Timing
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Replace the cap and rotor.
Set up timing light. Be sure that you are connected to spark plug wire #1. I usually mark the timing mark on the balancer with white out (used for typing corrections). This makes the mark much easier to see.
Disconnect the EST single brown wire next to the brake booster. Start the car and check the timing mark position. If you need to change the timing, loosen the hold down bolt for the distributor. Rotate the distributor as you check the timing mark position. When you have the timing were you want it, tighten down the hold down bolt. It is ofter a good idea to recheck the timing mark to see it is still where you want it.
Shut off the engine. Reconnect the EST wire. Setting the timing will register a code 42, so disconnect the batter to erase this code.
Set up timing light. Be sure that you are connected to spark plug wire #1. I usually mark the timing mark on the balancer with white out (used for typing corrections). This makes the mark much easier to see.
Disconnect the EST single brown wire next to the brake booster. Start the car and check the timing mark position. If you need to change the timing, loosen the hold down bolt for the distributor. Rotate the distributor as you check the timing mark position. When you have the timing were you want it, tighten down the hold down bolt. It is ofter a good idea to recheck the timing mark to see it is still where you want it.
Shut off the engine. Reconnect the EST wire. Setting the timing will register a code 42, so disconnect the batter to erase this code.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
It's advisable to position the timing at 6° BTDC (if you have an L98). Every timing calculation (adv, cold start, etc...) is based off the ECM knowing where the distributor is positioned.
I don't know if LT1's have the same base timing. Before you set it, you should find out where it's supposed to be set.
Some people figure advancing it to 10° or 12° BTDC won't hurt since it's such a small adjustment. It may not as long as your knock sensor/system continues to work correctly. It may feel snappier at some rpms/loads but it's also bound to hit knock conditions way more often and have it's timing retarded by the ECM. IOW, your knock counts will go way up.
If you REALLY want to change timing, invest money in a software package and buy a Moates chip. That way you can monitor the knock counts, changes, and make better decisions about if/where you want to bump timing. For the most part, the L98 timing tables are bumped to the max. GM wanted the impression that the car was hot. It's why they also thru the long-tube runner setup on top.
Last edited by GREGGPENN; Jan 19, 2011 at 01:27 PM.
