i have a 66 440 with the 6 pack lower end, edelbrock heads 10:1 CR comp solid 520/540 cam holley street dominator with a quick fuel 850 mechanical carb

i just installed an MSD pro billet distributor (mechanical) and im wondering where the idle speed, initial timing and total timing should be with this combo and how to change the mechanical advance to where i need it

also my valves were rattling on startup. what is the correct lash setting? i have crane gold roller rockers

thanks

the lowest idle speed that'll maintain a stable as possible idle at a stoplight/let you take off smoothly wo dieing. you have some leeway there. Timing: Use the vacuum gauge method to get the initial your particular combo needs to have then w that figure in hand shorten the slots to get 36 total (note: initial and total are set w vac adv (if used) unhooked and capped). then work w the springs then work w the vac adv. IN ORDER. bottom line is if it is not pinging no damage is being done but if it is too slow power is being left on the table that could be had. You ideally want enough octane so you can run a fast supporting curve. What brand/part # is the cam to get the lash

This ur cam?
Brand COMP Cams
Manufacturer's Part Number 21-232-4
Part Type Camshafts
Product Line COMP Cams Xtreme Energy Camshafts
Summit Racing Part Number CCA-21-232-4

Intake Valve Lash 0.016 in.
Exhaust Valve Lash 0.018 in.
there's ur lash. I'd suggest un-hooking the vac advance, try 18* initial and 36* total early like 2000-2200 and go from there. Of course you have to tune the carb for best idle/vaccuum reading and so on.

its a comp cams solid 520/540 lift grind number XS282S

thanks for the responses guys, it is a mechanical advance distributor. any idea how much vaccum i should get at idle?

in gear/parking brake locked, keep advancing the timing until the (manifold) vac is as high as it will go then back off the timing until the vac drops 1 in hg and as you are advancing the timing to get to this point keep bringing your idle speed (in gear) back to where it initially was. EDIT forgot the chart, they say it's not dead on but fairly close for a start. MORE EDIT forgot you have an MSD so the below chart (which is intended for stock dists') may not apply

First put the lightest advance springs in set total to 38 and see what it gives for idle when all set up.

I use the lightest springs with the smallest stops (most deg of advance allowed) to get good idle but ease of starting.
I even go as far as to use mopar or Mr gasket mopar springs which are lighter again than MSD's lightest on bigger cams to have it all in by 1200 to 1500.

after putting the lightest springs in try for an in gear idle of 900 to 1000 with that cam big cams like faster idle.

Set the valves .010 intake and .014 exhaust cold as the aluminum heads open the lash up as it warms up!

Put the black advance bushing or the next smaller diameter one on it and time it for 34-36 total and see how it runs.

Idle will probably be in the 900-1000 range