Looking for some advice on my EFI/Carb fuel system swap

[78Delta88]

What I did was look at the old data. The 454 In the 70 Corvette was 9 psi and between 28 to 32 GPH (Gallons Per Hour) so the TPI or TBI electric FP (Fuel Pump) would suffice. I would be more inclined with the TPI Pump. Has a little more Capacity.

The regulator needed is Holley 12-803BP. I attached info from Jegs. You can get it for less if you look around. Don't get the cheaper ones available eBay and Amazon. Quality is not there. They work ok, but I've had good and bad experience with these.

There's a kit on Amazon about $44, has line and fittings and regulator. The Kit is ok for the fittings saves you some money there, but go with high quality line and use the Holley Regulator. You will be happier in the long run.

Someone else posted the diagram using the fuel log... Yes use that. That is the way to go.

From there you just need to work out pressure you need. Will be trial/error. Stopwatch runs or chassis dyno.

 

[scoti]

I'll ask those that have experience w/regulated set-ups.... Would a return style regulator that's used for TBI/TPI (& current EFI style fuel systems) work for an app like this? Seems that would allow a TBI/TPI lower psi pump the ability to keep the carb fed @ the required pressure (under load or not) albeit w/slightly more complicated plumbing.

 

[Supercharged111]

I'll ask those that have experience w/regulated set-ups.... Would a return style regulator that's used for TBI/TPI (& current EFI style fuel systems) work for an app like this? Seems that would allow a TBI/TPI lower psi pump the ability to keep the carb fed @ the required pressure under load or not albeit w/slightly more complicated plumbing.

I had a 92 Crown Victoria that I swapped a 289 into. Car was originally a 4.6 with EFI, probably ran at 39psi stock. I used the aforementioned Mallory regulator (return style) to turn it down to 6 psi to run it with a carb. Worked like a champ. That is why I recommended the Vortec pump from a 96-97 truck. Pumps don't make pressure until something resists their flow.

 

[tokarz1]

Thanks again for the advice guys. The online places seem to have some decent sales going on so I will be putting in some web time the next few days.

 

[78Delta88]

One of the reasons I looked into the older stuff is because from the factory you could easily buy a big block single carb, 4 speed and 4.11 Posi with no trouble at all. Picking the Corvette you know the setup is going to be used and most likely driven hard. It's not going to be a big block in an RV or a tow truck.

This eludes to what works, and if 9 psi 30 GPH worked back then..., probably will work today.
Compression is lower and more ethanol in fuel today, but gives you a more relative starting point.

Diagram attached from other member is the setup you want, but move the regulator much closer to the end of your fuel log. You can use 3/8 line input and output, which would be AN-6 and I would still use a filter inline and just in front of carb, plus a small gauge in the fuel log.

 

[tokarz1]

I have the Spectra Gbody GM306C fuel injection tank enroute and the Spectra FG156A fuel injection sending unit. I searched for a direct replacement pump for a 1987 Buick Grand National on TI Automotive/Walbro. They list the stock replacement (5CA400) with a flow rate of 22 gph and 56 psi operating pressure. The next step up (GCA701) is 40 gph and 45 psi operating pressure. The last is pump (GCA758) is 55 gph and 43 psi operating pressure. These pumps also are a direct fit for many GM vehicles that share a similar 80's and 90's platform like Chevy Camaro's, Caprice's, Corvette's ect.
I am thinking of going with the larger pump as it will give me some room to grow in the future. For the sending unit, I saw a few videos on YouTube of people using 6AN Male to 3/8" & 5/16" quick-disconnect fitting on the Spectra FG156A sending unit.

The 3/8" stock feed line is no issue, but it has a 1/4" non barbed stock return line and a 5/16" vent line. I will be using the 5/16" line for the return and the 1/4" for the vent as the 5/16" will work better for the return. Adding a line from the 5/16" vent down to the bottom of the tank for the return should be no problem and using the 1/4" line for the vent with some modification should work as well.

 

[Supercharged111]

There ought to be a calculator out there to tell you what those pumps are gonna flow at 9psi. They will flow more at a lower pressure. I'll be d@mn3d if I can find one at the moment.

 

[tokarz1]

There ought to be a calculator out there to tell you what those pumps are gonna flow at 9psi. They will flow more at a lower pressure. I'll be d@mn3d if I can find one at the moment.

Thanks, I will look around as well. The Quick Fuel brawler 750 says to use 6.5 psi.

 

[78Delta88]

There is and I'll try to find it.

It's basic fluid dynamics and same thing I did for the Fire Department, even though I was working with 120 psi and 4 inch an 6 inch supply lines. Concept is the same.

Basically its cross section x pipe length, then factor the flow at meters per second at the rated pressure. Zahn cup viscosity of water is about 12 to 15 seconds, viscosity of fuel is on a chart I'll have to dig up.

Quick Fuel should have the data of actual fuel consumption based on CFM per the actual engine and the RPM.

Rich is 12:1 Stoichiometric of 14:1 is theoretic goal.

So 12 pounds air per 1 pound fuel to 14 pounds air to 1 pound fuel in a cubic foot multiplied by how many cubic feet moved in that minute.

The engine is just an air pump, so find your max goal of RPM and a 454 is not normally turning 7k.

Bore x Stroke is (4.25 x 4.00) or (4.28 x 4.00) if 30 (0.030) over. Area of a circle (04.25) is 14.186 square inches and total cylinder volume is 56.744 cubic inches.

At 5500 RPM this engine is going to move (56.744 x 8) x (5500/4) = total cubic inches consumed in one minute.

449.448 x 1,375 = 618,046 cubic inch per minute. Equals 355.608 CFM.

From there .0807 lbs air x 355.608 = 28.697 lbs air and 2.391 pounds of fuel at a rich 12:1 AFR.

So 2.39 pounds per minute and 9 psi at 30 GPH is .5 gallons per minute..., so will this work??

One gallon of fuel is about 6 lbs per gallon, so this makes the requirement at or about .398 gallons per minute at 5500 RPM at a Stoichiometric of 12:1 and a little more running richer.

28 GPH = .467 gallons fuel per minute
30 GPH = .500 gallons fuel per minute
32 GPH = .533 gallons fuel per minute

Just doing this from memory, but seems to show 9 psi at 30 GPH is sufficient and this is exactly what OEM set this at for the 427 and 454 Big Block Chevy going back to when it came on the market.

 

[pagrunt]

I have the Spectra Gbody GM306C fuel injection tank enroute and the Spectra FG156A fuel injection sending unit. I searched for a direct replacement pump for a 1987 Buick Grand National on TI Automotive/Walbro. They list the stock replacement (5CA400) with a flow rate of 22 gph and 56 psi operating pressure. The next step up (GCA701) is 40 gph and 45 psi operating pressure. The last is pump (GCA758) is 55 gph and 43 psi operating pressure. These pumps also are a direct fit for many GM vehicles that share a similar 80's and 90's platform like Chevy Camaro's, Caprice's, Corvette's ect.
I am thinking of going with the larger pump as it will give me some room to grow in the future. For the sending unit, I saw a few videos on YouTube of people using 6AN Male to 3/8" & 5/16" quick-disconnect fitting on the Spectra FG156A sending unit.

View attachment 231402

The 3/8" stock feed line is no issue, but it has a 1/4" non barbed stock return line and a 5/16" vent line. I will be using the 5/16" line for the return and the 1/4" for the vent as the 5/16" will work better for the return. Adding a line from the 5/16" vent down to the bottom of the tank for the return should be no problem and using the 1/4" line for the vent with some modification should work as well.

View attachment 231403 View attachment 231405

Not to hijack, but will those fitting fit about all barb end lines or would they nave to be simular to the way the sender is made. I'd like to try them on some of my other hard lines.