Some of the real late model ones 85 or so and newer are even further off, the timing mark is actually straight up and down at tdc. This is how my 85 Blazer was, you had to point the timing light straight down behind the water pump to set the timing.
Advanced Automotive Machine
1971 Heavy Chevy - original owner
Team Chevelle #100
Chevy has gone full circle on this deal. My 93 vette has the following configuration. There is no balancer like you think of a balancer, there is a crank hub that is not keyed to the crank, there is a pulley that bolts to that and there are no timing marks. You talk about a weird deal.
If you step on the motor and start to make some serious power, say 400hp, the crank hub starts to creep or rotate on the nose of the crank!
OK. So how do I check/set timing? Right now, I get about 16 deg initial at idle with the vacuum disconnected using the mark that I THOUGHT was TDC. If that mark is 10 deg BTDC, does this means that I've got way too much timing? The car seems to run well, no knocking at part/full throttle with the vacuum disconnected. When I put ported vacuum on, it knocks a bit. I think that's because I've got adjust the limiter in the distributor...
The key is having matching balancer and timing mark. If you don't get knocking with the vacuum disconnected but do with it connected, I would go to the nearest AC Delco dealer and get a 10 degree vacuum advance canister. The one you now have is probably a 20 degree. You could get an adjustable one, Crane makes one, but the 10 degree will probably do the job. Cost is around $10, IIRC.
You can't necessarily trust the timing mark on an older Balancer. The outer ring can move in relation to the inner hub when the rubber ring gets old. This happened to me and I wondered why I needed 65° of advance at idle.
The 77 and up engines had the timing mark moved to nearly 12:00 due to the new power steering pump and bracket. These were used untill the 90's. However the balancers were the same as the older ones, they changed the keyway location in respect to the actual TDC. There is a special balancer available to compensate for this if you are running older accessories, from GM??? cant remember where I read that.
A forum community dedicated to Chevrolet Chevelle owners and enthusiasts. Come join the discussion about restorations, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more!