OEM prefilter Walbro pump...do i need another filter

[Chevy]

I'm converting my 68 camaro to EFI, using Holley Stealth Ram with Commander 950. Engine is a 355 with AFR190 heads and roller cam. According to Cam Quest software should make 420 hp. I have 30 lb Ford injectors and Walbro external 255 pump. I am using 3/8ths inch steel line from the tank, a short section of SAE J30 hose on barbs, then more 3/8th steel line to an oem EFI filter (WIX 33481) as some here have reported using. Then i have the Walbro 255 pump, and more steel line up to the engine bay. My question is this...with the WIX 33481 filter before the pump, do i need another filter before the injectors? If so, must i use 10 micron? I have an inline 40 micron sintered bronze one i was thinking about dropping in line just before the fuel rail...

Thanks in advance for your thoughts.

[Hammered]

Most everything I've read says 10 micron after the pump and 100 micron before the pump. Anything less after the pump and you could plug the injectors.

[Chevy]

Yeah, the aftermarket systems do all say pretty much the same. I'm having a hard time investing more money in plumbing and filters than i did in my fuel pump in the first place though.

Some here used inexpesive OEM filters (maybe Doug F?) and i wanted to know if they ran them before or after pump, or both, or in conjunction with other filters. I searched past posts but didn't see these details.

I know the "by the book" answer but want to know if you go with the OEM style filter what people's experience is.

If anyone wants to share i'd appreciate it.

thanks!

[Hammered]

OEM is a fuel sock before the pump and filter after. The fuel sock is close to the 100 micron spec and the filters are close to the 10 micron spec so basically no difference.

[GetMore]

FWIW, most (if not all) people using that OEM filter have their pumps in the tank, so the sock is the first filter, like Hammered said.

Electric fuel pumps do not like to pull fuel. They like to blow, not suck. ;)
If you install a 10 micron filter before the pump you will probably burn up the pump rather quickly and it might not push much fuel if you accellerate hard.
I don't think you've got much choice.

[mooky]

I've done the exact same thing ('68 Camaro/StealthRam).

I have 3/8" fuel hose plumbed from the factory fuel pickup to a see-through inline fuel filter (the one I had used with the carb), then another section of fuel hose from that filter to the pump. From the pump is a section of 3/8" steel line which runs under the right side of the car to the rear of the front subframe. From there I have 3/8" Aeromotive high pressure fuel line running through the subframe to a Fram canister style filter mounted on the firewall. From the canister to the fuel rail is another chunk of the Aeromotive stuff.

And in case you're interested, I used the original factory fuel feed plumbing for my return system (it didn't have a return system prior). I rerouted it to the tank filler neck.

FWIW

-Brian

[Jim Craig]

The 10 micron that is used between the pump & injectors is used to protect the injectors from contamination -- if you've got room in your system use it.

Do not use any type "sintered bronze" filter in an injected system -- great for low volume factory carb stuff, but an absolute "no no" for any type of injected system.