NPT size

[Kenneth]

On my 72 Dodge Charger with a 318 cui I have 1/2 tube going to the heat valve controller from the intake manifold.
Instead of 1/2 I want to convert to 5/8 tube - and for that I need some help , can anybody tell the treadsize of peacock mount on intake - It will be a great help before I order anything

 

[69Bee]

3/8"npt

 

[Kenneth]

Something else - can anybody tell why the tubing from intake manifold to the heat valve control are 1/2" and after the the heat valve control its 5/8" - ?? any explanation - and will it have any negative effect when I turn all the tubing to 5/8 ?

 

[Satellite72]

I was a little hesitant like you to stick a 5/8" hose on a 1/2" nipple when I was replacing fittings. I ended up using some good hose clamps and didn't have any leaks.

 

[Big Jim]

NAPA used to sell the fitting(3/8 NPT X 5/8" hose) IIRC it was used on early-mid 70's 3/4 ton turcks with small blocks. But you'd probably have to find an "old guy" at the coounter to find one.