Setting ignition timing with performance cam

I always used the vacuum gauge method in the old days before computers. I would set both the timming and idle mixture screws for the highest vacuum reading at idle. However you may have to back off a little if the motor pings.

Gary

I had a 403 TA years ago, and my mods were a little different, I had ported heads and a milder cam (Nothing is going to make that motor a real revver, and you don't want it to!), headers, intake manifold, and the stock Quadrajet carb rejetted on a chassis dyno. The 403 is a torquer, and it makes a really fun street car.

This was over 20 years ago, so if I have a number wrong, don't nitpick.

Just changing the horrible intake and adding headers made it a tire smoking machine. It wasn't all that quick on the strip, but was already a fun car to drive and to smoke the awful tires it had on it when I bought it. I needed an excuse to buy new tires, but they stock Goodyears lasted to almost 48K.

The cam came from Joe Mondello, I can't remember the numbers on it at all, but it was probably similar to one of the milder street hydraulics listed here:

The first thing I had to do after changing the heads and manifold, and cam was totally recurve the distributor, stock the timing was set to 18 BTDC (shows how bad the stock heads were),and the maximum was only 30 degrees total, I think. A guy a friend knew was an Olds guru, and he gave me a set of modded distributor weights and new springs, and told me that to start at 6 BTDC and work my way up, and with premium gas I could probably do 8 BTDC for sure and maybe 10 BTDC. This gave 34-36 degrees total. After all the tuning was done, it ended up at 8 BTDC with the best gas I could get in 1987 when I stupidly sold it!

If you haven't redone the distributor, it's going to be a problem, I would recommend you call or email Mondello and follow their advice, they know what they are talking about. If they say the cam you have is all wrong, get one that works. Even with the ported heads, cam, and other mods, it was flat at anything close to 5000 RPM, but between 2000 and

4000, it pulled hard as hell, and with the scoop opened up, it sounded great.

Instantly, the new curve showed he knew what he was talking about as it came to life big time. This was my favorite of all my cars as it had major low end, and throttle response was amazing. Friends drove it and were shocked at how hard it hit, even with the stock insane 2.41 gears w/Posi! I changed the rear to 3.73 for a short time, but ended up with

3.42 or 3.55 as a compromise, as it was too easy to kick the back end loose when the pavement was even slightly damp, dirty, oily, etc.. any aggressive driving was asking for the back end to kick out if the pavement wasn't nice and clean and dry (with the stock tires). When I finally got new tires, it was so much easier to drive it like I wanted to.

I never cracked the 13's with it, but was oh so close and the MPH showed it was simply the crappy launches I had to make to keep it from spinning the tires excessively. I wish I could have found a pair of slicks and wheels that would have fit it, just to see what it would do, ET wise.

I left the trans alone, and since it was so punchy on the low end, I didn't see any reason to change the converter. I did have a heavy duty rebuild done when reverse disappeared and the shop put a shift kit in it, and it shifted great, soft at part throttle, hard as hell when you had it close to the floor.

Good Luck. I sure wish I had mine back!

BDK