Distributer curve it
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I used to recurve all my pre-computer SBC motors with the Mr. Gasket kits. It had 3 sets of springs and a set of weights. Buy a timing tape so you can check total advance. About 36 degrees total works for a SBC. Start with the heaviest springs and switch one spring at a time, checking for pinging when you road test. It will take some testing to find the fastest curve that won't ping, as well as the initial timing setting, but the reward will be a noticeable difference in low-end throttle response. Once you get the initial timing and the curve set, you may have to install a thicker bushing on the advance stop pin to limit the amount of total advance. A general rule of thumb is that advance boosts low-end response, but retard boosts top-end power.
Bill
Bill
You're welcome. Back in the 70's I was a college student with the desire to go faster, but no money to buy parts. I decided the best path was to learn carburetor and distributor tuning. Both are time consuming and labor-intensive, but cheap. Worked for me.
Bill
Bill
Billyjack, since you are an expert let me ask you this. I just got an adjustable vacuum advance. Goes from quick, super quick to ultra-quick. I haven't installed it and have already bumped up my timing a little and noticed a big difference. Why would I want more vac advance?? Isn't that for when you aren't throttling? I figure if you bump up the total advance, you are running too much at idle on "ultra" or "super" quick. Also, I assume the heavier springs are to retard at higher RPMS?
I'll try and address your questions One at a time.
I recommend that anybody contemplating tweaking their distributor do some serious research first, so you have a grasp for what you're trying to accomplish, and how to get there. Remember seat-of-the-pants feel and detonation (pinging) are all you have to judge your results. This is one of those times a super loud exhaust works against you, as you really can't hear what's going on inside the motor.
Bill
I'm far from an expert. I just have enough experience to be dangerous! On our race car (see avatar) the timing is locked at 36 degrees- 36 degrees at idle, 36 degrees at redline and everywhere in between. A decent drag racer or road racer will humble me with their knowledge of advance curves.johnny79 said:
Actually, you want to do the opposite. Since a curve kit and more initial advance will yield greater total advance, you want to reduce the amount of vacuum advance. The vac advance is only a factor at high vac conditions- i.e. small throttle openings. Reducing the amount of vac advance helps avoid pinging at light throttle. When you're on the throttle heavy, it's all in the initial advance and the curve. There's little engine vacuum at hard throttle, so the vacuum advance unit is idle.johnny79 said:
The springs only control the rate of climb in advance with respect to rpm. On a properly set up distributor, all the advance is in by 3000 rpm or so. Nothing more happens after that.johnny79 said:
I recommend that anybody contemplating tweaking their distributor do some serious research first, so you have a grasp for what you're trying to accomplish, and how to get there. Remember seat-of-the-pants feel and detonation (pinging) are all you have to judge your results. This is one of those times a super loud exhaust works against you, as you really can't hear what's going on inside the motor.
Bill
All you need to know right here. Hits on what he was saying but goes more in depth
http://www.v8buick.com/showthread.php?t ... =fuel+pump
http://www.v8buick.com/showthread.php?t ... =fuel+pump
IMO the most bang for the buck when it comes to tuning is ignition.I have resprung every non computer controled distributor I have tweaked and you would be suprised just from cleaning up the flyweights and posts and replacing any oilite bushings if so equipped as to the responsiveness gained even if no weights are changed.
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