3Y timing

[ar kay]

so, if i understand correctly, the 3y is timed at 8 deg. btdc (not 12 like 4y)while plugging the vacuum lines. when reconnected, does it jump up like the 4y? to what exactly? after doing a bunch of work on the van i attempted to check timing, was a little off, but did not appear to advance when lines were unplugged. bad vacuum advance? how to test and fix? van seems to run great, tho! makes me worry.

[llamavan]

Yes, 3Y engines are timed at 8° BTDC.

The way it's supposed to work (in print according to Toyota), you remove the vacuum connections at the vacuum advance, clamp them off, set the base timing and then ... according to my interpretation of "the book", when you hook up the vacuum connections again, the timing should advance then and there. I don't get an instant advance. I do see the timing advance when I rev the engine (and the instructions with the timing light, running counter to Toyota's instructions, indicate this IS what I'm supposed to be seeing). :confused:

My van (Trusty) runs great, too ... and yet I am still somewhat concerned. Trusty ran for quite awhile with a stuck-open t-stat :redface: which can cause excessive carbon accumulation, and he does have emissions issues, too, which could also stem from carbon blockage ... or not. So IF he actually has a timing advance problem, I would suspect vacuum system issues rather than the vacuum advancer itself. That having been said, I've been told by another '80s Toyota buff that the diaphragm in the vacuum advancers DO die. Part no longer available from Toyota (I already tried).

Wish I could add more; maybe someone else here will shed some light on this. Otherwise, I'll report back when I get PJvan running (finally) and discover whether her timing advance behaves the same way.

Gwen

[ar kay]

hey thanks, any help is good help. i didnt rev the engine while checking timing, so maybe ill do that just for fun. i guess i shouldnt really be worrying about it if nothing seems wrong and the van runs well, but you know what happens when you start over thinking stuff.. i just dont want to miss something. should probably begin to refocus my attention on important, obvious issues, like shocks.

[gushaman]

interesting. the 4y carby lpg engines at work have vacuum advance, and when the advance goes bad we replace the whole distributor. with time and parts cost its cheaper anyways. we dont have to rev the engine. these are 4ys so the may be different, but i doubt it. we set the timing with the vac line off , then pop the hose on and boom its ready to go