rotion is clockwise. so one would turn the distributor housing counterclockwise to *advance* timing. *faster/slower* is not relative here.
i wouldn't even hit this with a gun. fuel avail back then is not what it is now. you can take advantage of that by road timing this. disconnect and plug the retard vacuum hose on the distributor. leave it that way for like from now on. disconnect no other vacuum lines/hoses. leave the dist hold down bolt slightly loose. go up a hill slowly 20mph or so. in say 3rd on the 4sp, 2nd on the 3sp, and second for the auto trans. go slow and mash the throttle to the floor. you want to somewhat lug the engine down. repeat the proccess. advancing the dist till you hear pinging when throttle is mashed. repeat run and retard dist till you hear just a slight ping. tighten the hold down bolt. she's timed for the fuel your using. idea being is you don't drive it that way. and the potential for ping, while not actually pinging does not hurt anything. this will take advantage of max ignition advance trim, be a wee bit peppier, at the same time, best mpgs.
do not remove the AIR system. the pump for that takes no effert to turn. one can remove and spin those by hand easily. and the fresh air introduced into the exhaust area not only re-ignites unburned fuel, but it helps keep the exhaust valves cool.
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when your done. to check things as this is purdy old, disconnect and plug the advance vacuum hose on the dist. hit it with your gun. at 900 rpm, warm idle rpm, should read no less than 8 degrees TDC. if it does, i submit you need a carb rebuild, new timing gear (symptom might be timing dearches) or your cam is a bit flat. there could be other causes for not being able to get to base timing w/o pinging. especialy if there's a vacuum leak somewhere. but assuming all that, and the chambers are still sealing, that's prolly your issue on this old puppy.
FYI, the intake manifold on this may leak over time. usually due to the intake bolts just needing a re-torque. or carb base gasket leak. i'd retorque all fasteners on the carb save set screws.
on a manual trans optioned 73 nova platform, when all is done, i prefer a 550-650rpm idle. 6 or 8 cyl. no matter the method of timing, setting the idle down a bit, if no issues become present, i.e engine stall/stumble, won't hurt a thing. but it will save on idle fuel consumption. helps keep engine idle temps down in stop and go traffic as well.
this is a fairly forgiving platform when it comes to tinkering to get the best you can out of her.
if there was only one thing i could mod on this, that would be the ignition system. i'd upgrade to at least a plug/play CDI system or go full on HEI.
bought new 74 nova back in the day. off show room floor. the info applies to all engine configs on this.
and pls, respect to all others, if you aren't familiar with road timing on non computerized ignition/fuel delivery platforms, pls refrain.
EDIT,
"Lediy99" recieved thumbs down. i don't do that. and while it's clear the member is not familiar *first hand*, up close and personal with the platform (respect), there is info i left out that is important. that is the specs for a tune up on *all* optional engines.
still, after doing it by the book, which iffin one is not familiar one should do, i'd road time it when done. just to squeeze a little extra out of her. for the reasons i listed.
Look at the vacuum advance canister. Think of it as an arrow. If you move the distributor the way the arrow points, that is advance. Loosen the bolt holding the distributor down, and advance the timing until you hear rattle when the engine is lugged, or the engine becomes hard starting. That should help power and economy.
Get a timing light. Find the timing mark on the vibration damper & mark it with chalk. Clean the degree gauge off & chalk it too. Take the hose off the vacuum advance & plug it. Attach the timing light to the #1 cylinder. Start it up & loosen the 1/2" bolt at the distributor base. Set the timing per engine specs. Tighten the bolt, remove the light, and reattach the vacuum line.
Being a "Pack Rat" has its moments.
According to "Glenn's Chevrolet tune-up and repair guide, models from 1955 through 1974" I give you the following:
6 cyl. L-6, 250 cu. 100 hp, comp. 130 psi, spark plug # AC-R46T @.035, Dwell 31-34 deg., gap .016(used) .019 (new), condenser .18-.23 microfarad, Timing 6 deg B (btdc), Idle 700 for manual, 600 for auto. Valve lash one turn down from zero lash.
For V-8, plugs AC-R44T, gap .035, point dwell 29-31 deg., point gap .016-.019, cond. same as 6 cly. timing 307 is 4 deg B, 350 8 deg B, 454 10 deg B., Idle rpm 900 for man. 600 for auto.
Start with the plugs, wires, dist. cap, points, cond. rotor and coil. Then run engine to temperature. Disconnect vacuum line to distributor, adjust idle as needed, check dwell (adjust if needed) set timing, re-check idle, dwell. reconnect vacuum hose, readjust idle.
If you have hydraulic lifters they surely need adjusting or replacing.
In any case you would do well to get a dwell meter and a timing light. If your distributor doesn't use points that adjust via a small allen wrench through the side of the cap I strongly recommend changing to that style as it makes life sooo much easier.
If you can locate an old shop manual such as mine you will thank yourself over and over.
Mine contains so much information about older ignition systems and carburetors it boggles the mind.
And no, it is not for sale! lol
Good luck.
it is not so much speed that is adjusted with the distributor but advanced or retarded. there is a bolt at the base of the distributor that holds it in position. with a timing light in use and the procedure used to check it like disabling vacuum advance, timing is checked and adjusted. if you wish to adjust the rpm, the distributor does not do that.
There is one bolt that clamps the distributor to the intake manifold or block, I don't remember. Loosen the bolt and rotate the distributor. Tighten the bolt when you are done.
Oops! Ambedext one of many YAHOO non-mechanics is DEAD-WRONG. To advance ignition timing the distributor should be twisted OPPOSITE the direction of rotor rotation. When you use a timing light there will be no question weather you're advancing or retarding the ignition timing.
take the cap off and watch the rotor turn. if it turns clockwise then turning the distributor clockwise will advance the timing counter clockwise will retard it. this will be the opposite if the rotor turns counterclockwise
Yo can't just guess the timing, you need a timing light so you know how much to "advance" or "retard" the timing to get it spot on. If you are off by much either way you can destroy the engine.
im pretty sure its just the distributor cap but which way is faster and which is slower
