dbragg

iTrader: (7)

im running a dellorto 48 on my SP 13b without a return. fuel economy and all that arent an issue in that case. however, ill be installing a 48 dellorto on my 12a DD soon and im trying to decide if a return line in needed. will it actually help fuel economy any? im not worried about the life of the pump. lots of guys are running the carter without a return with no issues. so, give me your input.

heres where to get dual dellorto inlet, for future reference:

http://cgi.ebay.com/ebaymotors/DELLO...3483QQtcZphoto

Rx-7Doctor

iTrader: (13)

On a friends Sp 12a with the Sp header system and a 45OER carb, he was getting between 17-19 mpg on the highway without a return line.

dbragg

iTrader: (7)

i know who youre referring to. he also went boom to. so i dont think i need to take notes from him jk doc. hopefully he wont get mad if he sees this, no hard feelings

ill have a exhaust on before the dellorto. i currently have a 2nd gen coil and i hope to have a TT for it when the bugs are worked out. i thought about adjusting my timing to help out a little, but im a little scared to do so.

Midwest 7's

iTrader: (4)

im not using a return on my stock 12a with dell.
dont know about the mileage because i always have the pedal to the metal.

Rx-7Doctor

iTrader: (13)

Yep, that was not a good thing. I'm done with his replacment motor in the car and am now cherrying out the rest of the car so he can sell it.

Read peejays thread on his timing settings.
https://www.rx7club.com/showthread.php?t=604918

dbragg

iTrader: (7)

haha i knew youd show up here. yeah, i try to drive moderately now. i know after i get the header and exhaust on and the dell itll be hard for me to stay out of the throttle..oh well. ill just get from point a to point b faster

dbragg

iTrader: (7)

thanks doc. i have read peejays explanation many times. im just slightly skepticla to try full advanced timing on my DD. i cant risk my engine going pop.

dbragg

iTrader: (7)

Well, I am again debating doing this. It's a different car now.

How many people have dellortos with returns?

t_g_farrell

iTrader: (1)

I don't know if you remember me from Zoomfest last year but I was running my Dell
with no return using dual facet fuel pumps and getting 25+ mpg on the highway.
That setup lasted almost 20 years on my car. So no return probably is not a big
issue.

I had to install a Carter because the facets finally gave up the ghost on me in
the mountains this fall on the B3R run. You will need a regulator for the carter to get
it down to 2.5 psi. I'm debating running a return with this just so the pump doesn't
have to work so hard. Also adding a return can help avoid vapor lock which I did
experience driving home from Zoomfest in 104F heat.

Like you I'm not that worried about mpg, its just a side affect.

Congratulations on reviving your own thread from 2007. You should get a prize
or something for that

rxtasy3

iTrader: (2)

now i can see how running a return line will slightly reduce fuel pressure at the carb, but i just can't see how it will actually affect fuel mileage. the carb is tuned/jetted for optimum performance. how does running a return line or not change that?

edit: 2007? didn't even notice that. vapor lock tim? i've never experienced that.

DriveFast7

iTrader: (1)

the return line won't affect fuel mileage in and of itself. rxtasy3 is right you'll need to reset fuel pressure afterwards. the return line makes the fuel pump last longer, stay cooler, run quieter, and you get a cooler supply of fuel to the carb. It's a win-win.

The idle fuel jet and idle mixture screws have the largest affect on mileage, especially highway. Dellorto is a great carb, I too got 25+MPG on the highway.

ratboy

iTrader: (1)

I have a delorto on a half bridge without the return line. This was the best source of info on delorto carbs I could find when I had the same question....

http://www.gruntled.com/Dellorto/

dbragg

iTrader: (7)

Tim-- Yes I remember you. I was hoping you would chime in.

I think I may go with a return line for a few reasons: ease up on the pump a little, get colder fuel, and why the heck not? I just need to make sure the PO didnt remove the return hardline, which may be the case. If not, I will run it just to see what changes.

Now, I need to decide the best route to do so. Any input on which would be better: a return line from a FPR, or from a dual outlet fuel inlet on the carb? I don't really want to buy another FPR, but just the dual inlet is $30, so I may if its benefits justify it.

installer67

iTrader: (18)

I'm about to do the same thing on my dcoe 45, and from all I've read, it doesn't matter one way or the other, if you have an FPR with a return, use it, if not return from the carb, you just have to use something on that line as a "restrictor". The factory return line had one in e the line.(little barrel looking peice). Some people have used a simple extra jet drilled out etc.

DriveFast7

iTrader: (1)

I've used both types, just make sure there is some sort of restrictor in the return line. I used a brass barb fitting with a smaller hole in it for the return line. Got it at Lowes. I'm using 3/8" host to the carb and the brass fitting is also 5/16" which in itself is also a slight restriction. But the smaller hole is the bees knees.

pinoyremix

on my 12a dellorto 48 used the mallory fpr and a gslse tank, pump and hardlines. it works great

Keith13b

iTrader: (6)

I'm running the same on a 13B except I'm running a Mallory LP Comp pump. However, my Mallory FPR does not have a return outlet! I haven't used a return line in 17+ years - I get 26 mpg on the highway and never thought of using a return except for pressures over 15 psi.. I am about to replace the Mallory FPR with the Holley unit. Anyone know if it has a return outlet? Ironically the factory return line is sitting there - plugged next to the FPR. Never new people used them on low pressure set ups. I still have a Mallory HP FPR w/ the return outlet.