On my L car with stock engine, I want to retard the ignition very slightly, play by ear as I am getting slight detonation. It is clock-wise rotation of the distributor to retard the ignition right?
Original Post
Replies sorted oldest to newest
yes ... I'm playing with the ignition on my car also. It seems when I connect the vac adv after putting the timing light on it and disconecting the vac hose ...when I reconnect it to idle speeds up ... I have about 9.5 in vac at stand still ... I would think the vac adv shouldnt adv the distr until acelleration . NO ?? its driving me crazy.
Ron
Ron
Are there other ports on your carb? You might be connecting to the wrong port and providing a higher then expected vac signal to the dist.
Yes there are two ports .. one on the side of the fuel metering block and the other in the carb base plate...
Thanks,
Ron
Thanks,
Ron
Thanks, I turned it clockwise just a smidgen and it is running better now. Is there any disadvantage of too much retard...loaded question. Some day I will get out the dusty garage sale timing light and try to figure the techinical way of doing it. But for now Ferrari's can see the rear of my car again, and hear the Thunda. 
Attachments
Images (1)
If I recall correctly, the port on the metering block (side of carb) should be connect to the distributor. That is the sense port.
Too much retard reduces high RPM power as the spark occurs too far after the piston passes TDC. This you might feel from the butt dyno. Too much redard could also cause the engine to run hotter.
Too much retard reduces high RPM power as the spark occurs too far after the piston passes TDC. This you might feel from the butt dyno. Too much redard could also cause the engine to run hotter.
quote:Originally posted by DOES 200:
Thanks, I turned it clockwise just a smidgen and it is running better now. Is there any disadvantage of too much retard...loaded question. Some day I will get out the dusty garage sale timing light and try to figure the techinical way of doing it. But for now Ferrari's can see the rear of my car again, and hear the Thunda.
Turning the distributor clockwise advances the timing.
For optimum performance, you want as much timimg as possible while avoiding detonation/pinging..
Your telling me ...... LOL
No .. really its set at about 5 or 6 degrees initial and advances to aporx 30 at about 3500 rpm ... I rebuilt the carb and installed a 55 power valve and only idles when it warms up.
Have no vac leaks tested it ... do you think the vac adv diaphram has a leak and I'm loosing vac. it has 6.5 when warm and 9.5 when hot.
Didnt have enough time Sat to figure it out ..but I'm on it along with a thousand other things ..LOL
Ron
No .. really its set at about 5 or 6 degrees initial and advances to aporx 30 at about 3500 rpm ... I rebuilt the carb and installed a 55 power valve and only idles when it warms up.
Have no vac leaks tested it ... do you think the vac adv diaphram has a leak and I'm loosing vac. it has 6.5 when warm and 9.5 when hot.
Didnt have enough time Sat to figure it out ..but I'm on it along with a thousand other things ..LOL
Ron
quote:Originally posted by accobra:
Your telling me ...... LOL
No .. really its set at about 5 or 6 degrees initial and advances to aporx 30 at about 3500 rpm ... I rebuilt the carb and installed a 55 power valve and only idles when it warms up.
Have no vac leaks tested it ... do you think the vac adv diaphram has a leak and I'm loosing vac. it has 6.5 when warm and 9.5 when hot.
Didnt have enough time Sat to figure it out ..but I'm on it along with a thousand other things ..LOL
Ron
What cam, heads, intake manifold are you running? Your initial/total timing is off by about 10/8* assuming a conventional, moderate iron head motor. What happens when you advance the timing to 14/16* initial according to your balancer?
Its a 79 GTS 100% stock ...I THINK .. except for a Blue Thunder intake and a Holley 650 but I have to admit it idles a little wilder then stock maybe a cam was replaced but dont think so. It has Tri Y headers and stock exhaust Have not tried advancing it ... but I could try.
Assuming the indicated timing is correct, I think you need an additional 8* of timing, or use George's method of setting timing where you adjust the initial timing to produce the highest RPM, drive it, and back off a degree or 2 at a time until any detonation or pinging disappears. That should make a significant difference in idle quality and drivability. Good luck..
quote:Originally posted by accobra:
Its a 79 GTS 100% stock ...I THINK .. except for a Blue Thunder intake and a Holley 650 but I have to admit it idles a little wilder then stock maybe a cam was replaced but dont think so. It has Tri Y headers and stock exhaust Have not tried advancing it ... but I could try.
Ron, I dunno if it is true of your car or not but we both have euro spec GTS. Mine had compresion so high that I had to run premium and octane boost just to keep it from pinging. Maybe that is why you can only run 8 degrees instead of 16. I had mine at 16 and it ran like a stripped ass ape. BUt then again I had to boost octane.
Ron's motor originally had exhaust gas recirc, that means the compression ratio is 8.0:1. I normally twist the distributors on those motors for around 20 degrees initial advance and hook the vacuum advance canister straight to "ported" vacuum, no little vacuum signal control goodies in between. (the factory spec for that motor is 16 degres initial, so 20 degrees shouldn't give you any concern) I leave the vacuum retard side of the canister disconnected, always.
Even so, you should be able to operate the motor on 87 octane fuel. If the motor tends to "run on" or diesel with 87 you may need to switch to 89. Operating on the lower octane fuel will actually improve your fuel economy.
the cowboy from Hell
Even so, you should be able to operate the motor on 87 octane fuel. If the motor tends to "run on" or diesel with 87 you may need to switch to 89. Operating on the lower octane fuel will actually improve your fuel economy.
the cowboy from Hell
George, what kind of total advance does a stockish, iron-headed, 8.0:1 motor generally like? ~38*?
Yes, 38 degrees sounds about right to this old memory. the exact numbers are dependent upon the fuel & carb tuning, camshaft, etc. Been a long time since I had an 8.0:1 motor on a dyno. Mind you, I always stuffed a different cam in those motors, but nothing too radical.
Flat top pistons, zero decking the block & milling the heads can take the compression ratio into the 9.5:1 range with that motor. A slightly stouter hydraulic cam, better exhaust, big valves & porting for the heads, can get the motor into the 400 bhp range, even with the 4300D carb. The engine maintains excellent drivability.
In the seventies when I was doing this work, most big block equipped cars didn't have 400 bhp.
the cowboy from Hell
Flat top pistons, zero decking the block & milling the heads can take the compression ratio into the 9.5:1 range with that motor. A slightly stouter hydraulic cam, better exhaust, big valves & porting for the heads, can get the motor into the 400 bhp range, even with the 4300D carb. The engine maintains excellent drivability.
In the seventies when I was doing this work, most big block equipped cars didn't have 400 bhp.
the cowboy from Hell
quote:Originally posted by george pence:
Ron's motor originally had exhaust gas recirc, that means the compression ratio is 8.0:1. I normally twist the distributors on those motors for around 20 degrees initial advance and hook the vacuum advance canister straight to "ported" vacuum, no little vacuum signal control goodies in between. (the factory spec for that motor is 16 degres initial, so 20 degrees shouldn't give you any concern) I leave the vacuum retard side of the canister disconnected, always.
Even so, you should be able to operate the motor on 87 octane fuel. If the motor tends to "run on" or diesel with 87 you may need to switch to 89. Operating on the lower octane fuel will actually improve your fuel economy.
the cowboy from Hell
I had the run on problem but it was because my timing was set at bout zero. It ran too hot, but then I cranked her up to about thirty and that was just a tad too much so I think I have twenty or so right now. But I don't have a vacuum thingie on my distributer, it must be a chepie. It is a Mallory unilite. SO far it ain't been no trouble, but it must be inferior cause it doesn't have a vacuum advance.
The Mallory Unilite is available with or without vacuum advance. I just bought it with VA. Both are adjustable in terms of mechanical advance, rate of advance, and vacuum advance. I 'assumed' it came with the adjustment tool like they used to. Nope, had to order it seperately, just arrived today. Good luck.
I dunno John. Mine came on the car so I don't know much about it other than I went to unhook thevacuum line to time the car and there wasn't one. So I just did thebest I could without it and called it good enough.
George you maybe right with 8 to 1 and I know the motor has never been apart. But the car ran awfully nice with 100 octane cam 2 unleaded out of the pump and suprisingly too good at Pocono. Quick question what cylinder pressure should I get with 8 to 1 .. compression. You have me curiuos.
I'm sure your right though with the timing that 5 or 6 degrees that I have it set at is not enough. But another question ..I dont have any vacumn cansiter that I know of ?? maybe I have to check that too ... I sound like a RETARD but have not spent much time on this car .. I have been working on 6476. whats the proper set up for vacumn to the distributor .. from the fuel block on a holley to the distributor ?? No ?
Thanks
I'm sure your right though with the timing that 5 or 6 degrees that I have it set at is not enough. But another question ..I dont have any vacumn cansiter that I know of ?? maybe I have to check that too ... I sound like a RETARD but have not spent much time on this car .. I have been working on 6476. whats the proper set up for vacumn to the distributor .. from the fuel block on a holley to the distributor ?? No ?
Thanks
Ron,
Regarding compression readings: I don't remember what compression readings an 8.0:1 351C had, I don't think I ever had to take compression readings on a 351C.
Regarding the distributor: A vacuum line from ported vacuum to the advance canister is a starting point, and I know for sure it works just fine on a '73 - '74 vintage 351C 4V (Cobra Jet). Ported vacuum will be found at the nipple that sticks out of the side of the carb/metering block. The vacuum nipples on the carb base (throttle plate) are manifold vacuum.
the cowboy from Hell
Regarding compression readings: I don't remember what compression readings an 8.0:1 351C had, I don't think I ever had to take compression readings on a 351C.
Regarding the distributor: A vacuum line from ported vacuum to the advance canister is a starting point, and I know for sure it works just fine on a '73 - '74 vintage 351C 4V (Cobra Jet). Ported vacuum will be found at the nipple that sticks out of the side of the carb/metering block. The vacuum nipples on the carb base (throttle plate) are manifold vacuum.
the cowboy from Hell
In addition, be aware that on modern Holley double pumpers, the ported or 'timed spark advance' port may actually in the base plate directly below the idle mixture screw in the metering block.
quote:Originally posted by johnk:
Turning the distributor clockwise advances the timing.
For optimum performance, you want as much timimg as possible while avoiding detonation/pinging..
Huh? I thought cockwise retards the timing.
Nope. Perhaps on some engines, not ours.
Here's a good ignition tutorial covering the basics.
http://www.fordmuscle.com/archives/2000/03/timing/index.shtml
Here's a good ignition tutorial covering the basics.
http://www.fordmuscle.com/archives/2000/03/timing/index.shtml
quote:Originally posted by johnk:
Nope. Perhaps on some engines, not ours.
Here's a good ignition tutorial covering the basics.
[URL=http://www.fordmuscle.com/archives/2000/03/timing/index.shtml[/URL]
Thanks for the info Johnk, nice reference website. I thought for sure rotating the distributor clockwise retarded the timing...this is why I stay away from engine work. Sometimes you begin with one simple question and it goes who knows where. That explains why it is slightly more difficult to start my car now, but it runs like a bat-out-a-hell. I may get up the nerve to scrunch back in the engine bay again and turn the distributor counterclockwise to retard the timing just a bit, but not back to where I was in the first place.
I just bought a remote MSD ignition timing control that allows you to change the timing from the drivers seat.
Going to install it when it gets here and see how it works.
Going to install it when it gets here and see how it works.
I bid on one on ebay but lost out. Let us know how it works out, I'm still thinking about getting one!
I did the MSD 8680. I control the timing fron the cabin. I found that under heavy load uphill floored I can turn it down untill there is no knock. One question..... why would I want to turn it back up? Power? economy? I found better octane fuel?
Attachments
Images (1)