having power to 6200rpm's. however my engine flattens out at about 5600. i am running the stock heads. they have has as much done to them as possible. Could they be the week link?

it ramps up with lots of juice til then but then flattens out to nothing.
could the timing need some tweaking. right now it is at +18* if i get below +16* it will not even idle.

 

Have you checked for a vacuum leak? If it won't idle with 16 base timing then something is wrong.

 

I doubt it. I'm running port-matched stock heads on a 289HP, and it's still giving power when I back off, at 6500+. What have you "done" to the heads?

As for timing, have you had the distributor curved? The rate of increase in the timing is critical, most folks, even speed shops, only concern with total advance but that's a small part of timing.

If your engine requires 18° BTDC initial timing, something is seriously screwed up.

 

I am not running any vaccum parts. I have a mech advance MSD dizzy and a streetfire box. Wieand Stealth intake and a holley street avenger carb.
the heads have been proted and polishedand i am running the lunati ssprings that came with my 610003 cam. I am also running 1.6 magnum roller rockers.
I have noticed that it will rev a little higher if i am running octane booster on top of the 91 octane fuel.

 

So you have a mechanical-advance-only-no-vacuum-advance distributor. So do I. Who set up the mechanical advance in yours?

 

Let me stress again that if they car won't idle and dies under 16* timing at idle, then something is wrong somewhere. You have a vacuum leak, your balancer marks are incorrect, loss of compression....something.

Find out if your timing marks are correct first, then if they are find out what's causing the problem.

 

I second the timing marks issue. Top that with the 61003 topping out at 5600, and you either have intake/exhaust restriction (small carb/no secondaries, not enough port, not enough exhaust) or a timing problem. Since it won't idle at reasonable timing (according to the marks) start here. Is the cam straight up, positive, or negative?

 

fully agree here.
if you have it 16+ your total timing might be too far in and that causes pre-ignition then this is the reason for no power at 5500+ and might end up in sudden engine death.
There is many mechanical things that could be wrong like timing gear not set correctly (advanced/retarded) or the valves not closing properly (valve adjustment).
I still would start with the obvious first
- check vacuum leaks
- check timing marks (get a piston stop, let us know if you need instructions, i posted that before)

as for the vacuum advance missing. it won't help fule efficiency or streetability, but is not related on your issue. Neither should be the advance curve as it should be maxed out at 4000 latest. Problem is total timing, vacuum leaks, valve adjustment, mechanical adjustment somewhere

 

well i will get a piston stop today. I will search for the correct timing marks. i am running the professional products balancer which can has 3 different sets of timing marks.there is only one set that comes close to lining up though so i doubt that is it.

 

it's better be sure .. otherwise you'll have that nagging in the back of your head.
How was she running before and what have you changed?