Anything's possible, but the recommended timing for a small block Chevy is usually at least 8 or 10 degrees BTDC. Try kicking it up a few notches to see if it runs better before trying anything else.
timing is 10 degree before TDC
8 degrees before top dead center.
4 degrees before top dead center
It is 8-10 degree before top dead center with engine warmed to operating temp., RPM's at the proper range and the check engine connector jumped at TE1 and E1.
4 degree before top dead center, is always a good place to start.
Timing chain "jumped"? 1 or 2 teeth?
The degree timing for a 327 cubic inch engine for a Chevrolet Corvette with is 4 degrees before top dead center. This engine is rated at 300 horsepower.
6 to 8 degrees BTDC, Before top dead center
8 Degrees BTDC. ( before top dead center )
Don't know what vehicle you are talking about but with most vehicles if the timing chain jumped you won't get out of your driveway. With the timing cover off, most chains and gears have marks stamped into them that should line up when the number 1 piston is at Top Dead Center.
Top Dead Center
I the Blazer will run then the timing can be checked with a timing light. If not, the there are timing marks on the timing gears that will have to be checked to see if the timing jumped.