Help with timing
Intermediate
Joined: Sep 2014
Posts: 45
Likes: 9
From: Queensland
Thread Starter
Racer
Joined: Mar 2016
Posts: 470
Likes: 31
From: Melbourne Victoria
I got the timing tape today and just need some help on how and where to apply it?
I presume just put the 12 deg mark on the tape and line that up with the white mark on the harmonic balancer seeing that the timing is 12deg BTDC? Please tell me if I'm doing it wrong?
Last edited by Corvetteoz; Mar 2, 2017 at 04:06 AM.
Thread Starter
Racer
Joined: Mar 2016
Posts: 470
Likes: 31
From: Melbourne Victoria
I measured the balancer and to my surprise it measured 6 3/4 inch. That must be what the standard ones were.
Last edited by Corvetteoz; Mar 2, 2017 at 04:35 AM.
Thread Starter
Racer
Joined: Mar 2016
Posts: 470
Likes: 31
From: Melbourne Victoria
Tested it tonight. Unfortunately when I got up to the 4000rpm test the tape flew off and I've been unable to find it since. I'll have a good look tomorrow when I have some day light.
800rpm- 12 deg
1000rpm-12 deg
2000rpm-24deg
3000rpm-32deg
4000rpm-Lost tape
I won't take it up to 5000rpm as it's only a stock engine and don't want to do any damage.
800rpm- 12 deg
1000rpm-12 deg
2000rpm-24deg
3000rpm-32deg
4000rpm-Lost tape
I won't take it up to 5000rpm as it's only a stock engine and don't want to do any damage.
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
In regards to the bold section in your quote. You mean the 0 deg on the timing tape should line up with the 0 line on the timing cover, yeah? So I'll make sure I put the tape on so the 12 deg mark lines up with the line on the balancer, that will mean the 0 deg mark on the tape lines up with the 0 deg mark on the timing cover.
I measured the balancer and to my surprise it measured 6 3/4 inch. That must be what the standard ones were.
I measured the balancer and to my surprise it measured 6 3/4 inch. That must be what the standard ones were.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Say you have a 8" diameter balancer ( I believe this is the stock diameter). The circumference should be 2xPIxR.
PI=3.14
R= radius.
So in this case 25" in circumfrence. 2x3.14=6.28x4=25.12
Divide 360* by 25. You get 14.4. That's 14.4* of advance for each inch past 0* on your balancer.
So for 36* of advance divide 36 by 14.4. You get 2.5.
This means 2.5 inches from 0* on your balancer is 36* of advance.
Or just wrap a tape around your balancer to measure the diameter and use the above math to see where 36* should fall.
This is where the tape you buy should indicate 36*, or if the tape comes off or you don't use it.
Math, complements of Lars IIRC.
PI=3.14
R= radius.
So in this case 25" in circumfrence. 2x3.14=6.28x4=25.12
Divide 360* by 25. You get 14.4. That's 14.4* of advance for each inch past 0* on your balancer.
So for 36* of advance divide 36 by 14.4. You get 2.5.
This means 2.5 inches from 0* on your balancer is 36* of advance.
Or just wrap a tape around your balancer to measure the diameter and use the above math to see where 36* should fall.
This is where the tape you buy should indicate 36*, or if the tape comes off or you don't use it.
Math, complements of Lars IIRC.
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Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Oh ok I see your tape did fly off. Typical.
Like Resdoggie I use white paint, white out to be specific, the stuff we used to use to make corrections in typing.
It's very visable with the timing light. I also use it on the pointer.
If you get ambitious you can also mark your balancer every 90*. This comes in very handy while setting valve lash. I even went so far as to put what cylinders were TDC at that mark. IE at 0* #'s 1 and 6 are TDC. So next to the 0* mark I also have those two mumbers written.
Like Resdoggie I use white paint, white out to be specific, the stuff we used to use to make corrections in typing.
It's very visable with the timing light. I also use it on the pointer.
If you get ambitious you can also mark your balancer every 90*. This comes in very handy while setting valve lash. I even went so far as to put what cylinders were TDC at that mark. IE at 0* #'s 1 and 6 are TDC. So next to the 0* mark I also have those two mumbers written.
Melting Slicks
Joined: Oct 2012
Posts: 2,156
Likes: 273
From: Dunedin NZ.
Good thing it flew off methinks as 0 deg on the tape should line up with the mark on the balancer, then when say 10 deg on the tape is pointed at by the pointer on the timing cover the engine will be at 10 deg before top dead centre.If the timing tape is the wrong length to wrap around the balancer completely or is too long the degrees indicated will be incorrect.
You can remove one spring from the centrifugal advance so you don't have to rev the bejesus out of the engine to find out what the max advance is!
You can remove one spring from the centrifugal advance so you don't have to rev the bejesus out of the engine to find out what the max advance is!
Last edited by Haggisbash; Mar 2, 2017 at 01:30 PM.
Thread Starter
Racer
Joined: Mar 2016
Posts: 470
Likes: 31
From: Melbourne Victoria
Say you have a 8" diameter balancer ( I believe this is the stock diameter). The circumference should be 2xPIxR.
PI=3.14
R= radius.
So in this case 25" in circumfrence. 2x3.14=6.28x4=25.12
Divide 360* by 25. You get 14.4. That's 14.4* of advance for each inch past 0* on your balancer.
So for 36* of advance divide 36 by 14.4. You get 2.5.
This means 2.5 inches from 0* on your balancer is 36* of advance.
Or just wrap a tape around your balancer to measure the diameter and use the above math to see where 36* should fall.
This is where the tape you buy should indicate 36*, or if the tape comes off or you don't use it.
Math, complements of Lars IIRC.
PI=3.14
R= radius.
So in this case 25" in circumfrence. 2x3.14=6.28x4=25.12
Divide 360* by 25. You get 14.4. That's 14.4* of advance for each inch past 0* on your balancer.
So for 36* of advance divide 36 by 14.4. You get 2.5.
This means 2.5 inches from 0* on your balancer is 36* of advance.
Or just wrap a tape around your balancer to measure the diameter and use the above math to see where 36* should fall.
This is where the tape you buy should indicate 36*, or if the tape comes off or you don't use it.
Math, complements of Lars IIRC.
Oh ok I see your tape did fly off. Typical.
Like Resdoggie I use white paint, white out to be specific, the stuff we used to use to make corrections in typing.
It's very visable with the timing light. I also use it on the pointer.
If you get ambitious you can also mark your balancer every 90*. This comes in very handy while setting valve lash. I even went so far as to put what cylinders were TDC at that mark. IE at 0* #'s 1 and 6 are TDC. So next to the 0* mark I also have those two mumbers written.
Like Resdoggie I use white paint, white out to be specific, the stuff we used to use to make corrections in typing.
It's very visable with the timing light. I also use it on the pointer.
If you get ambitious you can also mark your balancer every 90*. This comes in very handy while setting valve lash. I even went so far as to put what cylinders were TDC at that mark. IE at 0* #'s 1 and 6 are TDC. So next to the 0* mark I also have those two mumbers written.
Good thing it flew off methinks as 0 deg on the tape should line up with the mark on the balancer, then when say 10 deg on the tape is pointed at by the pointer on the timing cover the engine will be at 10 deg before top dead centre.If the timing tape is the wrong length to wrap around the balancer completely or is too long the degrees indicated will be incorrect.
You can remove one spring from the centrifugal advance so you don't have to rev the bejesus out of the engine to find out what the max advance is!
You can remove one spring from the centrifugal advance so you don't have to rev the bejesus out of the engine to find out what the max advance is!
So when I check total timing doing it your way would mean that the total timing reading would be out by 12 deg?
Fully understand if the wrong tape is on the balancer then the readings will be incorrect. The balancer measured 6 3/4 in diameter. I'll measure the circumference today and report back.
I think as long as I find out what the 4000rpm advance is, it should give me an indication of whether it's still advancing or not. If it's not at 36 deg at 4000rpm, I may have to go to the 5000rpm test.
I did with cleaning solvent about 2 hours before applying the tape.
Thread Starter
Racer
Joined: Mar 2016
Posts: 470
Likes: 31
From: Melbourne Victoria
Circumference of the balancer is 538mm (21.20inches). 21.20 divided by 3.14159265358979= 6.75 inches diameter.
Got a chance to go out and check the timing properly tonight. Superglued the same timing tape at both ends this time. Here are the results.
800 rpm- 12 deg
1000rpm- 12 deg
2000rpm- 24 deg
3000rpm- 31 deg
4000rpm- 31 deg
The timing started to advance at 1300rpm and maxed out at 31 deg at 2500rpm. What do I make of this?
Got a chance to go out and check the timing properly tonight. Superglued the same timing tape at both ends this time. Here are the results.
800 rpm- 12 deg
1000rpm- 12 deg
2000rpm- 24 deg
3000rpm- 31 deg
4000rpm- 31 deg
The timing started to advance at 1300rpm and maxed out at 31 deg at 2500rpm. What do I make of this?
Last edited by Corvetteoz; Mar 4, 2017 at 04:51 AM.
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From: Madeira Beach, FL
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You can loosen the distributer hold down bolt slightly and turn the distributor counter clockwise until you have 36 total at 3,000 rpms.
Don't forget to disconnect the vac advance line and tighten the hold down bolt when done making the adjustment.
Marshal
Don't forget to disconnect the vac advance line and tighten the hold down bolt when done making the adjustment.
Marshal
Circumference of the balancer is 538mm (21.20inches). 21.20 divided by 3.14159265358979= 6.75 inches diameter.
Got a chance to go out and check the timing properly tonight. Superglued the same timing tape at both ends this time. Here are the results.
800 rpm- 12 deg
1000rpm- 12 deg
2000rpm- 24 deg
3000rpm- 31 deg
4000rpm- 31 deg
The timing started to advance at 1300rpm and maxed out at 31 deg at 2500rpm. What do I make of this?
Got a chance to go out and check the timing properly tonight. Superglued the same timing tape at both ends this time. Here are the results.
800 rpm- 12 deg
1000rpm- 12 deg
2000rpm- 24 deg
3000rpm- 31 deg
4000rpm- 31 deg
The timing started to advance at 1300rpm and maxed out at 31 deg at 2500rpm. What do I make of this?
Thread Starter
Racer
Joined: Mar 2016
Posts: 470
Likes: 31
From: Melbourne Victoria
Thread Starter
Racer
Joined: Mar 2016
Posts: 470
Likes: 31
From: Melbourne Victoria
Adjusted the timing yesterday. Unfortunately I couldn't get the timing to come in at 36 deg at 3000rpm. The best I could get it was 36 deg at 2500rpm. The initial timing ended up at 17 deg and progressing from there.
Anyone know why my engine is like this? Could it be something else like carb tuning that is limiting it?
Anyone know why my engine is like this? Could it be something else like carb tuning that is limiting it?
Last edited by Corvetteoz; Mar 6, 2017 at 06:17 AM.
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Your getting close. Leave your initial @17*. Try using the next heavier spring on your dist'r weights. You can change the springs one at a time mixing spring ratings. This will increase the rpm's to reach the desired 36*@3000 rpm. You maybe ok right now but try for 3000 rpm and note any difference in performance. Once your curve is set, then onto carb tuning if needed.
Thread Starter
Racer
Joined: Mar 2016
Posts: 470
Likes: 31
From: Melbourne Victoria
Your getting close. Leave your initial @17*. Try using the next heavier spring on your dist'r weights. You can change the springs one at a time mixing spring ratings. This will increase the rpm's to reach the desired 36*@3000 rpm. You maybe ok right now but try for 3000 rpm and note any difference in performance. Once your curve is set, then onto carb tuning if needed.
I'm not really familiar with Chev distributors or Chev engines for that matter. I tried to pull the rotor button off yesterday and it wouldn't budge, not sure whether there is a screw or something that needs to be removed first to even pull the rotor off. Any advice with this also would be helpful?