Hey everyone got a question about ignition timing. First off let me
give some possibly relevant details about my car:
1979 Trans Am 403
Holley 770 Street Avenger carb
Edelbrock Performer Intake
Comp Cams xtreme energy cam & lifters
Flowmaster 30 series exhaust
TCI auto transmission 3200 stall
I just put in a new distributor and I'm trying to get the ignition
timing sorted out. I think the specs for the 403 call for initial
timing to be set at 10 degress BTDC. I've tried it there and it really
runs bad like it needs more advance. I just set the timing by ear but
I'm a little leery about giving it too much advance (It's now set at
like 18 degrees inital). I read on some mustang ng about a guy setting
his timing using a vacuum gauge.. anyone here have any luck using this
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
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
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
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
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!
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