jpc647

So I bought a new Craftsman Timing Light with Tach/Advance built in.

Checked the initial timing tonight with the vacuum advance unplugged, base timing is approx 39*. I have to dial it back 27* to get it to the 12* mark on the timing tab. Motor is a 72 350, HEI ignitiion out of what appears to be a newer 76 vintage car.

Around 3800 rpms(timing light calculated), I have to add 43* to make the damper mark hit the 12* mark on the tab, or 55* timing all in.

For reference, I checked the rpm's in drive and park at idle and I got 560 and 800 respectively. This is about right, right?


Now I'm all confused. If I try to dial the initial back to 12/14degrees the engine starts to want to die. Can't increase it much either, maybe a degree or two as the vacuum canister is hitting the firewall.

The instructions for the timing light say to have a vacuum pump to add vacuum to the port per OEM spec. How much would I pump into it to check.

Also, if I connect the distributor to the manifold port of the carb(for non emission controlled engines per edelbrock book), the timing mark jumps way out. It was getting dark and I was getting tired so I didn't try to dial it back to find it, but I thought that was weird.

oldcutlass

Do you have the timing light connected to the number 1 spark plug(drivers side front plug)? To use your light set the dial or what ever needs to be set to 36. With the engine rev'd to 3500 and the vacuum advance disconnected, you adjust your distributor so that the mark on the balancer reads "0" on the timing tab.

jpc647

Yes the timing light is on the number 1 cylinder. That's essentially what I did, except I brought it to the 12* mark on the timing tab because the timing light is digital and it moves in .1 fractions, so in the essence of time(and it was getting dark), I stopped at 12, and did the math. Same as going back to the 0 on the tab really. Does that make sense? Just for the sake of checking the timing light, I'll stop at the 12 mark again tonight, and then add 12 more to the light and see if it drops me to zero on the timing tab, I'm sure it will, seems I have something else going on here.

Maybe my curve is off, maybe the weights in the dizzy need replacement of adjusting or replacing, but if normal is 16ish (with hei) initial, and 36 all in, that's 20* advance, just way high initial. I'm looking at the same advance. All I can think of is a cam, so the initial needs to be higher. Sort of stuck at the moment. Don't know what to think.

oddball

Something isn't right. It's actually quite hard to start an engine with that much advance - you'll get kickback any time the engine is warm.
You should verify TDC on the #1 piston with the timing tab and the balancer mark.

MDchanic

You are checking the timing with the vacuum advance disconnected, right?

Since 39° at idle, 55° at 3800 RPM seems a bit too advanced, the next question is, have you verified that the timing mark on your balancer is accurate?

The first thing to check in these cases is whether your balancer ring has walked.

- Eric

442Harv

Did you disconnect the vac hose,and plug it?

jpc647

Car starts better than it used to. No problems, no kickback nothing. I will double check everything tonight. I know the distributor is in right, I checked that. At TDC its pointing to 1 on the rotor, but I'll check the mark.


Yup, disconnected and plugged. I'll double check the mark on the balancer again this evening.

What do you mean balancer ring has walked?

MDchanic

The outer portion of the balancer is attached to the inner portion with a thin band of rubber.

If that band breaks down, the outer portion can move with respect to the inner portion, and the line no longer corresponds to TDC.

- Eric

Tony72Cutlass'S'

Also could be his vaccum advance is stuck in full advance?

Just a thought.

jpc647

So how do I check that? Rotate the engine by hand and see if they move together or independently? Sorry if stupid question, just don't know.


If the advance is stuck in full advance, wouldn't I not see a change in the advance from idle to 3800rpms?

MDchanic

You have to use a dial indicator, a spark plug hole whistle attachment, or a spark plug base threaded to accept a bolt, to determine within a degree or two when the #1 piston is at top dead center.
At that point, the line should point to the Zero.



No, if the centrifugal advance were stuck, you would not see a change from idle to 3800 RPM.

Since you haven't tested the vacuum advance so far, if it were stuck, you wouldn't notice anything at all.

That being said, the vacuum advance return spring is pretty strong, and they don't generally stick in the advanced position.

- Eric

RetroRanger

Tony is suggesting the vac advance portion is stuck. You can check that at idle with manifold vacuum disconnect and plug vac line on the dist and the idle slows reconnect vac line to the dist and idle speeds up.

the change your seeing from 39-55 degrees is mechanical advance and the HEI has about 16 degrees mech advance so that fits


Idk how to chk the damper other than maybe a visual inspect ? Then if you see nothing mark a line across it so if it does happen you can see it easily

rjohnson442

Verify#1 is at TDC on compression stroke Few way to do it just dont look at the balancer to do it. Then Once you are sure your on tdc THEN look at the balancer it should be at the zero mark on the damper. If not, it's spun from the zero mark

MDchanic

To verify the TDC marking, it doesn't matter whether the piston is on compression or not.


Actually, later balancers have punch marks on both halves adjacent to one another so that, if you remove the pulley and look straight at it, you can see if it's walked.

- Eric

oldcutlass

To check your harmonic balancer is quite easy. Remove the number 1 spark plug and distributor cap, leave the rotor on and mark the #1 wire on the side of the housing in accordance to its location on the cap. Hand turn the crank until you hear a swooshing sound or have someone stick their finger over the spark plug hole to feel when the air comes out and the rotor is pointing to where you marked the #1 spark plug wire. Then look at the balancer and see if the mark lines up with the "0" on the timing tab. If it is way off the balancer has spun.

Centrifugal advance can be anywhere from 17-20 deg's on an HEI. IMHO,I think you need to recheck your new timing light settings and try again since it's new to you. If your using an MSD system some timing lights do not like them.

Octania

So I bought a new Craftsman Timing Light with Tach/Advance built in.

Checked the initial timing tonight with the vacuum advance unplugged, base timing is approx 39*. I have to dial it back 27* to get it to the 12* mark on the timing tab. Motor is a 72 350, HEI ignitiion out of what appears to be a newer 76 vintage car.
====================
My experience with putting non-computerized HEI into a high compression 403 was that it needed a lot of fiddling and unconventional work to be happy.



Now I'm all confused. If I try to dial the initial back to 12/14degrees the engine starts to want to die.
====================
EXACTLY. Retarded to std issue specs I was used to, like 10'BTDC, it was a sloth pig that overheated on a 2 mile test run. Could not outrun a V6 from the light. Would not idle.
===> ATTACH A VACUUM GAGE and watch it
I suspect the super low vacuum- it dropped off to under 8 at idle- allowed the power piston in the carb to enrich the mixture which just made things worse and worse. You NEED enough advance to make YOUR combo happy. Then I had pinging, so the vacuum canister was replaced with an adjustable one which was set to ~11 degrees allowed, which I calculated from the engine's happy static and allowable maximum. Same with the mechanical advance, I measured and tried various weights and springs until I got the required amount of MA.


Can't increase it much either, maybe a degree or two as the vacuum canister is hitting the firewall.
==================
EASY REMEDY by removing the spark shooter and reinserting it ONE TOOTH off in the favorable direction.



The instructions for the timing light say to have a vacuum pump to add vacuum to the port per OEM spec. How much would I pump into it to check.
===============
It varies.
check the ROP thread where I wrote all about that.
Oh, yeah, lost all that.
Google search for vacuum canister specs, or request my PN database where PN's and vacuum vs. advance, and total advance, specs are listed.


Also, if I connect the distributor to the manifold port of the carb(for non emission controlled engines per edelbrock book), the timing mark jumps way out. It was getting dark and I was getting tired so I didn't try to dial it back to find it, but I thought that was weird.
==================
I ended up with the timing too advance to start ok, unless I hooked VA to manifold vacuum. Voila, problems solved... while starting, lax timing for ease... as soon as it's running, LOTS of advance for good- no GREAT performance and throttle response.


You have to use a dial indicator... to determine within a degree or two when the #1 piston is at top dead center. At that point, the balancer line should be at the tab's Zero.
====================
ck this thread:
https://classicoldsmobile.com/forums...do-timing.html
Wherein, it is written:
"To check your mark very accurately, within a degree or two, insert a copper wire or coat hanger or the like until it touches the #1 or #6 piston, whichever is handier. One person holds and gently guides the wire or rod [in line with the cylinder is best, but anything close to that is OK] while another turns the crank back and forth until that wire is pushed out as far as possible. That is true TDC within a degree or three, depending on your skills. Compression stroke or exhaust, makes no difference. If your balancer mark is not almost exactly, within 1-2 mark widths, at zero degrees, then you need to replace, alter, or adjust parts to correct that."

MDchanic

Not worth a major argument, but the copper wire technique for checking TDC in unlikely to be accurate to within a degree or three.

The piston slows markedly as it approaches (and departs) TDC, so there is very little variation in height (feel on the copper wire) as you turn.
Even with a dial indicator, it's a little tough.
You can use the wire (or screwdriver, or pencil...) technique, and it will get you close, but if your balancer is off by 10-15°, it may or may not clearly show with this technique.

- Eric

jpc647

I'm outside looking at the balancer. It appears the marks on the outer line up with those on the inner:
20130620_1826441_zps8540c792.jpg

But when I put cylinder one at the top of it's stroke, and the rotor is pointed to the #1 plug wire, the timing is 3/4" off the tab. So does this mean the balancer, and therefore the cam/crank are off balance too!?
20130620_185621_zpsc079598e.jpg
20130620_185626_zps8eaa4823.jpg

MDchanic

Yes, I would have to agree - you can just see the edge of the inner portion with the pulley attached, then the rubber material after that, and then the outer portion, and it looks as though there are factory marks that are still lined up.

That doesn't make this any easier...

- Eric

jpc647

So the crank are off? Does this mean my cam is approx 15* advanced of what it should be? Or the timing chain isn't right? Not sure what else I can check.

MDchanic

The numbers you are giving for ignition timing do not make sense under the conditions you describe.

It appears as though your timing mark is accurate, so unless another source of error can be found (timing light on wrong cylinder, wrong timing scale somehow installed, etc.), I have no good explanation.

Something is wrong here.

Perhaps a comprehensive set of pictures would help.

... And, no, this has nothing to do with your cam timing or timing chain (they can throw off ignition timing, but then you would see that it was off when you used the timing light).

- Eric

jpc647

Okay. Well the timing light is on the drivers side front cylinder. The one closest to the front of the car. The timing light shows the same location of the tick mark. Maybe the new dial back one isn't accurate in the readings it give me for the "dial back amount"? I can try to take a picture of the location of the timing mark when it's running. Can do that tomorrow.

What other pictures would help? the car runs okay it doesn't ping or knock. Just trying to get more out of it. I feel it should have a little more kick to it. The exhaust sounds different right before it shifts. Like a popping in a way. I'll get a video of it and post it. Maybe it's just hte tone of the dynamax mufflers, I'm not sure. But after the new carb and intake, it was there. I'll get a video. Maybe it's unrelated, but it's the only idea I have.

Charlie Jones

A good way to check your timing chain is as follows;
1. Remove Distributor cap.
2. Get a large breaker bar and a socket, so that you can turn the engine by hand.
3. Turn the engine by hand in the normal direction of rotation, until the balancer mark reaches TDC.
4. Slowly turn the engine back in the opposite direction, watch the distributor for movement. ( If you can't see the rotor too well while turning the engine, then get an assistant to watch. )
5. Stop turning when you see the rotor move. The number of degrees of "slop" in the timing chain will be displayed on the timing scale. Do this several times until you get essentially the same figure.

4 degrees or less is OK (At least for everyday driving)
At six degrees the engine will run, but poorly.
Anything over 8 degrees is "out to lunch"

oldsbucket

what happens when you hook the vacuum to a ported or above throttle plate vacuum source set your initial timing by the book . all my non egr motors are hooked up this way, no vacuum at idle. if you use manifold vacuum u actually have less vacuum under load than at idle. i do not have that type of light and its hard for me to follow the issue but your vacuum source caught my attention. I'm running a petronix mod in the original dizzy and no issues

RetroRanger

There was another thread on here recently ~2weeks ago or so where the OP posted she had similar very high ~30 degree +- base timing, I can't find the thread does anyone else recall that ? I don't recall if there was a resolution but it may make for an interesting comparison.

For reference I have the same set up as The OP 72 350 w HEI, my base is ~16 degrees w ~33* at ~3500 rpms. I also used a sears dial back light. I think I could stand a bit more more base timing as it is a bit sluggish on the low end and exhibits absolutely no hot start issues at all....IDT it would stomach 39* degrees tho!!!

oldcutlass

Most HEI distributors have a around 17-20 mechanical advance built in. Your engine could stand 2-3 degrees more as most V8's like 36+ or - deg BTDC.

Back to the OP, JPC, I agree that your balancer did not slip and therefore agree that the settings you provided earlier do not make sense. Did you reset your timing light and recheck? What did your set it to?

jpc647

The timing doesn't change when I initially connect it to the ported side of the carb. If I put it on manifold vacuum though, it jumps off the scale.


I looked, I didn't find such a thread.


I did a "recalibrate" on the timing light, which in essence reset it. Still the same readings. Not sure what else to do. Maybe car in fact has a mild cam? Maybe it's in wrong, but I don't think I'll be tearing it apart to check.

waterzap

Did you verify TDC?


This little thing is very handy

jpc647

Yes, with a screw driver and then with my finger over the plug hole as mentioned above.

Is is possible something was changed on the distributor causing this? Why would this be? Springs or weights wouldn't cause the timing light to give an inaccurate reading, would they?

Only other thing I'm going to try is to dial the timing back on the light to 12, then dial it back to 10, 8, 4, 0 etc. I will check the increments on the light again as opposed to those on the balancer and confirm, the light isn't multiplying by 2 or something. I mean, it is set to 8cyl mode. But maybe the chip is messed up.

When the #1 cyl is at TDC, the balancer mark is 3/4" off the timing tab. But the rotor is pointing to #1. Something is off by ~20 degrees. I don't understand. Please help.

oldsbucket

The timing will jump when connected to the manifold vacuum that is normal after all that is the highest signal you will have at idle which is not when you need vacuum advance. that is why the vacuum advance is a "ported" source above the throttle plate on the carb.
the carb body sees higher vacuum under acceleration less at idle.
apart from your issues with the light how is the car running ? you can set the timing by ear loosen the dist. so you can turn it when running, retard it until you hear the motor slow and start to die, slowly advance until the speed just picks up again, tighten . take it out and test for preignition if none, advance more, if yes retard after all is said this driving test is the last word on your setting as it takes into account all the variables
Oops sorry i skipped you last sentence on the previous post . if you are at really at tdc the dampener should be on zero if not the key way needs to be checked there is nothing else to move as you have already verified that it has not slipped.
To check tdc with a feeler to the piston top rotate until contact before tdc mark the location rotate the opposit direction with the same feeler until contact mark the location divide the distance by 2 and that is tdc accuracy depending on your marking ability that takes away the dead spot at tdc

jpc647

Thats is what I was doing originally. but the dizzy is advanced as far as it can and it still doesn't ping. The vacuum advance is rotated right into the firewall. I think the car wants more timing, but to do that I would have to make the dizzy "jump a tooth". But I can't understand how a car could possibly tolerate that much timing, unless something else is wrong. And the car probably won't perform at it's best until I solve the underlying issue here and then fix the timing.

72 w29 all green

If you're sure you have piston #1 at TDC and sure that the rotor is pointing to the #1 on the cap, then the picture above, which from what i can tell was taken with the engine not running , is all you need to know because that mark should be pointed at or pretty darn close to zero. Print the picture, take it to a local mechanic, describe what you did, and let him figure it out for you.

oldsbucket

has the distributor been out, is this a new problem, what is the condition of the chain, sorry i haven't read all the posts but i think the timing chain was mentioned to check. i'm going on a limb here but the rotor should be just past #1 at tdc i've only ever used it to check for compression stroke not actual timing position.
if you have had the distributor out before and need to reinstall then move the tooth but if not and this is a new issue its back to basics, and i would have to look at the timing set. its hard to help over the internet and apologies if this is old ground for you

MDchanic

Yeah, this is starting to look like one of those "that never happens" kind of problems.

Piston is connected to crankshaft by connecting rod.
Neither piston height nor con rod length can change.
Crank throw is a certain distance at a certain number of degrees.
Neither of these can change either, and they didn't make cranks with different angles on the #1 throw.
Crank is attached to damper with key in keyway.
Neither crank nor damper was ever made with keyway in a different location (except for 1964 damper, but that one's farther out than yours).
Since the damper really looks like it hasn't moved, that leaves only one possibility that I can see:
What if someone installed your damper with only a piece of the key in the keyway (enough to engage the crank gear), then tightened up the damper "close" to its correct position?

Far fetched? Yes, but I can't think of any other cause.

I would strongly recommend using a very accurate method of determining TDC, like a dial indicator or one of those stop bolts adjusted very slightly in, and marking your balancer with the exact TDC, then timing your car like it should be.

After that, I'd pull the balancer for a closer look.

As far as your distributor - just restab to a different position so you can turn it farther.

- Eric

Octania

I don't believe your timing is as advanced as you think it is.

Oldsbucket describe the time honored method of timing "by ear" or more accurately, by engine response to the settings. The factory timing marks are supplied so that it will be easier and faster in general for the service man to duplicate what the factory engineers found to be optimal. Sometimes, as in your case, these marks are no longer present or truthful, and the "by ear" method is better.

I looked at your balancer's inner to outer alignment marks and I DO NOT believe that to be the factory alignment marking. First off, it's in line with the timing mark, which has NOT been my experience. It's also wider and deeper than I usually see.

I will vote for unauthorized damper mods, and a line stamped by "someone". And/or the damper installed w/o a key. Easy enough to check. Pull the damper and compare to another.


"Not worth a major argument, but the copper wire technique for checking TDC in unlikely to be accurate to within a degree or three."
================
Depends on your skill of course.

MDchanic

If I were VERY patient, I might be able to get it this way, but I would consider this to be well above the skill level of the average home mechanic.

... And I'm not that patient.

- Eric

RetroRanger

I just removed my 72 damper the mark is similar to jpcs

never mind my wifes fingernail polish on it..i markd it out to 36°....

I had it apart cuz my 72 died last sunday

heres the thread w some timing chain pics

https://classicoldsmobile.com/forums...tml#post564180

MDchanic

For illustrative porpoises:

20130620_1826441_zps8540c792.jpg



- Eric

Octania

Well, I stand corrupted I guess

there's another just like it, huge long deep align mark in line with the timing cut.

Brings us back to no key or similar explanation. Ran damper loose on crank and jiggy'd the balalncer keyway out to 20 degrees wide? I have seen 'em pretty fubar'd after run loose.

jpc647

Just wanted to bump this thread up to the top. This was put on hold when my intake started leaking, and then again for some other crap, but It'd like to figure out why this damned engine has so much timing.

The damper looks like the photo another member posted, so that's okay. I'm really not sure what else I can check.