1968 gto timing issue???? - Pontiac GTO Forum
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post #1 of 29 (permalink) Old 09-10-2018, 01:48 PM Thread Starter
 
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1968 gto timing issue????

Hello All: It's bob again:
I would like to know why my GTO runs so great at 22 degrees BTDC. Intial Timing. Idle rpm's 700
1. Total Timing kicks in at 2800 rpms at 34 degrees ????
2. I have a MSD electronic system. 6AL model.
3. Stock Distrubutor with just a rotor and magnictic pickup.
4. Engine 400cu with Hooker Header's and Elderbrock manifold.
5. Elderbrock carburator model 1460 600cfm
6. No cam
7. Runs like shit at 14 degrees BTDC.
8. Runs better at 18 degrees BTDC
9. Runs much better at 20 degress BTDC
10. Runs like a Jet at 22 degrees BTDC
11. Engine sounds so smooth and Idel's great.
12. Start's right up when Hot. Engine running much cooler.
13. I just don't understand???? I believe I should not be at 22 degress at base timing??????? No pinging at all. Engine rmp's at 4000. No pinging???
What's with this engine?????
Curious minds would like to know???
Have a great day, Bob :-)
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post #2 of 29 (permalink) Old 09-10-2018, 05:30 PM
 
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Have you verified the timing mark is accurate and actually represents TDC? Have you tried another timing light to make sure the readings are the same? My neighbor had a Harbor Freight timing light with adjustable dial. The sticker with the increments came loose and gave false readings so you can't always trust the readings. There have been multiple times in the past where I had to set timing bu ear because the balancer mark was not correct....mostly on small block Chevy engines...

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post #3 of 29 (permalink) Old 09-10-2018, 05:32 PM
 
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Did you Un hook the vac advance? 22 degrees sounds about right when the vacuum advance is hooked up. And that would be about 12 degrees without vac advance. And as far as the 34 total that is also about perfect. Now keep in mind that the vacuum goes away under throttle, so all numbers you mentioned sound good if you had your vac advance hooked up.
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post #4 of 29 (permalink) Old 09-10-2018, 07:46 PM Thread Starter
 
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1968 gto timing issue????

Hello My65Goat:
I got no vaccum advance. MSD Ignition system. No vaccum line going to the Distrubutor. Just Distrubutor cap. Read my post closely....
Got me... Timing Light OK.... Got new Balancer, but could it be off??????? Will ask #3 mechanic about that. It seems to run like it did before, before the new timing cover with the new balancer????? Dame engine is running like a F16 Jet.... LOL I will talk to my #3 mechanic about this. I'll have him work my Timing light. It's a high end one with all the toy's on it...... I just got a Devil Engine.... Kick's ass right now. Up's and goes in 3rd gear at 70 mph. Right up to 100mph.... No pinging?????? It's MAGIC.... LOL I have a HT400 Trans.
Anyone out there got any Idea's why this engine runs great at 22 degress at Base timing????
Bob :-)
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post #5 of 29 (permalink) Old 09-10-2018, 09:31 PM
 
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Beast - Cams ?? Cam timing / degreed ?

With regards to timing, you already answered your question - you have no vacuum advance and total timing is 34* which is pretty much what most say is about right. So as MyGoat65 said, you are right where you should be ~22* at idle & 34* total timing by 2800. (Congrats!)

You may want to read Lars' How to Set Timing document.....

So in summary, you don't have an anomaly and you are running the standard timing.
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1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #6 of 29 (permalink) Old 09-11-2018, 08:35 AM
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Forget factory specs when you've made changes to other things - they're meaningless. Don't let the specs play mind games with you and make you feel like you must be "wrong" because your car is different.

You're doing fine. First order of business is to find out how much total at WOT your engine likes, and at 34 degrees it sounds like you're probably right on the money. Most engines usually LIKE a lot of advance at idle no-load conditions, but as they move off of idle and start to see some load, not as much. That's one of the functions of the vacuum advance mechanism that a lot of people don't realize. At idle/no load your engine is making lots of vacuum so the diaphragm is adding a lot of advance. However, as soon as you add throttle/load and vacuum starts to drop, it has the effect of actually pulling advance OUT of the engine which is exactly what needs to happen under those conditions in order to stay out of detonation. Then as RPM increases, the mechanical advance starts to add it back in.

As long as it's not hard to start, doesn't overheat, runs like a healthy Pontiac should, and doesn't ping/rattle under load - you're fine. Don't sweat it.

Bear

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post #7 of 29 (permalink) Old 09-11-2018, 02:48 PM
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I'm confused, is the 68 engine in the 2004-2006 GTO or vice versa?
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post #8 of 29 (permalink) Old 09-11-2018, 03:47 PM Thread Starter
 
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1968 engine timing issues

Hello Goat Roper: The 1968 GTO has a 1968 engine. 400cu.
Read the spec. in first post... I think I posted in wrong area...
Thank you all for the input.
I'm a proud owner of one wild running Jet Engine 1968 GTO. She is screaming.
I don't think I should go any higher than 22 degrees at bast timing. My engine is so smooth at Idel you can put a glass of water on the air cleaner and not spill a drop.... My #3 mechanic saw it today and we checked out my timing light. Everything OK.... I'm going to run the 1/4 mile at 8 sec. at 170 mph. LOL LOL
You all have a great week. Tks
Bobby :-)
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post #9 of 29 (permalink) Old 09-13-2018, 03:01 PM
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Quote:
Originally Posted by BearGFR View Post
Forget factory specs when you've made changes to other things - they're meaningless. Don't let the specs play mind games with you and make you feel like you must be "wrong" because your car is different.

You're doing fine. First order of business is to find out how much total at WOT your engine likes, and at 34 degrees it sounds like you're probably right on the money. Most engines usually LIKE a lot of advance at idle no-load conditions, but as they move off of idle and start to see some load, not as much. That's one of the functions of the vacuum advance mechanism that a lot of people don't realize. At idle/no load your engine is making lots of vacuum so the diaphragm is adding a lot of advance. However, as soon as you add throttle/load and vacuum starts to drop, it has the effect of actually pulling advance OUT of the engine which is exactly what needs to happen under those conditions in order to stay out of detonation. Then as RPM increases, the mechanical advance starts to add it back in.

As long as it's not hard to start, doesn't overheat, runs like a healthy Pontiac should, and doesn't ping/rattle under load - you're fine. Don't sweat it.

Bear
This^^^. I secretly think you are less than a true 22 initial, due to markings, parts, etc. I can tell you, my GTO's would not crank over with that much advance unless the spark was disabled. Waaaay too much, if accurate. You should run a vacuum advance, though, for better power, better economy, and lower engine temperatures. Win-win-win.
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post #10 of 29 (permalink) Old 09-14-2018, 09:23 AM Thread Starter
 
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1968 engine timing issues

To: GeeTeeohguy

I just got this car running great, and you want me to set it up with a Vaccumm Advance system. Why do so many people like the MSD ignition system.

Your car is a different animal than mine so I'm assuming the timing would be different. Like everyone says let your engine tell you when she is happy. I will double check now the Balancer to top dead center. Timing light is ok. I got new everything on the car. Don't those MSD ignition system kind of help the timing???????? Have a great day,
Bobby :-)
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