Hey guys,
I want to get new injectors for my 91 GTA. Am I correct that the stock size for a 350 is 21 lbs? Mine isn't exactly stock anymore though. I had it bored .30 over, edelbrock headers, 52mm throtle body, etc, etc. I heard that 21 lb injectors are good for even a bit over a 383, but it looks like parts suppliers like Summit and Jegs recommend 24lb injectors for a 350 5.7. Which would be best for me? 21 or 24? Is there much of a difference?

 

Clicky

It's not a matter of what you're running CID wise but what HP you're making. There are 6 cylinders that can max 83# injectors. Scroll down and you'll see a table, it's a good rough guide for what you're doing. You can bump your static FP if you're marginal size wise. With the mods you have I doubt I'd sweat it.

 

Ahh ok....i'm getting numbers basically between 21 and 24 in my searching. I'd say my HP is around 300. Never dyno tested it, but i'm thinking it's close enough to that if I had to take a guess. In the chart you gave me it says 22 lb injectors for 300HP. Right now the car is running very old injectors that i'm sure are 21 lbs. The car runs "fine" with those, so I'm sure with brand new 21 lb injectors it should run even better. I'm having a bit of a problem when I first start the car after it's been sitting overnight or for a long time where it wants to stall out unless I keep my foot on the gas for a few seconds. Once it warms up, it's fine. I have a feeling the old injectors are one of, if not, THE problem i'm having.

 

a leakdown test would prove your theory correct or incorrect; if you're holding it above about 3/4ths throttle that's the "flood clear" mode. Have you gotten a chip cut for your car or had any tuning done yet? If yes, go with a stock sized injector and use the chip you have, if not get a larger injector and a new chip; should be some power there.

 

Yeah, I have a chip programmed with all the mods I had done. So go with the 21 lbs. injectors, huh?