help high idle on a 620!

[sick620]

k so i changed my spark plug wires a few days ago ever since then my truck has been idleing really high all the time. like almost high enough that i let go of the clutch it gos by itself with no throttle. its not too terrible except when i shut off the engine it diesels like a mofo for like 10 seconds. the plug wires i put on are just some cheepos nothing fancy. I also installed a new cap and rotor, and plugs but thats been a month or 2 ago. Could this problem be my timing just being off... the adjustment for my distributor is all the way to one side.... do u think that it was all the way over to that side to make up for it needing a tune up? where should i adjust it too?

[banzai510(hainz)]

where should i adjust it too?

 

olddatsuns.com has all the specs on there.

 

put a timming light on there but 1st make sure the carb linkage kicks all the way back. or oil the cable inside.

 

you sure you didnt pull the 12v choke wire where the choke is on all the time?

 

loosen the 10mm bolt that holds down the timming plate to the mount, then check under side of the distributor is a 8mm bolt that holds the timming plate to the dizzy. if you loosen this the timming plate can be adjusted more adv or retarded. set it up till it come out to what the specs you want.

 

PS remember to put Potato in Front not the back!!!!!!!!!

[sick620]

thanks man. lol i was wondering when you would notice that haha.

where should i adjust it too?

 

olddatsuns.com has all the specs on there.

 

put a timming light on there but 1st make sure the carb linkage kicks all the way back. or oil the cable inside.

 

you sure you didnt pull the 12v choke wire where the choke is on all the time?

 

loosen the 10mm bolt that holds down the timming plate to the mount, then check under side of the distributor is a 8mm bolt that holds the timming plate to the dizzy. if you loosen this the timming plate can be adjusted more adv or retarded. set it up till it come out to what the specs you want.

 

PS remember to put Potato in Front not the back!!!!!!!!!

[datzenmike]

If it diesels then it's getting air and fuel from being on the fast idle cam. And that's only possible if the choke is on. Blue wire is choke heater. Should be at 12 volts when motor running.

[ggzilla]

Changing the plug wires won't cause this. Perhaps you disconnected the vacuum advance hose or moved the points gap... or?

[datzenmike]

There shouldn't be any vacuum for advance at normal idle speed. '79 had EI dizzy but timing could have been bumped ahead while yanking the cap off to change it. Most 'smog' motors after '70 will rev up if you advance the timing.

 

Occam's razor applies here. The simplest answer is likely the right answer.

[banzai510(hainz)]

maybe dizzy bolt was loose and dizzy moved to one side and thats why the fast idle.

[sick620]

If it diesels then it's getting air and fuel from being on the fast idle cam. And that's only possible if the choke is on. Blue wire is choke heater. Should be at 12 volts when motor running.

 

where is the wire located? can someone get me a diagram or something or explain this to me like im retarded because i dont know how the choke works on my truck.....

[nukeday]

I don't have a 620, but this site is THE resource for this sort of thing.

 

Might want to download the wiring diagrams or the factory service manuals?

 

Good luck, hope you get it sorted out.

[datzenmike]

Back of carb there's a round black thing with a wire going to it. It may have a covering but the wire inside should be Blue in color. There is also an idle cut solenoid but it has a Red wire to it and the plugs are different and can't be swapped by mistake.

 

The Blue wire should have 12 volts only when the truck is running. This provides power to the choke (round Black thing) which has an electrical heater in it. This warms the choke up over a measured time and turns the choke off.

 

With the air filter off look down inside the carb. If the motor is warmed up the choke plate at the top should be open all the way if working right..