Timing problems?!?

[Fox80]

A new dist. is probably not a bad idea, just make sure you set the timing how I described before, using the "8 degrees" initial timing method is not always a good idea. If the dist. you buy has to soft of advance spring in it and the dist. goes to full advance as soon as the motor fires and you set the dist. with the initial timing method you will have only 8 degrees total mechanical advance in it. That will retard you to past TDC when you shut the car off and it probably won't restart. ALWAYS set the dist. full advance first at 3,000+ rpms and taylor your springs and weights to get the initial timing to settle in around 8 degrees at idle. The softer the spring the less rpm it takes to achieve full advance and vise versa. Good luck

 

[Fox80]

Sorry one more thing after you set the total mechanical advance sometimes I will stop and wire the advance weights closed restart the car put the light on it if it now runs at 10 degrees then the advance plate is off by a bit not enough of a slot in the advance throws. It doesn't give you the desired 28 degrees total mechanical advance. I've seen some china eBay Hei's make over 45 degrees mechanical advance if you run into that I wouldn't use the dist. MSD makes by far the best vacuum advance HEI I've ever used and I've seen a bunch of them. The slots in the advance plates are a very precision piece and the cheaper dist. are not made with the same quality. Just always remember the vacuum advance can add over 30 degrees more timing into it so the max and min on the mechanical advance needs to be right on. A car won't idle at 800 rpms with 60 degrees of timing in it

 

[pontiacgp]

So I hook up the vacuum from the 13 degrees and bring the advance on the digital readout to line the mark at 0 and I read 53. I have timed many sbc's before this and never had an issue but on my own car it's kicking my a$$

if you have a msd box you can't use a digital timing gun

 

[Fox80]

I wasn't referring to a box style MSD, I was talking about a standalone MSD HEI. But yes I believe you are right

 

[pontiacgp]

I wasn't referring to a box style MSD, I was talking about a standalone MSD HEI. But yes I believe you are right

I didn't read your posts, I noticed in his signature he has a box and in his post he mentioned he was using a digital timing gun and that prompted me to mention msd warns against using a digital and an advance timing guns

 

[Jshock]

Sorry I guess I should update my signature.. I had an MSD 6a box but it shorted out and I am just running the standard HEI ignition system. But I never noticed the warning against the digital timing light... :shock:
Again thank you for your help you guys are life savers. I'm buying the new unit tonight and ill test that advance unit and go from there. Also I noticed in Fox80's post it was saying I should run the advance off of manifold vacuum vs the ported vacuum, would you guys concur? I've never run a distributor (stock or performance) off of anything bu the ported vacuum line before.....

 

[pontiacgp]

it depends who you talk to about ported or manifold vaccum, the idle speed will increase if it's manifold. I run the msd 85551 distributor so I don't use vacuum advance

 

[Fox80]

Manifold vacuum is the only known true vacuum source, the spark advance in SOME carbs is right at or just a little above the throttle plate, anything above the plain of the throttle plates is not a good vacuum source for the advance. Put a vacuum gauge on the manifold source, you need 15 at idle for the stock canister to work like the article states. You would be amazed a small change in cam specs can drop idle vacuum by a lot. A vacuum advance dist. is NOT a drop in item it must be tuned to the motor. If you buy the MSD 8362 dist it comes with nice instructions if I remember right, it's been a while since I had a new one in my hands. But most quality dist. will tell you how much vacuum is required for the canister they used to work properly.

 

[pontiacgp]

the factory set up was hooked up to a thermal switch which was feed by a ported vacuum, that prevented vacuum advance until the engine was at operating tempature

 

[Fox80]

Yes you are right, but he is far past a stock set-up. And it says he has an Edelbrock carb, that have a very poor ported vacuum signal. Not to mention that the temp. controlled advance system was just one of the many dumb ideas from the emission era. Motors do not need the timing retarded to run cold, that is what a choke is for. The article I copied hints at why they did that to be able to run a leaner cold idle mixture