Flow tested injectors.. how low is bad?

[Skunksmash]

This will be for an 87 TBI 5.7L

There is a guy that I was thinking of buying some flow matched injectors from. He says that he uses gasoline to flow test them cause that is the only real way to get a perfect match. He says that everyone else uses naptha or something and it doesn't really work out right. But anyway, He says that they vary wildly when you just buy a set from somewhere like the auto parts store or something. He said that he can get them down as low as 550 lbs per hour. (was it pounds per hour... can't remember) Anyway, would that be a good idea?

Seems like GM would have had a minimum and IIRC, it was somewhere in the area of 650. And the 305's ran 500. So it seems like it wouldn't be a good idea to go putting injectors that flow less on a vehicle that was designed for them to flow more. Or would it? Perhaps this could actually save a little money at the gas pump?

Then again, is all this even necessary? Cause doesn't the computer control this?

[Blue 82]

Fuel injectors are measure in lb/hr (in the case of a 5.7 TBI it would be near 55 lb/hr)
Or they can be measured in cc/minute
I think he is refering to cc/minute (550lb/hr x 2 injectors = 176 gallons/hr)

A rough was to convert lb/hr to cc/minute is to multiply by 10.5

So 55lb/hr x 10.5= 577.5cc/minute
(the 55lb per hour would be at a specific fuel pressure)
Increasing/decreasing the pressure would affect rate of flow


It is nice to have injector fuel flow close to the fuel requirements of the engine,
The computor can only control so much.

[Skunksmash]

So having injectors that were exactly matched to the fuel requirements of the engine would help with... what? Fuel economy maybe? Or maybe it would idle a little bit smoother?

[Captkaos]

Stock 5.7L, not going to effect anything but your checking account.

[Blue 82]

here's a video on what a leaking/dirty TBI injector looks like
http://www.youtube.com/watch?v=lnsLJeboslk

You want a spray pattern, a fine mist.
I use a timing light to check the spray pattern
it helps when it's dark outside.

If you bave leaking/dirty injectors on a TBI, it's a good idea to replace em in pairs
That's been my experiance.

Here's another Video
http://www.youtube.com/watch?v=HUbsOYPoQcw&NR=1