Question: timing for 81

[dwayneroos@yahoo.com]

Hi everyone,had a question about the timing on my 81. All the emissions equipment has been removed and MSD streetfire distributor installed with 6A ignition. Has mechanical and vacuum advance and is running good but want to get some thoughts on how much advance I should be aiming for. Have it set at 12 deg at idle and not sure where it tops out at due to limited visibility due to waterpump and end of scale. catalyst sticker says 6 deg at 700 rpm. I realize theres alot of varibles involved but just curious what numbers others are playing with. Thanks for any thoughts, Dwayne

 

[bill81vette]

I would still set it at the factory settings,and according to factory procedure.

 

[Peer81]

If you have a distributor that isn't controlled by the ecm (mechanical and vacuum advance) I think you need to set it up the old fasion way. Around 36 degrees above 2500 rpm if i remember correctly.

Greetings Peter

 

[dwayneroos@yahoo.com]

timing

I've been told a multitude if numbers. some have told me if all the emissions have been removed then should advance more than normal. I'll just have to play around with it see what works best for my application. At current settings it seems to be running good,no high rpm missing idles better than it ever has and good acceleration, I must be close, going to install a stop for the vacuum advance. I'll post any findings

 

[Peer81]

Look if your distributor has the 5 or 6 pin connector toward the ecm. I don't think so but just check

Greetings Peter

 

[dwayneroos@yahoo.com]

Hi Peter, my stock distributor had a 4 pin but thats all gone as i now have a MSD distributor and ignition.It seems that in 81 they installed 4,5 and 7 pin depending on the time of the year it was made. I was surprised to see a 4 pin in mine but glad it was because the MSD distributor only works with the 4 pin setup
Dwayne

 

[Hib Halverson]

You want 34-38 deg. total advance all in by 2500-3000 rpm.and 8-12 initial. If you have an adjustable vacuum adv. on the distributor you need 8-10.

Least expensive way to be able to read total adv. is with a timing tape. I tend to avoid dial-back timing lights as the dial back feature can make the light a little inaccurate.

 

[dwayneroos@yahoo.com]

timing

Hi Hib
The numbers you gave me are very close to what I've been told by a few of my car buddies. I'm using a inductive timing light that has no setting features on it. My MSD distributor has a vacuum advance stop plate that I'm going to install, it has four different stop points, 5-8 deg,8-11 deg,11-14 deg and 14-17 deg. figured I'd try the 8-11 deg first and go from there. On holidays next week so should have lots of time to play around with it. I'll pick up some timing tape too,thanks for the input
Regards Dwayne

 

[Don61]

Just curious

Hi everyone,had a question about the timing on my 81. All the emissions equipment has been removed and MSD streetfire distributor installed with 6A ignition. Has mechanical and vacuum advance and is running good but want to get some thoughts on how much advance I should be aiming for. Have it set at 12 deg at idle and not sure where it tops out at due to limited visibility due to waterpump and end of scale. catalyst sticker says 6 deg at 700 rpm. I realize theres alot of varibles involved but just curious what numbers others are playing with. Thanks for any thoughts, Dwayne

Just curious about what carb you are running? I'm thinking about removing all of the emissions equipment on my 81. My understanding is that I will have to replace both the computer controlled carb & distributor.

 

[dwayneroos@yahoo.com]

timing 81

Hi Don
First of all from what I have discovered is in 81 there is a few variations of computer controlled.My car was early 81 so the computer only controlled the emissions. When I bought the car all of the emission systems had been disconnected or were no longer functioning.Through process of elimination I eventually removed all emission components without affecting the running of the engine. I purchased a QuickFuels 4 barrel carb and installed it,I needed an adaptor plate as my intake was for a quadra jet carb then bought a low profile air breather so it would clear the hood. The carb made a considerable difference as far as performance goes but noticed the exhaust was rich,I had jetted the carb as lean as I could so this spring I added a StreetFire MSD distriutor and 6A ignition with 8.5 mm plug wires. I dont notice the rich exhaust smell anymore and she is very snappy now with throttle response. Heres the catch, you can only use the MSDdistributor if the OEM dist. is a 4 pin, if your OEM is a 5 or 7 pin then you'll have to use a new OEM distributor but you can still use the MSD ignition system which fires the plug mulitiple times on each compression instead of once. From the way I understand it is the 4 pin distributor is vacuum/mechanically advanced only and the 5 and 7 pin are ecm controlled,any of you engine gurus can jump in and correct me if I'm wrong but this is the way I understand it. Any other questions please feel free to ask
Regards Dwayne

 

[TimAT]

The 4 pin ignition module has to have external advance devices- centrifugal/vacuum, where the 5-7 pin modules get the advance from an external source (electronically).

Is the rich smell at idle? Check your manifold vacuum at idle and then see what power valve is installed- it could be opening up at idle and adding fuel.

 

[dwayneroos@yahoo.com]

timing

The rich smell was very strong at idle and not so much under load but with the new ignition system it seems to be eliminated. I never checked the timing with the OEM distributor in,I think it may also have been out of whack as well as vacuum as you stated

 

[Don61]

Hi Don
First of all from what I have discovered is in 81 there is a few variations of computer controlled.My car was early 81 so the computer only controlled the emissions. When I bought the car all of the emission systems had been disconnected or were no longer functioning.Through process of elimination I eventually removed all emission components without affecting the running of the engine. I purchased a QuickFuels 4 barrel carb and installed it,I needed an adaptor plate as my intake was for a quadra jet carb then bought a low profile air breather so it would clear the hood. The carb made a considerable difference as far as performance goes but noticed the exhaust was rich,I had jetted the carb as lean as I could so this spring I added a StreetFire MSD distriutor and 6A ignition with 8.5 mm plug wires. I dont notice the rich exhaust smell anymore and she is very snappy now with throttle response. Heres the catch, you can only use the MSDdistributor if the OEM dist. is a 4 pin, if your OEM is a 5 or 7 pin then you'll have to use a new OEM distributor but you can still use the MSD ignition system which fires the plug mulitiple times on each compression instead of once. From the way I understand it is the 4 pin distributor is vacuum/mechanically advanced only and the 5 and 7 pin are ecm controlled,any of you engine gurus can jump in and correct me if I'm wrong but this is the way I understand it. Any other questions please feel free to ask
Regards Dwayne

Thanks for the info, I'll keep looking into it & see what I can do. I'd really like to dump all of the emissions stuff since it doesn't have a cat or O2 sensor anyway.