Bigger Injectors
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Bigger Injectors
I have been looking for some 19# injectors to step up from the 17# injectors in the truck. I cannot seem to find any(for a reasonable price). I am NOT spending 75 bucks A PIECE for new ones, so I would like to know some junkyard motors to look for. I recently swapped in a rebuild 300, and I need to shame the people who told me to put a V8 in... 
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I'm fairly sure the 17# injectors came stock on 300's, and I heard of someone a while ago putting the 19# injectors on, but I don't know where to find them. I also have a 302 throttle body and plan on port-matching the 300 plenum to it.
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Stock 4.9's use a 14 lbhr injector.
If you step up to the larger injectors, ideally you'd reprogram the computer. Most add an adjustable fuel pressure regulator. Reason being, the stock 4.9 fuel pressure is set at 58psi or so, the v-8 engines use something closer to 39/40psi.
If you step up to the larger injectors, ideally you'd reprogram the computer. Most add an adjustable fuel pressure regulator. Reason being, the stock 4.9 fuel pressure is set at 58psi or so, the v-8 engines use something closer to 39/40psi.
Last edited by Motorhead351; Dec 3, 2005 at 08:44 AM.
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Look on a 5.0/5.8 engine, a yellowish orange injector top would indicate a 19lbhr injector. Some of the 5.0 car engines received a 14lbhr injector like the 4.9, it has a gray top.
or you can look on 4.0 rangers/aerostars, if you see a black top injector, this would indicate a 19 lbhr injector.
or you can look on 4.0 rangers/aerostars, if you see a black top injector, this would indicate a 19 lbhr injector.
Postmaster
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From: Coal Region
if ur 300 is stock or close to stock (bolt ons) u do not need larger injectors plain and simple.
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just another Rockwell looser
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From: Cocoa, FL
what all is involved in putting 302 throttle body on a 300? do the bolts, wiring, and air intake all match up? if i put the 302 throttle body on should i use its injectors as well?
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Originally Posted by RedneckF-150
Sweet... I can already get some. I thought the truck 302 had the same injectors as a 300, but sometimes ignorance/stupidity rears it's ugly head over my brain function. Thanks a heap!
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Something else to consider and a good reason to either use an adjustable fuel pressure regulator or reburn the computer.
Right now you have a 14 lb hr injectors that operates at 58 psi
You wanna add in the 24lb hr injectors that normally operate at 39 psi
I am not 100% sure what psi each is rated at but for this, we will say the stock fuel psi setting.
If you take a 24lb hr injector rated at 39 psi and increase the fuel psi to 58 psi, which is the stock 4.9 setting, your 24 lb hr injector will flow 35 lb hr.
Using a injector flow/ HP support formula
14 lbhr = 135
24 lbhr = 240
35 lbhr = 336
This is with BSFC being .5 and duty cycle .8, # injectors 6
Right now you have a 14 lb hr injectors that operates at 58 psi
You wanna add in the 24lb hr injectors that normally operate at 39 psi
I am not 100% sure what psi each is rated at but for this, we will say the stock fuel psi setting.
If you take a 24lb hr injector rated at 39 psi and increase the fuel psi to 58 psi, which is the stock 4.9 setting, your 24 lb hr injector will flow 35 lb hr.
Using a injector flow/ HP support formula
14 lbhr = 135
24 lbhr = 240
35 lbhr = 336
This is with BSFC being .5 and duty cycle .8, # injectors 6
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From: Broken Arrow, OK
Almost all injectors are rated at 3 bars (43.5psi). A 24 lb/hr injector running on the stock fuel pressure regulator will make the truck undriveable, been there, done that. Even with the adjustable regulator I couldn't get it to run good enough to drive. It was gutless and got about 4 mpg. At 60 psi a 24 flows around 33 lb/hr; nearly double what the engine needs.