Alot of timing to make it run...48

[F-BIRD'88]

Escessive timing @ wot will damage the engine.

Watch the seat of the pants feel.

Find the true wot best power timing at the track (based on track mph. or get it on a dyno.)

If it needs more than 42 deg wot. the jetting is off.or the spark is self retarding. (electronics lag, timing chain/both.

Excessive exhaust reversion/delution of the chamber mixture will also make the engine timing hungry.
The EGR effect slows combustion burn speed.




Indicates the headers/exhaust system and cam valve events are a missmatch and or excessive exhaust restriction.
and /or + the piston dome is unfriendly to combustion and scavenging.
usually bbc want 38 deg) (pump gas)


Nothing worse on a bbc than a poor exhaust system.

[SonnyJames]

Been through it all. 48 is what it wants so it got it. Ran like that for 8 mo with multiple 7200 pulls almost daily. Upon disassembly all looked good as far as detonation goes. I just wanna be safe and pull out timing above a certain rpm and see how it runs. Looks like the only way to do do it is with 6AL2.

[Dave Flanders]

If you're looking for validation on it I will say that I have seen something similar before. Had a friend with a 460 Mustang with some of those big old dome pistons and it would only run with 60 degrees of timing. They had to manually move the timing back to get it to start in the lanes then bump it back up for the pass. This was almost 20 years ago and the car did run pretty well for the time - IIRC 10.20's back when that was respectable. Not the best way to make power sure, but it actually did (kinda) work.

[avengerengines]

Are you verifying TDC? That sounds like way too much.

[SonnyJames]

Tdc was verified.

[JoePorting]

Have you done a compression check?

[Barry Burch]

Try a different spark box. I've seen two different boxes
run the same times even though they would flash the timimg light
showing different amounts of total lead.

[Strange Magic]

In general, these combo's are poor due to the combination of deck height, stroke and shear cubic inches for the given volume from the back side of the intake valve to the booster. In many of times, timing will be the vehicle to assist in fuel shear. Running timing in excessively will be a band aid to help shear fuel for lack of acceleration rate from numerical gear. The engine in discussion will no doubt like rpm to make air speed. I would highly question anything above 43 degrees for total and by locking the distributor out, it will help shear fuel at lower engine rpms for this application. The digital 7 boxes have a built in magnetic compensation that will keep it from retarding as the rpms go up. Just a migration with everything else left alone usually helps for power due to the nature of the magnet vs. processor. Compression helps air speed as well and in this application it is critical and I would push the limits for the given fuel budget.

[fdicrasto]

I suppose you tried at least one different timing light? I have to admit that in the 40+ years of racing and tuning I have only once had to run timing this crazy and that was in a 277 cu. in. small block that required a dome and combustion chamber that choked off flame travel hence ridiculous timing. Might be Tuner has the answer as to why but I still can't fathom it. I go along with the light ping in 3rd gear under moderate load as an indication that you went beyond max total and with mufflers and street app, this still is an acceptable tool inspite of our Hi Tech world we live in. Can't wait to hear what the final answer is to your timing issue.

[SonnyJames]

whenever I get it out for a ride and some tuning ill be sure to post back. runs like chit in the garage with a hesitation from hell at 38. add 5 deg its better. add 10 and its much more responsive with hesitation "almost" all gone.

[Strange Magic]

You might want to shyt can that half bread distributor with it's magnet and buy a new one. One that is mechanical only. One that doesn't have a vacuum advance regardless if it's locked or doesn't work at all.

[SonnyJames]

Noway the Dist is throwing it off ten deg.

[groberts101]

You can wonder why until a hundred Tuesdays from now.. but giving the motor what it wants will usually give you the biggest grin.

The other thing to consider is that carb fuel curve will always change the amount of timing requirement. Usually not to this degree if tyhe plugs are decent looking.. but there is still some margin. Have you tried to tune the bleeds and or emulsions for less timing? If not.. then it just may be that the carbs current config is set up to prefer more timing, is all.

To give perspective.. my little 385 Chevy absolutely LOVES 54 degrees at idle(locked out) all the way up to about 1,700-1,800 rpm under light-load cruise. From there my programmable 7AL uses the MAP sensor to start pulling timing back to about 36-37 degrees once I reach my redline at 7,200 rpm(still likes around 40 degrees at 6,000). I've been to hell and back with carb tuning because everyone tells me that I shouldn't need that much timing with 11.5/1 compression(tight quench and flat-tops) on pump premium.. but the plugs like it and the motor makes more average power all day long through the entire season. So, that's what I continued to give it after I quite asking why and started trusting my vacuum guages readings.

The nicest thing about the programmables is that the MAP sensor will enable load based maps so your street car can burn tires at low rpm and still eat lots of cake at high rpm too. Good luck with it.

[SonnyJames]

Thanks Groberts!

[SonnyJames]

Ok, I changed all the ignition. Installed new programmable 6al2, billet distributor, new coil. Idles better with 40 deg timing and hesitation has improved a ton. Haven't opened it up yet but suspect good things.