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Timing Question

Eggo

Well-Known Member
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3:09 PM
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Feb 16, 2021
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Location
Newcastle, UK
Timing is something that I'm not very good at as haven't done it much before. Been having a string of issues with my '73 Satellite and checked the timing over the weekend and it was way off, it needed advancing quite a lot. Reset the carb mixture and idle screws and it's now running better than it ever has in the past 3 years of owning it. It's got a stock 318 apart from the carb, got an edelbrock avs2 650 cfm. The mixture screws are backed out 2.5 turns.

I took it to a car meet yesterday and was a 150 mile round trip which it did super well. The only thing wrong was between 70-75ish (hard to tell exactly as the speedo jumps around a bit) it felt like it was almost lurching a bit. Faster than this and slower it didn't have the issue. Could this mean I need to back the dizzy off a bit or maybe I've not set the timing gun quite right? Set the gun so the dial was pointing to 5 and got the line to line up with the 0 mark on the block. Don't want to mess with the timing if that's not the issue though. Please may I have some advice on what it could be?

Have uploaded an image of what my timing light looks like.

Screenshot 2024-04-29 074115.png
 
Timing needs to be checked with the car up to operating temperature and with the vacuum line from the carburetor to the distributor removed from the distributor and plugged off temporarily.
The recommended settings for initial timing setting for a stock engine is easy to find but may not be the ideal number for you. Usually, engines do run better and make more power with more timing than the factory had listed in the repair manual. There are limits as to how far advanced you can go, of course. The 318s were usually low compression engines so you aren't likely to hurt it if you go too far. It may just not run well, maybe knock some.
This is just a guess but I'd think you could take it to 15-16 degrees safely. This is at idle.
Racers look at the number at a higher rpm point.
This was the curve of my car after working on the distributor a bit:

1714376006238.png


Just to clarify....That is 20 degrees initial, 35 total with the full advance being in place between 2250 and 2500 rpms.
This works for me but may not be optimal for you. My heavy initial timing number is needed for my engine since I have a pretty rowdy camshaft.
Stock distributors may have 24-28 degrees of mechanical advance built into them, meaning if you set the initial at 10 degrees, you may end up with a 34-38 degree number at 3000 rpms. This probably isn't too much for you. Feel free to experiment and see what feels right.
 
Timing needs to be checked with the car up to operating temperature and with the vacuum line from the carburetor to the distributor removed from the distributor and plugged off temporarily.
The recommended settings for initial timing setting for a stock engine is easy to find but may not be the ideal number for you. Usually, engines do run better and make more power with more timing than the factory had listed in the repair manual. There are limits as to how far advanced you can go, of course. The 318s were usually low compression engines so you aren't likely to hurt it if you go too far. It may just not run well, maybe knock some.
This is just a guess but I'd think you could take it to 15-16 degrees safely. This is at idle.
Racers look at the number at a higher rpm point.
This was the curve of my car after working on the distributor a bit:

View attachment 1654958

Just to clarify....That is 20 degrees initial, 35 total with the full advance being in place between 2250 and 2500 rpms.
This works for me but may not be optimal for you. My heavy initial timing number is needed for my engine since I have a pretty rowdy camshaft.
Stock distributors may have 24-28 degrees of mechanical advance built into them, meaning if you set the initial at 10 degrees, you may end up with a 34-38 degree number at 3000 rpms. This probably isn't too much for you. Feel free to experiment and see what feels right.
This is super helpful thank you! I didn't disconnect the vacuum when I did it so will try again doing that. If I set the dial on the timer to 10 should I be aiming to have the light line up with the 0 mark?

Sorry if this is a stupid question but how do I know how many rpms there are when I'm testing it?
 
Yes, with a timing light that is adjustable, you described the proper way to read the number.
A tachometer is needed to read the engine speed. Without one, you're only guessing.

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The only thing wrong was between 70-75ish (hard to tell exactly as the speedo jumps around a bit) it felt like it was almost lurching a bit. Faster than this and slower it didn't have the issue.
Sounds like a lean surge to me, so my first guess would be to richen the carb up just a tad.
 
Sounds like a lean surge to me, so my first guess would be to richen the carb up just a tad.
will try that before I leave work and see how it goes, thank you! A tad as in each just 1/4 of a turn back out?
 
I hate to say this but dial back timing lights are usually off. Digital are fine.
 
will try that before I leave work and see how it goes, thank you! A tad as in each just 1/4 of a turn back out?
That just adjusts idle mixture. You would need larger jets (or in the case of an AVS2, smaller metering rods). What has me a bit stumped is I assume you haven't changed anything internal to the carb, so that 650 should be providing plenty of fuel for your 318. I wouldn't start messing with anything there until you get better information on what is going on. You should pull a spark plug, especially after a longer trip and see what it looks like to verify the lean condition.

But for now, yes, try 1/4 turn out on the idle mixture screws. Maybe you are using so little of the carb that it will make a difference. It's easy to try and can't hurt anything.

I'm sure some of the carb tuning gurus can check in and provide some suggestions too.
 
That just adjusts idle mixture. You would need larger jets (or in the case of an AVS2, smaller metering rods). What has me a bit stumped is I assume you haven't changed anything internal to the carb, so that 650 should be providing plenty of fuel for your 318. I wouldn't start messing with anything there until you get better information on what is going on. You should pull a spark plug, especially after a longer trip and see what it looks like to verify the lean condition.

But for now, yes, try 1/4 turn out on the idle mixture screws. Maybe you are using so little of the carb that it will make a difference. It's easy to try and can't hurt anything.

I'm sure some of the carb tuning gurus can check in and provide some suggestions too.
ah ok i understand, thank you. the carb is new, it had a 1406 on before i think (99% sure but at work so can't check). have also recently changed essentially the whole ignition system bar the ballast and dizzy. it's not been running right for ages and haven't touched the dizzy at all so didnt initially think it'd be the timing, but when i checked it with the dial pointing to 5 the light was showing at -10 on the block. the dizzy was on tight so i dont think its been moving as ive been driving but a bit confused how its got so far out from where it should be.

the car is running real nice and its very responsive now too since i messed with the timing on saturday. literally only doesn't feel quite right between 70-75mph ish, which has confused me a bit but i guess if they dont go wrong i'd never learn how to fix them!

will try turning the screws out 1/4 and see if that makes a difference, good excuse to take it for a good blast on the way home lol
 
ah ok i understand, thank you. the carb is new, it had a 1406 on before i think (99% sure but at work so can't check). have also recently changed essentially the whole ignition system bar the ballast and dizzy. it's not been running right for ages and haven't touched the dizzy at all so didnt initially think it'd be the timing, but when i checked it with the dial pointing to 5 the light was showing at -10 on the block. the dizzy was on tight so i dont think its been moving as ive been driving but a bit confused how its got so far out from where it should be.

the car is running real nice and its very responsive now too since i messed with the timing on saturday. literally only doesn't feel quite right between 70-75mph ish, which has confused me a bit but i guess if they dont go wrong i'd never learn how to fix them!

will try turning the screws out 1/4 and see if that makes a difference, good excuse to take it for a good blast on the way home lol
So a couple of other things to check as well:
* Check your distributor and the advance mechanism. Take the cap off. Step one is to grab the rotor (while it is on the shaft) and try to wiggle it back and forth/ side to side. There should be essentially no play. If there is, your shaft/ bushing could be worn and this requires some attention. For test 2, grab the rotor and advance it. It should advance a few degrees. When you let it go, it should snap back to where it was. It should do this smoothly and repeatedly. Honestly, one of the best things you can do for good performance is to make sure your distributor is set up well. @HALIFAXHOPS is a very well respected vendor on this site and specializes in distributors. Sending your distributor to him (or to another vendor who REALLY KNOWS what they are doing), is highly, highly recommended. It can totally change the behavior of a car.

* You need to know how much timing you have for base, mechanical and vacuum. All three are important and each has it's own role to play. Total timing without vacuum advance should be 36-38*. You should check this and verify (and it is part of the distributor setup as well).

* Once your timing is right, then setting up the carb properly is the next step.


I think you are headed the right direction though. Good luck and keep at it - you are close!
 
So a couple of other things to check as well:
* Check your distributor and the advance mechanism. Take the cap off. Step one is to grab the rotor (while it is on the shaft) and try to wiggle it back and forth/ side to side. There should be essentially no play. If there is, your shaft/ bushing could be worn and this requires some attention. For test 2, grab the rotor and advance it. It should advance a few degrees. When you let it go, it should snap back to where it was. It should do this smoothly and repeatedly. Honestly, one of the best things you can do for good performance is to make sure your distributor is set up well. @HALIFAXHOPS is a very well respected vendor on this site and specializes in distributors. Sending your distributor to him (or to another vendor who REALLY KNOWS what they are doing), is highly, highly recommended. It can totally change the behavior of a car.

* You need to know how much timing you have for base, mechanical and vacuum. All three are important and each has it's own role to play. Total timing without vacuum advance should be 36-38*. You should check this and verify (and it is part of the distributor setup as well).

* Once your timing is right, then setting up the carb properly is the next step.


I think you are headed the right direction though. Good luck and keep at it - you are close!
ok thank you for all the advice! will do these checks when I get home. I'm in the uk so if there's play or it doesnt snap back i'll buy a new one. the dizzy is 3 years old so guess it could be worn as have daily driven the car pretty much every day since getting it.

fingers crossed it'll be ok!
 
ok thank you for all the advice! will do these checks when I get home. I'm in the uk so if there's play or it doesnt snap back i'll buy a new one. the dizzy is 3 years old so guess it could be worn as have daily driven the car pretty much every day since getting it.

fingers crossed it'll be ok!
May I humbly suggest you DON'T just buy a new distributor. Throwing parts at the car will not fix it.

A 3 year old distributor should in NO WAY be bad, and the advance of the new distributor may or may not be what you need. What your distributor needs is to be checked and be sure it advances as you need it. Really, the springs need to be checked, and maximum advance needs to be set. You want mechanical advance to start around 1000 RPM and be all in by roughly 2800 RPM. You distributor should have roughly 22* of engine advance (which equals 11* on the distributor). Then with timing set at 15* base, your max timing should be close (although vacuum still needs to be set and adjusted).

You can check this on your car with your timing light. Briefly:
* Disconnect the vacuum advance (and plug the line to the carb so you don't have a leak)
* At idle (below 1000 RPM), check and set the base timing to about 15*. (OR you can leave it where it is and simply record what it is.)
* Now have a friend hold the throttle to get the car to about 3000 RPM. Adjust your timing light to see how much total timing you have. (Even without knowing RPM, you can still see where the advance stops increasing. This, or above this RPM, is where you want to check timing.) Record this number. If it is, for example 35*, then you know that your distributor is adding 20* of mechanical advance timing (35* total - 15* base timing). It still doesn't tell you the curve of how and when it comes in is good, but it'll go a long way.
 
May I humbly suggest you DON'T just buy a new distributor. Throwing parts at the car will not fix it.

A 3 year old distributor should in NO WAY be bad, and the advance of the new distributor may or may not be what you need. What your distributor needs is to be checked and be sure it advances as you need it. Really, the springs need to be checked, and maximum advance needs to be set. You want mechanical advance to start around 1000 RPM and be all in by roughly 2800 RPM. You distributor should have roughly 22* of engine advance (which equals 11* on the distributor). Then with timing set at 15* base, your max timing should be close (although vacuum still needs to be set and adjusted).

You can check this on your car with your timing light. Briefly:
* Disconnect the vacuum advance (and plug the line to the carb so you don't have a leak)
* At idle (below 1000 RPM), check and set the base timing to about 15*. (OR you can leave it where it is and simply record what it is.)
* Now have a friend hold the throttle to get the car to about 3000 RPM. Adjust your timing light to see how much total timing you have. (Even without knowing RPM, you can still see where the advance stops increasing. This, or above this RPM, is where you want to check timing.) Record this number. If it is, for example 35*, then you know that your distributor is adding 20* of mechanical advance timing (35* total - 15* base timing). It still doesn't tell you the curve of how and when it comes in is good, but it'll go a long way.
ok that makes sense, will give it a go :)
 
just a lil update, i checked the dizzy rotor and it seems absolutely fine, redid the timing following the suggestions and ended up advancing it slightly. it’s still a bit lurchy around 80 but loads less so will have a go at messing with the carb to see if that sorts it for good. took it on a 900 mile trip this weekend from the north east of the uk to the south west, then across to near london and then back up to the north east. it did the journey without a hiccup and i’m super pleased with it! it’s mega fuel efficient now as well, calculated it’s been doing about 20mpg which is the best it’s ever done

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