S-10 timing

[crabuback]

I am trying to time my son's 1990 S-10, 4.3 l (Z vin). Every manual and online source says to check the sticker on the engine for how many degrees BTDC to set it for. There is no such sticker. Anyone know how I can determine what his should be set for?

[16th hippy]

as for the exact spec, i am not totally sure, but i think it is 0deg. but you need to unplug the timing connector for the electronic spark timing(EST). first with connector plugged in, warm engine up to normal temp. shut off engine and unplug EST connector. it usually has a tan/light brown wire with black stripe out each end. is either located close to distributor, or under dash on passenger side. once timing is set, turn off engine and re-connect the EST connector, and road test. I did some digging and cannot fine the exact spec anywhere, so you may have to play with it a bit, but trying to set it with the EST connector connected will result in the computer freaking out trying to undo what you are doing. It is normal fo the check engine light to be on while that connector is unplugged just so you know. best of luck and let us know how it works out.

[crabuback]

I knew about unplugging that wire. (Interestingly, AutoZone.com's repair guides seems to be the only place that ever mentions this.) I was trying to set the timing to 8 or 10 degrees BTDC. Guess that explains the driveablity problems. I'll try resetting to 0 today or tomorrow. Looks like you kind of have to guess to do that, though. The scales reads from 4 degrees to 12 degrees, best I can tell, so it will be off scale by 4 degrees.


I'm assuming that if I get any where close to 0, the computer will be able to work with that once I plug the wire back in?

[16th hippy]

that't what the computer does. adjusts timing for load and spark knock and so on. is why the connector needs to be unplugged so you don't freak out computer while setting base timing. without the exact spec, you will have to play with it a bit. if it runs fine on a road test with base timing set to 0deg, the good togo, if not tweak it a couple deg here and there until set. reason i came up with 0deg is a friend of mine with a 5.7L from around same year replaced his distributor, and that was the spec we set his to, as per sticker on rad shroud. a 4.3 is in essance a 5.7 missing 2 cylinders. best guess without causing alot of pinging. let us know how it goes.

[crabuback]

0 degrees it was. My found a friend that had the same year truck with the 4.3 engine and that's what it said on the sticker on his radiator shroud. So we tried it and it worked fine. The truck is up and running again and seems to be doing just fine.

thanks for your help.

Looks like the water temperature gauge somehow bit the dust. I'm assuming it is located next the the thermostat on top of the intake manifold up front and that I can check the gauge by putting a couple of different value resisters across the two wires. That will probably tell me the gauge is okay and I need to replace the sending unit.

[16th hippy]

no worries, that's what we're here for. usually the sending units are pretty cheap. could just be a bit of gunk built up on it too. remove sensor and check it out. the resistors idea should work, although i never personally tried it.

[old_master]

The sensor next to the thermostat is for the computer only. The sensor for the dash gauge is in the left cylinder head between plugs 3 & 5.

[16th hippy]

thanks master...never had to replace one so i didn't know about that. will keep that in mind for the future!