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Timing problems

hubdawg

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Feb 4, 2013
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Put new head gaskets back on to fix a cooling problem and now seem to have a small problem and need my math checked. 72 302 w/3 sp & HEI and have the distributor in properly. Set the initial timing to 12 with the vacuum advance plugged at the carb and finally got it started and ran for 5 minutes idling. When I plugged the vacuum advance in the idle went up so I backed it back down and checked the timing again with it now at 30 or so. Also my hose from the pcv valve to the front of my edelbrock was collapsed. The pcv check ball rolls and seems to be working. I attached the carb end to the carb itself but there is a spacer between the carb and the holley manifold. It has a plugged off inlet as well. Decided to take for a test drive and stalled and now won't start, sounds like its timing is off again and working hard when I crank. Ideas?
 

gr8scott

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Sounds like you plugged the vacuum advance into the driver side port. It has full manifold vacuum. Use the passenger side port, which is timed or ported vacuum.
 
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hubdawg

hubdawg

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The vacuum advance hose is plugged into the drivers side which according to the edelbrock book is for non emission controlled engines and the pass. side is for emission controlled, shouldn't mine be drivers side?. Got it started and if I pull the collapsed pcv carb line it dies immediately and if II pull the vacuum advance line it stutters hard.
 

savage

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I tried to use the vacuums port on the driver side and I could never get the idle down low enough, so I use the passage side and my 302 runs great. It has no emission stuff on the engine. This has been debated if you use timed vacuum or manifold vacuum, use what works the best for your engine. I would recheck your timing, find top dead center on the compression on number one spark plug ,to make sure its not off a tooth , then retime from their. Good luck
 

B RON CO

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Hi, I would say most of the time your engine will be happier with ported vacuum, on the right side fitting. Set the timing with the vacuum disconnected and plugged, and try the ported vacuum.
If the ball shakes in the PCV valve it is usually ok. Try this. Pull the PCV valve out of the valve cover and keep the hose hooked up. With the engine at idle, put your thumb on the bottom if the valve and see what happens to the idle. Maybe you have the wrong Pcv valve. I would try a new one, correct for your engine. If any of the vacuum ports are open you will have trouble.
Good luck
 

Broncobowsher

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Ported vacuum is correct for most applications. Manifold vacuum usually causes issues, sensitive to an automatic being put into gear, erratic idle, more sensitive to stalling. But some engines will run better, but not that many.
 
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hubdawg

hubdawg

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If I pull the pcv valve out while still connected to the carb from the valve cover the motor stumbles and dies. I'm going to try a heavier duty hose today as well as a new valve. Does it make a difference on whether it's hooked up to the spacer or the carb?. Also when I plug everything for initial timing should I plug the other end going to the vacuum advance distributor line and the carb end.
 

B RON CO

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Hi, the PCV needs a large vacuum source, and usually goes to the carb base. All vacuum ports near the carb need to be hooked up to something or plugged off.
Run a vacuum hose from the ported vacuum source ( the way Ford did it) to the distributor. When you set the timing with a timing light this distributor vacuum hose gets removed from the distributor and plugged. You don't plug the metal can on the distributor.
Good luck
 

Broncobowsher

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PCV should feed a large port that evenly distributes the gasses to all cylinders. Avoid connecting to a single intake runner or a port that only feeds a single throttle bore.

Plug any open vacuum port, even if just temperarly to set timing.

Don't plug the distributor, putting a cap on may put a slight positive pressure on the vacuum advance. Just leave it open and free to breathe.
 

gr8scott

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As was said, timed port for vacuum advance. The large port on the front works best for the PCV valve.
 

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DirtDonk

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The vacuum advance hose is plugged into the drivers side which according to the edelbrock book is for non emission controlled engines and the pass. side is for emission controlled, shouldn't mine be drivers side?

I think they're a bit misguided. Any engine since '66 could be considered a "smog controlled" engine. And even during the height of the seventies learning curve some engines ran on full vacuum, while others ran on ported vacuum.
And besides, they don't know whether or not the end user has all the smog equipment connected still or not. So I think it's a misleading way to describe how to connect a vacuum advance.

Got it started and if I pull the collapsed pcv carb line it dies immediately and if II pull the vacuum advance line it stutters hard.

Normal. Pulling the PCV hose is a huge vacuum leak and without knowing how everything else is tuned, it could run rough, idle could go up, or it could go down, or it could just die. Pretty normal behavior.
Pulling the advance hose suddenly lowers your timing drastically, which causes the engine speed to go down, and your vacuum leak is big enough to make things run rough. A bad combination even if you put your finger over the hose to stop the leak.

If I pull the pcv valve out while still connected to the carb from the valve cover the motor stumbles and dies.

As mentioned, this is one of the normal reactions. In pulling it out of the grommet, or pulling the hose off of the carb, you're creating a huge vacuum leak.
If the engine is already running too rich, you might actually see an increase in your idle. But more often than not the vacuum leak is just too much and the engine will get rough and die. Often it will just keep running, but not well.

I'm going to try a heavier duty hose today as well as a new valve.

Must be an old hose already to be collapsing under minimal vacuum. I wonder if the PCV is clogged at all anyway? Or maybe just the hose is deteriorating internally and the vacuum is too much for it. How does it look on the outside?

Does it make a difference on whether it's hooked up to the spacer or the carb?

Nope. Not as long as it's on one of the 3/8" barbs and not a small one. As long as the carb base or spacer, it's sucking from the full intake plenum, so that's fine. Just never connect one to a port on a single runner.
Your Edelbrock carb probably has one on the front and on the back with a plug in it already.

Also when I plug everything for initial timing should I plug the other end going to the vacuum advance distributor line and the carb end.

Easiest is to disconnect the hose at the distributor and simply plug the hose end. We used to carry golf tees in our tool boxes as a means of capping off vacuum lines. A small screw will do nicely as well.
As mentioned there's no need to plug both ends, or go to the trouble of capping the distributor.

One thing about ported vacuum though. At idle it's not supposed to have any vacuum signal at all. So unplugging the hose is just a careful best practice. But when all is well, should not be necessary. It's a practice mainly for those that use full vacuum.

It's a useful test though, when the timing light is connected. If you see your timing change when you connect the hose, your carburetor is not adjusted properly.
Granted, you can usually feel the vacuum with your finger tip. But if it's very subtle it's hard to tell by hand sometimes. But the timing light rarely lies.

Paul
 
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hubdawg

hubdawg

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Thanks for all the help and I think I'm getting closer. Changed the pcv hose and dist. hose to a new ones and a new pcv valve. Plugged the vacuum advance hose and it started right up, once the manual choke was fully opened I reset the timing to 14 connected the vacuum and reset the idle lower. Ran at idle for 15 minutes just fine and temp was perfect (head gasket and re-milled heads worked) but after shutting it off it would not start again...like a really heavy dead battery strain. Sounds like timing again correct? Dizzy is bolted down and not moving
 

B RON CO

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Hi, yes 14 degrees advance is a lot of initial timing. It might ping a lot under load. You are right to back it down to 10 or 12. Good luck
 

broncogt

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Mar 1, 2010
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93
Is your harmonic balancer old?

Check to make sure the outside did not slip. Stock ones are 2 parts with a rubber bonded between them. Timing marks are on the outside part.
 
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hubdawg

hubdawg

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Feb 4, 2013
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When I had the heads off I turned the engine to TDC and the marks were right on. Can a balancer actually move if so how do you check besides just grabbing it and holding the crank still. 74 fairlane motor according to the block
 

DirtDonk

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An old damper can move, yes. But it would be pretty rare for a newer one to do it. Is yours original?
There is a tick mark usually on them to let a tech see if the outer damper ring has rotated in relation to the inner hub. If you can find that marking and note that it's changed, it's time to replace the damper.
But since you checked before and it seemed correct, it would be hard to imagine it's twisted itself up in just the amount of time you've run it.
Stranger things have happened though, so don't rule it out. Check first.

While 14° might be a tad high, it's not enough to cause a hard start situation without a lot of help from other quarters. Such as a weak starter, undersized battery and starter cables, a weak battery, too much compression, and a dose of you-get-the-idea on top of it.
But here's a potential dilemma of using full manifold vacuum for simple basic timing duties. An engine will build vacuum just from cranking, so as it's spinning up with the starter, the timing is being advanced. Possibly to a point that it's effecting your starting.
This is likely one of the main reasons for the manufacturers adding timing-retard features to their electronic ignition controls.

If you were using ported vacuum that time, then it still sounds like something is wrong because you said your idle increased and had to be turned down once you connected the vacuum line.
Either way, try disconnecting the vacuum advance again to see if it still gives you trouble when you try to start it hot. If it does, then you have another issue.
If it doesn't however, you might try less timing or go over to ported vacuum.

Paul
 
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hubdawg

hubdawg

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Feb 4, 2013
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12 degrees of timing and ported not manifold made a huge difference. Took her out in the snow and also identified another problem but I have a solution. Put new clutch and resurfaced flywheel in while down, both were shot. Still had clutch chatter so I disconnected the rear driveline and ran in 4H....no chatter...must be the driveline angle from a 40yr old block lift. Glad I read the diagnosing answer on the forum.
 
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