Walboro 307 versus 340

[turbojimmy]

I should know this, but......

I put a Walboro 307 in my car when I first put it on the road back in 1999. I'm running high-11s now with aspirations of very low 11s this year (switched to a PT-61 and 60# injectors and some other stuff). Am I out of fuel pump with a 307? Is a 340 enough?

Thanks,
Jim

 

[DCVING 6]

Some will say that you "should" be fine with a 307. If it were me, I'd go ahead and get a 340 since its not that expensive. Cheap peace of mind i guess.

 

[d0n_3d]

personally I think running a TE-44/50's combo is the limits for me with that pump...i was running 45 psi fuel pressure and boost most of the time at 25 psi so at WOT the fuel pressure was at 70 psi and they say that 307 pump doesn't like to go over 60-65 range...guess i proved them wrong but i don't know how long the pump will last if i keep doing that...

"I" would bite the bullet and be safe with a 340...in fact some say Red's XP + pump flows a teeny tiny more than the Walbro 340...but that might open another can of worms on this site!

 

[turbojimmy]

Thanks for the replies. After doing the research I read that the 307 is the same pump as a 340 but that the 307 isn't good for higher pressures.

I couldn't find any definitive recommended max pressures for each, but I'd have to agree with you guys that a $100 investment in a 340 is cheap insurance.

As an aside, my hanger/sender is beat from the accident that totaled the car in '97. I fixed it with JB Weld, but since I'm taking it apart again I may as well see if I can get the fuel level gauge working correctly. It's a digital dash car - anyone know of a source for a hanger/sender other than a double-pumper setup?

Jim

 

[87GN_70GS]

Test it for yourself to be sure before you go swapping out pumps just for the heck of it. Get a fuel pressure gauge that you can monitor from the cockpit. Check your fp and ensure that fp is not falling off as you go through the traps.

 

[87GN_70GS]

307 is the same pump as a 340

Used to be, but not anymore. The 340 has a more efficient armature (motor).

 

[turbojimmy]

Originally posted by 87GN_70GS
Test it for yourself to be sure before you go swapping out pumps just for the heck of it. Get a fuel pressure gauge that you can monitor from the cockpit. Check your fp and ensure that fp is not falling off as you go through the traps.

I have a gauge mounted inside - I'll have to keep an eye on it. It seemed to be keeping up last time out w/ 110-112 MPH trap speeds.

Thanks,
Jim

 

[Dean]

Originally posted by turbojimmy
It's a digital dash car - anyone know of a source for a hanger/sender other than a double-pumper setup?

I believe the hangers that come with the DPs are analog.

 

[Dean]

Regarding the maximum pressures, see: http://home.pacbell.net/sfnelson/walbro242_307_340-2.html .

Caveat: These are manufacturer's #s, not mine. Per my testing:

12.0V/60psi = ~49.5, vs. 50
12.0V/65psi = ~46.8
12.0V/70psi = ~42.3, vs. 45
13.5V/60psi = ~57.0 vs. 59
13.5V/65psi = ~54.4
13.5V/70psi = ~49.6 vs. 55


Note how the gal/hr drops with the psi at a given voltage. If you are running stock lines, add ~3psi to your rail pressure readings to figure the pump pressure.

BTW, you can have pressure w/o volume. Do a volume check.

 

[ttypewe4jim]

turbojimmy if your sending unit is messed up then..... why not get a double pumper????

are you ever planing to do heads and a cam soon?..... if so i would DIFFENTLY think that you should have a double.....


you know how the saying goes better safe then sorry

hth
jim

 

[turbojimmy]

Originally posted by ttypewe4jim
turbojimmy if your sending unit is messed up then..... why not get a double pumper????

are you ever planing to do heads and a cam soon?..... if so i would DIFFENTLY think that you should have a double.....


you know how the saying goes better safe then sorry

hth
jim

I've got ported & polished irons, port matched intake and a beefier cam. Maybe I should do a double and forget about it. $500 is about 5 times what I wanted to spend....but I guess you gotta pay to play.

Thanks,
Jim

 

[JCotton]

I used the 307 in my stock block car running 10.70 @ 126mph before running out. That included a hot wire kit and a volt booster as well as 55lb injectors. The ratings I had received were as follows, 307 was good for 255 lph @ 70lbs
340 was good for 255lph @ 60lbs

Now we can debate all these numbers till the cows come home and it will make no differance, Walbro has dropped the 340 pump and is now only using the 307M.

 

[turbojimmy]

Thanks for the info, Jack. Looks like the 307 *might* be enough, but the 340 would be better. Double pumper sounds like overkill based on your results and my goals.

Out of curiousity, though, does your double pumper kit have the right sender for a digital dash (it's different than an analog car, right?)?

Thanks,
JIm

 

[87GN_70GS]

Per my testing:

What was your sample size?

 

[87GN_70GS]

307 was good for 255 lph @ 70lbs

Hmmm. Looking at the published flow characteristics supplied by the MANUFACTURER of the pump (i.e Walbro), I get 50 gph or 190 lph @ 70 psi. Not sure where those other numbers came from.

Both pumps are marketed as "255 lph" pumps, and that number comes from the flow at 3 bar or 43.5 psi, which is generally regarded as the operating pressure that most OEM fuel systems are rated at. This is also done to line up with the ratings of fuel injectors and thier marketing: i.e. a "42 pound" injector flows 42#/hr at 43.5 psi.

340 was good for 255lph @ 60lbs

Straight from the chart, I read 224 lph (59 gph) at 60 psi.

has dropped the 340 pump

You can still get the "heart and soul" of the 340 by using part # F20000169, same guts, same flow.

 

[91Bird305]

Originally posted by JCotton
I used the 307 in my stock block car running 10.70 @ 126mph before running out. That included a hot wire kit and a volt booster as well as 55lb injectors. The ratings I had received were as follows, 307 was good for 255 lph @ 70lbs
340 was good for 255lph @ 60lbs

Now we can debate all these numbers till the cows come home and it will make no differance, Walbro has dropped the 340 pump and is now only using the 307M.

how long did it take to run out on u when u were running 10.70s?

 

[Dean]

Originally posted by 87GN_70GS
What was your sample size?

Ran pump for 60 seconds into a container, weighed it on a digiatal scale that goes to the 1/10 oz. (deducting tare weight of container), ran the math out based on the specific gravity.


Dean

 

[87GN_70GS]

Ran pump for 60 seconds into a container, weighed it on a digiatal scale that goes to the 1/10 oz. (deducting tare weight of container), ran the math out based on the specific gravity.

No, sorry, I meant how many pumps were tested?

 

[Dean]

Oh.

So far, 1 old stocker (it was amusing watching that thing gushing fuel out of many crevices), 1 ~3k mile 340M, and some testing on 1 new 340m. The numbers I noted were from the 2k mile 340M. I haven't done as extensive a test or plugged in the data for the new one. (BTW, on that 3k 340M, the AMP draw was consistently ~2A lower than the manufacturer's data. Dunno what that means, but there ya go.)

Unfortunately I am not a man of great wealth, so I can't afford to go out and get lots of pumps to test to give a better average. At this point, I can only ASSume that my pump is as average as anyone's out there, but who knows. The reason I did this was because the only non-mfg data I have ever seen on pump flow was not through the stock lines and fittings. At 70# Those test showed:

~54.1 @ 12.2V vs. my ~42.3 @ 12.2V
~63.5 @ 14.0V vs. my 56.2 @ 14.0V

Quite a disparity, even though they were using a new pump... most folks I know don't change their pumps on a regular basis.

I'm also testing with -6, and probably -8, supply lines. -6 is looking good.


Dean

 

[Mike Licht]

If you pull the 307, take a punch and tighten up the overpressue valve spring you will have a 340. If you need help with this let me know. The replacment pump for the 340 is F20000169. This pump will out perform a 307 by a large margin and allow fuel pressure over 65 psi where the 307M rapidly drops off in performance.
Mike