LIM swap threaded or pressed on coolant line

[fastback4]

My swaped 3.4 large port LIM currently has no coolant line attached. It is a smooth bore ready for the pressed on coolant line. My 3.1 has a threaded port with the coolant line attached. Anyone have an intake threaded for them lately and if so how's it done? Anyone have the coolant line pressed on and how's that done? My second question is the 3.1 LIM coolant return line attached to the threaded port is very loose but it does not leak (see pic). Is this typical?

[bszopi]

You have a couple options. You can try to find the pressed in pipe section, and adapt it to your existing lines (via rubber hose), or you can tap out the port with a 3/4" NPT (IIRC). If you tap it, just be careful to keep the tap straight when first starting it and don't go too far into the pipe.

As far as the existing connection, it should be fine. The plastic part is actually a quick disconnect, but if you try to use it as such, it usually breaks.

[IsaacHayes]

are you swapping heads too? If not make sure your heads have roller fulcrum rockers or the ball/pivot style will hit the lower intake. You'll have to grind the lower intake in those spots to clear it then... If the heads have notches you can swap to roller fulcrum rockers though.

[fastback4]

Thanks for the responses. I'll shop around for a while for the pressed in coolant line. I have the rollers on this M code 3.1... I have to do a head gasket job so i thought why not throw on the 2000 3.4 LIM.

[IsaacHayes]

97-98 3400 equipped vans (venture) had the pre-tapped LIM. Those were the only ones that are threaded old school style.

Are you putting on an upper too? You do know you have to match the upper... the old won't bolt up..

[SappySE107]

You can just tap it as it is, no drilling required. That is what I do when someone needs it threaded for a small port to large port swap. The van lowers suck so I would never recommend using one of those. It is pipe thread, but I forget the size right now.

[IsaacHayes]

Harbor freight has taps on the cheap, so you could go that route since you'll probably only use it once.

I went with the van one, but oh well. If anything the earlier van casting is more closer to the earlier 3100 heads... lol It's still miles ahead of the small port stuff it had on there, and the upper part was pretty much dead on to the felpro gasket size so not much gasket matching had to be done.

[fastback4]

Thanks Ben...I know 1 pipefitter....He owes me one.......lol

[fastback4]

Had the 3400 manifold tapped. It's a 1/2 NPT thread..Thanks.......Tom