bought a new speed demon a few months ago and everything has been a heck of alot better than the holley racing double pumper i had on this car. that idle EZ screw is throwing me for a loop... can someone please explain to me how to properly set it up? i can get the car to idle dependably at 550 rpm and the manual says 750 rpm. whether its idling at 550 or 750, the timing never moves off of the 8 deg btdc where i have it set and it seems to like to live there. the specs in the repair manual say 750 rpm at 4 deg btdc. And before people chime in saying read the "sticky" about timing...i have done this a dozen times now. I can set the timing to 36 deg at 2500 rpm, come back an hour later and car won't start until i retard the timing back to 8 or 10. all help appreciated. heck i'm going to change it 4 deg btdc and set the idle to 700 right now and see what happens at 2500 rpm with my timing light.

 

with a distributor set up correctly the centrifugal advance shouldn't usually start to come in until a few hundred RPM's above the idle speed so if initial is set at say the 8º you mention it's not surprising that there wouldn't be a change in the timing between 550rpm or 750rpm, as at either idle setting level you should still only be on the initial setting and not into the centrifugal advance yet. I don't have the factory spec distributor curve of your car ( I may have it if you can give me the distributor number) but the centrifugal advance probably isn't going to start coming in until somewhere between 900-1100rpm, give or take.

I'm confused when you say though that you set total timing to 36º @ 2500rpm but than the car won't start again until you turn timing back down to 8-10º. At 36º total where is your initial timing falling that you need to retard it back to 8-10º?

BTW, a little more info would be helpful:
year of car
type of motor
type of distributor (points, HEI, aftermarket such as MSD, etc)
motor stock or modified
etc

 

is the reading supposed to be at 12 btdc when the timing light says 2500 rpm or zero mark? (according to the timing sticky)

 

if you are using a dial-back timing light and setting total timing, set the dial on the light to 36º (for your total timing amount), bring the motor up to speed - between 2500-3000rpm) and adjust the distributor so that the timing line on the balancer aligns with the "0" mark on the index plate.

if you are setting initial timing, set the dial on the timing light to whatever initial setting you desire (8º, 12º, whatever) adjust idle speed to correct idle speed level, than adjust distributor so that again the line on the balancer aligns with the '0" mark on the index plate.

When using a dialback timing light you are always setting the timing amount you want on the light, than aligning the balancer to the '0" mark on the index plate.
If you set the timing amount on the light than still try to align the balancer at say 12º on the index plate you are adding in that additional 12º OVER AND ABOVE the amount you dialed into the light and are timing it way too advanced.

Depending on the type and model distributor you have you can have anywhere from 18-30º of centrifugal advance so if you just set total timing at 36º your initial should fall somewhere between 6º - 18º. Chances are it's somewhere inbetween that in the middle somewhere so will probably be just fine where ever it falls but after setting total timing it would be good just to check to see what the initial timing is falling at. Do that (AFTER setting total timing at 36º) by letting car sit at idle speed, point the light at the balancer and while shooting the light turn the dial on the light until the line on the balancer aligns to the "0" mark on the index plate (do not move the distributor!). Once it's aligned, look to see where the dial is now set on the light and that is telling you what your initial timing is

I'm going to bed now, will answer any other questions if needed in the morning.

 

Your mechanical advance could be sticking. That is what it sounds like based on what you have said so far.

When you set it to 36 at the top of the curve and the mechanisim is sticking, the timing does not back off as the RPMs decrease. The distributor will be too far advanced when you crank it and the engine will not turn over easily. You may need to dissasemble the distributor and clean/lube it back up. That would be a good start. If the parts are worn too far you may need to have it professionaly rebuilt.

That's my guess.

-Mark.