C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Holley AFPR hitting the upper plenum?

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Old Feb 6, 2004 | 06:42 PM
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Default Holley AFPR hitting the upper plenum?

I switched to a Holley AFPR from a different brand AFPR, and I can't adjust the Holley to the point of the correct fuel pressure. The top part that turns hits the upper plenum and so can't turn any more. Anyone else have this issue? I have a feeling I'm doing something wrong.

The car is an 88. I was getting 44 psi before and now the most I can get is about 25.


[Modified by Tourney3p0, 5:46 PM 2/6/2004]
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Old Feb 6, 2004 | 06:53 PM
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Default Re: Holley AFPR hitting the upper plenum? (Tourney3p0)

I installed the same AFPR on my '86 & simply (but carefully) used an angle grinder to grind a small notch in the plenum at the point of interference.
By the way, tightening the adjustment "wheel" increases the fuel pressure, so as you increase fuel pressure, the wheel moves further away from the plenum.


[Modified by geezel, 4:56 PM 2/6/2004]
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Old Feb 6, 2004 | 07:06 PM
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Default Re: Holley AFPR hitting the upper plenum? (geezel)

By the way, tightening the adjustment "wheel" increases the fuel pressure, so as you increase fuel pressure, the wheel moves further away from the plenum.
[Modified by geezel, 4:56 PM 2/6/2004]
Hmm.. not on mine it doesn't. I turned it clockwise as much as it would go (toward the manifold and away from the upper plenum) and my pressure was 0.

Would this mean I have the guts upside down?
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Old Feb 6, 2004 | 07:15 PM
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Default Re: Holley AFPR hitting the upper plenum? (Tourney3p0)

I couldn't tell ya... Mine came assembled, guts and all, so I just installed it as is.
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Old Feb 6, 2004 | 07:23 PM
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Default Re: Holley AFPR hitting the upper plenum? (geezel)

That's strange. Mine came in many parts. There was a spring, a cap for the spring, and a cap for the opposite side of the spring that had the gasket built into it. Then of course there was the main cap. I spoke with someone from Holley and they told me to put the caps on both sides of the spring then put the main cap on. There is no "one unit" so to speak, because it's not truly attached.

My old units (both stock and non-holley AFPR) were nothing like that, and I thought it was strange.. that's why I got in contact with the Holley rep.

Also when my fuel pump is priming, it makes a gurgling sound at the regulator. No doubt something's up with my AFPR, probably user error.
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Old Feb 6, 2004 | 07:30 PM
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Default Re: Holley AFPR hitting the upper plenum? (Tourney3p0)

It's really easy to scratch or tear the rubber diaphram so that it won't seal right. If that happened, you'll never get the pressure you're supposed to.

Chris
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Old Feb 6, 2004 | 07:42 PM
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Default Re: Holley AFPR hitting the upper plenum? (okinawa86vette)

Thanks for the response, okinawa86vette.

I was very careful with the diaphragm as to not tear it, but I'll definitely give it a good inspection when I pull the AFPR back out tomorrow. If nothing else I'll put my old one back in for the time being.

Others with Holleys.. how did you assemble them, or did you have to?
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Old Feb 6, 2004 | 08:01 PM
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Default Re: Holley AFPR hitting the upper plenum? (Tourney3p0)

Had to assemble mine, the directions were in the box and specific :seeya
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Old Feb 6, 2004 | 08:08 PM
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Default Re: Holley AFPR hitting the upper plenum? (86Moon)

Hmm... I have a superram so the clearence is no problem. But clockwise should be MORE pressure, not less. I would inspect the diaphram. My holley is lightyears better than the one I had before.
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Old Feb 6, 2004 | 08:09 PM
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Default Re: Holley AFPR hitting the upper plenum? (86Moon)

Had to assemble mine, the directions were in the box and specific :seeya
Aha.. mine had no directions. It was just a Holley box with a plastic bag containing parts. I bought it from Summit, too.

At least I know it wasn't supposed to come assembled somehow though. I'll contact Holley or Summit and see if I can get them to email me or mail me a paper copy of the true directions rather than informal directions from a Holley rep.

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Old Feb 6, 2004 | 08:11 PM
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Default Re: Holley AFPR hitting the upper plenum? (scorp508)

Thanks for the response Scorp.

Mine is obviously operating backwards for some reason (again, probably because of an error on my part). I'm sure when I correct it everything will be great and the clearance will no longer be an issue.

Thanks everyone for the responses.
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Old Feb 6, 2004 | 08:19 PM
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Default Re: Holley AFPR hitting the upper plenum? (Tourney3p0)

I'm pretty sure I still have the instructions. If you are not able to get the info by tonight e-mail me and I'll try to get them to you tomorrow. :cheers:
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Old Feb 6, 2004 | 08:41 PM
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Default Re: Holley AFPR hitting the upper plenum? (Tourney3p0)

I had the same problem with plenum clearance when I installed the Holley AFPR. I used a dremel with a grinding bit to clearance the area of the plenum it was hitting. Just take your time so you don't go all the way through.
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Old Feb 6, 2004 | 10:37 PM
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Default Re: Holley AFPR hitting the upper plenum? (Tourney3p0)

Well for an hour now Iv'e been trying to download a driver for a scanner I borrowed so I can copy the paperwork that came with my holley afpr.
It seems it's not xp freindly so now I have copied driver on to cd to load into laptop with 98.
Give me some more time and I'll try to scan from laptop, then transfer info to desktop, then post it for you :smash:
:cheers:
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Old Feb 6, 2004 | 11:18 PM
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Default Re: Holley AFPR hitting the upper plenum? (Tourney3p0)

:smash: I give up with this scanner :smash:
If you want the directions, I could take a pic of them.
Let me know :seeya
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Old Feb 7, 2004 | 12:33 AM
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Default Re: Holley AFPR hitting the upper plenum? (AGENT 86)

You're a good guy Max. That's what I was gonna do too Scanners are outa my league
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Old Feb 7, 2004 | 08:53 AM
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Default Re: Holley AFPR hitting the upper plenum? (Tourney3p0)

You have mail :seeya
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Old Feb 7, 2004 | 01:10 PM
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Default Re: Holley AFPR hitting the upper plenum? (AGENT 86)

Thanks Agent 86. :thumbs: That's what I needed.
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Old Feb 7, 2004 | 09:47 PM
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Default Re: Holley AFPR hitting the upper plenum? (Tourney3p0)

Mine looked like it was going to hit, but it just barely cleared when I got everything bolted up. I have an aftermarket intake manifold and LTR's if it makes a difference.
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Old Feb 8, 2004 | 03:41 PM
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Default Re: Holley AFPR hitting the upper plenum? (Tourney3p0)

Alright, it looks like I must have.. erm, I mean, someone must have put the diaphragm in upside down at night while I was asleep. That's what causes it to work backwards, so to speak. Everything is once again right in the world now.

Thanks again everyone for the help.
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