Anyone convert to V8 carb?

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Sburke
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Anyone convert to V8 carb?

Post by Sburke » Wed May 31, 2017 2:40 pm

My background is mainly with 4cyl turbo stuff, and motorbikes.

These xr4ti are new to me, and v8 carb stuff.

I'm going to order the v8 mount kit, whenever I get a return email.

The car currently has an 8.8, with a t5, so that portion of the puzzle is solved.

I have a mildly worked 302 5.0 cobra motor, with a Holley 600dp carb. Sticking with carb for the ease of wiring, and the new carb setup came with this motor.

The xr4ti has an intank Wally 255, which I would like to keep, and use a regulator designed to drop the pressure down low enough for the carb. I've read mixed reviews of this method.


If anyone here has converted to v8 carb, what did you do for the fuel system?

This is all I have currently ha

Image

my8950
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Re: Anyone convert to V8 carb?

Post by my8950 » Thu Jun 01, 2017 1:14 pm

Not a fan of carbs, but....

Regarding your pump situation, I assume its a high pressure in tank 255?
I'd say that's no good for a carb, regulating it down from 45psi to 9, 10psi?
Your going to get a lot of bypassed/hot fuel...
I'd switch the pump if you want to stick with the really old stuff, i.e. carb.
The 2.3T/XR4ti is already old, but...

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Iowaxr
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Re: Anyone convert to V8 carb?

Post by Iowaxr » Thu Jun 01, 2017 2:22 pm

You may have to run a return line to cut down the pressure.
Brett
86 XR4TI- V8 5speed project

Sburke
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Re: Anyone convert to V8 carb?

Post by Sburke » Thu Jun 01, 2017 2:28 pm

Iowaxr wrote:You may have to run a return line to cut down the pressure.

Yeah, they make regulators to cut the pressure down, and return the extra fuel for EFI pumps. The only downside is if it fails, will wash the motor down with fuel.........


I've never touched an XR4TI and mine won't be dropped off at my place till next week, or so. Is it easy to run a braided fuel return line to the stock tank? I would go with a rubber setup, but pretty sure I would never pass tech like that...

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John Brennan
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Re: Anyone convert to V8 carb?

Post by John Brennan » Thu Jun 01, 2017 2:53 pm

Sburke wrote:
Iowaxr wrote:You may have to run a return line to cut down the pressure.

Yeah, they make regulators to cut the pressure down, and return the extra fuel for EFI pumps. The only downside is if it fails, will wash the motor down with fuel.........


I've never touched an XR4TI and mine won't be dropped off at my place till next week, or so. Is it easy to run a braided fuel return line to the stock tank? I would go with a rubber setup, but pretty sure I would never pass tech like that...
Stock XR system already has a return line going to the tank for the FI. Would highly recommend you sell the carb and get some FI stuff from the JY.
This is my car, and these are my people!
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Sburke
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Re: Anyone convert to V8 carb?

Post by Sburke » Thu Jun 01, 2017 2:58 pm

John Brennan wrote:
Sburke wrote:
Iowaxr wrote:You may have to run a return line to cut down the pressure.

Yeah, they make regulators to cut the pressure down, and return the extra fuel for EFI pumps. The only downside is if it fails, will wash the motor down with fuel.........


I've never touched an XR4TI and mine won't be dropped off at my place till next week, or so. Is it easy to run a braided fuel return line to the stock tank? I would go with a rubber setup, but pretty sure I would never pass tech like that...
Stock XR system already has a return line going to the tank for the FI. Would highly recommend you sell the carb and get some FI stuff from the JY.

Considering I will be using the intank 255, the return line will have to be larger than the feed.


I don't want to deal with the wiring, injectors, maf, and needing a tune for the mods my car has. It's just not worth all the extra hassle for a car that will spend the majority of it's life on the track.

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Re: Anyone convert to V8 carb?

Post by Sburke » Thu Jun 01, 2017 4:21 pm

John Brennan wrote:
Sburke wrote:
Iowaxr wrote:You may have to run a return line to cut down the pressure.

Yeah, they make regulators to cut the pressure down, and return the extra fuel for EFI pumps. The only downside is if it fails, will wash the motor down with fuel.........


I've never touched an XR4TI and mine won't be dropped off at my place till next week, or so. Is it easy to run a braided fuel return line to the stock tank? I would go with a rubber setup, but pretty sure I would never pass tech like that...
Stock XR system already has a return line going to the tank for the FI. Would highly recommend you sell the carb and get some FI stuff from the JY.

I don't feel like dealing with a wiring harness, upgraded injectors, maf, ecu, and tuning EFI.

The carb setup came with the motor.

They make regulators for that purpose, you just have to run a return. I know the merkur has a return, but are both lines the same size? The return will have to be larger than the feed, for my setup.

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Re: Anyone convert to V8 carb?

Post by Iowaxr » Thu Jun 01, 2017 5:51 pm

Run a fuel cooler on the return and it should help keep fuel temp down.
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86 XR4TI- V8 5speed project

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Re: Anyone convert to V8 carb?

Post by jkxr4ti » Fri Jun 02, 2017 8:57 am

For all that work and money on the regulator set up I think you would be best served to drop the tank and replace the walbro with a low pressure pump. Heck you can get one of those for probably $20 from rock auto. Then leave the rest of the fuel system as is and cap the return line. If you ever change your plans all the other stuff will still be there.
Merkur....Its German for Mutt....Mustang, Saab, Volvo, Lincoln, Contour, Cummins... and the list goes on.

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Sburke
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Re: Anyone convert to V8 carb?

Post by Sburke » Fri Jun 02, 2017 10:38 am

jkxr4ti wrote:For all that work and money on the regulator set up I think you would be best served to drop the tank and replace the walbro with a low pressure pump. Heck you can get one of those for probably $20 from rock auto. Then leave the rest of the fuel system as is and cap the return line. If you ever change your plans all the other stuff will still be there.

Intank low pressure pump, will still be too much for a carb. Going to need a regulator regardless.

Going to try and run the 255, with a regulator designed to trim high pressure down to carb safe level, and run a larger return line back to the tank. Do you need to drop the tank on these cars, to swap the return line?

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Re: Anyone convert to V8 carb?

Post by my8950 » Fri Jun 02, 2017 11:00 am

jkxr4ti wrote:For all that work and money on the regulator set up I think you would be best served to drop the tank and replace the walbro with a low pressure pump. Heck you can get one of those for probably $20 from rock auto. Then leave the rest of the fuel system as is and cap the return line. If you ever change your plans all the other stuff will still be there.
This....
And then when you drop the tank and find out its rotted and the feed/return lines are rotted as well, and or broken.

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Re: Anyone convert to V8 carb?

Post by reddy2300 » Sat Jun 03, 2017 12:46 pm

Gonna reinvent the wheel, huh? So many people have been down the path you're on. Most are saying "go efi". You can sell that carb and intake for enough money to buy a good used (racer upgraded) stock style (but still aftermarket improved) intake and wiring harness/computer. That solves the fuel system problem that you're fighting. (Scabbing together to make work. For what? To save money? Really?) Once you've turned the key on a FI 5.0, you will never want to wait for a carb again. I've built an XR with a carb'ed 5.0. I'll never do it again. It's too easy to get FI stuff. And the reliability is worth the effort.

I would suggest, if you are completely sold on running the carb, put a plain (no fuel pump attached) in-tank pickup in the the tank and run an external pump. (Keep the fuel level sender on it for obvious reasons.) You can modify your existing fuel pickup by deleting the existing up tube and replacing it with a piece of 5/16" (or bigger) steel line. This is the proper way to start a carb'ed fuel system.
1987 5-speed XR4ti-70K mile "barn find", Rosso Red, Grant wheel, short throw shifter, PE/big VAM, 255lph pump, 3" exhaust w/Magnaflow, MD "shorty" radiator/IC, "Pony" wheels, Koni Yellow, Rapido sway bars, poly/aluminum bushes, Gillis valve,

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Re: Anyone convert to V8 carb?

Post by Sburke » Sat Jun 03, 2017 1:24 pm

reddy2300 wrote:Gonna reinvent the wheel, huh? So many people have been down the path you're on. Most are saying "go efi". You can sell that carb and intake for enough money to buy a good used (racer upgraded) stock style (but still aftermarket improved) intake and wiring harness/computer. That solves the fuel system problem that you're fighting. (Scabbing together to make work. For what? To save money? Really?) Once you've turned the key on a FI 5.0, you will never want to wait for a carb again. I've built an XR with a carb'ed 5.0. I'll never do it again. It's too easy to get FI stuff. And the reliability is worth the effort.

I would suggest, if you are completely sold on running the carb, put a plain (no fuel pump attached) in-tank pickup in the the tank and run an external pump. (Keep the fuel level sender on it for obvious reasons.) You can modify your existing fuel pickup by deleting the existing up tube and replacing it with a piece of 5/16" (or bigger) steel line. This is the proper way to start a carb'ed fuel system.

It's not to save money. I don't want to deal with wiring. This is a road race project, and will spend very minimal time on the street. I don't care about mpg or low rev range driveablity.

Does the tank need to be dropped for that?

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Re: Anyone convert to V8 carb?

Post by reddy2300 » Sat Jun 03, 2017 3:37 pm

Yes. Drop the tank. Wont take any time at all. Probably an hour or two, start to finish, depending on how quickly you like to work. Took me about 20 minutes to mod the pickup and braze the tube in place. Be sure to set it so the "pickup" is not touching the bottom of the tank and not too high to pull the last gallon or so out.
1987 5-speed XR4ti-70K mile "barn find", Rosso Red, Grant wheel, short throw shifter, PE/big VAM, 255lph pump, 3" exhaust w/Magnaflow, MD "shorty" radiator/IC, "Pony" wheels, Koni Yellow, Rapido sway bars, poly/aluminum bushes, Gillis valve,

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Re: Anyone convert to V8 carb?

Post by timxr8 » Sat Jun 03, 2017 10:52 pm

Ok, I think everyone is trying to be very nice about this. I'm going to put this as plainly as I can, and like a few on here, it's speaking from experience with both carb and efi. Ran a 91 T-bird 5.0 with a Holley 650 prior to going to EFI. I thought the exact same thing when I was building it, keep it simple, but ultimately the EFI was far superior and cost less (including time tuning).

Your argument that you don't want to mess with wiring is invalid. It is the exact same amount of wires to connect between the EFI harness vs the ignition wiring for the Carb setup. It's 3 wires, 12V run/ign, 12V start, ground that's it. Takes a little bit of homework to figure which 3 unless you go with a plug and play harness, then they are marked. Tuning is easy because it's a MAF. Get the A9L (87-93) or equivalent computer and simply get the appropriately tuned MAF to match the injectors. The MAF will adjust for the Cam. Very versatile, so much so that some aftermarket EFIs use modified Ford EEC-IV units with reprogrammed GM MAFs.

Here's an example of what could be: http://www.ebay.com/itm/1987-93-5-0L-FO ... oQ&vxp=mtr

If you still want to stick with Carb, the fuel pump will need to be wired since it runs from the computer anyway. The stock return line is the same size on the rail only (5/16"), so the connection at the front should be good. The problem will be at the tank, since that hard line at the pump/level sender assembly is 1/4". Much harder to deal with than simply running a bigger return line. I'd run the low press OE in-tank pump. It runs at about 5 psi (mine registered about 4psi on a cheap gauge). Honestly, it's perfect.
Tim Spencer
1988 XR4Ti Duratec project car
2011 Taurus SHO daily driver...not stock.

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