In my now dated build thread, I listed a mess that lead to rebuilding my motor. My 351M is now about a 409. I went with the TMeyer pistons and 400 crank, along with having the heads milled. I'm running about 9.4:1 CR now.

What would be a good starting point for initial timing? I was at 14* and the truck is a dog. I bumped it little by little until I got to about 24* and the truck gained considerable power but I had detonation along the way. I went with lighter springs in my MSD distributor for more timing advance and backed the initial timing down to about 14* again. I just don't have any power. I know there are a lot of variables but this is not my wheelhouse. If any of you have similar setups, I'd be curious to know what you're running.

 

What are the numbers on your cam?

What are the numbers on the distributor's cams..or weights?

Are you hooked to ported or vacuum advance, and in what shape is the vacuum advance can/lines?

 

Crane 133042: Duration 272/272, Lift .524/.524
You've got me on the distributor's weights; I'm not sure on that.
I do not have vacuum advance

 

Total timing is more important to consider once you start modifying from stock. I would suggest setting it up at 34-36 degrees (without vacuum advance) and play with it from there. There are many factors that affect what you can get away with, fuel, elevation, weight of truck, gearing, intended use, etc. If you haven't already, I strongly suggest reading this article... https://www.fordmuscle.com/archives/2000/03/timing/ It may point you a different direction depending on your intended use.

I like the advance to be heavier on the initial side than the mechanical side for better idle. But if you do adjust for more initial, you have to limit the mechanical so you don't exceed the total timing typically 34-38.

Also if the distributor is not mechanically advancing properly it will run poorly.

 

Ok, thanks.
With that cam, or any cam other than stock, the engine wants the initial timing to be higher. Say like 16 - 18 degrees BTDC.

Without knowing what mechanical advance (distributor's cams/weight numbers) you have, total timing is just a guess.

If you're running vacuum advance lock out I would try around 20 degrees BTDC....and back it down if pinging. The lighter springs you're running just allow the mechanical advance to come "all in" sooner. You could try one light spring and one medium spring and check the curve.

One way to check your "all in" timing is to keep the vacuum advance plugged, stick a timing light on her with an RPM indicator attached to any plug wire....with you being able to see both. While watching the timing light and RPMs, give 'er some throttle and watch at what RPMs and the timing tops out.....If, for example, your timing doesn't increase after....oh, say....38 at 3000 RPMs, and your initial is at 16 BTDC, you have 22 mechanical..... 38 total timing and "all in" around 3K RPM.

With your running no vac advance, I'd try and get the most timing out of her as you can, without pinging and hard hot starts.....just like you've been doing.

Clear as the muddy Mississippi?

 

Assuming with that CR you're running 91+ octane fuel? If not, the ping could be misleading.

 

Actually, I'm running around 9.5 CR, on regular 87, with no problems. But! I also have the vacuum advance hooked up.

Good point, there D-rat, though.

 

The lighter springs do not give you more timing advance.

They advance the timing quicker than heavier springs, that's all.

Set your idle timing to 10, set your total timing to 30, install the medium springs, and then determine the timing curve.
(Those numbers are low initially just to be safe.)

Then compare your observed timing curve to the MSD charts.
That way you'll know if the dizzy is crap or not.

Assuming that the timing curve is correct, you will have a reliable base to work from.

Even if the dizzy is brand new, that's no guarantee that it's not faulty.

Is your detonation at WOT or partial throttle ?

Why do you not have the vacuum advance connected ? (Just curious)

What's the deck height ?

 

Set the timing to stock as a base. Disconnect the vacuum advance from the distributor and plug the line. Hook a vacuum gauge to manifold vacuum. Hook up a tachometer if you have one. With the engine hot, in Park, adjust the timing for highest vacuum. Only rotate a little at a time and blip the throttle a couple of times for each setting. Find the maximum vacuum and you'll be close. Take it for a drive and check for preignition. You'll probably need to back off the timing a bit

However, your timing can vary day-to-day depending on the outside temperature, air density and gas you're running

 

I was curious about vacuum advance when I installed this (pic attached). Am I missing something?
I am running 87 octane and the pinging is not just WOT but under decent acceleration or better only.
I'll bump down to medium springs. Is my only shot at advancing to change the weights?
As a side note, I do have some tweaks on my carb as well. I'm running a Carter AFB on an Edelbrock Performer dual plane manifold.
I appreciate you guys' input!

 

hmmm....somebody stole the vacuum advance off your distributor!!!

 

Holy Smacks! You're right! Light Finnered Louie strikes again!

I can't make out the distributor's manufacturer....who made it, and who would do such a dastardly deed as to leave the advance can off it? Wait...MSD - pro billet...PN E(?) 577....?....nope - PN 8577.

Anyway.... changing or modifying the distributor's cams/weights won't affect your advance....just your total timing and what change in initial/base timing you can make.

If you want vacuum advance (a good thing in my opinion) you'll need a new distributor....unless there's an opening on the dark side of your current red one.

 

From MSD's overview page:

Mounted to the top of this shaft is a fully adjustable mechanical advance assembly. The rate at which the chromoly assembly advances the timing is easily controlled by changing the supplied advance springs and stop bushing for total advance.Features:

• Billet housing is 5/8” smaller in diameter than stock Ford distributors
• Must be used with an MSD Ignition Control
• Supplied with small diameter cap with HEI style terminals and race rotor (will accept 8441 Cap-A-Dapt)
• Nylon pads ensure smooth operation of the advance weights
• Advance weight pins are staked and tig welded to the plate
• Mechanical advance assembly can be locked out for crank trigger systems
• Advance plate and weights are fine blanked from chrome moly steel and QPQ coated for friction reduction
• Polished steel shaft is QPQ coated and guided by a sealed ball bearing
• Maintenance-free magnetic pickup and precision reluctor create stable trigger signals throughout the rpm range
• CNC machined billet aluminum housing and billet aluminum base
• Easy-to-adjust mechanical advance with supplied springs and stop bushings

From MSD's overview page, clicked on "specs"

http://documents.msdperformance.com/8577.pdf

 

I can't recall which stop bushing I'm using but it matched the light springs/curve I thought suited me from MSD's kit. I certainly do not see anywhere to adapt vacuum advance.

 

Ok. After reading some of the specs sheeit, you have no vacuum advance...just mechanical. I believe this type of distributor wasn't made for our vehicles.

What you can try to find a happy medium for the curve you want:

Make yourself a Cartesian graph, starting at 0. From there, on the bottom, going from left to right, mark out your timing (on the balancer) in increments of 5 BTDC, 10 BTDC, 15 BTDC, etc, up to 40...or what you can see.

From the bottom left again, going up, mark out RPMs in increments of 500, 1000, 1500, etc, up to 4K.

Use your instruments and set them up like I suggested in post #5 (?).
Mark down a point at each increment of RPMs that you read on the timing light....you'll need some assistance here.

Plot the points - let's then play "connect the dots!" Take 'er for a spin after each spring change and see how you feel.

Different spring tension(s), or a combination thereof, will give you a different curve. Find one you and your engine are happy with.....or ditch the MSD set up and go with the DSII or an HEI. They have a vacuum advance set up.

No offence meant about the MSD stuff......