First of all...WOW!!!!!! Never expected this much replies. Personally, I've never used a regulator mounted after the carbs in all of my dual configs. If I did use a regulator, it was always before the carbs and it was always Malory's part# 4309 (from jegs, summit). I've only used the regulator twice, mainly due to the cost of one, and all the fittings that go with it. I've used carter fuel pumps in 4 different trucks dishing out a steady and reliable 4psi and thats without a regulator. With webers, its not so much about a regulated fuel pressure, its about volume as Nook stated. As long as the fuel bowl stays full, they should be happy. A regulator will only do two things: It will regulate the fuel pressure in your fuel system and it will inhibit fuel fuel (depending on where its located). Also, if you look at my initial post, you will see part numbers. The regulator that is in the picture is Mallory's part#4309. It is a BYPASS type regulator, meaning fuel will be bypassed in the case the fuel bowl is full. With that said, it doesn't matter if you mount it before or after the carbs because the excess pressure/fuel will be bypassed. NOW, someone will be bound to say, "Why would you mount a bypass regulator in front of the carbs...it will only inhibit flow". WROOOOOOOONG!!! If you look at the 3rd picture posted, I have a pressure gauge block used after the regulator and between the two carbs (its actually before the carbs, but I had it installed between the carbs in my config). I had the truck for 9 months before I sold it, and the pressure never fluctuated outside 3.5 to 4psi. To put this to rest, YOU CAN PLACE THE FUEL REGULATOR BEFORE OR AFTER THE CARBS AS LONG AS IT IS A DIAPHRAGM BYPASS TYPE REGULATOR...END!

 

this is a great write up,i really needed something like this for my side drafts

 

Nice truck, I saw it in the customer rides of LC Engineering Newsletter.

 

I'm not sure where you got that information, but the stock 20/22r engines does NOT have a regulator on carb applications. Nook is right, the excess is dumped via the mechanical fuel pump. If you have a picture proving otherwise, i'd love to see it posted. I started this thread to help people out, not to confuse them. I used the setups displayed in 5 of the toyota pups i owned and helped friends using the same setup with no problems with fuel delivery. All problems that I had related to sidedrafts was to do with equal tunning of throttles, and linkage issues.

 

^ I think you forgot about the later 1st gen 20R celica's that had in-tank electric pumps... The banjo "T" on the carb had two different size ID pipes, no external/visible regulator...

Agree with 20/22R mechanical returns...

My sidedraft setup runs fine with the stock mechanical pump...

 

Carbed upp

THIS ISNT A 20/22R BUT,THIS IS HOW I RIGGED UP A PAIR OF DUAL MIKUNI 44 CARB'S ON THIS Z~24

 

thanks I was gunna call you later and ask if I need a fuel pump to run my weber 40s

 

New here and I'm sorry for the intrusion.

The topic piqued my interest because in my first and only carb/side draught project on a 20R motor (1979 Corona Sedan), I took the existing fuel line in the engine bay and did as follows:

fuel line->filter->holley 12-804 (non-bypass regulator)->mikuni 44phh carbs

Now in that setup, the car already came with an in-tank fuel pump from the factory. I installed the liquid filled gauge on the fpr and just dialed in the pressure to 2.75-3psi IIRC. I don't recall hooking up a return line but I can always give the owner a call to check for me. It has a torquer cam and a fresh head. The car pulls great after dialing in the fuel pressure. In all of the carb setups I've done (all 4AGE motors) I've never had to run a fuel return and some in the 4AG community early on have stated that it isn't necessary and actually suggest against it. It's always been a nagging thought especially when a good deal of my inspiration came from growing up around muscle cars.

I'm reconsidering future and existing setups but the bypass fpr options I'm seeing go no lower than a purported 3psi.

Then there's Todd Walrich out of NY running an all out Race 510. His last setup that I was familiar with did not incorporate a return line.

See, I go back and forth.