I just ordered my new 540ci, 685 hp Shafiroff motor, I got the Merlin block, so I have provisions for a mechanical fuel pump. Am I crazy to use a mechanical pump? The car will be a street cruiser, with the occasional trip to the strip. How many GPM will it need to flow? What size line do I need to run? Where is the regulator normally mounted? And finally, do I need to do anything with the pick-up in the tank?
Sorry for all of the questions, this much power is totally new to me.

Nice setup. What is causing you to stick with a mechanical pump? I wont say your crazy, just a little loopy...

If I were doing that setup, I'd go with an electric pump with at least 140-150 gph, such as a Holley black or Aeromotive street rod pump, with a bypass. You could use -8 but I'd suggest -10 line. From a sumped tank. You should never skimp on a fuel system. Your regulator can be mounted in a number of locations (firewall, fuel rail front or rear, etc.). I like it at the fuel rail with a gauge at the furthest carb inlet.

Good luck with the project. Enjoy.

Jim

My dad has a Shafiroff 548 and I think he ran a 250 gph pump with no problems but I'm not sure how much smaller you could go, that was through -8 line. I can't say I've heard of someone running a motor that big with a normal mechanical pump but that also means I don't know that it won't work.

IIRC, Tom Baird over on team chevelle runs a 540 in an early monte carlo and uses a 172 carter pump with -10 lines and is running very bottom 11's with it. I don't know any more details than that but I think he is also running an electric pump out back. You've spent a lot of $$$'s on that engine...I definately wouldn't skimp on the fuel system.

Theoretically, the mechanical pump could provide the (approx) 60 gallons per hour that the engine would need, using the formula of 1/2 lb of fuel per horsepower per hour. That's if you used a quality mechanical pump and not a stocker. So, 700 x .5 = 350 gal. I'm assuming 6 lbs per gallon here. 1/2" aluminum hard line to the pump is recommended and -8 from the pump to the regulator finishing with -6 to each bowl would be fine. One other thing, if you plan to race at the track occasionally, don't put the regulator on the firewall, that's against the rules. Mount the regulator as far forward as you can (toward the radiator support). You want it "ahead" of the engine. Hope this helps.

Wouldn't it be best to contact Shafiroff? They built the darn thing.

My two cents; a 700 horse motor does not drink it slurps. Two problems with a mechanical pump. One: it is on the wrong end of the car. It needs to be lower than the tank outlet and behind it. That way it can push the fuel to he front with all of the surplus pressure you can muster. Second: a pump attached to a hot motor transfers heat to the fuel, making for lower density fuel. Since carbs measure volume not pressure this is a bad thing.

I like an AN10 line there and back again. Use a bypass pressure regulator instead of a dead head style because as pressure goes up volume goes down. A carb is a volume operated (calibrated) low pressure (about 1/2 psi) devise that likes a constant temperature and a static environment; neither of which it finds in an automotive application. So anything you can do to make for a less stressful day for your carb the happier it is in mixing toxic chemicals that go boom.

Worst case scenario would be a single 3/8th line from the tank pick up above the frame rail to front of the car were it gets passed through a single rubber hose to a mechanical pump bolted to the block that uses the built in transport spring as the pressure regulator as well (just the way the factory designed it).

Larger Dave

My two cents; a 700 horse motor does not drink it slurps. Two problems with a mechanical pump. One: it is on the wrong end of the car. It needs to be lower than the tank outlet and behind it. That way it can push the fuel to he front with all of the surplus pressure you can muster. Second: a pump attached to a hot motor transfers heat to the fuel, making for lower density fuel. Since carbs measure volume not pressure this is a bad thing.

I like an AN10 line there and back again. Use a bypass pressure regulator instead of a dead head style because as pressure goes up volume goes down. A carb is a volume operated (calibrated) low pressure (about 1/2 psi) devise that likes a constant temperature and a static environment; neither of which it finds in an automotive application. So anything you can do to make for a less stressful day for your carb the happier it is in mixing toxic chemicals that go boom.

Worst case scenario would be a single 3/8th line from the tank pick up above the frame rail to front of the car were it gets passed through a single rubber hose to a mechanical pump bolted to the block that uses the built in transport spring as the pressure regulator as well (just the way the factory designed it).

Larger Dave

Yes, what Dave said.
I have 700hp. I use a Mallory Comp 140, -10 to and from the regulator. Sumped tank (Cell) etc. Full return is just the best way to do it.
Also, you can't mount the regulator on the firewall. It's an NHRA no no.

BTW....Tom Baird's Monte is in the 10.30 range now I believe.

Ron

I'll be the bad guy here and say a mechanical will be fine. I know this for two reasons..........

#1... I've done it.

#2... A friend still does........EVERY WEEK.


Let me fill in the blanks...... My buddies 68 camaro runs a 496 that dynoed 680 hp. It weighs 3450 lbs and has run 10.0 @135. All he has every run is a edelbrock 140 gph mechanical pump with -8 line and a sumped fuel cell. We bracket race weekly and he's going on 450 passes and 5 years with NO ISSUES. I personally have a very similar combo but have switched over to a holley black pump.........with no performance gain whatsoever.
We both have pressure gauges and my pressure never drops below 6psi at any point neither does his. Also we use very little fuel to make a complete 1/4 run. Last week I used less than 5 gallons of fuel to make 8 passes. In my opinion mega pump not needed.....ESPECIALLY for a mostly street driven car :thumbsup:



bob

My car is about half that horsepower, and several seconds slower... using a non stock mechanical pump and 3/8" line. Took her to the track last month, with newly installed WB and fuel pressure gauges in the dash.

Fuel pressure was ZERO for nearly the whole back half of the track.
W/B said AFR was holding at 12.5, so I guess she was getting enough gas, but I don't know how or why.

I'll be going with an electric pump and bypass regulator and return line.

I just ordered my new 540ci, 685 hp Shafiroff motor, I got the Merlin block, so I have provisions for a mechanical fuel pump. Am I crazy to use a mechanical pump? The car will be a street cruiser, with the occasional trip to the strip. How many GPM will it need to flow? What size line do I need to run? Where is the regulator normally mounted? And finally, do I need to do anything with the pick-up in the tank?
Sorry for all of the questions, this much power is totally new to me.


I agree with Bgonz 69, he is absolutely correct. He and his buddy race and do just fine. You said your's is primarily a street cruiser, so you'll be more than fine. So many people do stuff because everyone else does it, with no regard to what they actually NEED. Most cars are setup with overkill for no real reason.

A buddy of mine dyno'd his 540, which made 890hp and while doing that, he was using 55 gph. Joe Sherman, yes THE Joe Sherman, whose dyno it was, said you need to have a free flow rating of twice that to keep up. So by that measurement, a 110 gph free flow, mechanical fuel pump would be just fine. Your engine would need even less, but if I were you, I'd go with a mechanical pump free flow rated at 110 to 140 gph, and never give it another thought. I'm building my 540 with an Edelbrock mechanical fuel pump free flow rated at 130 (could have been 140, I don't recall exactly off the top of my head, its been awhile) gph.

My car is about half that horsepower, and several seconds slower... using a non stock mechanical pump and 3/8" line. Took her to the track last month, with newly installed WB and fuel pressure gauges in the dash.

Fuel pressure was ZERO for nearly the whole back half of the track.
W/B said AFR was holding at 12.5, so I guess she was getting enough gas, but I don't know how or why.

I'll be going with an electric pump and bypass regulator and return line.



Gauges usually dont lie but I bet the problem is in the design not the pump. A completely stock tank and sender and 3/8" fuel line was fine up until my car reached the high 10's which is probably about 550-600 hp. We modified a stock sender with a 1/2" aluminum tube and soldered it to the housing, then ran -8 all the way up. That was good for low 10's @130+ again with a mechanical 140gph pump in a car that 60'ed in the mid to low 1.50's. I'm sure the reason your pump isnt providing enough at the gauge would/could be easily cured. Maybe your pumps a dud ??? I like the idea of a mechanical pump in a street/strip car much better than an electric, its one less thing to leave you stranded.



bob

Carter (172gph) mechanical
or
Aeromotive SS (160gph) electric

This is a great thread guys. I am also putting a 540 682 hp Dart block and heads motor from T&L engines in my Chevelle. This car will be street driven only. I have been looking at both mechanical and electric pumps. It is pretty easy to see the benefits of either one. I like the simplicity of a mechanical pump. What I was thinking is running one 1/2" AN line from the sending unit, through a filter, and on to a high flow pump like the Carter 172 or a holley. After the pump I am thinking go through another filter with 1/2 AN line then regulate down to 6.5 psi with a regulator mounted on the right inner fender. After the regulator run 1/2" AN to a guage and split from there into two 3/8" AN lines to the carb. No return line to the tank needed is there?

It also seems as though this would be less expensive than the electric pump and less worries about getting stuck on the side of the road. If the pump ever should fail it is a 1/2 hour job to replace and could be done in the parking lot of the parts store if need be.

Sorry if I hijacked the thread a little bit. Does going this way make sense?

On higher horsepower engines, installing those mechanical pumps goes against all my better judgment. My head is going to explode... :clonk::D

Jim

I'm glad to see that this isn't real cut and dry. I feel less dumm now, if that is possible. This car will be a street car that occasionally sees the track, and not a track car that occasionally sees the street.

That said, here's what I plan so far...

I will go with the Holley 170GPM mechanical pump. Less stuff to break. It has a -10 inlet and -8 outlet. I will run -8 from the gas tank (I really don't want a cell) to a frame mounted filter. From the filter, I will run -8 to the mechanical pump. From the pump, I will run -8 to a regulator mounted on the top of the motor, very similiar to .gearhead.'s 68 (very cleanly done), and then on to the carb. I won't need a return line, correct?

But, if I am running 1/2" line all of the way, it has to hurt by having a 3/8" pick-up in the tank. What can I do about it? Does anyone make a new pick-up I can use, or do I have to fabricate one?

What kind of pump does a cup car run at 800 HP....

What kind of pump does a cup car run at 800 HP....

it's a belt drivin pump

I'm glad to see that this isn't real cut and dry. I feel less dumm now, if that is possible. This car will be a street car that occasionally sees the track, and not a track car that occasionally sees the street.

That said, here's what I plan so far...

I will go with the Holley 170GPM mechanical pump. Less stuff to break. It has a -10 inlet and -8 outlet. I will run -8 from the gas tank (I really don't want a cell) to a frame mounted filter. From the filter, I will run -8 to the mechanical pump. From the pump, I will run -8 to a regulator mounted on the top of the motor, very similiar to .gearhead.'s 68 (very cleanly done), and then on to the carb. I won't need a return line, correct?

But, if I am running 1/2" line all of the way, it has to hurt by having a 3/8" pick-up in the tank. What can I do about it? Does anyone make a new pick-up I can use, or do I have to fabricate one?

You might want to consider a slight change in your plans. The filter should always be AFTER the pump on an engine driven mechanical fuel pump setup. The reason is because you don't want additional restriction on the suction side. Doing that could lead to enough restriction to cause fuel flow problems at the track, that might otherwise not occur. At the track you'd be fighting that restriction AND the G forces of accelaration. Depending on how things all work out, you might even experience problems with that on the street when driven aggressively. Just put the filter AFTER the pump, and you should be good to go. Everything else sounds good to me.

BTW, I know of guys who run low tens with 3/8" pickups in the tank, and 3/8" line all the way up to the pump. So, I can't imagine your pickup really causing you a problem, assuming the sock is clean.

Thanks. I am assuming a quality in-line filter? What micron rating should I go with? Does anyone have a pic of the plumbing from the mechanical pump to the carb? I'm just looking for ideas on how to make it look neat and clean.

it's a belt drivin pump

A Carter 172 GPH should be fine.

And camaronut79 is partially correct.

The latest factory effort R07 has provisions for driving a conventional diaphragm fuel pump off of the camshaft.
A remote-mounted mechanical fuel pump can also be driven via a cable from the rear of the camshaft. When using the cable drive, the fuel pump can be relocated to the rear of the car near the fuel cell. This enhances safety in an accident by mounting the fuel pump in a less vulnerable location.

There`s a bit of plagiarism going on here btw... but never the less a mechanical pump can be used without alot of money and hassle

Thanks. I am assuming a quality in-line filter? What micron rating should I go with? Does anyone have a pic of the plumbing from the mechanical pump to the carb? I'm just looking for ideas on how to make it look neat and clean.

Hybryd:

I have some pics I took at the great Northern Chevelle gathering the weekend before last. This is one f the things I specifically was looking for at that show. I will hunt them up and post them here or email them to you in the next couple of days. Syracuse Nationals are here and there are 6,000 yes 6,000 classic, muscle and hot rod cars coming into town :cool:. It may be Sunday before I get to it.

Mark

3/8ths fuel line and AN-8 are synonymous. A 1/2" line equates to a AN-10. There is no reason to yank out a perfectly good 3/8" fuel line to install AN-8 braided hose.

Big Dave

3/8ths fuel line and AN-8 are synonymous. A 1/2" line equates to a AN-10. There is no reason to yank out a perfectly good 3/8" fuel line to install AN-8 braided hose.

Big Dave


Ever measured the ID of 3/8 fuel line? It ain't 3/8, you have to subtract 2x the wall thickness of the tubing. Steel or even alum tubing is measured in OD. ID is considerably less. Alum being thicker, is even less than steel tubing.

I'm sitting here with pieces of both -6 and -8 braided line. These are measured in ID.

-6 = .340 ID.
-8 = .460 ID.

3/8 tubing OD = .375
Subtract 2X wall thickness which is typically .035 and you get .305 ID.
1/2 OD = .500
Subtract 2X .035 and you get .430". Even smaller than -08.

While it's true that -10 hose will allow 1/2 tubing to slip inside......the ID's are quite dissimilar.

-8 if used throughout the fuel system, is quite adequate. -10 adds insurance.

Ron

So if I go with a HP mechanical fuel pump like a Holley 170+ GPH and put a regulator in do I have to run a return line or can I just use a single feed line like is on my L78? My new tank and sending unit is only a single line and it would be a pita if I have to do a return line.

Thanks

Mark

Bump. Will a normal vented gas cap and one feed line be sufficient for the 540? The car will be street driven only and we are putting in a standard fuel tank. Do we need to be concerned about too much vacuum on the tank?

Also does anyone have any suggestions or experience changing out the 3/8" feed line to a #8 AN line? What about the fitting on the sending unit?

Thanks

Answers are easy....
1. Alot
2. Big one, better to be oversized than undersized

I would recommend the Aeromotive SS pump and a bypass style regulator. I know first hand it will will support 650-700 HP and 10.0 @ 130mph ET's. 1/2" hard line and -8 braided is enough as well. My LM1 shows AF ratios as flat as a pancake so I know it is not "on the edge". Keep in mind I am running E85 which requires approximately 30% for fuel than gasoline to make the same HP.

We just did a pair of 572 / 750 HP motors in 2 cars and run a Holley Billet mechanical pumps on them and they are fine. And self regulated. Neither car has any stravation issues except being always thristy.

As fr how much it may drink. We filled up Project Prodigy (aluminum 540CI/684HP) 100 feet from the on ramp to the interstate, drove exactly 60 miles, got off the interstate and went to a station 100 feet off the exit ramp, and filled it. It took 6 gallons. So 10 miles to the gallon on the highway at cruise with a TKO600 and a 3.73 gear, no beating on it!

Eric and Frank: What did you do at the tank? Did you just go with a vented gas cap or did you have an additional vent tube? If you went with an AN fitting at the sending unit how did you attach it? Did you just cut out the 3/8" fitting on the sending unit and weld in a -8 AN fitting?
I was thinking about this today and am wondering if we can put a T fitting at the sending unit and then use one side for a vent tube and one for the feed line going to the fuel pump.
We have a Holley 170 gph fuel pump and the engine builder said to regulate the feed to 6.5 psi so we are planning on running -8 AN line from the tank to the pump, then filter, regulator and gage after that. The Holley regulator is a dual feed so we will run one side to each feed on the AED 850 carburetor.
Frank, my 540 motor is basically the same as the one you describe, 540 cu in. and 682 hp with the alternator, PS pump, pulleys etc on the front end. We are putting a 2004r from the real Art Carr in with a .67 overdrive gear. The rear end will be 3.73 like the example you gave. Didn't figure to get great mileage and anything in double figures will be good. Being an optimist I was hoping for 15 mpg on the highway. We'll have to see. Regardless it will be a lot of fun.

Cup cars all used to be conventional diaphragm fuel pumps until the COT which are now cable driven. They've never used a belt driven pump. The non-COT cars are still using conventional pumps.

3/8ths fuel line and AN-8 are synonymous. A 1/2" line equates to a AN-10. There is no reason to yank out a perfectly good 3/8" fuel line to install AN-8 braided hose.

Big Dave
Right at this moment I am doing a AN-8 line in steel, tank to pump,redoing sending unit to 1/2 inch also. The AN in AN-10 or 8 or 6 or whatever stands for Army-Navy it is a standard that the military came up with. AN-10 is 5/8, AN-8 is 1/2 and AN-6 is 3/8 . 10,8 and 6 are 1/16ths of an inch 10/16ths is 5/8ths 8/16ths is 1/2 inch, 6/16ths is 3/8ths and so on. Did anyone consider that AN fittings are not 45degree SAE fittings- they are 37.5 degree GIC fittings so when you are running fuel line this is very critical considering gas will find a crack in a heartbeat. :thumbsup:

Eric and Frank: What did you do at the tank? Did you just go with a vented gas cap or did you have an additional vent tube? If you went with an AN fitting at the sending unit how did you attach it? Did you just cut out the 3/8" fitting on the sending unit and weld in a -8 AN fitting?

At the tank I welded a sump. The front edge of the sump starts at the rear edge of the deep part of the tank. I punched a series of 9 one inch diameter holes in the tank to make sure there was enough flow from the tank into the sump and there was still a baffle effect. Not sure if this is really necessary, but it was cheap to do and the timing was right since I changed tanks

For the fuel line return I welded two bungs at the top front of the tank. I used a combination of 1/2" hard line and -8 braided hose to route the return from the reg back into the tank.

For the vent, I had to get creative. Since on the 67-68 the gas cap is straight back, vented caps leak when you launch hard. I plugged the vent on my locking cap and made a separate vent. I drilled a hole and tapped pipe threads near the top of the fill pipe and ran a plastic line to a home-made check valve, then out the bottom of the trunk floor. The check valve is basically two brass fittings with a steel ball inside -- the steel ball stays open all the time, but closes under hard acceleration. This keep fuel from shooting out the vent. There are probably easier ways to accomplish the same thing, but that was all I could think of.

I was thinking about this today and am wondering if we can put a T fitting at the sending unit and then use one side for a vent tube and one for the feed line going to the fuel pump.
We have a Holley 170 gph fuel pump and the engine builder said to regulate the feed to 6.5 psi so we are planning on running -8 AN line from the tank to the pump, then filter, regulator and gage after that. The Holley regulator is a dual feed so we will run one side to each feed on the AED 850 carburetor.

I would not mess with using the stock sending unit. You can modify the sending unit easy enough to get a bigger tube through, but the bend has to be aweful tight to clear the trunk floor. Too tight for me to get the tube in the way I wanted so I decided on a sump.

I also use an AED 850 carb. I routed -8 from the sump to a can style filter (Aeromotive) which is hanging from one of the tank straps in front of the tank. Then -8 from the filter across to my fuel pump which is mounted on a home made sound isolator. From there another short piece of -8 and then a hard tube adapter and 1/2" hard line to the engine bay. In the engine bay I have a screen style in line filter (to catch any bits in the event my fuel pump ever craps.). The outlet of the filter is -8 into the regulator and from there -8 to the fuel log which feeds the carb and my fuel N2O solenoid.



Also, -8 is 1/2" in diameter and matches with 1/2" hard line real nice IMO.

No need to make it real complicated IMO but I personally have had better luck with an electric pump since I started going sub 1.5 sixty foots. If you decide against the sump and electric pump, I would consider using -10 to the pump inlet of that Carter 172. I used one on my old 383 before this motor and lost fuel pressure on hard acceleration. At the time I was using 3/8 hard line, -8 hose to the pump, dead head style regulator and the stock 3/8 pick up.

Hope that helps.

CALL SHAFIROFF :yes:

CALL SHAFIROFF :yes:

I started this thread, but I didn't revive it a few days ago. May car is done and running great. Hear is what I ended up doing:

I am very determined to keep the stock look of my car, so installing a sump was never an option. I started by trying to tuck a 1/2" stainless line next to the factory 3/8" line in the sending unit. A couple of days later, after the new sending unit arrived, I then decided to solder (I used Silver solder, it is an extremely strong solder normally used for refrigeration lines) a new line directly into the tank. It enters the front of the tank and stops directly next to the original stock pick-up. I left the original pick-up in place in case I would ever need a return line. After the 1/2" stainless leaves the tank, I installed a -10AN 100 micron filter. I then ran 1/2" hard line to the Carter 172 GPH mechanical pump. I ran -8AN out of the pump and to a 30 micron filter that screws onto the front of the fuel log. I bought a regulator, but ended up returning it because I didn't need it. I had the car to the track once so far, and didn't have any problems turning the 540 to 6700. The only thing is that my fuel gauge is on the fuel log, so I can't read the pressure at full RPM, but the car doesn't seem to die off at all.

We drill out the 3/8 pick up tube and weld in a steel 1/2 tube with a steel male JIC fitting welded to the stube at the end so the AN will screw right on. The vented cap is plenty of vent. I may have a pic somewhere. I need to look through 100s of pics.

A couple of days later, after the new sending unit arrived, I then decided to solder (I used Silver solder, it is an extremely strong solder normally used for refrigeration lines) a new line directly into the tank. It enters the front of the tank and stops directly next to the original stock pick-up.

This winter I want to upgrade my fuel lines too. I assume you could also use a bulkhead connector on the front of the tank?

This winter I want to upgrade my fuel lines too. I assume you could also use a bulkhead connector on the front of the tank?

I considered that also, but didn't go that route for 2 reasons. First, I wasn't sure that a bulkhead fitting would seal the tank. I thought they were more just for going through a firewall or something similiar, where a liquid-tight seal is not needed. Second, it would be a real pain the get either the fitting or the nut attached on the inside of the tank. Working through the small hole for the sending unit would be challenging, if even possible. I'm sure someone here has done it though, probably by using a combination of duct tape, silicone, 4 mirrors, 3 friends, and turning all of it upside down at the same time!

The pick up mod is fast and easy. Unless it is a drag car and needs a rear mounted sump, it will be fine.

I started this thread, but I didn't revive it a few days ago. May car is done and running great. Hear is what I ended up doing:

I am very determined to keep the stock look of my car, so installing a sump was never an option. I started by trying to tuck a 1/2" stainless line next to the factory 3/8" line in the sending unit. A couple of days later, after the new sending unit arrived, I then decided to solder (I used Silver solder, it is an extremely strong solder normally used for refrigeration lines) a new line directly into the tank. It enters the front of the tank and stops directly next to the original stock pick-up. I left the original pick-up in place in case I would ever need a return line. After the 1/2" stainless leaves the tank, I installed a -10AN 100 micron filter. I then ran 1/2" hard line to the Carter 172 GPH mechanical pump. I ran -8AN out of the pump and to a 30 micron filter that screws onto the front of the fuel log. I bought a regulator, but ended up returning it because I didn't need it. I had the car to the track once so far, and didn't have any problems turning the 540 to 6700. The only thing is that my fuel gauge is on the fuel log, so I can't read the pressure at full RPM, but the car doesn't seem to die off at all.

I did the same to my tank (with my electric pump and -8 line) before I swapped tanks and installed a sump, except I used an AN bulkhead fitting in the front of the tank and it seemed to work fine. I never did get the pickup exactly on the bottom of the tank -- but I bet the solder technique you used allowed better positioning.

We drill out the 3/8 pick up tube and weld in a steel 1/2 tube with a steel male JIC fitting welded to the stube at the end so the AN will screw right on. The vented cap is plenty of vent. I may have a pic somewhere. I need to look through 100s of pics.

Frank, pardon my simple mindedness but I am not familiar with the term JIC fitting. Can you explain?

My new sending unit has a second vent tube so no problems there. So far we have drilled out the 3/8 line, bent up a new 1/2" stainless steel tube and silver soldered the 1/2" line to the sending unit plate. That pate is thin so we were worried about warpiing the plate. Next we will spot weld the brackets and everything back in at the same height as the original replacement unit. Then I will drill out the flange the little in tank filter is attached to and slip fit it over the 1/2" tube. We will run a vented cap and also run a line up from the secondary vent tube and put a filter on the end of that.
We ran the tube out past the end of the tank so we can get a wrench on it. We still haven't decided what or how to attach a fitting to the end of the tube.

BTW this is going on a Chevelle. Don't want to mess with the original Camaro :)
Thanks for all the input and keep it coming. This is a good informative thread. As usual TC ROCKS :yes:

Well here is a question if you need at least a 1/2'' line or -8 hose then why is it that holley "HP" elec pumps only have 3/8 NPT for inlet and outlet and claim up to 700Hp on there 125 and up too 900hp on the 150? Would seem to contradict some thoughts here.

Success!! Here are some pics of the fabrication to use a stock sending unit to feed 1/2" line to the carb. Don't want to take any chances with starving the motor or surge. As the previous post said we opened up the hole, carefully and then silver soldered the 1/2" SS line in place. The flare on the flange worked to our advantage and the solder filled in nicely and came through the back side to assure a good fit. Then the sensor was tacked back in the exact same location. My buddy Rick took it to his shop and did it there. He is an awesome fabricator and this was pretty simple for him. Thanks Rick. Pics are in my photobucket too. Just click on the link in my sig

http://s109.photobucket.com/albums/n66/Mstehle/th_DSC00028.jpg http://s109.photobucket.com/albums/n66/Mstehle/th_DSC00029.jpg http://s109.photobucket.com/albums/n66/Mstehle/th_DSC00030-1.jpg