What should my timing be set at to stop pinging at wot

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I'm going to go out on a limb and say you have a vacuum advance that needs adjusting and you should look at your timing curve. And I would do it, rather than try to use manifold vacuum on it. On the vacuum dashpot on the distributor... Take the hose off, and slide in an 11/32 allen wrench. You should feel it engage a hex inside the dashpot. This is the preload on the dashpot, and is almost never perfect out of the box. If you turn the wrench clockwise, the advance will occur with less vacuum applied. If you go counterclockwise, it will take more vacuum to occur. While at WOT there should be no vacuum, if the carb is small, you may be pulling some at the carb, causing the advance to come in and ping. By tuning that advance, you get the performance and mileage. Vacuum advance means it's also advancing at idle and possibly when it's turnign with the starter and trying to start.
Last, find out what rpm the mechanicla advance comes in, and when it's all in. With a stock type convertor you will want to have more initial, but have the mechanical come in slower, so the total advance isn't reached untill closer to 3K, rather than the normal "2500" deal.
 
moper said:
I'm going to go out on a limb and say you have a vacuum advance that needs adjusting and you should look at your timing curve. And I would do it, rather than try to use manifold vacuum on it. On the vacuum dashpot on the distributor... Take the hose off, and slide in an 11/32 allen wrench. You should feel it engage a hex inside the dashpot. This is the preload on the dashpot, and is almost never perfect out of the box. If you turn the wrench clockwise, the advance will occur with less vacuum applied. If you go counterclockwise, it will take more vacuum to occur. While at WOT there should be no vacuum, if the carb is small, you may be pulling some at the carb, causing the advance to come in and ping. By tuning that advance, you get the performance and mileage. Vacuum advance means it's also advancing at idle and possibly when it's turnign with the starter and trying to start.
Last, find out what rpm the mechanicla advance comes in, and when it's all in. With a stock type convertor you will want to have more initial, but have the mechanical come in slower, so the total advance isn't reached untill closer to 3K, rather than the normal "2500" deal.
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The trouble was there was no vacuum on the outlet from the carb , I had already tried adjusting the distributor , when it wold not work tested the port on the carb , was getting nothing , that's why I switched vacuum ports .
Can there be damage with the way it's set up now ? It seems to be working well , no ping , good acceleration .
 
There should be no vacuum at the carb at idle when you are testing the ported vacuum source. little risk of damage. Nothing like driving with pinging. It's just a question of getting it to work properly for the best performance. You solved a problem (ping), but you have sacrificed performance to do it. You tired adjusting the sitributor... How? The limits for the mechanical? Or the dashpot? You don't say where you checked the rpm points of the mechanical either. Did you just change things to see what they did, or you knew what you were doing? (not meant to sound condescending. Just looking for your thought process)
 
Adjusted the distributor with allen key , was not getting vacuum advance at 2000- 2500 , there was almost no vacuum from the port on the carb , it was causing it to stutter from dead stop and flooring it , then started pinging as revs climbed . Seems to work better now , had to re adjust distributor with allen key again to get it right with vacuum from brake booster port .
I have been playing with this for weeks trying to get rid of the ping adjusting distributor , never looked at if it was getting vacuum from the port on the carb , just happened to check and it was getting almost nothing at 1800-2500 , figured I would try another port .
Thanks anything you can think of helps , if you think I screwed up , no problem , never to old to learn . Rather you call me on it than I end up with bigger problems .
 
Here in pa alot of the local small airports will sell you gas its 100 low lead but the takes the ping out of mine and I can usually just mix it about 40%. good luck.
 
jerry6 said:
was getting ready to change the cam , already bought one , this time a comp cam . . Mybe I'll change it any way
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If it really has that much cyl pressure, it would probably make more power with a larger cam anyway.....spark knock or not.
 
StrokerScamp said:
If it really has that much cyl pressure, it would probably make more power with a larger cam anyway.....spark knock or not.
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It really has that cylinder pressure , I was surprised when it was measured . Can you suggest a cam , but I have power brakes and it is a street car that hits the track 3-4 times a year . It's making 412 hp now , edelbrock air gap , 650 AVS ,headman tight tube headers with 2 1/2" exhaust .
 
I'm in the same boat only worse......11-1 210# pressure w/J-heads.......I'm going meth/water injection and enjoy the performance on 93 octane :glasses7:

Rickster
 
Either back the total timing down till it quits 'though accept that u need a bigger cam/or thicker head gaskets if you find you need less than 29* or so degrees'...or buy a higher octane.

remember.... You can always shorten the slots to bring up the initial timing...
 
jerry6 said:
Adjusted the distributor with allen key , was not getting vacuum advance at 2000- 2500 , there was almost no vacuum from the port on the carb.
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Wierd. You should have close to the same vacuum on both ports at that rpm. I wonder if there's some internal issue with the passage in the carb. What is your idle rpm? Is there "0" at idle, and something at like 1500? Or zero vacuum all the way up? Have you tried jetting or power valve?
 
moper said:
Wierd. You should have close to the same vacuum on both ports at that rpm. I wonder if there's some internal issue with the passage in the carb. What is your idle rpm? Is there "0" at idle, and something at like 1500? Or zero vacuum all the way up? Have you tried jetting or power valve?
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Idle rpm is 900-950 there was nothing at 1500 , something must be blocking the port at the carb . Have the original carter avs on now that was rebuilt last year .
 
That's what it sounds like. I doubt it went it's whole life with that passage plugged up, but IMO it's worth trying to unplug it.
 
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