I was wondering if anyone knew the specifications to test the spark advance on a 1987 22R carbureted. I know that the base timing is set at 0*, but I need to know the specs to test the advance, such as x* at 2000 RPM.

 

I checked Mitchell on-Demand, and according to them
For 87 pickups @ 950 RPM with vac. connected to the Vac. advance, the timing should read 12*.
For 87 4Runners it gives 5* with vac. plugged and N/A with vac. reconnected.

 

Thanks for the info. I now have another question: my engine seems to suddenly get a lot louder around 2800-3000 RPMs. It will also ping when I get more than half throttle, usually when there is a load on the engine, like climbing a hill in 4th or 5th gear. It sounds to me like the timing is off, so my questions is, would the vacuum advance be a likely problem? What else should I inspect?

 

Have you tried running higher octane? What do you mean by it gets louder at those rpms? My fan is alot louder at those RPMs, and with the intake mod, it gets louder/deeper when I push into the secondaries.

Sorry I can't help you out... But nice to see more and more carbosaurs joining up!

 

I tried running a higher octane and it did not seem to do much for the pinging. It started pinging when it had about 148,000 miles on it (It has 155,000 now) but it never did it before. It has always had regular (87 octane) gas in it.

When I say it gets louder, I mean it gets louder than it used to when I reach those RPMs. It seems like it does not run as smooth around those RPMs. It is kind of hard to describe, but it sounds similar to revving the engine without the vacuum advance attached. The noise seems to quiet down when I push it above 3000. It sounds a lot different than the air noise the fan makes.

 

Have you tried doing a good o'le fashioned tune-up? You know, plugs, wires, rotor, cap, air filter, and fuel filter. I'd be willing to bet that would make it run much smoother and possibly quieter. It's worth a shot.

 

All the tune up components are nearly new, I guess I could use an air filter though. I have a new cap, rotor, spark plugs, fuel filter, and timing chain. I will try putting a new air filter in, I guess that it worth a try. I remember I tuned it up when it started pinging and it did not help. I am thinking it is either the vacuum advance or I have heard people say that an EGR valve can make it ping, so any input on that would be great. Thanks for the info.

 

Yes, don't forget to test the EGR. Also if your thermostatic air cleaner door is stuck in the "hot air" position, pinging is likely.

 

What would be the best method to go about testing the thermostatic air cleaner? Thanks a lot for the info, that being stuck makes a lot of sense of why it would be pinging.

 

You can look in and see if it's working or not. Lube down the linkage real good; it's probably corroded.

 

I have checked the HAI system and it seems to be working like it should. I have also noticed that when I check the timing at idle, it stays at 0* whether the vacuum advance is connected or not, and if I pinch the hose on the top of the advance unit it will advance the timing, but if I rev the engine a little and then pinch the hose it will retard the timing. Is this normal? The air filter seemed to solve the noise issue, but the pinging is still there. Thanks for all of the information, this site is great!

 

It has been a few days since there have been any replies. Does anyone have any ideas or input?

 

I still haven't got a clue... but I do have a bump

 

Mine gets louder above 2,500 RPM, too. I figured it was because I have 2/3 of a muffler. I replaced the muffler and it's still loud. It doesn't bother me too much since it's my beater. If it was the 4Runner, I'd be downright

 

Thanks for all of your input. I will keep trying things and maybe I will fix it, or at least have some more specific questions next time.

 

How about a good old valve adjustment (if applicable)?

 

I believe that my manual says to adjust the valves every 30k and I had them adjusted about 7k ago.