AO Code?
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AO Code?
gobstopper and his brother may remember this one. its been on my mind for a while just never got to you guys to ask it. we were doin my injectors and they say AO on them. not AA AD or anything else but AO. what the hell are these things? lol alien breeds from mars?
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From: North East Ohio
AO are very close to being identical to AA, with only one small difference that doesn't amount to much.
From what I have seen they came in the '95 trucks, and I assume 94.5, too. Then late '95, when they made the other changes to the PSD, went to AA's.
From what I have seen they came in the '95 trucks, and I assume 94.5, too. Then late '95, when they made the other changes to the PSD, went to AA's.
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From: North East Ohio
Every A and B code injector has 2 HPOil supply holes in the midle of the injector. Actually comes up from the bottom of the upper half. If you had one in your hand, you'd see them. Anyway, the AO were the only ones that had the holes 90* apart, whereas all the others I have seen are 180* apart.
No friggin clue why they did that, but that's the only difference between an AO and AA.
Edit: What's weird is the HPOil comes into the inejctor cavity on the left side, as you're looking down. All injectors, except AO have the holes at 12:00 and 6:00. The AO are 12:00 and 3:00, with one actually on the complete other side of the injector from where the oil comes in. I would think you'd want a hole on the left side 9which NONE of them have)cuz as it is now the oil has to travel all the way around the injector to reach the hole. Might not sound like a big deal but when we're trying to optimize the performance from them, every little bit helps...
Anyhoo, you asked. Kind of...
No friggin clue why they did that, but that's the only difference between an AO and AA.
Edit: What's weird is the HPOil comes into the inejctor cavity on the left side, as you're looking down. All injectors, except AO have the holes at 12:00 and 6:00. The AO are 12:00 and 3:00, with one actually on the complete other side of the injector from where the oil comes in. I would think you'd want a hole on the left side 9which NONE of them have)cuz as it is now the oil has to travel all the way around the injector to reach the hole. Might not sound like a big deal but when we're trying to optimize the performance from them, every little bit helps...
Anyhoo, you asked. Kind of...
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'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
'17 6.7 F-250 KR ccsb 4x4
'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
'17 6.7 F-250 KR ccsb 4x4
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From: North East Ohio
Shoot, the cold medicine must be making my brain fuzz. I got that backwards.
The AO have 2 holes, at 9:00 and 12:00. All other A codes have them at 9:00 and 3:00. The HPOil comes in at the 9:00 side so all other A codes, the oil has to go to the other side of the injector to get into the second hole.
Whereas the AO had the hole closer to the 9:00 side.
That's what I meant to say.
Still not really sure why they changed it...
The AO have 2 holes, at 9:00 and 12:00. All other A codes have them at 9:00 and 3:00. The HPOil comes in at the 9:00 side so all other A codes, the oil has to go to the other side of the injector to get into the second hole.
Whereas the AO had the hole closer to the 9:00 side.
That's what I meant to say.
Still not really sure why they changed it...
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From: Belair md
i am taking a wag at this but in my opinion they dont have the holes lined up to try and let the pressure equalize in the heads before entering the injector. i dont think a few degrees matters at 3000 psi but perhaps it made a difference in the engineers head that designed it??????
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Joined: Oct 2003
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From: Ashland City, TN
The distance traveled means a lot in hydrollics in something like this.
Depending on how the pressure is equalized in the container.
I dont understand the system very well however though, cause i'm new to the way the injectors work in the oil rail system.
if it enters at nine, it travels counterclockwise to 12?
or 3 in the other injectors?
Im' going to take a guess that there is a rail in the system where the oil returns as well.
And the HPOP rail is entering at 9, so if the oil exits at 3, the presure in the system, depending on how the oil travels in the injector will be equal on both sides.
I'm guessing the AO injectors just travel around the one side mostly?
And then the AA and AB AD injectors can travel around both sides of the injector?
If its an open cavity on the AO injectors, there would be a pressure difference on the big side compared to the little 1/4 sized side.
but like coon said, at 3000 PSI, i doubt it makes a big difference.
Depending on how the pressure is equalized in the container.
I dont understand the system very well however though, cause i'm new to the way the injectors work in the oil rail system.
if it enters at nine, it travels counterclockwise to 12?
or 3 in the other injectors?
Im' going to take a guess that there is a rail in the system where the oil returns as well.
And the HPOP rail is entering at 9, so if the oil exits at 3, the presure in the system, depending on how the oil travels in the injector will be equal on both sides.
I'm guessing the AO injectors just travel around the one side mostly?
And then the AA and AB AD injectors can travel around both sides of the injector?
If its an open cavity on the AO injectors, there would be a pressure difference on the big side compared to the little 1/4 sized side.
but like coon said, at 3000 PSI, i doubt it makes a big difference.
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From: North East Ohio
There is no return in this system. Once the oil is 'used' by the injector, it's spit out the aluminum spout and goes back to the pan via under the valve covers.
One of the mods we do for the really big injectors is to add more HPOil holes, so I'd think that you'd really want the supply holes closer to the supply inlet at the 9:00 position. I'm no hydraulics guy, but it cannot be a good idea to have the other hole 180* away from the supply. Just my theory.
I don't get the 'balancing out the system' theory. If the whole system is under pressure, the head rails & injector components, then it shouldn't matter where the holes are. You want to get the oil in and out as quickly as possible so more holes (or larger ones) closer to the supply should be the goal.
One of the mods we do for the really big injectors is to add more HPOil holes, so I'd think that you'd really want the supply holes closer to the supply inlet at the 9:00 position. I'm no hydraulics guy, but it cannot be a good idea to have the other hole 180* away from the supply. Just my theory.
I don't get the 'balancing out the system' theory. If the whole system is under pressure, the head rails & injector components, then it shouldn't matter where the holes are. You want to get the oil in and out as quickly as possible so more holes (or larger ones) closer to the supply should be the goal.
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'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
'17 6.7 F-250 KR ccsb 4x4
'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
'17 6.7 F-250 KR ccsb 4x4
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From: North East Ohio
Ah, but there are 2 holes coming into the Poppet valve from the outside, but only one larger hole going from the Poppet to the Piston. I beleive the taper on the top of the Piston is to alieviate the side loading.
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'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
'17 6.7 F-250 KR ccsb 4x4
'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
'17 6.7 F-250 KR ccsb 4x4