Trouble with timing
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5th Wheeling
Joined: Nov 2020
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Trouble with timing
I think I'm failing to understand some basics of timing so hopefully the knowledgeable folks here can help me out. I recently took an engine out of an rv and swapped the timing chain on a 460 with a straight up timing chain from edelbrock. I think I may have misunderstood another another instructional post and I put it back so that timing mark aligned with 13degrees with the engine off and distributor button aligned with cylinder 1. On first start after the swap the engine started right up and ran great, but the timing light is showing it at something like 30°btc. Can somebody enlighten me as to where I went wrong?
Lead Driver
Joined: Oct 2018
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Valve timing and ignition timing are not the same thing. but I'm not exactly sure what you're describing.
As far as your ignition timing goes , are you checking it with the vacuum advance disconnected? and is you vacuum coming from the ported source?
30 is too much initial, but I'm not surprised it's running okay. set it at 15 or so and hook your vacuum back up. if it runs good great, but you need to check your curve with a dial back.
As far as your ignition timing goes , are you checking it with the vacuum advance disconnected? and is you vacuum coming from the ported source?
30 is too much initial, but I'm not surprised it's running okay. set it at 15 or so and hook your vacuum back up. if it runs good great, but you need to check your curve with a dial back.
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5th Wheeling
Joined: Nov 2020
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So basically you're suggesting I bring cylinder 1 back to top dead center on the compression stroke, align the timing tab with the 0 degree mark, and pull the distributor and realign so the button is on cylinder1?
Lead Driver
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It makes no difference what position your distributor is in or which terminal on the cap is #1, as long as your firing order is correct and you have room to move it to set your timing.
Most of the time the spec you're given for base timing isn't the optimum setting, but it's a starting place. if you set it there, or a little more than spec then hook your vacuum line up to PORTED vacuum you'll probably find it runs okay assuming everything you did internally is correct.
Manifold vacuum will work but most rigs from the beginning of the smog era like these are were curved for ported vacuum. if you get it running decent you should check your curve with a dial back to see what your mechanical advance is, this is by far the most important thing you can do in tuning your engine. not only does it determine your performance and economy but if it's too advance it'll destroy your engine.
Most of the time the spec you're given for base timing isn't the optimum setting, but it's a starting place. if you set it there, or a little more than spec then hook your vacuum line up to PORTED vacuum you'll probably find it runs okay assuming everything you did internally is correct.
Manifold vacuum will work but most rigs from the beginning of the smog era like these are were curved for ported vacuum. if you get it running decent you should check your curve with a dial back to see what your mechanical advance is, this is by far the most important thing you can do in tuning your engine. not only does it determine your performance and economy but if it's too advance it'll destroy your engine.
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5th Wheeling
Joined: Nov 2020
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Manifold vacuum will work but most rigs from the beginning of the smog era like these are were curved for ported vacuum. if you get it running decent you should check your curve with a dial back to see what your mechanical advance is, this is by far the most important thing you can do in tuning your engine. not only does it determine your performance and economy but if it's too advance it'll destroy your engine.
Hotshot
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Lead Driver
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No, like tbear says only at idle and low RPM will it matter. most aftermarket distributors are just a solution looking for a problem, if you can't find a better use for the money you have a really nice pickup.
Performance comes at WOT, and your vacuum drops out and does nothing, it's all on your mechanical curve at that point and that's why it's so crucial to have it right. the vacuum advance is for cruise speeds and lowers your EGT's and improves fuel economy.
Performance comes at WOT, and your vacuum drops out and does nothing, it's all on your mechanical curve at that point and that's why it's so crucial to have it right. the vacuum advance is for cruise speeds and lowers your EGT's and improves fuel economy.
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Lead Driver
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From: Albuquerque
I suspect your problem lies with the cam timing. there is a dot on each of the gears that must line up. After that check no. one cyl. at top dead center for zero degrees on the balancer. Then you can set the ignition timing. I don't care for ported vacuum, it was just a crutch for emmissions but if that's the way it came you can stay with it.
Laughing Gas
Joined: May 2021
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From: Anderson, California
No, like tbear says only at idle and low RPM will it matter. most aftermarket distributors are just a solution looking for a problem, if you can't find a better use for the money you have a really nice pickup.
Performance comes at WOT, and your vacuum drops out and does nothing, it's all on your mechanical curve at that point and that's why it's so crucial to have it right. the vacuum advance is for cruise speeds and lowers your EGT's and improves fuel economy.
Performance comes at WOT, and your vacuum drops out and does nothing, it's all on your mechanical curve at that point and that's why it's so crucial to have it right. the vacuum advance is for cruise speeds and lowers your EGT's and improves fuel economy.
Since 1993, after having the engine rebuilt by a local speed shop, I had pinging gremlins. I fiddle farted around with this and that and even tried Bobs2000 Ford distributor tune to no avail.
Final outcome that got me away from pinging was to just disconnect the vacuum advance and just running mechanical and initial fine.
The engine runs so dang good, whenever I think of trying to re-use the vacuum advance, I change thoughts. hahaha
I've probably over-looked something simple. hahaha
Lead Driver
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Check your timing with the vacuum hooked up at 2800 rpm or so and see what you have, probably you could run your vacuum advance if you limit it. pretty common situation I usually limit mine to about 10-15 degrees. for a total in the low 50's, some engines do well at 60 btc.
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