The Stovebolt Site Forums The Shop Area Engine Shop Trouble getting timing advanced

In need of ideas again. Since getting the truck on the road again, I can't seem to get it to run where I had it before. This is on a '60 235, 2 Stromberg 97's, Fenton headers. I used to run it at the BB. Pre68Dave's site shows it to be 5 deg. advanced. Now I have trouble at zero degrees represented by the vertical line between the U and C. The only changes I can think of is that I changed one of the carb's base plate to have ported vacuum. But I have the issue whether I use the vacuum advance or plug the line. I did not use the vacuum advance before. The other change is I had the head off chasing a knocking problem that turned out the be a deformed oil pan. One more change was to the exhaust where I routed both pipes to the drivers side instead of one on each side. Almost forgot, I did pull the distributer for painting but did make any changes. New wires, plugs, points, condenser. Any ideas?

Dennis

"can't seem to get it to run where I had it before."
Won't start at all?
It sputters?
It back fires?
Doesn't perform as well as in the past?

What sort of "trouble" are you having? You've made enough changes that it's hard to pinpoint any cause in particular, especially when you don't describe the symptom you're trying to correct. The first thing to do is establish exactly where TDC is by using a "positive stop" in place of a spark plug. Once you're sure the marks on the flywheel are accurate, you can use a delay flash timing light to make an accurate measurement of ignition timing, not a SWAG based on a lot of guesswork and some possibly mismatched parts.

Many years of doing precision timing measurements during dyno runs has taught me something about ignition timing- - - - -ONE degree of over-advance robs as much as power as 5 degrees retarded from the optimal advance point. Always err on the low side! I've proved that fact dozens of times.
Jerry

I hate it when I do that! It runs fine but pings on acceleration. I'm 2-3 degrees retarded to keep it from pinging. Is it possible to be off one tooth on the distributer?

Dennis

Yes, but that's not likely to cause the problem you're having. Chances are the difference is being caused by finally getting the vacuum advance functional- - - -most vacuum systems add 8-10 degrees of advance to the centrifugal setting, but most, if not all of it goes away as soon as a little load goes on the engine for passing or hill climbing. Until you get an accurate measurement of total timing, in crankshaft degrees, and also plot an advance curve with measurements every 500 RPM or so, it's impossible to tell whether the initial, centrifugal, or vacuum advance setting needs to be altered to get the proper performance from idle to full throttle. That's almost a dyno-only exercise unless somebody's willing to ride a fender with a timing light in hand and measure advance out on the road! Otherwise, you'll need to cut and try and road test a lot.
Jerry

Good point. I'll start by verifying TDC with the positive stop. I'm leaning towards maybe a tooth off since I still get pinging when blocking the vacuum advance. But first things first.

Dennis

No joy with the positive stop. Here is what I've done. I don't have a proper stop so took an old spark plug and removed the insulator and everything. I drilled taped for a 3/8 threaded rod. Screw what's left of the plug in then threaded the rod in as far as it would go. This measures 1 5/8" past the seat of the spark plug base. The engine is nowhere near TDC when I do this. I can cycle the piston without touching my 3/8 rod. Seems like the spark plug hole doesn't have enough angle to hit the piston. Ideas?

Dennis

Do it the old school way. Put your finger over the plug hole to seal it off. Have a buddy bump the starter around til your finger is blown away from the hole. Then look at the timing mark and move the crankshaft forward or backward to get it spot on. Do your distributor cap/wires from there.🛠

According to the 59-60 manual: The ball is ZERO! 5 deg BTDC is the first short radial mark clockwise of the ball. Looking in the hole above starter. NOT drivers side. Set timing to that mark. Find approx. TDC of number one cylinder on the COMPRESSION stroke and set ball on pointer. Start motor and point timing light into hole. Turn dizzy CCW to get to the 5 BTDC mark. Tripple check the points to .019 new or .016 used. Set Idle to 475 RPM. Hook up the vac advance. If you have a U I C, then I guess flywheel was changed or different factories, so see below.

This is what pre'68Dave says about timing.

"The line between U and C is upper center, same at TDC.
The 5 is the timing ball, signifying 5 degrees before UC/TDC."

So if your fly wheel has UIC, and clockwise of that it has a ball with a five (5) next to it, set the pointer on the ball.

Dave has said he gets good results closer to 10 BTDC. tclederman has commented that factory timing was calculated/tested/decided/specified with era gas quality and at unknown altitude.

Seems like you are fairly near me. You may be at 1500-2500 above sea level. Timing/atomization/vaporization is affected by altitude. (More advance needed).

Put a 45 degree bend in the all-thread, insert it into the cylinder, screw the plug shell over it, and then lock the probe in with a jam nut against the plug shell with the bend pointing down. That should allow you to intersect the piston. Any other method of finding true TDC isn't going to be accurate, as there's a few degrees of "dead zone" with the piston at the top. I've used the positive stop method of finding TDC for 40-something years when checking race cams.
Jerry

OK teach, I'll put a bend in it tomorrow and give it another go. Bartamos, I used to time to the ball, but like I said, I get pinging now with or without the vac. advance. Now I'm running 2-3 ATDC.

Dennis

How is your throttle response just off idle with the timing that late? You're getting into the area where a bog or a backfire might happen when pulling away from a stop. It might be worthwhile to restrict the centrifugal advance a little and make up the difference with initial. I used to do that on small block Chevy hotrods with moderately radical cam timing- - - -reduce the centrifugal advance about 5-8 degrees by limiting the travel of the weights, and add the same amount to the initial setting for good throttle response. Total timing doesn't change, it just gets rearranged as to where it enters the advance curve.
Jerry

Isn't the idea to get the needle on the ball/mark at no.1 TDC compression stroke? The piston and the ball are already timed. Don't need anything but a Kleenex stuffed in the no. 1 hole. Hand crank the motor with all plugs out, when kleenex blows out, the ball/mark will be right there near/in the peep hole. Look at rotor and see if its pointing at no.1, wire dizzy per firing order and then tweak dizzy with a light to stay on the -5 mark. Been doing it that way for 41 years.

If he wants to make a SWAG at the timing, shade tree methods work fine. There's a lot of variation in factory tolerances. Some people are satisfied to get a hit in the ballpark- - - -some of us want to hit a home run.
jerry

No backfire and I don't notice a bog. I think I'll look at the centrifugal adv. weights/springs too. Maybe a spring has lost its spring. Hope I don't have to, but how do you limit the travel of the weights?

Dennis

I like to drill a 1/16" hole in the slot where the weight travels, and drive a short piece of spring steel roll pin into it. That takes up a little bit of the slot and keeps the weight from making its full travel. Then use a delay flash timing light to see how much the centrifugal timing has been reduced. Add that amount, or part of it, to the initial timing.
Jerry

After re reading everything, I see there is no problem reported. It runs, it does not ping. No bog, no misfire. Where's the beef? We are all talking how we time a motor and there is no reason to be discussing that. Bad on me. Let's put this whole thing in spoon. Wherever it runs the best is the best timing. Period. I say if it runs good, start messing with it until it doesn't.

The Swagmaster
P.O Box wrench,
Shadetree, AZ

Thanks HR. I'll report back what I come up with. Bartamos, inquiring minds want to know.

Dennis

With the low compression that engine has, you have to be way advanced for it to be pinging. I am betting on one tooth off. None of the other solutions have changed from when it was last run. The internals in distributor won't change just from painting it. Use a wood rod down the spark plug hole, and just watch it. The timing marks will line up and will be close enough for distributor alignment.

Just remember, it was running OK before the changes, and the only change you made to timing was with the distributor location, points and plug wires, so start there.

Joe

It would not run like that with one tooth off. Probably would not run at all. Sometimes the vacuum advance parts hit something or get "hung up" on something, preventing rotation..or screwed around with too much by inquiring minds.

HEI is nice.

Shade tree wild guesses on timing are fine for engines with all original equipment. The pointer and BB are there as a starting point, even if everything else was stock, which it obviously isn't. This one doesn't fit that category. It's WAY over-carbureted, plus if the exhaust is assembled anywhere near correctly, it's got enough exhaust scavenging to change the entire volumetric flow. Some pretty sophisticated analysis of the ignition timing curve is going to be required just to compensate for all the rookie mistakes that have been inflicted on the fuel and exhaust system. It's probably way too lean which is going to make it prone to detonation at the drop of a hat.
Jerry

The positive stop worked great after bending the all-thread. Verified the UIC mark is as expected. Reset the distributer and will let you know how it runs after I get the driveline back in.

Dennis