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Old 01-13-2006, 02:28 AM
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Weird Distributor problems.

I recently bought a classic truck with a fresh goodwrench 350.

It has an HEI distributor that is not fresh, but working will enough.
It started nicely and ran well. Had a slight occassional miss at warm idle.

I put in a new set of MSD 8.5 mm plug wires. It ran better. I pulled a plug out for inspection and decided to replace the AC 1 plantinum plugs. They had good color but were worn to a .055 gap. The locals didn't have AC 1's so I put in AC R44TS plugs gapped at .045. Thought I'd check the timimg while I was in the neighborhood. The timing light is a Sun induction type that I've had forever. To my surprise, the timing mark (at #1 cylinder) is reading completely off the indicator, 20 plus degrees. I adjust the timing back to 12 degrees and power is waaay down and it's tending to back fire. It runs better when I put the timing back up at 20 plus degrees at 650 rpm with the advance hose off and plugged. It does not ping at this level of advance.
I take the #1 plug out, pull the valve cover off and find that TDC is at exactly zero (0) on the timing indicator. I pull the distrbutor cap and find the #1 distribtor cap post and rotor have good alignment.

What's happening here? I'm missing something.
I'm going to check TDC at # 1 again. Any ideas? Is my timing light demon possessed?

Thnx,
Akbat (newbbie)

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Old 01-13-2006, 03:13 AM
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I'm not a timing guru but since were both online at the hour...

I'd put your timing light back on and rev her up to about 3500 and see if your total timing is outta wack too.

Any chance they didn't install the cam straight up?
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Old 01-13-2006, 03:20 AM
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Doc here,

From everything you said you did good...

EXCEPT for, when static timing it did you pull and plug the Vacuum advance..? (or defeat electronic)

It should be about 12 degrees with no advance hooked up, and about 32 to 34 with..

NEVERMIND...I just reread your post and I see where you have done that...You might try Different mechanical advance weights.

Also check to be sure neither advance is stuck (rusted shut, held open, or blown diaphragm.)

Doc
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Old 01-14-2006, 12:08 AM
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Akbat, I would also check to make sure your idle rpms are below 800 because if you are not you could be looking at your mechanical advance on the light!
Holy advance, Batman!!!
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Old 01-14-2006, 07:41 AM
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Weird Distributor Problems

Thanks Aloha, Doc and Steve.

The idle speed was about 650 according to the dash tach. I'll get out the remote tach and double check it. I'm beginning to think Doc is right about the mech advance.

The distributor is out and now I can see that it's pretty nasty. It's loose at the bushings, the wiring is dried out and cracked on the module, etc. I haven't had time to break into it yet but I'll let you know if I find anything

I've decided to replace it, so a new MSD distributor is going in today. The MSD has a tach terminal on the cap, just like the original GM cap, but the instruction sheet calls it a "optional HIGH voltage tach terminal". I assume this in a conventional tach terminal but the words "high voltage" make me nervous. I'd hate to ruin my nice dash tach. Does anyone have experience with this item. It's the MSD Pro-Billet PN 8365.
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Old 01-14-2006, 09:36 AM
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Low vacuum condition, as in retarded cam timing, could bring on the need for the mucho timing crutch.

Also, if the engine ahs a lot of cam duration, and the inlet valve closes way late, the DCR will be quite low, and a lot of initial timing will be needed just to make the engine idle and respond.

Air leak(S) will also like lots of timing as well.

Any idea how big the cam duration is, and if there are leaks in the inlet system??

It also sounds like the coil is starting to weaken, not an uncommon problem with coil in cap large cap HEI. When this begins, it usually also wounds the HEI module as well. Auto Zoned Out stores have testers for the components in that HEI, I'd pull the coil and module and go get 'em tested. Also, the HEI coil has to be grounder to the dist body, It does that with the center black wire in the three wire connector from body to cap. There is also a blade connector from that wire, in the cap, to just under one retainer bolt for the coil, make sure these connectors are tight and clean.
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Old 01-14-2006, 01:53 PM
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Thanks Ignitionman

The cam is unknown to me, but the engine is a relatively new item from GM and doesn't show signs of tampering at the timing cover. It idles fine and runs much like a stocker.

I believe the intake is OK. I can find no signs of leakage.

The carb throttle shafts on the old Qjet are badly worn and are sucking a lot of air. My dial indicator says about .090" wobble which is badly out of spec. I was trying to freshen up the ignition prior to installing a new carb when I discovered the timing issue. I'd rather work with one set of variables at a time, so I put off the carb until I could figure out the timing question. Would the air leaks at the carb shaft be enough to make it want that much advance?
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Old 01-14-2006, 05:19 PM
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Doc here,

If you have that much leaking, The timing would be all over the map, Total timing at idle.

Static should be slightly more stable, (no advance hooked up) but will still oscillate up and down. Mechanical Advance...

Fix the leaks first, then go back and look at the timing problems.

Let's see what Ignition man thinks on this subject, Since he's seen a bunch of them.

Doc
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Old 01-14-2006, 10:50 PM
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.090 shaft clearance between shaft and base plate??? .009 possibly.

One of my precious jobs was working qt Holley, bandsawing Holley Dominators in half and wideneing them for Pro-Stock racers. The most successful ones used teflon bushings in that areas, NOT a sloid metal one.

What I have found on Q-jets is, the actual "bushing to shaft" interface area is quite small, and inwards towords the sidewalls if the throttle bores. When the base plate wears, there is a larger than the bushing diameter area on both sides of the throttle shaft, that have not been damaged.

Whenever I do a Q-jet baseplate, I find that the larger areas in the base plate, and the shaft have NOT been touched by the wear. What I do is cut srtips of .014 teflon to fit the bored areas of the baseplate. I have measured bouches of Q-jet baseplates and found that htis large bore area to shaft is .030 overall, .015 per "side". It is simple to insert the teflon into the unworn area between plate and shaft.

I use new throttle plate screws as well, button head Allen screws, staked and Lock-tite'd into place.

I find the solid bushings need way too much clearance to not bind when the carb is torqued down to its proper 60 inch pound torque, that is 5 foot pounds of bolt to manifold torque, not the usual impact wrench to 200 foot pounds torque I usually see on one of those carbs. The solid bushings still leak after install, but the teflon doesn't leak nearly at all, and the throttle action is one heck of a lot smoother.
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Old 01-14-2006, 11:03 PM
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more info

Doc and Ignitionman

I installed the new MSD distributor today. Hereís a rundown.

1.Made a piston stop out of an old spark plug to verify that the marks on the balancer and the indicator accurately represent TDC. They were right on the money.
2.Set the timing mark on the balancer at 14 degrees BTDC with the exhaust and intake valve shut.
3.Installed the distributor with the left side of the #1 plug post on the cap aligned with the right side of the rotor.
4.It fired right up. Rough idle at 450 rpm. Timing light showed less than 14 BTDC. Moved the timing up to 14 BTDC at 650 rpm. Decent idle.
5.Test drive indicated LOW power. Barely able to pull the 700 R4 in overdrive.
6.Remembering Ignitionmanís comments about vacuum leaks, I got out the vacuum gauge. The needle was very steady but only pulling about 15Hg at 14 BTDC. The diagnostic markings on the gauge indicated ďLate Ignition TimingĒ! at that level of vacuum.
7.I ran the timing up to 25ish BTDC in stages. The vacuum climbs steadily as the timing goes up. By this time the notch on the balancer is almost straight up. The Vacuum is up to 20 HG and has moved into the ďNormalĒ diagnostic marking. The idle is perfect at 650 rpm. Steady needle at all settings. No needle flutter.
8.A road test indicated better power. No valve ping on a mild pull at this hign initial advance setting. The power is still down, which means the advance was probably higher yet when I first put the timing light on it, but because I wasnít expecting it to be that high, I didnít believe what I was seeing the first time and didnít get a very good initial reading. Iím reluctant to drive it at timing settings this high.

The only leak I can find is at the carb throttle shaft and itís pretty bad. Hard to imagine it could make that much difference but I guess Iíll install the new carb next. Iíve restored several vehicles over the years, but Iím fairly new to GM V8ís. Iíve never seen this situation before and I really appreciate your help.

PS
Yes 0 to 90 on my Starrett dial indicator. More than 1/16th and less than 1/8th.

Ron B.
Anchorage, AK
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Old 01-15-2006, 11:19 AM
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OK, Q-jet first. Find a better baseplate and go with the teflon bushings as outlined. Teflon in .014 sheets is available from industral houses and better hobby stores. Use button head Allen screws to reattach the throttle plates to the shafts, peen the screws in place and Lock-Tite.

Now, just what engine is this? If it is a crate engine, wither performance or relpacement goodwrench, and is intended to use a long style water pump, take a look at the timing cover, the stock one that comes on the engine, and see if it has timing marks at what would be the 12:00 position on the cover.

Most later small block crates have a timing mark now at the noon position, because the older side marks aren't readable with all the accessory mounts in place.

Yes, I know you dialed the timing setup in, but, might humor me and move the timing light sensor one wire to either side and see if the mark comes back to the side scale. As strange as it sounds, some engines just have to be timed like that, one cyl off of number 1. Haven't taken the time to figure it out, but I'm sure it'll wake me from a troubled sleep one night in the future.

I have a friend with a Ford 302 Windsor engine and a Mallory Pro-Comp dist, wired right, NEW balancer, scale qualified in the right place, but it simply will not time correctly off number 1, has to be one wire off to read the line to scale. Absolutely NO reason to it at all.
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Old 01-15-2006, 10:00 PM
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Sunday in the garage

It is a crate replacement Goodwrench long block. It has a Long water pump, but no marks at the top of the timing cover. I tried your suggestion about moving wires, which sounded very interesting indeed. Could not get it to fire, even with much rotating of the distributor.

I noticed in the MSD literature that they say some timing lights have trouble reading the more intense ignitions. I'll look into this as well. I'd like to believe that's the problem, but when I static time it (set the timing marks on 12 TDC and the rotor on #1 cap post, the timing light reads right where I expect it to be, 12 TDC.
About the Q-jet. I have a fresh one from The Carb Doc. I just didn't want to put it on until I knew more about the timing problem. I used a long piece of rubber tube to listen to the baseplate shafts again and discovered the choke pull down is hissing too, perhaps more than the shafts. Doc's right. time to pursue the leaks.

Next week is gonna be a busy one. I won't be able to touch it before the weekend, but I'll let you know what I find. Thanks a million for your help.

Ron B
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Old 01-18-2006, 08:36 AM
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weird distributor problems

I agree with IgnitionMan about the plug wires being off. I just put a goodwrench engine (350) in my 65 rambler 3 weeks ago and had the same problem.I loosened the dist. holdown enough that I could turn it by hand and started the engine.I then turned the dist. until it ran the best.Take note of where the rotor is pointing and then with the dist. vaccum pod pointing to where your motors manual says it should be or if you don't have one, put the pod in the center of rotation (where you can turn the dist. the same amount advanced or retarded) move the # 1 wire to match the rotor. Move the rest of the wires and from there you should be able to time it. This worked for me,hope it does for you. Stanjr41
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Old 01-19-2006, 10:19 PM
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Thnx Stan

which way did you shift the wires? Clockwise or counterclockwise?

Ron B.
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Old 01-19-2006, 10:58 PM
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Some old time mech's hide their timing light and just use a vac. gauge. They advance it to the highest reading and back it down if it pings. As long as it doesn't baulk, fart or overheat, their happy.
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