OK here's the deal. I have a 30 over 350 vortec motor with the folowing specs.



Heads: RHS Vortec Head
1.94 Intake 1,50 Exhaust Valves with 170 cc runners

Cam specs:
Intake Centerline 106
Exhaust Centerline 110
Duration 287/293
Duration @ .050” lift 236/242
Lift .520 Intake .540 Exhaust
Single Plane Intake 3200-3600 stall converter

The problem I'm having is wuth the timing. I'm running a mallory mechanical advance distributor and want so advice on what to set it at. The motor runs like crap at anything less than 20 degrees of initial and I'm afraid to go over 40 degrees total. Since this isn't a vacuum advance can I set it higher on the total? The cam card is at the link.

Cam card.

 

A cam with that much duration needs 12-20* of base timing. How much total timing it needs depends on the exact combination of parts. No two cars are the same. One may be happy with 34* total, another may like 40*. Disconnect vacuum advance when checking total. Vacuum advance is for part throttle operation and can change the total quite a bit.

Among any number of things, the timing marks may not be correct. Years ago when I put an engine together, it kept making more power the more I advanced the timing. When I hit 44*, I started to suspect something was wrong. I used a degree wheel and a piston stop to make sure the #1 piston was at exactly TDC and found out the timing marks were off 8*. I bought an adjustable timing pointer and corrected the problem.

 

I don't have vacuum advance. I'm using a mallory unilite with mechanical advance only. I'm going to reset the amount of total timing that it can advance so that I can set the initial up to 24 or 26 with a total of 38 or 40. I'm just concerned about that total being too much. The last motor I had with a cam similar was ran at 30 degrees initial and maybe as much as 48 total but that may have also be what caused it to blow a head gasket and gouge out a spot in it between the cylinders. Look here for the damage.

 

Like I said, each engine is different. My BBC runs with the timing locked out at 40* and I have around 7* in the start retard. Engines with a lot of power adders will use a lot less total timing.

 

Thanks AlkyIROC!

 

Most cams notwithstanding, the effecient Vortec combustion chamber tends to favour somewhat less ignition advance than other heads. Most dyno results that are posted are showing peak power is achieved with 34 degrees total advance.
While my cam is smaller than the one you're using, I have 16 degress of initial combined with a mechanical advance of 18 (limited HEI advance slot).
As AlkyIROC pointed out though, all engines are unique.
Curious as to what your compression pressure is (via a compression test).

 

Not sure about compression ratio. The blocks bored 30 over and decked .010 and the advertised compression ration of the pistons was 9.75:1.

 

If you come across the piston part number and the type of head gasket used, you can do quick calculation. Might be of benefit in the tuning process.

 

Head Gasket

Pistons

Piston pic

 

Based on a 4.03" bore, 3.48" stroke, 64cc heads and a few things assumed like a .039" head gasket, 5cc piston valve relief volume (couldn't find the specs anywhere on line) and a piston deck height of (stock .025" - .010" decking = .015") gets you a static compression ratio of about 10:1.
Dynamic compression is about 7.7:1.
A cam that size bleeds off a fair bit of compression pressure. This might explain why the engine likes a lot of initial timing.