FWIW, there is no such thing as a “good” dial back light, imo.

What's the gear in you ride???

Truth. Unfortunately, timing lights have become as common as carb adjusting tools in a regular mechanics box. Do a search here. There have been a number of conversations on the subject.

For the reasons stated above worry less about what the number is and more about how it reacts when you move the timing. Just make sure you use the same timing light for verification later on.

The MPH only at 117-118 shows that it's really down on power from it's potential with the parts you have... As mentioned above it's hard to know anything by ET, but the MPH is pretty telling.

I can tell you when my car spins, and I have to let off the throttle, then get back on the throttle, it may loose .5 sec in ET, but always comes back around on the top end within 2mph or so. Foot on the floor in high gear, there isn't much car "Setup" that can change that.

Hopefully you find something on the Dyno. I've seen so many simple things (bad timing light, throttle cable misadjsuted and carb not going WOT, etc...) The parts in the motor have good potential...

The motor “should” easily make in the 675-700hp range.
(MarkZ’s 505 with ootb TF270’s, gasket matched 337, similar sized cam as yours made a tad over 700/700 on the BES dyno).

Unfortunately, poorly set up street cars(especially those with a manual trans) rarely reward their owners with time slips representative of how much power the motor makes.

This is an example of(one of the many reasons) why I dyno anything I build.
If the motor had been dynoed, you’d know what it made, had it all tuned up, and have a reasonable idea of the potential performance in the car.

If the car was underperforming, you’d know it wasn’t the motor, so you wouldn’t waste time and energy trying to find the lost performance there.

At this point, the chassis dyno could be helpful.

FWIW, there is no such thing as a “good” dial back light, imo.

On the moroso chart 118@4000lbs shows 505hp.

With a reasonably well set up street/strip car, my experience has been that you should be able to run within 10% of the engine dyno numbers(provided they aren’t inflated).

If I assume the less than optimal manual trans set up costs you another 5%(15 total), and start at the low end of the predicted power output(670hp), you’re looking at running speeds that correspond with 570hp........ which would be 122.5mph.

However, without the dyno numbers....... we don’t know how much of that missing speed is lack of power, and how much of it is poor car set-up.

On a dyno jet with a manual trans....... you should be near 600rwhp, unless there are some serious fuel supply or exhaust system issues(or the motor is just down on power).

As an example of how good it can all work...... 69 A12 car in FAST......3900lbs, 600hp, 4 speed, g70-15 bias ply tires, ex manifolds...... 129mph in some killer air.

I have decided just to make the 100 plus mile trip to a chassis dyno.
It has been hard t get runs at the track.I mph at 117-118 11.6 secs

To recap, my heap weighs 4000 lbs with me in it.
I have a 520 ci rb stroker, 670 net lift cam 260@50
TF heads flowing 370 @ 700, 337 intake, 2 " primary headers.

Calculators say I am making about 550 hp. Not sure if they factor in shift changes for a manual trans.

After checking the AFR, with the exhaust intact, I am at 11.6-8 range at WOT. I do run it with exhaust off though, not sure how much leaner that would make it.

After getting a good dial back timing light, I am running 42 degrees total timing all in about 3000 rpms.

Any educated guesses on how much more power I'll make by leaning it up to high 13s and limiting the advance to 36-38?

Optimizing the tune will help, just was wondering what guys with experience tuning would see, 50hp? 100hp?

Hopefully the dyno operator has a good light.
Will be nice to know whats going as far as peak HP and torque points.

I was just curious how much I might expect to gain by jetting and timing.

Years ago on a chassis dyno we picket up 60+ hp at the tires on my 470 messing with timing, jet and bleed changes.......I was way lean and needed more timing iirc and that's when I got a WB and really started studying the different circuits in a carb. Found out about changing the curve with bleeds and how Holley's tunes were quite wacky in my case so after many low 10 second passes, I got my first 9.98 pass...........Lots to learn on the dyno to at least get ya close and in some cases, bragging rights backed up with respectable et's.....

Next steps will be a roller cam and Thumper 1050!

Like we talked, at that weight either a skirted banjo straight 1050 Dommy for the wow factor or a BLP Billet 1.610 bore 4150 that I have on 8000 rpm puller trucks, boats, street strip and drag only cars/trucks. You need velocity to move 4000 lbs. and those Billets deliver across the board........