running 55psi of base pressure pretty often

and yet again, I'd recommend kicking up your base fuel pressure to help out idle a touch, may not make a dif but might make it a touch smoother/more tolerable

[Dominick]

Yeah man I've had that kicked up the first day I read your 101s
You can definitely see that it atomized the fuel better.

I did get the injectors seated better an d they do spray at the
Valves now. Have not gotten a chance to run it yet.

[cgrey8]

I've seen DIY injection bungs welded into a 410 FE carb intake and angle was obviously not paid any attention to with the injectors installed straight up-n-down!!! And I'd bet it still performed better than with a carb.

[Dominick]

How far up the runner where they?

[Dominick]

Finally got my rails to seat properly injectors firing at the Valves. Idle has improved, missfire has disappeared, acceleration from stop is much much better, and AFR's have stabilised across the board.