Need injector dimensions

[dyeager535]

Working on my port injected Olds project, trying to find some injectors to use.

The rail has an ID of .40", or just over 10MM.

The intake has an ID of .525", or a bit over 13MM.

No meat in the rails to open them up more than just a hair, so probably not an option to go bigger there.

The only writeup for this project the guy says he used later LT1 injectors, but as far as I could find, the O-rings are 14MM OD on both ends for those.

If I had a listing of a bunch of injectors showing o-ring OD, I'd be fine. But finding the actual dimension for various injectors is proving pretty difficult.

To top it off, I need to find an injector to use before I can figure out how tall a throttle body spacer I'll need, if any. As it is now, the injector needs to be either incredibly short, or I'll need to make a 1" throttle body spacer, so the rails clear the IAC and throttle.

I'll be using a '7727 to run the system, if it matters. The regulator for the system sets pressure at 39PSI, but as long as the injectors are close enough, I know I can recalculate the flow rates to get it dialed in.

[Six_Shooter]

"Small Block" Olds? I can't see a "big block" Olds having any clearance issues with a port fuel rail, and especially the throttle linkage. You could possibly also turn the throttle body a bit if height is a concern, such as for hood clearance, to clear the IAC.

You will likely need to find or make a different fuel rail to use injectors that will easily fit. Of the injectors I've looked at, the only staggered sizing of the injectors has the top O-ring larger than the bottom, I haven't seen any the other way around. A 14mm O-ring will fit in the intake hole, since you want some crush on those O-rings anyway.

If you're real lucky, you might find an injector that uses a fat top O-ring and be able to swap it with a skinnier O-ring to use with the parts you have.

[dyeager535]

I *think* the BBO has a slightly wider intake than the SBO. I don't think the bank angle or anything changed between the two, as I know the heads are interchangeable. But really doesn't matter for this I suppose. (Except an FI intake/rail setup is made for the BBO)

Here is the conversion someone else did. http://grimers.com/vehicles/olds/403efi/index.html I tried getting hold of him, no luck as of yet. He used an SBC throttle body, I'm guessing my BBC throttle body is why I have issues with the IAC. I can't even see it in his pictures. You CAN see in the pictures though, that without the TB spacer, the throttle shaft wouldn't clear the rails. He obviously kept going on the project....http://www.grimers.com/vehicles/olds/cnp2.jpg

The injectors look very similar to the TPI injectors I was running before the EVO's, but the one injector I have (I think it was a port injected 4.3?) is way too large on the top end to fit. I'll pull the o-ring off, perhaps thats how he made it fit, smaller OD o-ring.

[1project2many]

That's Bob Valentine's car. There are more notes and tips if you can find the gmecm / diy-efi archives and I believe he answered the question about the rail. There are two different styles of IAC. One is bolt in and uses a small connector. One is screw in and uses a large connector. The screw in type makes the TB footprint larger. If you pick something like a 99 Cavalier, or maybe an old 2.5 with PFI then you can remove the injector fitings and attach them to the Olds rail. But knowing Bob the secret was to get the rail at the correct height then find suitable O rings to seal the top. Look at the Cadillacpower EFI forum (http://www.cadillacpower.com/forum/search.php) and the GMC motorhome pictures page (http://www.gmcmhphotos.com/photos/403-port-fuel-injection/p3685.html) and you might find tips.

HTH

[Six_Shooter]

There is a large difference in width between BBO and SBO, like 2" IIRC. The deck height is much taller on the BBO, which pushes the heads quite a bit apart.

The BBC TB would actually have a shorter distance between the TB itself and the end, than a SBC IAC, as 1project2many said. The original Olds MPFI intake used a throttle kicker, and not an IAC, which is why you are expeiencing fitment issues. Have you looked at setting the throttle body on an angle to fit between the rails better?

[dyeager535]

I've looked at it, but if you look at the photo on Bob Valentine's page, you'll notice that the throttle body "flange" isn't cast like a modern intake...the TBI has a bunch of hollow space under it, so the throttle body bores mate up to what equate to aluminum towers. Boring them to the required 2" isn't going to leave much wall thickness, but one "tube" IS thicker than the other, and may allow some angling of the TBI. What that will do to throttle cable/TV cable angle, who knows.

However, I'm going to have to make a spacer/adapter of some sort anyways (original TBI bolt pattern is 5 x 4.75", nothing similar), so simply raising the throttle body up is a completely viable solution. With the injector pod off, no spacer is needed for the air cleaner. With the pod off, and about a 1" spacer, it equates to approximately the same height as the Q-jet, so no hood clearance issues.

I've found that "non-standard" o-rings are made (http://www.rrrubber.com/oRings.asp for instance) and I think that explains a whole bunch towards the variety of o-rings found in GM fuel systems...I don't see a "standard" o-ring that is anywhere near as thick in cross section as what was used on the Multecs for instance.

*If* I can find someone that stocks or can get less than $1000 minimum orders of the non-stock o-rings, I think a .048 cross section o-ring in .298-.301 ID would fit a "normal" injector (either Multec or my 24lb SVO's) AND the .40 bore (.305 is injector o-ring surface OD+.048+.048=.401). That's IF I can find someone that sells them for a cheap enough price I can test it.

I think I'm going to be using phenolic for the spacer, so thicker is probably better, not having used it before. A ~5.5 x 5.25" aluminum block 1" thick is hard to find/expensive, and steel is just too hard to work with.

I'll need to spend time at the links provided to see what others may have come up with.

[1project2many]

Yes, you need to spend time with the links. :) There are some very cool EFI builds on the motorhome page.

Caption on this says "drill press table must be tilted 4 degrees."

http://www.gmcmhphotos.com/photos/data/3372/372_p3690.jpg