Klyde,
I too support the use of Jon's 280-155-715 as a perfect replacement for LT1's programmed flowrate of 24 lbs. The OP has a L98 which is programmed at 22.1, but he's capable of modifying his flowrate (most can't). What I object too is the sale of 280-155-700 as a direct replacement for L98's which only flows 20 lbs. The computer will make up for most of this undersized injector, but is really not what we should be doing. Depending on the error correction function of the ECM for L98's doesn't optimize drivabilty running the undersized Bosch yellow.

 

Call Jon at FIC. I did on my 88. The injectors fit a little different but work perfectly. Best money spent.

 

What do you mean by fit a little different?
I will be calling FIC monday for sure.

 

Currently, your's are clipped to the rail, and these new ones have no provisions for clips. The Bosch III is shorter than previous versions. When we first started using them on the L98 they would drop in too far into the manifold and would leak at the rail. A solution was to grind down the mounting bosses and lower the rail. Someone came up with the idea of using an oversize o-ring just above the bottom o-ring that solved this problem.

You will install them into the intake first, and put the rail on top. That's the real difference.

 

Interesting, and good to know. As I saw on the FIC website, they showed a video of the yellow injectors not being the correct length for a TPI motor. Had a few solutions, but ending up adding a second O-ring in the upper injector groove, and it also served as an insulator.
So bolting down the fuel rail will hold the injectors down, just like the stock ones, yes?

 

Actually the fuel pressure will push them into the manifold and the extra o-ring will keep them at the correct height. When you bolt down the fuel rail you can still move them around a little. Once the fuel pressure reaches 30 or 40 pounds they seat to the proper level. That's also the way the stock ones fit.

 

Hmmmm, interesting, also good to know. I do know the stock injectors are little loose, i mean you can turn them a little bit. Not really a concern to me. So the next question will be what FP to run these at. I am putting on an AFPR. I will be asking FIC this question as well.
Thanks again folks.

 

Take a pressure reading prior to installing the AFPR, and use that as a base to start from.

 

Well i talked to Jon at FIC, and got my injectors on the way. blue Bosch design III set of 8. also got the O-ring kit for the fuel rail, and he got me for the pressure regulator diaphram/spring kit. Said the stock one will get eaten by ethanol fuel sooner or later, and you will have mess. Also said that these blue Bosch units are a cheaper injector, but lots of folks are having good luck with them......hmmmm.
Tried to sell me the Delphi 22 lb'er flow matched new units, as a direct stock replacement. but i told him that i can change things in the chip, and can set the FP to anything.
He said to just set that to right at 43.5, since that is what they test at, and they flow exactly 24lbs/hr.

 

BTW...

never twist an injector after its been seated and under tension in the rail.
These are just O-rings. They do NOT tolerate twisting under compression. You'd need a lip seal to do that and not tear the rubber.

Find the proper position BEFORE snapping the rails on top. When I say SNAP, that's exactly what I mean. You have to set the rail on the set of inj each side then push down hard and sharply to SNAP the O-rings into the rail. It will pop or click or snap when it seats. From that point on, do not twist...it tears the rubber o-ring.
PS...I assemble with vasoline because its compatible and it vanishes with heat. Some say to use Palmolive dish soap...not sure on that one. Whatever you use, apply liberally to the rail holes and inj so they do not bind and damage the rubber. The no twisting applies to the rails as well...that's a bit more difficult, but do-able. The rails tend to wiggle around a lot.
After you "set" the rails/inj and bolt them down, connect the fuel lines next. Those have small O-rings as well. After the lines are tight then you need to turn the key ON and OFF then ON again to pressurize the rails. DO NOT CRANK the starter ! Now go under the hood and check for leaks. Look, sniff and feel. You want to find any leaks NOW before you start installing the runners and plenum.
Have fun !

 

More good info for sure. i usually use light oil on the injector O-rings, but vasoline can work for me as well. I will be carefull not to twist them. Tonight started pulling things apart. Got the the plenum/TB all loose, and disconected the fuel lines. After that, decided to clear the diverter valve, for more clearance. Shoulda pulled that first! Orings on the ends of the fuel lines looked cruddy, almost rust like. But not leaking.
I want to get this thing going soon, but i still want to take my time and not mess anything up. Gonna go get some new Orings and filter tomorow.

 

Ok here is an update and a new question. Pulled the runners tonight, and got the fuel rail up and out. 1 injector actually stuck in the manifold. i think the little retaining clip was broken. What i also found was there was 3 different types of injectors installed. 5 stock grey Multecs, 2 black unknown with small screens on tips with 6 small holes, and 1 black Lucas type w/ 3 holes on the tip. All quite a mess i think.

But my question is about the O-ring seals on the fuel feed lines. I got the replacement seals at the dealer today, smaller one for the return and larger for the feed. But do these seals go up inside the hard line inputs to the rail? i didnt see any seals there, but there are Orings around the flex feed lines that screw up into the fixed fittings. And those inputs are the same size. Seems like these o rings are aound the back of the lip, and would not do much. The input hard lines to the rail are definitly different size. Do i need to get another larger O ring?
I took a picture of flex line ends, but i didnt upload it.
Thanks

 

Toss them all and get new ones.

 

New Update. Got the new Bosch III injects in, and today finished it up and fired up the engine!! Woohoo!! All i did was just idle it, set fuel pressure to 44 and of course put in a new chip with correct injector constant. Car seems to run much smoother, just listening to it idle. Didnt drive it yet, but soon. Then get the laptop on it and get them BLMs dialed in!
So this was a decent project. Did a few other little things while it was apart. The fuel filter was kind of a pain, since one flare nut was rounded off a bit, thus gave me fits getting it off. The other helpfull tip i figured out, was that i should have pulled the diverter valve off sooner, to help access the fuel feed lines. That would have helped on disassembly, but got it off for reassembly. Made a note on that one.
Thanks everyone for all you help. Cant wait to run it and see how it purrs.....i think i did the right thing!

 

We all "know" you did the right thing. That's what we've been telling you.

 

I know this is an old post. I called FIC yesterday. The guy I talked to said the yellow Boschs are correct for my '91 L98. Now I'm reading they run lean. Which is it? Are the o-rings they provide ethanol resistant? I usually put in 100% premium gasoline when I can find it. It know for sure ethanol ruins 2 stroke engines. Small engine mechanics in the area all say they love ethanol. They make their living off of it. I don't know about the effects on 4 stroke. Do I need a new regulator? FIC offers the choice with the sale. I'm not a mechanic and I'm trying to learn. I'm smelling raw gasoline when I run my car. I think it's probably the old injectors, which are stock.