Drilling out Saginaw fittings

[dvernst]

OK. I've found in numerous posts that people have drilled out the feed line saginaw fitting to .280-.299 (9/32-19/64), but I have not found any solid info on the return line fittings. Anybody know the sizes? Thanks!

 

[Ttype6]

You don't have to drill either. The stock supply line can supply 1,000 plus HP worth of gasoline to a motor. The return line only needs to be modified if you install one of the new higher volume pumps. The problem they create is that they flow more fuel than the return line can send back to the tank at an idle when the motor isn't using much fuel,so you can't get the fuel pressure down to 36-39 psi. If you use a double pump set-up this doesn't happen because the second pump doesn't come on until the motor is using much more fuel.

 

[dvernst]

So what size?

 

[TT/Ameasap]

So what size?

I think you can find it here Dave.
http://www.turbobuick.com/forums/threads/modifying-stock-fuel-lines.382334/page-2

 

[jpwalt1987]

I had a car that a 255 lph pump was over powering the return a little bit. It would drop from 43 to 40 when the vacuum line was put on. I drilled the Saginaw fitting under the regulator to a little bigger than 5/32nds. That helped some. The biggest difference was at the frame rail. It looked like the Saginaw fitting was crimped down alot more than usual. Especially on the end. Drilled it to the same diameter and it now drops from 43 to 36-38.


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[dvernst]

I think you can find it here Dave.
http://www.turbobuick.com/forums/threads/modifying-stock-fuel-lines.382334/page-2

I read that whole entire thread twice. I think one person said what size they drilled it to, but I don't know what the biggest size possible is. Maybe I just missed it?

 

[dvernst]

I had a car that a 255 lph pump was over powering the return a little bit. It would drop from 43 to 40 when the vacuum line was put on. I drilled the Saginaw fitting under the regulator to a little bigger than 5/32nds. That helped some. The biggest difference was at the frame rail. It looked like the Saginaw fitting was crimped down alot more than usual. Especially on the end. Drilled it to the same diameter and it now drops from 43 to 36-38.

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My buddy Steve on his T had an issue with his return line too. He was logging his fuel pressure, and was getting a spike when the 2nd pump kicked on. He ran new feed, and return lines. I was going to do the same, but figured I'll try the stock lines first.

 

[turbo nasty]

IMO a 255/walro 340 isk pump will overwhelm the return as mentioned so it doesnt really drop to "normal" mid 30's range but its not a issue as the BLM's will slightly skew from this lil higher psi but nothing that needs drilling of the saginaw fittings.
Reality is for a E85 fuel system to support horsepower for 11 second or better will need a bigger return line.

 

[dvernst]

I'm just drilling them because I have everything all apart. Not gonna hurt anything by doing it.

 

[Ttype6]

Reality is for a E85 fuel system to support horsepower for 11 second or better will need a bigger return line.

E85 uses 30% more fuel throughout the entire rpm range,including idle. Because of this,high fuel pressure at idle is less likely to happen. I am making 750 hp on E85 with stock supply and return lines. This volume of fuel is equivalent to the amount of fuel that a 975 hp gasoline motor would use.

 

[Rafs-T-Type]

E85 uses 30% more fuel throughout the entire rpm range,including idle. Because of this,high fuel pressure at idle is less likely to happen. I am making 750 hp on E85 with stock supply and return lines. This volume of fuel is equivalent to the amount of fuel that a 975 hp gasoline motor would use.

To the wheels? Same setup as your sig? Mainly I am curious about the 120's.

 

[Ttype6]

To the wheels? Same setup as your sig? Mainly I am curious about the 120's.

Motor. Yes.

 

[dvernst]

1

 

[Pronto]

I suggest a good drill bit. I experimented drilling out a line and got nowhere. Guess my bit was not good enough.

 

[dvernst]

Have any of you guys personally experienced a problem with the stock fuel filter and e85?

 

[dvernst]

Drilled everything out tonight. Can't believe how restricted the fittings were. The Saginaw on the pump hanger for the feed wasn't even a 1/4".

 

[TT/Ameasap]

Why is there so much debate about stock lines? Shouldn't this be cut N dry? Or are some of these people have pinched lines and don't know it? I just don't get it?

 

[696]

I tried to drill out all my opening on the return and feed. With everything "opened" I STILL couldn't get me FP down (I was running a TT 340) to an acceptable level. I knew I would need it one day so I upgraded to the Racetronix 340 DP, -8 feed and -6 return and haven't looked back. I have "heard" the same thing on running a DP w/ a Walbro 340 as the primary and a TT340 or whatever on a hobbs switch when the boost comes in. In theory the Walbro 340 will be able to return the fuel and the boost will use the extra from the other pump. Otherwise, run a feed line and use the stock feed as a return and save some $$$. My $.02

 

[696]

Why is there so much debate about stock lines? Shouldn't this be cut N dry? Or are some of these people have pinched lines and don't know it? I just don't get it?

A lot of them seem to be different than others. Not taken into consideration if someone monkeyed with there 25+ year old car and tweaked them and didn't know it.
I couldn't get my FP down with my TT 340 but buddy has one on his 87 GN with stock lines and no problems????

 

[dvernst]

After drilling my feed and return lines with both pumps on, engine off, and a battery charger on it. I'm able to get down to 35psi. It's a little shaky on the needle, but it does drop that low. I'll be using a 7 psi Hobbs switch.