[tccrab]

Originally Posted by george henry

OK, need a little clarification here. I'm about to replace all my injectors in 1990 #1507 with Accels ($27 each at Auto Shop racing engines). I called Haibeck about these o-rings and he said the info is a little misleading and I don't really need them. So now I'm confused. Any help?
PS: I'm a new Net Registry member.

Hmmm.......
I bought a set of Marc's special "O" rings when I replaced my stock injectors with Accels last year based upon this information:

This probably belongs on a web site but I didn’t have a chance to add it to mine yet but anyway here is my story….and warning this one is a long one....

I was already cussing like a sailor when I found out that that I needed to replace essentially all of the injectors on a recently purchased 1991. Then when I found out that that you really have only a few choices: original stock “crap” with the same flawed design, rewrapped originals (aka MSD, and not avail for “correct” primaries for 90-91), or finally, RC’s. Also notably, most reputable “Injector Cleaning” services won’t service the originals because of the flawed design where the cleaning process itself has been known to kill them. Yes, there are some interesting conspiracy theories that GM pushed through these injectors knowing they were flawed to begin with but I won’t go there. Anyway, back to the story. With all options in excess of $1000 for a set of 16, my cussing turned into kicking and screaming since that $1K would come out of my “MORE POWER” budget.

As longtime F-Body and L98 converts like myself can attest, a common mod/cost savings for standard TPI cars is to ditch the stock 22lb injectors in favor of the much cheaper “Motorsport”/Bosch style, so I started my investigation as to whether or not this would work on our Z’s. Initially, I came up with the same results as many before me. Bosch style can be used on the secondaries, but most are poor quality, and then you have mixed sets on of primaries and secondaries. Unfortunately they also don’t work on the 90-91 primaries thanks to the unique design with the O ring in the injector housing and the “offset” guide for the electrical connector clip. It is possible to “update” to the later style injector when used in conjunction with a larger O-ring in the injector housing but that only works with Lucas/Delphi/Multec style injectors that do not have the plastic end cap like Bosch do.

So, after all that research, I planned to suck it up and buy RC’s. When I called RC in December 2005, they were out of the 205cc primaries until late March 2006. Crap, now what. Many just bought their 210’s during this time, but I already have a Haibeck chip designed for 205’s. Probably wouldn’t be a big deal to use to the 210’s anyway, but I decided against it.

The plot thickens. It turns out Accel ditched their old style “Bosch” injector in favor of a new stainless steel body, Lucas style housing. You guessed it, it’s a comparable housing to that used by RC. Curious, I found a set of 8 “new” style Accel 21 lb/hr on eBay for $209, and since I had a few months, what harm is there in experimentation? When I received them, they did indeed look like a much higher quality unit than the old design, and knowing that the old style Accel units typically flowed more than rated, I sent them off to the very reputable Rich Jensen to get some flow numbers.

Oddly, they flowed almost exactly 19.4 lb/hr across the board for all eight. That’s really great for me, but potentially really bad for Accel, since they are rated at 21 lb/hr. If you do the math, 19.4 lb/hr * 10.5 = 203.7cc, almost right on the mark for what I was looking for.

I immediately purchased another set, yes on eBay again, and sent them of to Rich. To my amazement, Rich had the same results on the next set of 8. On top of that, the flow numbers for all 16 were so close I didn’t even need any “pairing” them to balance lower flowing injectors with higher flowing.

Now to make them work:
For the primaries, remove the lower O-ring on the new Accel units. Replace the existing IH O-rings with the larger O-rings from Marc Haibeck (~$20+ship). The lower O-Ring will seat against the slight taper on the Accel injectors (see photo). For later models you don't need the larger o-rings and needless to say, do not remove the lower o-ring.

Just click for larger images...



Use a razor blade to remove the plastic guide for the injector harness clip.





Don’t worry, the guide is just that, a guide, the harness will still clip in place by using tabs on the sides. The guide was simply there so the primary and secondary were not swapped, but I’m not sure why they did that since it’s really difficult to stretch them to install them incorrectly. As for attaching to the fuel rail, simply use the original clip on the highest ring on the Accel unit(see pic above). Yes they do sit slightly lower in the rail but this does not impact sealing.


The secondaries work without modification.

What you need:

(16) Accel 21# fuel injectors PN 150121 ($228-$248 for 8 right now on eBay New In Box) I think they run ~ $280 from Summit

Large IH O-rings available from Mark Haibeck $20 (Sure you can probably get these elsewhere but Mark deserves the biz..)

Flow testing of your Accel injectors just to be sure… $5/injector

Total: ~$500


My 1991 is up and running in this configuration without any sealing issues on the injectors. I have yet to put it on the dyno to verify the A/F. My “seat of the pants o' meter” tells me they are working just fine, and yes, my seat is a very highly tuned measuring device. I am having a bit of difficulty with my idle a bit high but I’ve all but ruled out the injectors.

Take this info as you like. This is simply the way I did mine to save a buck, actually over 500. I will post more details on a web site when I have a chance but I wanted to pass along the info since “Injectors” seems to come up regularly.

I was hoping someone else might be as adventuresome and give it try to substantiate my claims….

To be honest, I didn't match up the originals to the ones I bought from Marc to see if there was a size difference. I just figured they were what I needed and was happy with that.

If Marc said you don't need them, then you don't need them. However, having said that, it would probably be prudent to call him one more time and ask him "Are You Sure???".
Marc is THE MAN and I would never question him on anything ZR1 (or anything else for that matter, but I digress). Maybe he's learned something since I replaced my injectors last year.

TomC
'90ZR1 #792