Deceleration Valve Options

[Ian Stott]

This is a very difficult to get item to get! Many have said soaking the existing one in kerosene for a few days will do the trick, have not done that yet as I am still trying to track down a new one. Wondering what the success rate has been with soaking it in kerosene, also wondering would WD 40 do the same thing. Would hate to ruin the one I have, which is original to the car!

Ian Stott
Moncton
Canada

[Rand]

It's like an appendix. You could just remove it and not care.

[ClayPerrine]

It's like an appendix. You could just remove it and not care.

Bad move. The decel valve opens when you close the throttle at high RPMs. It leans the mixture, and also it acts as a dashpot, keeping the RPMs up so the engine doesnt die under decel.

And all of the 1.8L engines had them. Brad is an expert on the D-Jet system, and I will always defer to him on it. He has studied it extensively. I don't believe he has studied the L-Jet system as extensively. I have worked on them for 34 years, and every one I have worked on, as well as the PET parts manual, lists a decel valve for both years of the L-Jet system. And the only difference between the ones for D-Jet and L-Jet is the adjustment setting.

[porschetub]

It's like an appendix. You could just remove it and not care.

Bad move. The decel valve opens when you close the throttle at high RPMs. It leans the mixture, and also it acts as a dashpot, keeping the RPMs up so the engine doesnt die under decal.

(IMG:style_emoticons/default/agree.gif) good description,my understanding is the L-jet TB's that have only one vacuum port (retard) so that valve would be essential to stop stalling when the throttle is fully closed after acceleration ,right ?
So it serves the above function and also helps to reduce emissions when the throttle is closed @ the same time ?.
Cheers.

[wonkipop]

It's like an appendix. You could just remove it and not care.

Bad move. The decel valve opens when you close the throttle at high RPMs. It leans the mixture, and also it acts as a dashpot, keeping the RPMs up so the engine doesnt die under decal.

(IMG:style_emoticons/default/agree.gif) good description,my understanding is the L-jet TB's that have only one vacuum port (retard) so that valve would be essential to stop stalling when the throttle is fully closed after acceleration ,right ?
So it serves the above function and also helps to reduce emissions when the throttle is closed @ the same time ?.
Cheers.

there were a variety of throttle bodies on the L jets.

we got the research done on them.

EC-B (49 state) 74 had both ports and both vac lines (adv + retard) connected to dist.
EC-A 74 (cal) had no connection of advance vac line to throttle body and port capped in throttle body in front of throttle plate. only retard connected.
75 EC (49 state) had only one port in throttle body. connected to vac retard on dist.
75 EC (calif) had both ports on throttle body. had retard connected on dist.
and had same port as EC-B in front of throttle plate connected to EGR.

finally got to the bottom of it all.

and all the different stories about them being two ports or one port, advance + retard,
or only retard.

folks saying one or the other were right (and wrong) in the past.
only had part of the story.

jeff bowlsby opened up the question recently and we cracked the mystery.

which means yeah.
a californian EC L jet coming down off throttle closure with or without a decel might behave slightly differently to a 49 state EC coming down off throttle with or without a decel? ?? (IMG:style_emoticons/default/confused24.gif)

i have a 74 EC-B. no decel. has had no decel for 33 years at least. no problems.
except when cold. rest of time i must admit i really like how it comes down when i back off the gas. no backfires either. which aren't backfires anyway. its fuel dumping in the hot exhaust and detonating. never get that. sometimes can hear a slightly burble.
but its pretty mild. keep it well tuned which might help.

yes i know there are some say you have to have them.
and i don't disagree. might even reinstall a decel just to see what its like as i have found one and have it racked and stacked. but for now. all is fine.

you certainly do need them for D jet.


EDIT.

here is stuff i pulled off an old 911 intake system.
think its for a K jet?
salvaged a decel valve and probably only have to adjust spring pressure for the 914.
bracket is wrong orientation but probably adaptable.



also have an aux air valve, which looks almost like a 75 decel valve. (almost but not quite)
the aux air valve is hooked up to an aux air regulator, which is what we would call an aux air valve on the 914. they seemed to need to use the two to do cold start extra air for warm up.

they just made these kind of standard parts and they had a nipple closed or open, or a diapram maybe stiffer or a spring adjustment different and used them on anything and everywhere.

in australia there is a mob in queensland who can rebuild these things.
they open them up and recrimp them, so long as they are made of metal.
so if your WD 40 trick doesn't work and you can't get hold of one down here, they are a good way to go here if you have a core you can send them.