[JLMounce]

I run the walbro 255 in my setup with -8AN feed and return (3/8"). 600 hp and under, there's no real need for a 1/2" line. Since you're pushing fuel, not pulling it, the same logic doesn't apply as when you're dealing with a mechanical fuel pump.

For reference, I run my pump at 95% (around 12 volts) constant. My injector duty cycle at 50 mph cruise is around 6%, it's 4.7% at idle. So I'm passing around 240lph of fuel through the EFI and feed/return lines without issue.

[Navy Horn 16]

Originally Posted by Interceptor

Just checked it out. Only supports 500 hp?

Saw that. That's a pretty low number as a limiting factor.

[DogMeister]

Thanks JLMounce and Formulajones for excellent points. Makes perfect sense. Not intending to cut corners, simply wanting to take advantage of a system that's already there. If I install this setup {still an if}, it'll be installed as specified by Holley. There's a reason they provide manuals and parts for this kind of stuff. Thanks again.

[JLMounce]

Originally Posted by DogMeister

Thanks JLMounce and Formulajones for excellent points. Makes perfect sense. Not intending to cut corners, simply wanting to take advantage of a system that's already there. If I install this setup {still an if}, it'll be installed as specified by Holley. There's a reason they provide manuals and parts for this kind of stuff. Thanks again.

Yeah, basically plan on ripping your entire fuel system out and replacing it. My advise is to go straight to an aftermarket tank and in-tank pump. Those who go that route typically have the fewest, if any issues.

I've had my FiTech on my car for 3 years and about 15000 miles with my in-tank pump setup. Outside of a failed electrical connector that cost me $40.00 to replace, it's been rock solid after I ditched the inline pump and factory return line deal.

[Formulajones]

Originally Posted by Navy Horn 16

Saw that. That's a pretty low number as a limiting factor.

I mentioned that earlier. I'm willing to bet give it a little time and they'll have a spread bore for bigger HP applications. Might be as simple as an injector swap for a small bump in supportive HP.

[DogMeister]

Was looking at the specs. 2.00" secondaries, not 2.25". 715 cfm, not 750.

Hmm.

[Interceptor]

Originally Posted by DogMeister

So I'm getting a little obsessed with this system, to the point of visualizing the feed and return lines in my engine compartment. What do you guys think about this: the manual shows 3/8" ID hose with fittings sliding into the hose for the return line. My '67 sending unit has a 5/16" return port that I'm currently not using. Or is it 1/4"? I'm thinking a 5/16" hard line return would be okay if the sending unit return fitting is 5/16". Changing it to 3/8" would be doable but somewhat of a pain.

You could try it I guess if it's 5/16 and not 1/4. I would definitely not use the factory front-to-back return line though, too many bends and kinks. Might want to run a new 3/8 feed and use the factory kinked/bent steel supply line as the return. Install a pressure gauge at the EFI unit to make sure you have Holley's specified pressure, making sure that little return port is not causing a restriction.

After having done two of these on Pontiacs, if I were to do it over I would use a retrofit tank with internal pump, no question. My GTO starves for fuel in even mild corners under 3/8 fuel level using the factory tank with no baffle and an external pump. Holley's EFI tank has a great baffle system.

[mbeeman400]

I am considering the Sniper EFI Quadrajet. Still in the research stage. Couple of concerns...
I need to be sure the drop base air cleaner and holds the scoop for a TA, will fit over the throttle body? This is a deal breaker for me!
Also Holley (and others) make a filter - regulator that mounts near the tank. This manages the fuel pressure and eliminates the need for a return line from the front of the car. So only one feed line is needed to the TB
Re a tank, like others have said, the Tanks Inc setup or the Holley tanks (I believe made by Tanks Inc) is the way to go. Pump runs cooler and will last longer, much quieter with the pump submerged in the tank, no fuel starvation on hard corners.

[Formulajones]

Yes the filter/regulator setups have been around for many years. Was used OEM by GM on Corvettes and probably others throughout the 90's and newer.

I never went that route on setups here mainly because they run anywhere from $50 to $70 here locally and it starts to be an expensive maintenance item replacing that every year.

If that doesn't bother you, or you don't mind ordering a few to keep on hand (ordering online is cheaper) then it's a great way to go. I've always preferred to keep the cars user friendly, meaning the throw away parts (consumables) available at local stores. So ordering a handful to keep on hand, and save money from the local store might be a viable option.

The only other issue with it is for those making decent HP that need bigger line eliminates the use of the OEM filter/regulator setup because they are just too small.

[mbeeman400]

Originally Posted by Formulajones

Yes the filter/regulator setups have been around for many years. Was used OEM by GM on Corvettes and probably others throughout the 90's and newer.

I never went that route on setups here mainly because they run anywhere from $50 to $70 here locally and it starts to be an expensive maintenance item replacing that every year.

If that doesn't bother you, or you don't mind ordering a few to keep on hand (ordering online is cheaper) then it's a great way to go. I've always preferred to keep the cars user friendly, meaning the throw away parts (consumables) available at local stores. So ordering a handful to keep on hand, and save money from the local store might be a viable option.

The only other issue with it is for those making decent HP that need bigger line eliminates the use of the OEM filter/regulator setup because they are just too small.

Thanks for your comments. You are correct the filter/regulator was used on the LS cars. I believe the Holley has a serviceable cartridge...again I'm still in the research phase.
Also would like to use the timing feature by modifying the original distributor.

[JLMounce]

The available headroom from the installed injectors on these units, does not necessitate the need for anything bigger than a 3/8" feed line. Remember, we're pushing fuel, not pulling it, so the same rules for fuel line size don't apply here.

A -6 AN hose will support in the neighborhood of 900hp in a pressurized application before it's size starts to become an issue. So if you want to run the corvette regulator/filter setup back at the tank, you'll be fine, as these systems only support 500-600 hp without upgrading the injectors.

[Squidward]

Originally Posted by Formulajones

Yes the filter/regulator setups have been around for many years. Was used OEM by GM on Corvettes and probably others throughout the 90's and newer.

I never went that route on setups here mainly because they run anywhere from $50 to $70 here locally and it starts to be an expensive maintenance item replacing that every year.

If that doesn't bother you, or you don't mind ordering a few to keep on hand (ordering online is cheaper) then it's a great way to go. I've always preferred to keep the cars user friendly, meaning the throw away parts (consumables) available at local stores. So ordering a handful to keep on hand, and save money from the local store might be a viable option.

The only other issue with it is for those making decent HP that need bigger line eliminates the use of the OEM filter/regulator setup because they are just too small.

I took the inspiration for my setup from the Corvette/LS system. I went with an efi return regulator back by the tank, and I run an inline filter and gauge before it hits the throttle body unit.

I've done the fuel command center, and the in-tank pump. Both work, but of the two, I prefer the in-tank pump. Cleaner, cooler, and less plumbing.

[mbeeman400]

Originally Posted by mbeeman400

I am considering the Sniper EFI Quadrajet. Still in the research stage. Couple of concerns...
I need to be sure the drop base air cleaner and holds the scoop for a TA, will fit over the throttle body? This is a deal breaker for me!
Also Holley (and others) make a filter - regulator that mounts near the tank. This manages the fuel pressure and eliminates the need for a return line from the front of the car. So only one feed line is needed to the TB
Re a tank, like others have said, the Tanks Inc setup or the Holley tanks (I believe made by Tanks Inc) is the way to go. Pump runs cooler and will last longer, much quieter with the pump submerged in the tank, no fuel starvation on hard corners.

I pulled the trigger and just finished the install. The base air cleaner DOES FIT with no issues. I used the Holley Filter/Regulator with the in tank pump (made by Tanks Inc). Was able to conceal alsot all the wires.
Getting ready to fire the motor today.

[67GTO4SPEED]

Originally Posted by mbeeman400

I pulled the trigger and just finished the install. The base air cleaner DOES FIT with no issues. I used the Holley Filter/Regulator with the in tank pump (made by Tanks Inc). Was able to conceal alsot all the wires.
Getting ready to fire the motor today.

Awesome! Looking forward to your feedback on it!

I'll go ahead ask the question we are all wondering - does it make that glorious Q jet sound at WOT???

[mbeeman400]

Originally Posted by 67GTO4SPEED

Awesome! Looking forward to your feedback on it!

I'll go ahead ask the question we are all wondering - does it make that glorious Q jet sound at WOT???

If all goes as planned, doing a road test Tomorrow afternoon. Ill let you know about the famous QJ sound! lol

[adynes]

500hp sounds like an awfully conservative rating.
4x 100 lb/hr injectors
@ 90% DC and .45 bsfc supports 800hp.
@ 80% DC and .5 bsfc supports 640hp.
Unless something else is the limiting factor (airflow, internal fuel feed restriction)

[DogMeister]

Not sure how many hp a Qjet supports, but the secondaries on the Sniper unit are a little smaller - 2" I believe, not 2-1/4."

[Firebob]

I'm curious about this discussion on the return line size issues. I'm running a 3/8" feed and the 5/16" return. Seems to work ok but I am running higher than expected fuel pressure to the TB. Regulator is supposed to be set at 58.5lbs but I'm reading a steady72@idle at the TB. I asked the Holley rep about it. He said it was fine to 90lbs and I haven't noticed any problems with the way it runs. Maybe I just lucked out of maybe it would run better with the specified pressure. Hmmm, curious.

[mbeeman400]

Originally Posted by mbeeman400

If all goes as planned, doing a road test Tomorrow afternoon. Ill let you know about the famous QJ sound! lol

Well I did a quick road test, several miles and the system did good. I believe it takes 100 miles of driving, under different conditions for the system to "learn".
Then I made the mistake of moving to the next level by switching out the stock distributor with dual sync Holley/MSD compatible distributor, with the Sniper coil driver.
Honestly I am thinking about putting the original distributor back in. I cant get the car to run right, runs hot, inconsistent, busted a muffler.
There is very little support to set up and tune the spark curves and I haven't found the right combination. The base files that are available from Holley are worthless for my situation.
Will post my progress later!

[Interceptor]

Definitely run a few hundred miles with the stock distributor if it is known to be good. EFI is a major mod and should be done with no other changes to muddy the waters.

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