Holley TBI Fuel Fittings

gr8amp · Post by **gr8amp** » Sat Jun 17, 2006 3:35 pm

I am trying to piece together fuel system, and have run into some difficulty finding some fittings.

I got a good deal on a holley 502-6 TBI, which I believe is sold as a replacement for 88-89 GM trucks. I am trying to find the proper fuel fittings and have come up empty. The information I have found online seems to indicate that the 3/8" and 5/16" fuel line repair kits by Dorman should be the proper connections for this TBI. Unfortunately, these connections are much too large for the connections on the TBI.

After doing some reading and looking at some pictures, I am beginning to think that think that GM uses adapter pieces that thread into the TBI body and then allow the connection of the 3/8" and 5/16" fittings. Yet, I have been unable to locate these adapters anywhere. (I get those strange looks from the guy behind the parts counter

)

Does anyone have any experience with this, or know of a good source for these connectors?

Thanks,
-Jim

Bernard Fife · Post by **Bernard Fife** » Sat Jun 17, 2006 3:48 pm

Jim,

On my Holley TBI (http://members.shaw.ca/corvette.84/MS_TBI.html), the fittings on the casting were standard NPT pipe threads. See the photo in the link to see what I mean.

I used a 1/4" NPT pipe thread (I believe - it was a while ago - check to be sure) to 3/8" compression fitting adapter to hook upt to the hard fuel line, and I was 'in business'!

Lance.

Bernard Fife · Post by **Bernard Fife** » Sat Jun 17, 2006 4:04 pm

Jim,

I just relaized that this is a 2-bbl replacement TBI. The GM TBI's do have 'adapters' on the fuel line to take the dorman lines you mention.

Unforuntely, they are NOT a standard pipe thread.

GM calls these:

- Nut, fuel inlet,
- Nut, fuel return.

But doesn't show them as individually sold separately from the TBI assembly. At one time you could buy them in a kit, listed as "Fuel inlet and outlet kit" in group 3.724 (the GM parts guys will know what that means). If you take this info to a GM dealer along with the application (88-89 GM truck), they ought to be able to find what you are looking for.

Lance.

gr8amp · Post by **gr8amp** » Sat Jun 17, 2006 4:14 pm

Lance,

Thanks for the quick reply.

I have tried a handful of NPT fittings without any luck. A 5/16 seems to work for the intake line (although it seems a bit loose....enough to tell me it isn't going to work right), and I haven't found anything that fits the return side (looks like a 1/4 "might" work there).

I did some more hunting and found some pics of what I think I need. The following image shows these adapters.

Looks like it might be time for a junkyard run.

::EDIT: Looks like you replied quicker than I could

. Thanks for the info, thats exactly what I am looking for.

Bernard Fife · Post by **Bernard Fife** » Sat Jun 17, 2006 4:16 pm

Looks like it might be time for a junkyard run.

gr8amp,

Yeah, these ought to be as common as dirt in the scrapyard!

Lance.

eliotmansfield · Post by **eliotmansfield** » Sat Jun 17, 2006 11:33 pm

Here's a GM TBI that I got in the UK, looks like same fittings:
http://www.mez.co.uk/dcam/10040005.JPG
Â
Eliot.

Posted by email.