How to Modify Holley Regulator to Full Bypass

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Bakerlite

Bakerlite

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Bakerlite submitted a new Article:

How to Modify Holley Regulator to Full Bypass

Here I'm going to show you how to modify a standard "dead head" Holley reg to a full bypass type.

Here is the stock regulator in pieces, you can see how small the stock feed hole is and why these things are capped to around 450HP.

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Here is the retainer, spring and ball valve. The part on the far right is the seat for the ball and this can easily be removed from the housing with a small drift or a bolt used as a drift (punch). Remove them and throw them away.

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Here is the standard diaphragm. Just cut off the pin with a hacksaw and file off any sharp ridges left from cutting it.

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Here it is modified.

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OK, next I put the housing in a vice and drilled out the housing with an 11.5 mm drill bit. You could use a 7/16. That port is a lot larger now :)

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Time to make the new seat. I took this , stuck it in the lathe,


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And made this seat out of it, The hole in the center is 3/8 or 10mm

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I then pressed it into the housing with a soft ( alloy) drift so it wouldn't hurt the face of the seat. The new seat has a slight interference fit. You could do this with a piece of tube that is a snug fit in the new hole and some Loctite. Just make sure the tube is cut square so it seals good enough to the diaphragm.

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I made the seat .100 thou high because as you can see there are stoppers in the original casting. If you are not careful , the diaphragm will contact these first before the seat and fuel will leak past the seat and there will be a poor seal.

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Now just reassemble with the pressure spring in its original location. The old "Inlet" has now become your return to the tank. One of the "Outlets" is used as your feed from your fuel pump and the other "Outlet" goes to your carby. You can also splice into the fuel pump line and feed multiple carbs if you like. Remember you want to have a return line around the same size as your main pump line. Returning fuel like this puts way less load on your pump, keeps it cooler and usually quieter. Keeping electrical components under high load conditions is what wears them out sooner.
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I always like people that think out of the box.
 
Well this is what Holley are hitting you an extra $50 for... A regulator with less parts. I bet the bypass ones are cheaper to make than the standard ones.
 
I`m working on an EFI setup and thought about modifying one of these regulators.
Your idea looks like it could work for an EFI setup too if I could find a spring with the appropriate pressure.
The only thing I'm not sure of is if the original diaphragm can support the added pressure.
 
Another benefit of or a bypass reg is that the fuel already has momentum and is not stalled in the line.
 
Well done!

Awesome tech for anyone with a small lathe available for use.
 
crackedback said:
Well done!

Awesome tech for anyone with a small lathe available for use.
Click to expand...

In a pinch, you could just use a piece of steel tube for the seat, you just need one that is slightly larger than the drill being used. Then don't drill all the way through the housing with the drill, leave a step at the bottom for the tube to bottom out on. But yeah, it's easier when you have a lathe.
I thought I should contribute for a change instead of hanging around just being a pain in the ***.
 
Only question I have is this. I assume you have to tap the "new hole" that was drilled thru the housing so that you can connect your inlet line to it. Could you please let me/us know what size or how you connected the inlet line to it. Thanks
 
Sure, that hole I drilled is smaller than the 3/8 NPT thread that is already there. The new seat does not reach down to the threaded section, so you can just screw in a fitting as usual. I'll see if I can take a pic to clarify what is going on in that area.
 
Bakerlite said:
Sure, that hole I drilled is smaller than the 3/8 NPT thread that is already there. The new seat does not reach down to the threaded section, so you can just screw in a fitting as usual. I'll see if I can take a pic to clarify what is going on in that area.
Click to expand...

Ok, I understand now, Im sorry I thought this was a single inlet single outlet regulator and by you drilling thru the housing, it now created another outlet/inlet. Pics would be appreciated anyways if you can provide them. Thanks
 
Here you go.. You can still see the 3/8 NPT threads .


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As you can see in this pic, the seat is a fair way away from any screw in fittings.


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