Timing for a 302 HO

[Rickd]

Just went from a bone stock 302 HO motor (from an '87 Mustang) to some modifications (slightly more cam, Trick Flow TW heads, and a Demon 575 Carb from Don Gould). Just curious as to the timing some of you guys are running with similar 302 motors (low to mid 300 HP potential - properly tuned).
I appreciate your comments. Thanks. Rickd.

[TurnpikeBoy]

Are you using a vacuum advance distributor? Or a straight centrifugal advance unit?

My 302, with Ford X303 heads, runs a total advance of 35*; I use a centrifugal advance distributor (MSD small-base) with 10* of initial - idle speed - advance and a 25*stop bushing. Set up to have all advance in by 3600 rpm. For long road runs I usually will kick it back a degree or two, only because I want to avoid any possibility of detonation. Not that this would happen at 35*, just caution on my part. BTW, Ford recommends 34* to 38* total.

Vacuum advance kicks things up at idle and part throttle, so a touch less initial advance (3*-4*) would be more appropriate. This is one area where you will need to experiment some, to see what yours will require.

[Jim Harding]

I have to disagree a little with TurnpikeBoy,,,,,

Depending on how your dizzy is set up, i.e. how much mechanical advance it will add and at what RPM it totals out, I'd disconnect the vacuum advance line (and plug it), up the RPM until no further advance is noted, and set the total timing for 35 to 36 degrees. Then, you can back off the RPM to idle and see what the initial timing is. My guess would be something like 12 to 16 degrees, again depending on the dizzys innards. The goal here it to set the maximum advance, and accept whatever initial advance you're left with, so long as it does not cause hard starting.

The vacuum advance should be connected to the ported vacuum port of the carb, not to the 'full-time' vacuum port. Vacuum advance will then allow maximum advance at partial throttle opening (like cruising down the highway) at something on the order of 45 to 55 degrees. Ported vacuum will not add any advance at idle, under heavy load or wide open throttle. Some vacuum advance units are adjustable, and can be adjusted to give maximum advance without producing any spark knock.

My engine is a 302, ported iron heads, mild cam, modified ford dizzy w/vacuum advance, and an Edelbrock 650 carb. Shows just over 300 HP at the crank. I run 12 degrees initial, total mechanical at 36 degrees/3200 RPM, and add an additional 12 degrees of vacuum advance for a grand total of 48 degrees under light load/partial throttle cruise. Engine is very responsive and shows no signs of pre-ignition under any circumstances.

- Jim -

[TurnpikeBoy]

Sounds like good advise.

[Rickd]

Sounds like good input. I am taking her in in the AM to my friendly mechanic, along with new distributor cap, rotor, and Champion 2107 gold plugs. I will run over the recommendations with him. Thanks again, Rickd

[eliminator]

My experience with Champion plugs has not been good. They are not what they used to be!!!
I have had good results with Autolite's.