I getting ready to swap to carb on the 305. Ill need an adjustable fuel pressure regulator right? What kind is good to use?

 

P/N 650-4309 Mallory 3 port return style 3-12psi $ 74.99

This is from jegs.

 

i used a holley 3 port. 25 bucks from jegs

 

mallory 3 port....i'd do that over a holley reg any day of the week for the return style features.

 

Holley 3 port on mine too. I use a 3 line return style mech. fuel pump, and a small 12 volt elec. "helper" pump.

Elec pump mounted back in the rear, 3/8" alum. line to the mech. block mounted pump, 3/8" alum. line to the fuel psi reg., 3/8" alum. line to farm clear veiw plastic bell fuel filter, 3/8" alum. line to carb.

3/8" alum. line off return fitting on pump, to the stock return line on car.

My stock rad. over flow jug was trash, so I removed it. and mounted my reg. on the side of the strut tower, and put an aftermarket overflow on the driver's fender close to horn

 

 

i mounted mine right there on the drivers side wheel well right next to the rad overfill jug (not installed for the picture obviously) because its right near the fuel lines and i just run the lines to applicable locations... heres a pic, may help if you've never done it, its cake though



sorry its so small but thats how it posted

 

http://cgi.ebay.com/ebaymotors/ws/eB...ayphotohosting

theres the mallory on ebay, looks almost exactly like my holley. whats the difference on it?

 

The Mallory is a return style. It regulates outlet pressure by allowing fuel to return to the tank (or, to put it a different way, raises pressure by restricing the flow back to the tank).

That Holley controls pressure by restricting flow to the carb. Also known as a "dead-head" regulator. Fine for pumps that can be dead-headed, death to factory in-tank type pumps.

We need to be careful about our terminology. By "3 port", we typically mean three different port functions (inlet, outlet, and return). That Holley "3 port" is actually 2 port, function-wise, inlet and outlet - it just happens to have two outlet ports.

 

well wuts worse using a mechanical and disabling the elec fuel pump and pulling through it or using a dead head on a elec fuel pump?

 

Dead-heading an electric in-tank. You'll fry it. I've seen people put a needle valve in a return line along with a dead-head reg. Not ideal, but if you play with it, you can get enough return flow to keep the pump cool but not starve under load.

Pulling through a disabled is a crap shoot. It may do just fine (many have), on others you'll starve the carb (many have found that out the hard way).

 

(i know this is a ghetto idea)..... but couldnt you use a clamp of some sort on the return line to restrict return flow, in other words, reduce the ID of the rubber fuel line to equal out pressures on the feed/return?

 

so five7kid, your suggesting that the only way to do it is with the mallory? in order to keep the stock in tank pump?

 

The only way to use the in tank elec fuel pump on a carbed engine and have it last a while is with a return reg. like the mallory

Now if you dont power the power the elec pump and use a aftermarket inline elec pump, or block mounted mech. pump, then a dead head reg. will work just fine. (five7kid, thanks for pointing out about the terms. You are right. I'm just use to calling the 3 port reg. like yall are talking about return reg.)

But the prob is will it suck fuel through the old in tank pump... It's a 50/50 shot. Some will, some wont. Mine wouldn't, so I cut the sheet metal over the fuel tank, pulled the stock pump out, and replaced it with a lenght of steel 3/8" line, and put it all back together.

BTW... IceManRS305.....

is that your holley reg pic? Not only is that not race legal, it's not safe. Way too much rubber line bud. NHRA says 12" total, theres a reason for that rule. I didn't feel like flaring all mine, so I used hard line, but no tube nuts. I used short 1-2" pc. of rubber line and 2 gear clamps on each of my connetions.

Here's pics of my reg., reg. mounting, fuel lines, and what I replaced the in take pump with

fuel pickup/sender.. Metal line replacing pump
http://community.webshots.com/photo/...25455184PUhyWt

reg. mounting and some of the fuel lines
http://community.webshots.com/photo/...34960338eSZSjo

another shot of reg, more fuel lines, and block mounted pump
http://community.webshots.com/photo/...34960783MZwYSq

Rear mounted elec. "helper" pump
http://community.webshots.com/photo/...34961311EXYpPR

 

57',
for a 'three' port, what is the functional difference between
the inlet and the outlet?
To me, they are the same thing.
I would call those two ports, the 'high side',
or the 'regulated' side.
Do those two ports have, different fittings?

To me, a 'bypass' regulator is a two port,
with the understanding that there may be a
third opening, to the air.

a bypass, is not a deadhead, btw.

 

Night rider327.... yes i know about the rubber lines.... it was used for test purposes / get my engine started.... i guess ill just have to do what you did with your lines.... also whats the part number for that helper pump?

 

"Dead-head" is what is typically called a 2-port - an "inlet" or "supply" port (where the fuel comes in), and an "outlet", "pressure", or whatever you want to call the regulated pressure outlet, regardless of how many of them there are. The typical $25 Holley reg is such a part, and it has two outlets so that you can attach one to each bowl (primary and secondary).

"Bypass" - I suppose you could call it that. More typically called "3-port" around here, or "return" type. It will have an "inlet" or "supply" port, an "outlet" or regulated pressure port, and the "bypass" or "return" port, whatever you want to call it. That last port doesn't open to the air, it returns the excess to the source (or wherever you want it to go - why any place but the tank?). This allows the pump to operate at a continuous flow.

The oil pump in your engine operates the same way as a "return style" regulator. Of course, its speed varies as does the flow with engine speed, but the "bypass" valve regulates the pressure in the engine lubrication system by allowing flow that the system cannot use to return to the supply - in this case it just dumps back into the pan.

You could do the same thing with fuel pressure if you wanted - just put a check valve at the carb that opens at 6 psi, and route the outlet of the check valve back to the tank. Check valves don't tend to be as precise as a regulator, though, which is probably why you don't see more people do it. I've considered rigging up a check valve on the opposite side of the Holley fuel bowl inlet and dumping it back to the tank just for that purpose - I haven't spent the time to locate such a valve, though. But, in concept, it should work. With the return right at the bowl, the fuel flowing by it should carry away heat from the carb as well. It would probably make sense to only have the check valve on the secondary, since it doesn't see as much flow, and whichever valve is cracking at the lower pressure is the one that is going to operate all the time, anyway, so only one would make more sense than having two. It would reduce chatter (constant cracking and reseating at low flow) as well.

 

IceManRS305...
Cool deal. I just wanted to point that out. Glad you already knew about the rubber line.

The little helper pump i'm running is the Purolator PRO 12SV. It's a 4-7 psi pump, that flows 35 GPH.

Not near big enough to feed a v-8 along, but it gives a nice little push to the fuel, so the mech. pump don't have to try to suck the fuel all the way from the tank. This mays sure my mech pump don't have to play catch up with the engine's fuel needs

I had mine on a throttle micro switch, so it only cuts on at 75% or more throttle opening, but I wired it to a toggel now, so I can get quicker hot starts, when the fuel settles down, or if I get any vapor lock.

I just flip on the toggel wait a few sec. then crank engine, then kill the elec pump. When racing, I cut on the pump after I do my burnout, and leave it on till I stop at the timing shack, then I kill it

 

Hey Five7 (or anyone else who may know),

What about Fuel VOLUME with a stock TPI pump, Mallory return reg on 670cfm? I know there is plenty of pressure but does the factory pump supply enough volume?

Also, since the regulator has extra ports for regulated output, would it be a good idea to use one port for the primary bowl and one port for the secondary?

And one more thing, about that vacuum connection...is that worth using?

Thanks in advance guys

 

That's the one I picked.

 

If the pump is in good condition, it will supply plenty of volume.

That, or the typical "Y" or "T" line will work equally well, provided they are of proper size and don't have restrictions built into them.

What vacuum connection?

 

i think he means the vacuum connection for raising the pressure under boost with a turbo. 1psi boost = 1 psi more fuel pressure.

nebu.

 

It's a nice feature on any engine even a N/A setup. There was a guy making an on demand vacuum regulator that worked in perfect sync with the engines fuel demand. I think his pattent was bought out.

Not to hijack the thread but have a question. If your running a return style block mounted pump with no push rod and an electric pump in the rear, non FI pump. Hows that setup on fuel pumps?

 

That Vacuum (?) port on the pressure reg. I have mine hooked to the carb so it allows more fuel as your vacuum increases.

 

I tried using the mallory 3 port reg w/ a stock TBI pump on my carb'd 406, i couldn't set the fuel pressure, it was constantly moving, and most of the time the gauge said 0, and yes the gauge was good. I assume it's the low pressure/volume of the TBI pump. I am going to put a walbro 255 in that I have laying around and be done with it.

 

LilJayV10, did u rewire the stock pump? because you need to. u cant just plug and play, what i did with mine was i just installed a switch and a 30amp inline fuse. works just fine, should pump out enough pressure for you, unless your pumps burnt