Thread: Ignition Timing on 350 SBC

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Can anyone describe the difference between "valve clatter" and "pinging"? I thought it was gone after I added octane boost (104) but the noise came back last night.

Balancer marking was the issue with the timing (new balancer, old crank), have a balancer cover on order from Summit to take care of that... currently at 11 initial and 35 total.

Adjusted the timing - 2 inches on the manifold vacuum and it seems to roar now, just want to get rid of that noise... only get it at 2500 rpm under load (up a hill, on the highway, etc).

valve clatter will occur all the time, pinging will only occur under load. Even a light load in severe cases.

Take 10 degrees of timing out of the motor and see if it still makes a racket.

DennyW/techinspector1,

Thanks, I will retard the timing and let you know how it goes. I think, based on your descriptions, that it is definitely pinging. Motor sounds fine at idle and low rpm/no load

Sorry about the duplicate post, the web connection here has been acting funky lately...

Denny,

I have accomplished the following:

-Verified TDC and marked the balancer (used a piston stop)
-Just for grins I also:
-verified compression, 135 psi (+/- 3) x 8 cylinders
-verified spark plug gap while I had them out (.045), by the way did you know that a chemical in octane boost (MMT) turns your plugs orange? I had a COW when I first pulled one out...
-verified fuel pressure going into the carb, 6.5 psi

Then I:
-Retarded the initial timing 10 degrees
-Adjusted the carb to 900 rpm after the adjustment (this brought my manifold vacuum down to 15 inches)
Of note, my idle mix screws, with this timing setting actually now have an effect on rpm which is a good thing!

Bottom line, the pinging is GONE now but there are some "flat spots" in the acceleration which I am attributing to carb settings. At this point I am going to make some adjustments to the carb to see if I can get rid of them. Any guidance on the best way to calibrate the primarys/secondaries/WOT without a dyno? The primary rode I have in there right now are 2% rich in the cruise mode and 3% rich in the power mode (relative to factory setting).

I don't plan on messing with the timing any more, with 10 degrees initial and 34 total, it seems to really idle well and put out plenty of power.

By the way, I really appreciate all the help, I have learned more in the past week than I can explain....

Do you possibly have a blown resistor on the Unilte?

No, I have blown the module on that before and remember what that was like. The engine would randomly stall/die. And run like crap. There is a quick test to determine if it is blown, I'll do that this evening when I get home just in case...

Right now it runs really well, just at certain times there seems to be a flat spot in acceleration. Almost like a hesitation, but it pushes through and then rapidly picks up power. No strange noises or anything, just like the fuel going to the engine gets stifled or something. That is why I think it is a matter of getting the rods/jets/springs in the carb all synched up.

Yea, I have been thinking about a fuel regulator, but it has not flooded yet and both the pump and carb are Edelbrock so I figured it was OK. Besides the pump manual stated that no regulator was required when used with my carb.

It is not a Holey, it's a 1406 Edelbrock. I will check the floats first as you recommend.

I rushed through the IMS setup so I'll redo that now that they have some effect on the rpm (and I also used the recommendation to use the vacuum gauge and that worked well).

Last I'll check the accel pump and I think that should do it. Will keep you posted...