Anybody know the fitting sizes for TBI fuel lines?

[UATahoe]

Thinking about building up some new AN braided hoses for my fuel lines from the throttle body but have no idea what size the fittings are on both ends of the stock lines. Anybody have any info? I am needing to ditch the stock lines because they now interfere with a vacuum fitting on my intake manifold.

[rfmaster]

GM used 16mm x 1.5 on inlet and 14mm x 1.5 on the outlet port. You'll need metric to -6AN adapters. Keep in mind that AN to metric adapters will be used with port extension adapters that actually screw into fuel pod. You've to keep them since these use special PS fittings with flat o-rings.

Fragola Performance Systems Part #491971-BL -6 AN Male to 16mm x 1.5 Female O-Ring Female Threads
Fragola Performance Systems Part #491970-BL -6 AN Male To 14mm x 1.5 O-ring Female Threads

There are other vendors that make the same adapters.
//RF

[UATahoe]

Wow, thanks for the info! I am thining now that this may be out of my expertise. I will give the factory lines another trial run to see if they will work.

Would i need to source the adpaters or are they already installed on the throttle body? I just recently purchased and ported TBI that i believe has the port fittings already installed. I will post up some pics when i get home.

I really appreciate the help!

[rfmaster]

Originally Posted by UATahoe

Wow, thanks for the info! I am thining now that this may be out of my expertise. I will give the factory lines another trial run to see if they will work.

Would i need to source the adpaters or are they already installed on the throttle body? I just recently purchased and ported TBI that i believe has the port fittings already installed. I will post up some pics when i get home.

I really appreciate the help!

Just use stock OE adapter fittings that screw into fuel pod with -6AN to mm adapters that I have listed in the earlier posting. Fuel pod is attached to TB with three long screws. I can post a photo of what setup looks like later tonight.

//RF

[UATahoe]

Awesome! Thanks! Getting closer to getting the 383 fired up. Hopefully it all goes off without a hitch. That rarely ever happens though. Fingers crossed i guess. Any recommendations on things to be sure and do before firing up a new motor with TBI? Its an 87. Wasnt sure if there were any special procedures that needed to be done to relearn anything or not.

[rfmaster]

Reset IAC position - ECM controls amount of air getting past closed throttle blades during engine cranking by moving IAC panticale into wide open opposition. Not enough air entering intake during cranking may lead to flooding or prolonged cranking. Procedure has been posted here and elsewhere.

Try to get base timing close -and make sure that you are on compression stroke on #1 cyl when rotor is aligned against #1 cap tower. You may have to play with dizzy shaft - body orientation.

Check fuel system for leaks - force FP to operate by applying +12volts to test pig tail connector at the FP relay. This will prime fuel system without engine cranking.

Check all connectors and plugs, do not forget engine grounds.

Otherwise it should fire up. Normal break procedure should be followed with flat tappet cam - i.e. 1800 to 2500 RPM for about 20 to 30 minutes with good doze of break in stuff (ZDPE) in the crank case.

//RF

[UATahoe]

Thanks for the info! The 383 actually has a hydraulic roller cam and the none builder said it only needs to un about 5 minutes then shut down and cool. I will try to track down the other procedures and read up on them. Thanks for the help!!
Posted via Mobile Device

[UATahoe]

Found the IAC procedure. I have a 383 going in with a other than stock camshaft, very mild performance cam. After reading through the procedure i am not too sure that i can do what is asked. Dont think i am smart enough on what is being done to do it accurately. May have to look in to calling in a favor to get it squared away.

[rfmaster]

Originally Posted by UATahoe

Found the IAC procedure. I have a 383 going in with a other than stock camshaft, very mild performance cam. After reading through the procedure i am not too sure that i can do what is asked. Dont think i am smart enough on what is being done to do it accurately. May have to look in to calling in a favor to get it squared away.

Procedure is very straight forward - just make sure to locate ALDL plug in the cab and shorting pins A&B with a paper clip can present a bend-over challenge sometimes:

1. Warm-up engine to normal operating temperature
2. Install jumper between pins A & B of the ALDL connector.
3. Turn on the ignition (but don't start the engine).
4. Wait 30 seconds.
5. Leave ignition on. Listen to IAC making clicking noises and disconnect the IAC connector.
6. Turn ignition off
7. Remove the Jumper from the ALDL connector.
8. Plug IAC plug into IAC socket
9. Turn ignition on and start engine.

Inlet TBI port with -6AN to 16.0 x 1.5mm adapter


Outlet TBI port with -6AN to 14.0 x 1.5mm adapter


//RF

[UATahoe]

Rf, what do the other end fittings need to be? The ones that tie back in to the fuel lines underneath at the frame rail?
Posted via Mobile Device

[rfmaster]

Originally Posted by UATahoe

Rf, what do the other end fittings need to be? The ones that tie back in to the fuel lines underneath at the frame rail?
Posted via Mobile Device

Sorry - do not know! I do my own plumbing during carb to EFI conversions, but I have never looked at 87+ TBI fuel lines. My guess (warning: a guess is coming) it is siginaw style (found on power steering) fittings (same as the ones you have at TB end).

[UATahoe]

Roger that! I will try to eyeball it and see. I will start with the guess though. Lol. Thanks again for all of the help!
Posted via Mobile Device