Flexplate knock or spark knock due to timing way off
#1
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Car: 88 Trans Am
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3:42 open diff
Flexplate knock or spark knock due to timing way off
Well, talk about having butterflies in my stomach. I know this kind of might be somewhat unrelated. I got my car somewhat all done. When I removed my transmission to rebuild it I had to remove my distributor so it wouldn’t hit the firewall and I didn’t mark anything. I have done this many times before and have gotten lucky finding top dead center compression stroke on number one with my thumb on the spark plug hole.
I was so excited and I think I’m not really thinking clearly. I think I have my timing waay off and at this point I’m starting to panic because I am hearing a little bit of knocking that wasn’t there before. I guess flexplate knock should be a lot louder. The somewhat good news is that I was able to add coolant and try out reverse and drive which worked so I’m kind of out of the woods?? Also when I give it a little gas it stumbles.
I would greatly appreciate some help in this desperate time!!
I was so excited and I think I’m not really thinking clearly. I think I have my timing waay off and at this point I’m starting to panic because I am hearing a little bit of knocking that wasn’t there before. I guess flexplate knock should be a lot louder. The somewhat good news is that I was able to add coolant and try out reverse and drive which worked so I’m kind of out of the woods?? Also when I give it a little gas it stumbles.
I would greatly appreciate some help in this desperate time!!
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Car: 88 Trans Am
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3:42 open diff
Re: Flexplate knock or spark knock due to timing way off
Ok let me explain some additional details that just occurred to me. When I was trying multiple attempts inserting and removing the distributor I did come very close in which the car started within a touch of the key. By the time I could run over to the other side and put the hold down clamp in place, the neck lifted slightly. I do slightly remember the engine was not ticking.
In the subsequent attempts I was aiming the rotor at #8 thinking in my mind that it was close enough. I know I should be over in the engine forum. Is there a really good way of checking for tdc #1. I was using the vacuum gauge with a compression tester gauge hose with the Schrader valve removed
In the subsequent attempts I was aiming the rotor at #8 thinking in my mind that it was close enough. I know I should be over in the engine forum. Is there a really good way of checking for tdc #1. I was using the vacuum gauge with a compression tester gauge hose with the Schrader valve removed
#4
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Re: Flexplate knock or spark knock due to timing way off
Pull off the valve cover on the passenger side. Watch #6 rocker arms. While rotating the engine observe when the exhaust is almost closed and the intake is starting to open. That would represent TDC and cylinder one will be at the top of its compression stroke. Your timing pointer (if it's accurate) should reflect this.
Last edited by skinny z; 06-11-2020 at 05:52 PM.
#5
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Re: Flexplate knock or spark knock due to timing way off
This is easy to get right, just don't rush it. If you need to, go back and get TDC on compression stroke of 1 with your finger and then check the distributor. Reset it if needed. Install the clamp and bolt. Loosen a little but do not remove the clamp. Just enough clamping so that you can turn the distributor by hand with some effort. That way it won't move on you. When I rebuilt my 350 and fired it up I was off two strokes! It ran like crap. No harm in it though.
#6
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Re: Flexplate knock or spark knock due to timing way off
It's in! Finally!
Just to pile on:
1. Remove #1 spark plug.
2. Rotate engine until timing mark is at TDC.
3. Stick a screw driver or other probe into #1 spark plug hole.
4. Feel for the piston.
5. If the engine is at TDC, #1 on compression, you'll feel the piston up near the top.
6. If you don't feel the piston near the top, the engine is at TDC #6 compression.
7. Install the distributor with the rotor is pointing at either the #1 or #6 plug wire (determined in Step 5 or 6).
This should be close enough to get the engine to run.
8. Connect timing light, adjust to spec (or where ever).
Just to pile on:
1. Remove #1 spark plug.
2. Rotate engine until timing mark is at TDC.
3. Stick a screw driver or other probe into #1 spark plug hole.
4. Feel for the piston.
5. If the engine is at TDC, #1 on compression, you'll feel the piston up near the top.
6. If you don't feel the piston near the top, the engine is at TDC #6 compression.
7. Install the distributor with the rotor is pointing at either the #1 or #6 plug wire (determined in Step 5 or 6).
This should be close enough to get the engine to run.
8. Connect timing light, adjust to spec (or where ever).
#7
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Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Flexplate knock or spark knock due to timing way off
It's in! Finally!
Just to pile on:
1. Remove #1 spark plug.
2. Rotate engine until timing mark is at TDC.
3. Stick a screw driver or other probe into #1 spark plug hole.
4. Feel for the piston.
5. If the engine is at TDC, #1 on compression, you'll feel the piston up near the top.
6. If you don't feel the piston near the top, the engine is at TDC #6 compression.
7. Install the distributor with the rotor is pointing at either the #1 or #6 plug wire (determined in Step 5 or 6).
This should be close enough to get the engine to run.
8. Connect timing light, adjust to spec (or where ever).
Just to pile on:
1. Remove #1 spark plug.
2. Rotate engine until timing mark is at TDC.
3. Stick a screw driver or other probe into #1 spark plug hole.
4. Feel for the piston.
5. If the engine is at TDC, #1 on compression, you'll feel the piston up near the top.
6. If you don't feel the piston near the top, the engine is at TDC #6 compression.
7. Install the distributor with the rotor is pointing at either the #1 or #6 plug wire (determined in Step 5 or 6).
This should be close enough to get the engine to run.
8. Connect timing light, adjust to spec (or where ever).
The pistons for #1 and #6 are both at TDC at the same time - it's just that one is on the compression stroke and the other is starting on it's intake stroke.
They are 180 degrees apart. The same goes for numbers 8 and 5, 4 and 7, and 3 and 2.
You could actually connect your timing light to #6 plug wire and set your timing. The mark on the balancer and timing tab will not know the difference.
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#8
Supreme Member
Re: Flexplate knock or spark knock due to timing way off
Pull off the valve cover on the passenger side. Watch #6 rocker arms. While rotating the engine observe when the exhaust is almost closed and the intake is starting to open. That would represent TDC and cylinder one will be at the top of its compression stroke. Your timing pointer (if it's accurate) should reflect this.
#9
Supreme Member
Re: Flexplate knock or spark knock due to timing way off
A little flaw in your logic - steps 5 and 6.
The pistons for #1 and #6 are both at TDC at the same time - it's just that one is on the compression stroke and the other is starting on it's intake stroke.
They are 180 degrees apart. The same goes for numbers 8 and 5, 4 and 7, and 3 and 2.
You could actually connect your timing light to #6 plug wire and set your timing. The mark on the balancer and timing tab will not know the difference.
The pistons for #1 and #6 are both at TDC at the same time - it's just that one is on the compression stroke and the other is starting on it's intake stroke.
They are 180 degrees apart. The same goes for numbers 8 and 5, 4 and 7, and 3 and 2.
You could actually connect your timing light to #6 plug wire and set your timing. The mark on the balancer and timing tab will not know the difference.
#10
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#12
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Car: 88 Trans Am
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3:42 open diff
Re: Flexplate knock or spark knock due to timing way off
Thanks everyone I figured it out, I ended up using a vacuum gauge.
#14
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Car: 88 Trans Am
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3:42 open diff
Re: Flexplate knock or spark knock due to timing way off
I just posted in another related post about the new problem I discovered during the test drive. The car feels very sluggish
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