Behind the timing chain cover on the front of the engine.
on a 91 blazer s10 4wd
Out side of the timing chain and gears being replaced there are no adjustments. The vehicle computer controls the timing. On other vehicles the distributor can be turned in either direction to advance or retard the timing. This is not the case for the 4.3 v6.
the 91-94 sentra has a timing chain
Timing chain
any first gen s10 0r blazer or bervada grills will fit
This can be done, though some modifications may be needed. If you need to replace your core support (rad support) as well, order a core support for a 91 S10 blazer. This will help do away with the mounting issues. I did this to a 1985 S10 blazer and the grill fit fine with the factory core support, but not all of the mounting locations matched.
On the drivers side of the throttle body.
The timing should be set at 10:4.
55
It is behind the throttle body, on the intake manifold.
To drain the oil on a 1991 Chevy S10 Blazer, located the oil pan drain plug. Use a wrench to remove the plug and the oil will flow into the receptacle you have provided.
I have always used 10w30. never had any problems.