I've noticed that my car doesn't feel as powerful as it did in hawaii. I recently changed out a distributor until mine gets repaired (I had a digital distrib). I went to reset the timing on it and I know it needs a little bit more advance, but my car feels closer to a 200 hp car than the 410 hp car I know it is. If I slam the gas the car doesn't rocket forward like it used to. It will stall out if I don't quickly take my foot off the gas and slam it down again. If I slowly accelerate it's fine, but I'm wondering if it's A) My timing or B) My carb needs to be retuned or C) both.

 

Hi Rick,

Timing - it is the only variable you have changed. It sounds like yoursubstitute distributor does not have the same advance timing curve characteristics that your digital set up has. Try advancing the timing a bit, watch out for knock or ping with too much timing.

More spec's might be helpful too.

[sm=icon_cheers.gif]

 

Sure thing. What specs would be helpful? Also, aye I know what you mean by the knock and ping. What exactly will that do? Other than make your car run like crud.

 

With elevation change, your timing and carb settings come into play.
I live at 5000 ft. If i go down to around 200 ft, she really comes alive. ( after a little tweeking on the timing and carb ) More oxygen in the mix. ( denser air ) Higher elevation, less oxygen. ( less dense air ) A nice cold night will effect the performace too. Colder air is denser air. Hot weather, less dense.....here again, density of the air comes into play.
Ask anyone that races for a living. Constant changing of jets, timing, and fuel mixes to meet the air temp and elevation conditions.

 

Hi Rickusaf, I retired from the usaf but that another story for another day, I agree with DV8, what distributer did you put in and what's the curve.
What's the initial timing and what is the timing with the vacuum advance connected andwithout it connceted andwhat's the total timing? And what was it before if you no? Also what year is your car and what motor, PG.

 

As for the timing #'s I'm not sure. I normally just do it by ear. As for the motor it's a 350 with an edelbrock 830cfm carb. (I know, it's too big for gas mileage) It's also a 1976.

 

The ping is the valves rattling in the head from the pre ignition. Not a good thing. It also beats the heck out of the pistons. Not to get to technical but look at it this way. Your timing ignites the compresed gas to force the piston back down which in turn gives you the power. If you ignite it to soon by advancing the timing to much, You wont have the power because you ignited the gas before it was fully compressed, also you are forcing the pistons to go down when the crank wants it to go up. And the other way around if the spark is to late, the pistons are going down already by the crank, loosing compression (power) when the spark timing occurs. Just like everything else in life- timing is everything!

 

HeyRick,
I borrowed this from another post here on the forum. PG has this thing nailed.

Here's what PG had to say....

We are talking about tuning your car here so lets go step by step in order to get it right.
First hook up a dwell meter and make sure the dwell is steady thru the entire rpm range. If not replace the bushings in the distributor, since if this is off than nothing else will help.
Than set the initial timing with the vacuum hose disconnected and plugged at the can end. Lets say you have 16 degrees at this point.
Than reconnect the vacuum line to the can, at this point you should now have 32 degrees timing at idle. That's 16 initial plus 16 from the advance can=32.
Now as you increase rpm the next thing that comes into play is the centrifugal advance, it will add about 20 degrees total.
So at a steady speed of 60 mph you have
initial timing of 16 degrees
plug 16 more from the vacuum advance=32 degrees
plus 20 degrees more from the centrifugal advance=52 degrees.
That is the maximum that you want to run at. You may have to set the initial timing lower to get this number or you will have to adjust the vacuum can.
GM put strong springs into the distributor at the factory so you will not get full centrifugal
advance untill about 5,000 rpm so you will have to change the springsto get full centifugal advance at 2,500 to 3,000 rpm.
At idle you have high manifold vacuum and also at steady cruise you have high manifold vacuum, at the moment you floor it, you have no manifold vacuum then when you reach steady cruise your vacuum again comes into play.
Hope thishelps, PG.

 

One thing I think IMO to do different is when checking the mechanical is to disconnect the vacuum advance and plug. That way you only have initial timing plus the mechanical to deal with. The vacuum is out of the picture. If you have someone to take data, you can actually plot the mech. advance curve by checking at every 500 rpm. pg is correct about the OEM curve. It comes in very late. Easily remedied w/ a kit with several sets of springs and weights.

 

Hi 73shark, you are 100% correct, it is easier to map the centrifugal advance curve with the vacuum line pluged, I tried to give Aldo the basic processand it's hard to post every detail.You are very knowledable and I appreciate your input, and I thank you for that. We also have to know how much vacuum his motor produces so that he can get the correct vacuum canso it doesn't start too soon or have too much advance. Thanks again for that additionaltip, PG.