Technical Fuel Pressure Regulators and Issues and Options

Stogy search for the thread "Holley 94 tech links" started by Dreddybear in 2009 if you have not already done so. Hours and hours of reading will bring you up to speed on 94s. (note spelling of Holley in the link) Regarding new or rebuilt bases:They cost about $100 each, I'm not at this point ready to spend $400. I have some ideas to try out on using the bases I have. No one ever said hot rods were cheap.

 

There is a social group named "Holley 94" that Dreddy Bear started years ago that is full of info. A must read for anyone intending to use these carbs.

 

So I got the New replacement promptly and installed the larger of 2 dias. of fittings shipped...Got it all together and can dial it now to near 0psi and have been running it at 1psi...No leaks at all and all seems stable...Yay!!



Now I did being a nosy Hoodlum disAssemble the old one looking for whys and here is my take...I noted 2 issues that I believe contributed to 9-10psi...There was corrosion but that was not causing grief...



...removed the screws and separated the 2 main pieces...the flexible diaphragm is visible in the back of the two main details...



...Here is I believe the problem...with the Diaphragm that has a rubber stem that sits in the bored pin in the center of pic removed, there is a circular retainer pressed in that you can visibly see is popped up in a crooked fashion...not out but not in its proper seated location in the counterbore which I believe is a slight interference fit with no adhesive. Note that off kilter retainer is a seat for an O-Ring on the other side that sits on the bored pin sticking up through the retainer that has pressure from another spring hidden. I believe the O-Ring was not seating with the retainer off kilter...



...preset at manufacture this set screw sits in the aluminum cup below



...this aluminum cup sits on the set screw (Note wear) in the pic above and the spring on this cup puts pressure on the disc on the diaphragm...This is moved up or down when you rotate the Regulator Knob...I noted the set screw was not Loctited or restrained and moved with an Allen key quite freely...leading me to believe the wear may have affected adjustment to a degree.

I was thinking I could repair this by replacing the O-Ring as a precaution, slightly tap the O-Ring retainer and press it back into its correct orientation and the Diaphragm looks okay and there was no leaks. I could put a little Loctite or Teflon Wrap on the set screw as well to give it more resistance to loosening. Note the setscrew is not on the fuel side.

I also thought I would drill a hole thru the Adjustment Knob So I could adjust the set screw to achieve proper psi...so I go and peel the sticker off and low and behold there is a adjustment hole there already...

That aside I still think it was the O-Ring not seating correctly due to the retainer moving due to 9+ years of vibration...

Another thing to note is the New Regulator which does not have a name brand or sticker at all has NO adjustment hole...BUT it does regulate properly...

Lastly Long winded Stogy......also noted that the only plastic on my old regulator was that hose fitting...the rest was Metal. I again wonder how Old this Regulator design actually is and don't forget it was no doubt a North American Designed Part for Hotrod Race despite being manufactured elsewhere these days...and some still claim they are made here and perhaps they are...

 

I have used the $30 Holley type for 20 years. I have been thru 2 of them. I am running a Holley red pump. I have a 3/8" NPT Tee and a fuel pressure gauge. I kept it set a 5.5 psi.

A few times over the years I worried they are too cheap to be good. At the 1st Bayou round up I actually took mine apart and cleaned out the crap from ethanol and put it back together just fine.

 

For a 94 holley carb ? or something else ? Thanks

 

Edelbrock 4 barrel 650 CFM I think the pn 1405