View Single Post
JFairman JFairman is offline
Registered User
 
Join Date: Jul 2006
Location: S. Florida
Posts: 7,289
Yeah I remember how weak they are with stock 1987 ignition timing. Is idle timing 1 degree ATDC with both vacuum hoses connected? It's been so long since mine was stock I don't remember what the origonal stock timing was at idle.

I have a K&N air filter on the CIS air flow meter instead of the origonal air cleaner so access to everything is easy.

If the origonal red fabric colored vacuum advance hose is still on there replace it with a new hose because they dry rot and crack under the fabric covering and you can't see that it has cracked. Then it leaks vacuum and doesn't do it's job. The origonal vacuum retard line is covered with blue fabric. They don't last and if they are still there they should probably be replaced.

I've modified the centrifical advance curve in my distributor and installed an MSD 8760 boost timing retard box with MSD 6al ignition. It makes a huge improvement in low rpm torque and drivability in these cars below 3000rpm.
My timing at idle is around 12 to 15 degress btdc. Steady cruise it's around 34degress btdc and during boost it's about the same as stock, right around 26 to 28degrees btdc. I also have WMI to reduce any detonation. E10 93 octane gas quality varies alot too.

Optimum ignition timing and aftermarket air cleaners have all been covered a bunch of times in previous posts. Some searching on ignition timing, MSD ignition, and K&N or fabspeed air cleaners on this forum will probably find all the information eventually.

Something you could easily try is just leave the vacuum advance line connected to the vacuum advance pot and remove the vacuum retard line from the retard pot and plug it with a small bolt or screw or just leave it hanging for a test.
Then check the timing at idle and see if it advances and idle speed comes up. That should help drivability a bunch right there and you'll still have the same boost retard if the vacuum advance line and pot are working correctly.
Like that you'll still have centrifical advance, vacuum advance, and boost retard and some more power and better gas milage below 3000 rpms.

Check the timing though to make sure everything is still in a safe range.

The vacuum retard line and vacuum retard pot only work to retard timing somewhere around 10 degrees from idle up to around 1500 rpms and during closed throttle deceleration at any rpm. It is for lower emissions and other than that they do nothing at all.
With your current 1 degree atdc at idle you could probably get out and run faster than the car will leave from a stop. I remember what it was like...
Old 04-14-2013, 11:18 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #20 (permalink)