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Old 08-23-2011, 07:56 PM   #1
56chev
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Installing new distributor/timing issues. Am I crazy?

So I got the bright idea to have my intake manifold and distributor replaced on my 350. I went with an Edelbrock manifold, and a MSD ready to run distributor. I have a mechanic that I have been using, that I am starting to have my doubts about. The engine was running just fine before he started the work on it. He replaced the manifold, and all went well. The problem comes when installing the distributor and setting the timing. From the research I have now done, I feel like I could do it myself, but that is a different story. He has been in business for 60 years, so I'm not sure if I am overreacting or if my concerns have some merit. He pulled the old distributor without marking the rotor position on the #1 cylinder. No big problem. He put the new distributor in, and was getting no fire. I pointed out that the 12v wire coming from the ignition was on the negative side of the coil. Switched it, and it fired, but it was back through the carburetor. He pulled the distributor back up and moved it one tooth because he thought it was off. I went back this afternoon, and he said that he has had no luck. It just backfires through the carburetor. It doesn't run at all right now. He says that he moved the #1 cylinder to TDC on the compression stroke, then marked the rotor position as #1 then connected the wires to the cap in the firing order. He thinks that either the camshaft gear is worn, or that the timing chain has jumped off a tooth. It was running just fine when I brought it in, and the gear on the old distributor looks just fine. I called MSD, and the tech said that it sounded like the distributor was 180* out, and what he thought was #1 was actually #6. My mechanic also grounded the distributor to a bolt on the valve cover. The tech said that a bad ground could also cause backfiring. I'm not sure where he had the #1 piston at, whether it was at tdc, before, or after tdc. Does anyone have any ideas or advice for things to look for? I'm going to go over in the morning and see if I can't figure out something myself. At this point I don't have too much faith in his abilities as he has been trying to time it for 3 days. He is convinced that the brand new distributor is bad, and wants to put the old one back on to get the truck running again. If I understand correctly once the #1 piston is at tdc, when you put the distributor in, wherever the rotor points on the cap is where the #1 plug wire should go. Then you should put the rest of the wires on with the right firing order going clockwise from one. Then, turn the harmonic balancer counterclockwise so that it reads anywhere between 6-12* btdc. The engine should start at this point, and shouldn't backfire. Sorry for the long post, but I'm really frustrated with the situation at this point. Thanks in advance.
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Old 08-23-2011, 08:33 PM   #2
Marv D
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Re: Installing new distributor/timing issues. Am I crazy?

1,, welcome to the site. Lots of good people here.

for the distributor....
Pull #1 spark plug. Put your thumb over the spark plug hole and roll the motor over with a breaker bar (starter if you have someone BUMP the key). When you feel it building compression and pushing your thumb off the plug hole, continue ONLY till the balancer timing mark is 8-12° before the TDC mark.

Pull the distributor cap and see where the rotor tip is pointing. HOPEFULLY it's pointing towards the drivers side, rear bolt for the carburetor. (really there IS reason for it being in THAT exact position)

If necessary remove the hold down and re-orient the oil pump driveshaft so the rotor tip IS pointing there. ALSO,,, Move the ground to the bolt hole at the back of the head, and make SURE the negative battery cable is bolted to the engine block!!! That's where GM put it,, it's there for a reason too!!! There should also be a braided cable between the frame and the block, and the back of the head and the firewall.

AS you replace the distributor cap, note the exact place the rotor tip is point. That is where #1 plug wire goes. From there replace the plug wires CLOCKWISE in the firing order (1-8-4-3-6-5-7-2).

Make sure you get a full 12 volts to the distributor module (if you replaced a points ignition, remove the ballast resistor unless your still running points and divorced coil)

If you follow those steps exactly,, I promise distributor install / orientation won't be the reason it doesn't start.

OK, Just saying 'do it this way' without explanation causes frustration. So,, here's WHY the rear drivers side carb bolt for the rotor tip on #1??? The motor will run perfectly fine with the #1 wire placed anywhere around the cap (with the rotor tip properly oriented for that terminal being #1) Issue is,, if you ever buy a set of pre-terminated spark plug cables,, they are cut at the factory for #1 being in that position. If it's elsewhere, some plug cables may be loose and falling against hot exhaust manifolds, others may be stretched tight and a PITA to install. Just do it 'right' It's no harder than the alternative. The factory looms are made in every attempt to reduce the possibility of crossfire. Ideally no plug wires will cross. You need to pay special attention to #5 and #7 having those two cross a couple of inches from the cap. #5 and #7 fire in succession and being close together, the 'juice' is looking for a way out of the cable. The further from the cap, the more resistance the spark encounters and the harder it looks for a way out. #5 and #7 have to cross somewhere,, making them cross close to the cap helps eliminate the chance for a crossfire.

As for the grounds, FROM the BATTERY, to the BLOCK, from the back of the HEAD to the FRAME, and from the back of the HEAD to the FIREWALL (connect the distributor ground to the head) Heres why, RFI is a SERIOUS issue in electronics. And poor grounds are probably the biggest reason for failed electronics. ESPECIALLY distributor modules. I've seen MANY 70's GM cars that some genius took the ground off the alternator bracket and bolted it to the frame because it looks 'cooler' They they melt the shift cable at the trans because that is the only path the alternator, starter, and ignition had to ground. From the battery to the front of the block,, from the back of the block / head to the frame / firewall. That keeps RFI problems at a minimum around the distributor. There really IS a reason GM did it that way
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Old 08-24-2011, 12:36 AM   #3
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Re: Installing new distributor/timing issues. Am I crazy?

^^^Yes Yes Yes. Everything he said. One more thing...if the dumbass mechanic thinks that he can get the engine running with the old distributor then by all means let him try. Call him out on his bull****!
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Old 08-24-2011, 07:23 AM   #4
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Re: Installing new distributor/timing issues. Am I crazy?

he didn't put the motor at tdc before installing the new dis
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Old 08-24-2011, 09:36 AM   #5
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Re: Installing new distributor/timing issues. Am I crazy?

The old mechanic has it timed 180 degrees out. Just redo it like Marv says.
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Old 08-24-2011, 09:56 AM   #6
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Re: Installing new distributor/timing issues. Am I crazy?

Hard to believe that anyone who's worked on engines for 60 years doesn't know how to time a vehicle or install a distributor. I'm not an auto mechanic by trade but that was one of the first things I learned 50+ years ago.

Regardless, follow the step by step instructions given and do it yourself. That's how one learns on this old trucks. If it still backfires reinstall the old one and If it works, go buy the old man a good bottle of whiskey.

btw: welcome to the site and let us know what happens. If you need some tips be sure and post again.
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Old 08-24-2011, 10:08 AM   #7
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Re: Installing new distributor/timing issues. Am I crazy?

Thanks for all of the replies. In retrospect I should have just done it myself. I think that I could have done it. I talked with him this morning, and he is going to ground it properly, and try again. If that doesn't work he wants to look and make sure that the timing chain didn't jump a tooth. At this point I just want my truck back. He said that when it backfired the first time that he thought it might be 180 out so he check and rechecked, and it was not. He said to check back around noon, so I will know more then. Hopefully he has some good news.
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Old 08-24-2011, 10:14 AM   #8
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Re: Installing new distributor/timing issues. Am I crazy?

go get your truck lol
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Old 08-24-2011, 12:28 PM   #9
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Re: Installing new distributor/timing issues. Am I crazy?

Yeah DON'T let him check the timing chain. The 'flat rate' way is to just loosen the oil pan and pry it down enough to slip the timing cover out, then silicone the crap out of things in hopes to seal the timing cover / oil pan back up. It was running right when it went inthere,, it's HIGHLY unlikely it picked that instant to let the timing chain jump a tooth.
Not saying the old boy is a moron and doesn't have a clue.... it just seems mighty suspicious to me!
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Old 08-24-2011, 01:46 PM   #10
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Re: Installing new distributor/timing issues. Am I crazy?

As my user name suggests, I work on distributors for a living. Around here, Those MSD distributors are not called "Ready to Run", they are firmly referred as "READY TO QUIT". VERY high module failure rates. And, the module is in the center of the distributor, in the taper under the cap ledge area, with the magnetic pickup leads SOLDERED to the module.

All that said, IF he has fire from the unit, you are half way there. As the others have said, back-firing through the carb is either the distributor is 180 degrees out of correct phase, OR, so far out of time, it is firing on the wrong spark plug for the cylinder it is supposed to fire on.

And, do a personal check, don't rely on the 100 year old mechanic, for the firing order to be correct, and, that the firing order is rotating the correct direction. Chevrolet rotates CLOCK WISE when viewed from above, and also Buick, with Olds and Pontiac rotating COUNTER CLOCK WISE. It the 100 year old sage of engines is an Olds/Pontiac person, he possibly could have the firing order rotation backwards.

Also, biggest issue with Chevrolet when all seems fine with the phasing in the engine, thre 5 to 7 swap. Correct for Chevy firing order is 1-8-4-3-6-5-7-2, clock wise. the 5-7 swap makes the firing order incorrect for that engine, becoming 1-8-4-3-6-7-5-2 (this will give a backfire through one cylinder in the firing order). If this has happened, don't get upset, it has happened to most of us, no matter our experience, and if you got it, you are now a member of the 5-7 swap club, welcome, brother.

Hope this info helps.

Another factor could be on the back-firing, intake manifold leak
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Old 08-24-2011, 02:34 PM   #11
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Re: Installing new distributor/timing issues. Am I crazy?

I went to his shop and got my truck back, and it was running! I suspect that yall are right and he had it 180 off. He never would say what the issue was that he was having. He did not check the timing chain or gears. It runs great now. Even better than before, with more power, or maybe it just seems that way. It could be that I'm just excited to have it back. One thing that he and I did notice is that the water pump shaft has a lot of play in it, and it sounds like the bearing is making some noise. I'm going to change that this evening, and hopefully that will be the last of my issues for a while. Thanks everyone for all of the answers and advice. I think that I am going to buy a timing light and see what the timing is set at. I know the old saying of if it isn't broke, don't fix it, but I just can't help myself.
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Old 08-24-2011, 03:05 PM   #12
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Re: Installing new distributor/timing issues. Am I crazy?

Great! Glad it's running and you got it back.

Re. timing light. Nothing wrong with having one. It's a basic tool and necessary to keep the old trucks running good. While you're at it and if you don't have them pick up a vacuum gauge, a volt meter and tach meter. Don't get to use them a lot but when you need them you'll have them.
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Old 08-24-2011, 03:21 PM   #13
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Re: Installing new distributor/timing issues. Am I crazy?

So, on the way home, it ran fine. No misses or anything. I get home and turn off the key and it diesels for about 5 seconds then shuts off. I've read that it could be because the initial timing is a little off, or some say that a higher octane fuel will help. I'm going to buy a timing light and start from scratch to see where my timing is. Could this be a timing issue?
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Old 08-24-2011, 04:04 PM   #14
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Re: Installing new distributor/timing issues. Am I crazy?

Usually, "Dieseling" is caused by one or both of these issues, timing too far advanced, and/or idle speed too high from holding the throttle too far open.

You really do need to post the initial timing and idle timing (idle timing is the combination if initial AND vacuum advance), and the out of gear idle speed the engine runs at, along with in gear (if automatic trans is used).

We can better go from there.
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Old 08-24-2011, 04:07 PM   #15
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Re: Installing new distributor/timing issues. Am I crazy?

I will post the timing setting this evening. I'm stopping to get a timing light on the way home.
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Old 08-27-2011, 05:01 PM   #16
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Re: Installing new distributor/timing issues. Am I crazy?

Sorry it took so long for an update, but here is what I found. The timing without the advance hooked up was about 14* btdc. I could hear what sounded like a little knock when it was set like this. I hooked up my timing light and took it to around 10* btdc. This seemed to help quite a bit. I hooked my vacuum advance line back up, but the timing didn't seem to change. I was having a tough time with my light though. It didn't want to flash. I took it for a drive, and it runs really well with no more dieseling. I'm going to give the light a try again, and check out the vacuum advance, but for now everything seems pretty good. Thanks for all the help.
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Old 08-27-2011, 05:51 PM   #17
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Re: Installing new distributor/timing issues. Am I crazy?

With the vacuum advance NOT moving the timing when it is plugged back in, tells me it is connected to a PORTED/TIMED port on the carb, exactly what we DON'T want to do.\

However, simply moving trhe supply hose to a full manifold vacuum source may well do more damage than help, UNLESS the AMOUNT OF VACUUM ADVANCE DEGREES ARE STOPPED DOWN TO A WORKABLE LEVEL.

To do the stopping down, I suggest you fabricate a thin steel plate, and mount it to the vacuum advance mounting bar with two 6/32 screws, and set the distance for one of two crankshaft degree settings, depending in the initial timing you will run.

If you run the 10 initial degrees, set the vacuum advance pull pin travel distance to 10 crankshaft degrees, for an idle total of 20 crankshaft degrees, pull pin travel of .110/.112 inch.

If you run the 12 initial degrees, set the pull pin distance to .086 inch travel, 8 crankshaft degrees, for an idle total of 20 crankshaft degrees.

Doing the stop will allow you to run the vacuum advance on the correct full vacuum source, and NOT over advance the engine on acceleration.

If you want pics on how to do this, I can supply them, just ask for the Ready to Quit, or stock GM points distributor vacuum advance stop pics, and I will be happy to send them to you. There is also a complete workup on how to correctly install a Crane 99619-1 scroll type stop, nice in that when done right, it has two degrees at a time stepped stops. Please use my regular e/mail, and let me know you want the vac adv stop pics, and which distributor you are running. This e/mail will get them to you: info@davessmallbodyheis.com
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Old 08-28-2011, 10:54 AM   #18
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Re: Installing new distributor/timing issues. Am I crazy?

Quote:
Originally Posted by HEI451 View Post
With the vacuum advance NOT moving the timing when it is plugged back in, tells me it is connected to a PORTED/TIMED port on the carb, exactly what we DON'T want to do.

However, simply moving the supply hose to a full manifold vacuum source may well do more damage than help, UNLESS the AMOUNT OF VACUUM ADVANCE DEGREES ARE STOPPED DOWN TO A WORKABLE LEVEL.
It sure is nice to see someone come along and back-up what I have been saying for years. The problem is that most people start to see Blah, Blah, Blah when it gets "complicated."
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Old 08-29-2011, 10:29 AM   #19
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Re: Installing new distributor/timing issues. Am I crazy?

I had a brand new mallorry hei upgrade type dist and I couldn,t get it to run at 12 btdc,woudl run after tdc but that doesn,t help,put in the old stock one with the good mallory coil and cap and runs fine,go figure.I,ve read lots of horror stories on the net.
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Old 08-29-2011, 11:30 AM   #20
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Re: Installing new distributor/timing issues. Am I crazy?

I have NEVER heard of, nor seen a Mallory HEI upgrade ignition system for a smaller body distributor. ALL I know is, Mallory drop in systems, their magnetic inductive, Unilite are NOT HEI, they do not have dwell extenders, cannot make HEI spark levels, but they do eliminate points maintenance.

Mallory distributors have an extremely archaic mechanical advance system, with two different weight springs, and usually, when the total amount of mechanical advance is less than 10 crankshaft degrees, EXPECT the lighter weight spring to be broken, and that amount of mechanical advance all in at idle and above. Replacing the broken spring will return the full amount of mechanical advance degrees back to the curve.
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