Fuel return line

[tanny]

On my 1973 Z there is a fuel return line. Since my car came with triple Webers, the return line was not hooked up. To help eliminate a vapor lock problem, I hooked the return line back up and put the fuel pressure regulator on the return line to create back pressure into the carbs. How did the stock fuel line set up create enough back pressure in the line to fill the carb bowls? There must have been some kind of restriction on the return line. Thanks, Victor.

[Bambikiller240]

On my Z's (all have/had stock SU's); the return line that wraps around the front and carb side of the engine is/was of a smaller diameter that the supply line.

[tanny]

So then the smaller diameter line was enough of a restriction to maintain enough fuel pressure to fill the bowls. I was thinking there might have been a restrictor valve of some sort. Interesting. I guess I'll try taking the fuel pressure regulator off the return line and install it before the carbs where I had it before I attached the return line. Thanks, Victor.

[240ZMan]

tanny,

On my 73 with stock fuel rail, the return line on the rail is smaller, but at the end of that nipple where the rubber fuel line connects there is a further restriction. It's almost as if the nipple had been fully closed and then a small hole had been drilled. It's been a while since I looked at it, but I'd guess it was smaller than 1/16".

Daniel

[tanny]

Thanks for the responses. I went ahead and removed the fuel pressure regulator and then measured the fuel line pressure. With just the electric pump running the pressure was 2.0 pounds, and with both the mechanical and the electric pumps running at idle, the pressure was 2.5 to 3 pounds. This is apparently enough pressure(and volume, which I didn't measure) to run my triples even at higher RPMs with my mostly stock setup. Victor.

[240ZX]

Tanny,

On a stock fuel manifold for SU carbs, the pressure was obtained via a small metering hole (restriction) inside the cube like little block on the return line. When I redid my fuel manifold I did not use the stock setup because I just didn't like the way it looked, so I cut open the little block just to have a look. Sure enough, there was a smaller diameter hole within the little block. If you are interested in how mine turned out, visit my humble photo album, under 240ZX.

[Chino 240Z]

Hey 240ZX,

I could sit and look at the motor all night long!

Your Z is my Zs hero! I need to show Mrs. Chino what we want Santa to do to ours!

[tanny]

I hope you don't drive that pretty thing. No way would I want to get that dusty. Victor.

[240ZX]

Chino,

If you want to stop by I can set up a lawn chair for you and I'll give you rags for polishing.....then you can spend all night looking and rubbing on my 240ZX! Just joking. I didn't know Santa was a Z guy! Doesn't he drive a sled with an 8RD power plant?

Hay, thanks for the compliments on my L28.

P.S. Tanny, yes I do drive it but never in bad weather. It's so much fun to drive it should be illegal. I was having so much fun last saturday afternoon, I got a ticket for it. Can you imagine, 67mph in a 55mph zone....I was just cruising along minding my own business when all of a sudden a CHP appeared out of know where with a radar gun. Damn, and I was the only person on the road until he showed up! I quess getting a ticket for 12mph over the limit is by far better than one for 30+mph over, cuffs, and a free ride to the station!!!

[tanny]

Geez! That cop must have been having a bad day or was just bored. Shouldn't be too many points on the license though. Victor.

[Bambikiller240]

It will only be one point on the record. My most recent speeding ticket was for 20 mph over the limit and the cost to clear it was $170, or Option B: $190 and traffic school ($20) to keep it off the driving record so the insurance co doesn't F*ck you.

[Chino 240Z]

Ya know 240ZX, it's the red color that got you stopped. Out of all the colors I have owned Red says 2 things Light'em up & Write'em up! as a matter of fact I have a compulsive disorder, and polishing cars is away to get in that zone. I once had a sand rail that was all polished alum. and it takes alot of work keeping it nice, a few 1st place off-road car shows is the pay off. Now it is just nice to have a clean ride. Our Z is clean for a track car but they get hammered, chipped and dirty easy in track traffic.

This is a pic of my daily driver, (sorry not a Z but it is RED sled!) I ordered it in 1993 to my taste, 10 yrs. & still looks like new. Just can't stop tweakin under the hood! That is a main reason for getting the Z, take the race to the track. It's working no more tickets!