NowhereFast

Being that I have my motor apart, I'd like to get a fresh set of injectors for it. I was looking at the 19lb Ford yellow tops from southbay. I've heard these injectors flow around 22lbs at the stock fuel pressure setting. Since my car is getting a mild cam upgrade, I need an AFPR. Would I be able to correct for higher flow of the ford injectors with the AFPR and have it run good, or would it be like throwing 22lb injectors on a 305 and having to do computer tuning? Would I be better off with these instead?

MrPackstin

iTrader: (9)

I have been injector bound myself lately. Gen 3 injectors would be better for fuel atomization. I would think 19lb injectors at a slightly higher perssure (maybe 45psi) would be best after the cam is installed. The 22# you linked to are actually not 22#, they are lower by factory spec/application, BUT they flow 22# at the increased fuel pressure on the TPI systems (43ish). The higher we go with ratings the harder it gets for the ECM to control lower demand situations (daily driving). I did get a set of rebuilt Bosch III's but they are mainly from the junk yards and can be hit/miss on quality/longevity even though they were cleaned. But, everywhere I look people are cursing injectors, i.e. Brand New (not rebuilt) Accel injectors. Southbay has an excellent reputation here and seems to be the best bet based on customer service-this is pretty important when dealing with junk yard pulls.

NowhereFast

I will not touch another set of Bosch IIIs, at least on a pre-88 car. I've put them in my '87 Iroc, and my friends '85 Iroc, and both cars took so long to start it was embarrassing(I'm talking 5-10 seconds), not to mention the increased wear on the starter.

MrPackstin

iTrader: (9)

Yeah, mine seems to take a little longer to fire off at normal operating temp with these Bosch IIIs. My car had LT1 24# (12ohm) injectors when I bought it and would not even start when warmed up. Took me a while to figure that out. ugh! Bosch IIIs are around 14 ohm and stock was 16. I am still digging into NEW Accel injectors. Had one injector "rebuilt" that was stuck open and now I am digging into a slow bleed off of fuel pressure at the rails. Chasing my tail here!

darbysan

I have the Bosch III's on mine, with a Holley AFPR. When I had the 305, I had to play around with the programming to get enough fuel. Finally ran them with a 17.1 spec in the LBS/HR tab, but they worked fine. I moved up to a 350, using the same injectors. Moved the rating up, as well as the pressure up to about 50 psi, and again running fine. I have a set of 21 lb injectors on the shelf, waiting for the next time I open up the intake, but for now the 19 lb units are working fine.

As for starting, no issues. I did switch to '89 programming ( 9th injector delete) and slightly modified the programming for the enrichment table. IIRC, the enrichment does not come until about the 9th rev. I moved it up to enrich after the 3rd.

Bigfoottpi11

Who told you that? The GM injectors are rated at 43.5 and they are 22lb. Most of the Ford are rated at 43.5 psi too! At the bottom of this link is a list of Bosch injectors and their ratings. http://www.fuelinjector.citymaker.co...low_Rates.html

NowhereFast

Just an example.
https://www.thirdgen.org/forums/tpi/...ing-going.html

Fast355 knows his stuff, I don't doubt they are rated lower. I've heard this numerous times from other people as well.

NowhereFast

Also, does anyone know the difference between these two? Obviously one was replaced, the one with the pintle is the same as the other 6. The first one is the oddball.

southbay08

The one without the pintle looks like it could be a lucas. The one with the pintle looks like an old bosch. Do you have part numbers off of them?

southbay08

Fast is correct. Example,, the 22lb injectors that everyone uses for their
350 are actually rated at 19lb using Ford pressure. When it comes to the
19lb yellow tops, we sell them as such for the 305's. I will not sell them as
22's.
You need a 22lb injector, then go to the 22lb Bosch lll you'll be happier.
Just my

NowhereFast

I'm looking for a 19#er using the stock GM pressure(43.5) on my 305, to avoid any kind of hassle with the computer tuning.

Like I said though, my experience with Bosch llls have put me off using them for good on CS injector cars. The extra MPG from the better fuel atomization is not important so much as the car actually starts like a TPI should, instantly, and not a carbed car that sat for a few years.

southbay08

Then the yellow tops will be fine.

NowhereFast

So they flow 19lbs at 43.5?

RBob

iTrader: (1)

Carbon build up on the back of the intake valves will cause this. The fuel mist from a Bosch III injector is quickly absorbed by the carbon, with none getting into the chamber for some time.

Need to saturate the carbon first before the fuel gets past and into the chamber.

The stock pencil stream injectors bounce fuel all over the intake runner. So a bunch gets past the injector valve and directly into the chamber.

Also during cranking the carbon on the top of the pistons also affects the volume of useable fuel in the chamber.

RBob.

NowhereFast

I had the 10 second starts when I put Bosch llls in my 87 Iroc 350, and that motor was brand new. I'm talking right off the palate.

RBob

iTrader: (1)

New motor along with new injectors? Maybe something else changed at the same time...

RBob.

NowhereFast

Maybe I misspoke, when I put the Bosch llls in, the thing had maybe 100 miles on it. It had 24# LT1 injectors for that duration, and I never had an issue with starting.

Regardless, I shouldn't have to jump through hoops to make an injector work properly. My experience with them has turned me off of them, and I never saw any kind of discernible benefit to having them. You have to understand, doing an injector swap is no ten minute job on these cars, and it would be extremely disappointing if I were to go through the trouble and then have problems a third time. Like I said, I've put them in two different cars, and both had the same issue with starting.