distr. delay valve

[Big GMC truck]

Does anyone know what the distr. delay valve does? It is found in the vacuum wiring between the ported vacuum switch and the vacuum advance. Is it a directional valve in which there is a specific direction it needs to be connected? The vehicle is a 1984 GMC K1500 305. Thanks for any help.

 

[diesel4me]

just as it says..

It delays the vacuum to the advance for a few seconds..why they felt it was nessasary is beyond me--its mostly for emission reduction ,I'd dare say it actually reduces power and mileage if you asked me!..I had a few 250 camelhumper 6 cylinders that had them..I'm not sure if they are "directional",like a check valve is..might be,they are 2 different colors on each end..I'll try to see if any of my books go into more detail about them if you'd like..I took mine off,they are sitting in a drawer in my tool box.

 

[roadnotca]

Along those same lines, does anyone know of a good source for factory vacuum circuit diagrams books, my case 1985?

 

[Big GMC truck]

The Chilton's manual just has copies of the hood sticker vacuum diagram. Do you think the delay valve will cause any damage if it is hooked up incorrectly? Thanks

 

[theperfectgarage]

Yeah the ones I experimented with were directional, got em off ford trucks. Couldnt feel a diff one way or the other seat 'o the pants. I have mine in a bin somewhere.