i think its best if i give some history into how i went about timing my car and the trial and tribulations that have brought me this far. 2 years ago when i overhauled my motor i used a new msd ready to run with the coil mounted in the bracket. my timing light is just the standard type that gives you INITIAL and that is all.i have never used one of the timing lights with the dial on the back to measure total timing. so i go about my business and dial in 14-18 on the balancer knowing that a distributor has about 20 degrees of advance in it giving me 34-38 or there abouts . once i did this i had the slightest hint of a ping so i backed of 2 degrees and it was gone.

now lets fast forward 1 year and many miles of driving. all of a sudden i develop this slight popping in my exhaust ( very much like small backfires) it took me quite a few trials and errors to pinpoint the problem after changing plugs,checking vacum leaks etc etc but yes after all that it was TIMING . i thought how the hell can it change when i set it but it was due to high rpm driving making the dizzy spin even though the hold down bracket was quite tight. it had turned so much i was running 44 advance.

ok im getting to my point now. i went out today and bought myself a new timing light. one of the ones with the dial on the back to measure TOTAL. i get my initial set up at 14 just to be safe. take the rev,s up to 3000 to let my dizzys mechanical advance unleash and HOLY S**T my total is 54. now im going crazy " i think how can this be????" i am no expert from cars, far from it but in the end i have disconnected my vacum advance and am running only mechanical and initial to get my 36degrees that i am happy with.car seems to be running fine and pulls hard.

i dont understand the whole initial + mechanical + vacum advance. i find if i run all 3 my timing is uncontrollably high . please teach me.

 

You check timing with vac line disconnected and plugged and aim for 36 deg all in by around 2800-3000. When you hook up vac again you will go up to around 52....this is normal.

Read the sticky above about timing, all info you need there.
http://forums.corvetteforum.com/c3-t...long-post.html

 

I'm no expert either, but if you're at 54 with the vacuum canister hooked up, I don't think you're way off. Should be around 52. If you have the adjustable vacuum can, you can back it off a couple of degrees. How does it run?

 

im pretty sure it is not adjustable basscat but i will look tomorrow. it is running fine now with no vacum advance. tomorrow i will reconnect it and see how it goes. my biggest problem was the dizzy moving giving me way too much advance.


i am going to go read the sticky now jotto. thanks

 

36 deg with disconnected vac is just right. Hook up the vac and your good to go.

 

Have you changed the advance springs that came on your distributor?
Per MSD, the springs that come on that distributor dont allow full mechanical advance until almost 4000 rpm.
So if you have been checking "total" advance at 3000 rpm, you still havent seen your total.
In order to get total advance in by 3000 rpm, you should use the two blue springs that came with your distributor.
They also say that with the blue advance limit bushing installed, which is the way they sell it, you should get 21° of mechanical advance.
If thats the case, setting initial timing to 15° btdc should get you in the ballpark of 36° total.

 

Take the cap off and look in the dist. It's the only way to know what you have.

 

yes drive shaft and dunlop when i put the dizzy in a deccided on 1 light blue and the next one up whatever colour that was that i thought was a good curve for my cam. i did rev it slightly higher and it didnt advance any more so i must be on the right track.

over here i have never ever heard anyone say run 52 total advance - it has alway just been the standard 36 or advance it till u get a ping and then back 2 degrees. i read jottos sticky and it was a good read for me otherwise i would still be driving around with my vacum advance disconnected. it seems im pretty close to where i should be .

when i bought my diz it came with the 2 heaviest springs in it.