damper timing question

[Hemidog]

I'm second guessing my ability to dial in the timing on this engine.
The engine seems to stumble at low rpms, shakes,  and feels very sluggish.

I've always dialed the timing on the thin notch at the inner side of the damper, but I've now noticed the big notch out the outer edge. Is that notch related to the big hole on the timing tab?

How do you time with this damper? Is it the thin notch, big notch or a combination of both?  

1976 400 CID, pretty much stock.

[lisiecki1]

the smaller notch is your timing mark, i believe the larger one is just the way it was cast.....I've never seen a timing tab like that though

[Hemidog]

Yeah, it is a weird one. but what is this thing for then?

Always tried to to set the timing to 10-15 degrees, but the 400 doesn't like it.....

[elacruze]

"All 1978 Chrysler V-8 engines had an adaptor to receive a magnetic probe for timing the ignition magnetically. The adaptor is a little steel sleeve attached to the bracket that has the traditional timing marks-you can still set the ignition with a timing light. However, ignition timing was set magnetically on all engines at the factory for accuracy. The magnetic timing adaptor will also help those who have the equipment to time Lean-Burn engines magnetically."

http://www.allpar.com/mopar/b-engines.html

I knew it was for an inductive pickup but didn't know the specifics.

[lisiecki1]

Yeah, it is a weird one. but what is this thing for then?

Always tried to to set the timing to 10-15 degrees, but the 400 doesn't like it.....

are you sure your advance is operating correctly?

[Hemidog]

"All 1978 Chrysler V-8 engines had an adaptor to receive a magnetic probe for timing the ignition magnetically. The adaptor is a little steel sleeve attached to the bracket that has the traditional timing marks-you can still set the ignition with a timing light. However, ignition timing was set magnetically on all engines at the factory for accuracy. The magnetic timing adaptor will also help those who have the equipment to time Lean-Burn engines magnetically."

http://www.allpar.com/mopar/b-engines.html

I knew it was for an inductive pickup but didn't know the specifics.

Thanks! That solved that!  

Yeah, it is a weird one. but what is this thing for then?

Always tried to to set the timing to 10-15 degrees, but the 400 doesn't like it.....

are you sure your advance is operating correctly?

You know, I fiddled a little with it now, and when I unplug the advance, there is no change in the timing.
It on the ported side, and I can feel a slight vacuum in the hose.

The timing is now at 10-12 degrees. I checked the vacuum with a vacuum gauge, and it showed "latened timing", so I upped it to 20 degrees to get it into "normal", but the engine really didn't like that (backfiring).

BTW, the engine shakes like crazy when I reverse, what's up with that?

[62 Max]

Yeah, it is a weird one. but what is this thing for then?

Always tried to to set the timing to 10-15 degrees, but the 400 doesn't like it.....

The picture shows the timing mark on the damper at almost TDC with the graduated marks on the timing cover tab.Forget about the notch and and use the middle mark on the tab as TDC.

[elacruze]

I use a hand-held vacuum pump (a brake bleeder works) to verify both the timing sweep in the distributor, and just as importantly the amount of vacuum it takes to achieve it. nothing like realizing you're giving up 10* of timing because you don't have enough vacuum to get there.

[Hemidog]

Yeah, it is a weird one. but what is this thing for then?

Always tried to to set the timing to 10-15 degrees, but the 400 doesn't like it.....

The picture shows the timing mark on the damper at almost TDC with the graduated marks on the timing cover tab.Forget about the notch and and use the middle mark on the tab as TDC.

What middle mark? you mean at 0 degrees?

[lisiecki1]

"All 1978 Chrysler V-8 engines had an adaptor to receive a magnetic probe for timing the ignition magnetically. The adaptor is a little steel sleeve attached to the bracket that has the traditional timing marks-you can still set the ignition with a timing light. However, ignition timing was set magnetically on all engines at the factory for accuracy. The magnetic timing adaptor will also help those who have the equipment to time Lean-Burn engines magnetically."

http://www.allpar.com/mopar/b-engines.html

I knew it was for an inductive pickup but didn't know the specifics.

Thanks! That solved that!  

Yeah, it is a weird one. but what is this thing for then?

Always tried to to set the timing to 10-15 degrees, but the 400 doesn't like it.....

are you sure your advance is operating correctly?

You know, I fiddled a little with it now, and when I unplug the advance, there is no change in the timing.
It on the ported side, and I can feel a slight vacuum in the hose.

The timing is now at 10-12 degrees. I checked the vacuum with a vacuum gauge, and it showed "latened timing", so I upped it to 20 degrees to get it into "normal", but the engine really didn't like that (backfiring).

BTW, the engine shakes like crazy when I reverse, what's up with that?

maybe a torque convertor problem?

[Hemidog]

I use a hand-held vacuum pump (a brake bleeder works) to verify both the timing sweep in the distributor, and just as importantly the amount of vacuum it takes to achieve it. nothing like realizing you're giving up 10* of timing because you don't have enough vacuum to get there.

Is the vacuum advance really that important? some people say I should just plug it, but I left it on because the throttle response was better.

What do you think about using the manifold vacuum on the driver side of the carb?

[elacruze]

The timing is now at 10-12 degrees. I checked the vacuum with a vacuum gauge, and it showed "latened timing", so I upped it to 20 degrees to get it into "normal", but the engine really didn't like that (backfiring).

BTW, the engine shakes like crazy when I reverse, what's up with that?

Low vacuum + backfiring + shaking = stuck, bent or burned intake valve or exhaust valve not opening properly; cam/lifter worn, bent pushrod/rocker.

I'm betting on the cam exhaust lobe because it becomes worse with increased timing and you haven't mentioned any noise. You said it's generally sluggish too, which may indicate that the entire camshaft is worn.

Telephone Diagnosis!  

[elacruze]

Is the vacuum advance really that important? some people say I should just plug it, but I left it on because the throttle response was better.

What do you think about using the manifold vacuum on the driver side of the carb?

Race-only cars may have the advance locked in one position, but it's not good for engines that need to operate over a broad RPM range.
Consider; Fuel/Air burns at a fixed rate. As engine RPM increases, the time available to the mixture to burn is reduced. To get the mixture to produce the most pressure at the proper crank angle, the burn must be initiated sooner because it takes the same amount of time for the burn event.

Your carb will have a port specifically dedicated to the distributor timing. Read your manual and know which one it is. It may vary with carb model.

[Hemidog]

The timing is now at 10-12 degrees. I checked the vacuum with a vacuum gauge, and it showed "latened timing", so I upped it to 20 degrees to get it into "normal", but the engine really didn't like that (backfiring).

BTW, the engine shakes like crazy when I reverse, what's up with that?

Low vacuum + backfiring + shaking = stuck, bent or burned intake valve or exhaust valve not opening properly; cam/lifter worn, bent pushrod/rocker.

I'm betting on the cam exhaust lobe because it becomes worse with increased timing and you haven't mentioned any noise. You said it's generally sluggish too, which may indicate that the entire camshaft is worn.

Telephone Diagnosis!  

Actually, I do hear some ticking noise at difference RPMs. At idle the engine shakes in periods.
Are there other symptoms I could look out for? Looks like the heads are coming of this winter....

wanna make a phonecall to Norway?   JK.

[elacruze]

Actually, I do hear some ticking noise at difference RPMs. At idle the engine shakes in periods.
Are there other symptoms I could look out for? Looks like the heads are coming of this winter....

wanna make a phonecall to Norway?   JK.

I'd just take off the valve covers and watch the rocker arms. If any of the lobes are worn enough to cause this you will be able to see it right away, it won't be moving much. Maybe they are all moving less than they should. You might be able to shine a torch down the oil drain cutouts and get an eye on the lobes themselves.

[Hemidog]

Is the vacuum advance really that important? some people say I should just plug it, but I left it on because the throttle response was better.

What do you think about using the manifold vacuum on the driver side of the carb?

Race-only cars may have the advance locked in one position, but it's not good for engines that need to operate over a broad RPM range.
Consider; Fuel/Air burns at a fixed rate. As engine RPM increases, the time available to the mixture to burn is reduced. To get the mixture to produce the most pressure at the proper crank angle, the burn must be initiated sooner because it takes the same amount of time for the burn event.

Your carb will have a port specifically dedicated to the distributor timing. Read your manual and know which one it is. It may vary with carb model.

The vacuum advance is hooked onto the right port, ported passenger side. 600 CFM Edelbrock.

[Hemidog]

Actually, I do hear some ticking noise at difference RPMs. At idle the engine shakes in periods.
Are there other symptoms I could look out for? Looks like the heads are coming of this winter....

wanna make a phonecall to Norway?   JK.

I'd just take off the valve covers and watch the rocker arms. If any of the lobes are worn enough to cause this you will be able to see it right away, it won't be moving much. Maybe they are all moving less than they should. You might be able to shine a torch down the oil drain cutouts and get an eye on the lobes themselves.

I'll give it a try, thanks!

[Hemidog]

took off the drivers side valve cover, and all the rockers seemed to be moving okay and the same height.

I noticed this hole on the heads, both sides.
I don't feel any air suction when the engine runs, are they not in use?

[histoy]

All big block heads have that gap.   It appears to be an air gap surrounding the heat crossover passage in the head that matches up with the intake manifold.

[FLG]

What ive found to work good on my 400 might work for ya.

Remove the vac advance and plug the ported nipple on the carb. Set the timing to about 12-14* then hook up the advance to FULL manifold vac, you will now just need to lower your idle because having it on full manifold vac will give it the most spark lead at idle and your RPMS will go up slightly. If there is no change then you might have something wrong with the vac advance.

[Hemidog]

tested the vacuum advance with the full time vacuum, and it works.

My engine is really wierd, I upped the timing to approx 25 degrees at 1000 rpm, and it really responded.
The engine is now:
- easier to start (cold and hot)
- accelerates harder, and doesn't hesitate as much.
- it doesnt shake alot when I accelerate from a low speed.
- no backfiring

But still, the engine still shakes at idle, and extremely in reverse. It hesitates at high rpms and I can't believe that the engine should have that much timing?  

What are the symptoms for too much timing?

[lisiecki1]

i believe excessive advance can cause overheating in some scenarios........

[mopar400]

i believe excessive advance can cause overheating in some scenarios........

I agree and I´ve even heard it can cause detonation in some cases..

[Purple440]

tested the vacuum advance with the full time vacuum, and it works.

My engine is really wierd, I upped the timing to approx 25 degrees at 1000 rpm, and it really responded.
The engine is now:
- easier to start (cold and hot)
- accelerates harder, and doesn't hesitate as much.
- it doesnt shake alot when I accelerate from a low speed.
- no backfiring

But still, the engine still shakes at idle, and extremely in reverse. It hesitates at high rpms and I can't believe that the engine should have that much timing?  

What are the symptoms for too much timing?

You should hear it detonating (pinging) under hard acceleration.   I have the same problem with the engine shaking at idle (periodically) and have not figured it out yet.  Check for vacuum leaks in your intake manifold and elsewhere.  That didn't solve my problem, but may solve yours.

g/l