Timing Marks Description
Thread Starter
Racer
Joined: Oct 2010
Posts: 498
Likes: 10
From: Tampa FL
Timing Marks Description
I am not a mechanic so don't laugh. I always though the timing marks on my 65 327 were After 0 Before but now I know it's Advance 0 Retard. The R always looked like a B to me. Anyway I am assuming that A is Before TDC. Correct?
Le Mans Master
Joined: Jan 2002
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Yes. And every line on the timing tab is 2*.
Team Owner
Joined: Oct 2000
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From: Washington Michigan
Thread Starter
Racer
Joined: Oct 2010
Posts: 498
Likes: 10
From: Tampa FL
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
Le Mans Master
Joined: Jan 2002
Posts: 8,913
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Have you ever confirmed Top Dead Center (TDC) on the #1 piston and confirmed the timing line on the balancer is lined up with the zero mark on the timing tab?
What RPM are you idling at when checking timing? Also, as JohnZ pointed out you have to set your initial timing with he vacuum advanvce hose disconnected.
What RPM are you idling at when checking timing? Also, as JohnZ pointed out you have to set your initial timing with he vacuum advanvce hose disconnected.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
Have you ever confirmed Top Dead Center (TDC) on the #1 piston and confirmed the timing line on the balancer is lined up with the zero mark on the timing tab?
100%. I deal with so many balancers that have the outer ring with the notch spun and not in the correct position so when using a timing light...it proves to be ineffective. I have to check a few every year.
What RPM are you idling at when checking timing? Also, as JohnZ pointed out you have to set your initial timing with the vacuum advance hose disconnected.
100%. I deal with so many balancers that have the outer ring with the notch spun and not in the correct position so when using a timing light...it proves to be ineffective. I have to check a few every year.What RPM are you idling at when checking timing? Also, as JohnZ pointed out you have to set your initial timing with the vacuum advance hose disconnected.
DUB
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Thread Starter
Racer
Joined: Oct 2010
Posts: 498
Likes: 10
From: Tampa FL
Ok, here is some more info. The distributor is 1111024. It has Pertronix Igniter II installed. The number one spark plug is connected to the distributor on the post just to the right of the dwell window. I have never confirmed that the TDC is on the #1 piston and confirmed the timing line on the balancer is lined up with the zero mark on the timing tab? Something I should check. When I set the timing I did have the vacumm advance disconnected and a vacumm gauge hooked to the port on the carb. The vacumm advance does appear to be working because when I connect it the timing jumps up several degrees. While adjusting the timing I have the engine idling at 800 rpm.
Le Mans Master
Joined: Jan 2002
Posts: 8,913
Likes: 283
The number one spark plug is connected to the distributor on the post just to the right of the dwell window.
- Perfect
I have never confirmed that the TDC is on the #1 piston and confirmed the timing line on the balancer is lined up with the zero mark on the timing tab? Something I should check.
- Yes. You could verify the correct balancer by part number, size, etc. I don’t know much about the variations in designs over the years, but I recall there is a difference. Same goes for timing covers WRT the timing tab, and also after-market
bolt on timing tabs. If you are 100% confident that yours are correct, then don’t bother with it. But if there is any doubt, then confirm with the TDC alignment test. I use a USB dental scope (poor mans borescope) hooked to my laptop to watch the piston. Just be sure to get it on the compression stroke!
When I set the timing I did have the vacumm advance disconnected and a vacumm gauge hooked to the port on the carb.
- Perfect. By chance do you remember your vacuum reading?
The vacumm advance does appear to be working because when I connect it the timing jumps up several degrees.
- How many degrees? Are you using a dial back timing light ?
While adjusting the timing I have the engine idling at 800 rpm.
- Try idling it down to the 500 RPM range, just for the purpose of setting the initial timing. I am not familiar with the specs on the 300 HP distributor, and at what RPM the mechanical (centrifugal) advance begins to deploy, but you may be getting a few degrees of centrifugal advance at idle. Not a huge problem but you want to know where the base timing is at. I think you are looking for 8* BTDC or what ever JohnZ suggested.
Get the initial timing confirmed and set then lock the distributor hold down bolt. The rest of the timing tuning will not require you move the distributor base.
- Perfect
I have never confirmed that the TDC is on the #1 piston and confirmed the timing line on the balancer is lined up with the zero mark on the timing tab? Something I should check.
- Yes. You could verify the correct balancer by part number, size, etc. I don’t know much about the variations in designs over the years, but I recall there is a difference. Same goes for timing covers WRT the timing tab, and also after-market
bolt on timing tabs. If you are 100% confident that yours are correct, then don’t bother with it. But if there is any doubt, then confirm with the TDC alignment test. I use a USB dental scope (poor mans borescope) hooked to my laptop to watch the piston. Just be sure to get it on the compression stroke!
When I set the timing I did have the vacumm advance disconnected and a vacumm gauge hooked to the port on the carb.
- Perfect. By chance do you remember your vacuum reading?
The vacumm advance does appear to be working because when I connect it the timing jumps up several degrees.
- How many degrees? Are you using a dial back timing light ?
While adjusting the timing I have the engine idling at 800 rpm.
- Try idling it down to the 500 RPM range, just for the purpose of setting the initial timing. I am not familiar with the specs on the 300 HP distributor, and at what RPM the mechanical (centrifugal) advance begins to deploy, but you may be getting a few degrees of centrifugal advance at idle. Not a huge problem but you want to know where the base timing is at. I think you are looking for 8* BTDC or what ever JohnZ suggested.
Get the initial timing confirmed and set then lock the distributor hold down bolt. The rest of the timing tuning will not require you move the distributor base.
Thread Starter
Racer
Joined: Oct 2010
Posts: 498
Likes: 10
From: Tampa FL
Ghostrider, You have a nice car there. My car is a 65. I think it has a 64 engine. The block had been shaved at some time in the past and most of the numbers on the pad are not readable. I have had the car for 30 years and it has always been set on the 8th mark on the tab. Other than some carburetor problems I have been having it has been running good. I do want to check that alignment again. It seems like I had done it many years ago but I am not sure.
Did they make any timing tabs that had gradients of 1 degree?
The vacuum reading was right on 20 I don't have a dial back timing light. The timing mark on the balancer moves up about an inch and a half maybe a little more. The reason I was idling at 800 is because the car is an automatic. When I put it in gear it drops down to 500. For the purpose of setting the timing I could lower it to 500 but it needs to be higher in service.
Did they make any timing tabs that had gradients of 1 degree?
The vacuum reading was right on 20 I don't have a dial back timing light. The timing mark on the balancer moves up about an inch and a half maybe a little more. The reason I was idling at 800 is because the car is an automatic. When I put it in gear it drops down to 500. For the purpose of setting the timing I could lower it to 500 but it needs to be higher in service.
Le Mans Master
Joined: Jan 2002
Posts: 8,913
Likes: 283
Ghostrider, You have a nice car there.
- Thank You.
My car is a 65. I think it has a 64 engine. The block had been shaved at some time in the past and most of the numbers on the pad are not readable.
- The balancer should have a part number on it somewhere. It may not be legible with it installed.
I have had the car for 30 years and it has always been set on the 8th mark on the tab.
- Maybe an aftermarket tab??
Did they make any timing tabs that had gradients of 1 degree?
- I am not sure. As far as stock GM stuff I have only heard of 2* per line on the tab WRT to classic corvettes.
The vacuum reading was right on 20 I don't have a dial back timing light. The timing mark on the balancer moves up about an inch and a half maybe a little more. The reason I was idling at 800 is because the car is an automatic. When I put it in gear it drops down to 500. For the purpose of setting the timing I could lower it to 500 but it needs to be higher in service.
Yes, just for setting the timing, idle it down low just to verify the fly weights in the dist. are not adding any advance. Turn it back up to what ever you like when you confirm and set the base timing.
- Thank You.
My car is a 65. I think it has a 64 engine. The block had been shaved at some time in the past and most of the numbers on the pad are not readable.
- The balancer should have a part number on it somewhere. It may not be legible with it installed.
I have had the car for 30 years and it has always been set on the 8th mark on the tab.
- Maybe an aftermarket tab??
Did they make any timing tabs that had gradients of 1 degree?
- I am not sure. As far as stock GM stuff I have only heard of 2* per line on the tab WRT to classic corvettes.
The vacuum reading was right on 20 I don't have a dial back timing light. The timing mark on the balancer moves up about an inch and a half maybe a little more. The reason I was idling at 800 is because the car is an automatic. When I put it in gear it drops down to 500. For the purpose of setting the timing I could lower it to 500 but it needs to be higher in service.
Yes, just for setting the timing, idle it down low just to verify the fly weights in the dist. are not adding any advance. Turn it back up to what ever you like when you confirm and set the base timing.
Le Mans Master
Joined: Jan 2002
Posts: 8,913
Likes: 283
A "piston stop" or "piston locating tool". If you have never used one, follow the instructions, and do all movements of the engine by hand.
You can most likely rent one from some of the box chain parts stores.
Here is one on ebay.
http://www.ebay.com/itm/Big-End-Performance-Top-Dead-center-locator-tool-14mm-piston-stop-/370970330074?hash=item565f8e03da&item=370970330074&pt=Motors_Automotive_Tools&vxp=mtr#ht_165wt_662
Try and find a dial back timing light as well. Will make the whole job alot easier.
- Mark
You can most likely rent one from some of the box chain parts stores.
Here is one on ebay.
http://www.ebay.com/itm/Big-End-Performance-Top-Dead-center-locator-tool-14mm-piston-stop-/370970330074?hash=item565f8e03da&item=370970330074&pt=Motors_Automotive_Tools&vxp=mtr#ht_165wt_662
Try and find a dial back timing light as well. Will make the whole job alot easier.
- Mark
Le Mans Master
Joined: Jan 2002
Posts: 8,913
Likes: 283
Here is a similar borescope to what I have. For the few dollars more then a locating tool ! I used it to snake into my intake to look at valves and gaskets just recently.
http://www.ebay.com/itm/USB-Endoscope-Borescope-Inspection-waterproof-Camera-w-Flexible-Supporting-Tube-/321395006661?pt=LH_DefaultDomain_0&hash=item4ad4a29cc5#ht_4649wt_873
http://www.ebay.com/itm/USB-Endoscope-Borescope-Inspection-waterproof-Camera-w-Flexible-Supporting-Tube-/321395006661?pt=LH_DefaultDomain_0&hash=item4ad4a29cc5#ht_4649wt_873
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
I use a home made tool that looks just like what is pictured in post #14. I made mine out of an old spark plug and tapped it so i could thread a long bolt just like what is pictured.
I also have a flywheel turning tool which makes it quite easy to find TDC for cylinder 1.
DUB
I also have a flywheel turning tool which makes it quite easy to find TDC for cylinder 1.
DUB
Thread Starter
Racer
Joined: Oct 2010
Posts: 498
Likes: 10
From: Tampa FL
I saw someone make one of those on YouTube. I also saw some on ebay for $9.00 and free shipping. This is my question about those devises. They look like they are adjustable. How do you know how long to set it at and if you made your own how would you know how long to make it?
Burning Brakes
Joined: Jul 2011
Posts: 1,105
Likes: 121
From: Oamaru north otago
Simple test gauge can be made from old spark plug brack up the porcorlen and hot glue a plastic tube into the plug insert it into no 1 on power stroke (both valves closed) as you turn the crank to tdc use soapy water to make a bubble on end of the tube large bubble = tdc.
Thread Starter
Racer
Joined: Oct 2010
Posts: 498
Likes: 10
From: Tampa FL
Simple test gauge can be made from old spark plug brack up the porcorlen and hot glue a plastic tube into the plug insert it into no 1 on power stroke (both valves closed) as you turn the crank to tdc use soapy water to make a bubble on end of the tube large bubble = tdc.
Safety Car
Joined: May 2014
Posts: 3,783
Likes: 655
Sounds like a good idea. I am going to see if I have an old spark plug laying around and give it a try. If I have to set my timing at 16 deg BTDC (8 marks on the tab) my harmonic balancer must be shifted and I need to verify that. I also am going to order the tester on ebay today.
Also, be very careful turning the engine with the spark plug/bolt piston stop.