Camshaft????
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Joined: Jul 2002
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From: Long Island USA
13.5 is pretty low, 14 is about right, especially by "todays" standards.
Anyway, ported vacuum:
Ford's distributors, when you apply vacuum, ADVANCE the timing. So, what you want is, at idle, no vacuum. Touch the gas, the vacuum is applied, and advances the timing a bit.
Manifold vacuum is exactly opposite of that. It's high at idle, and drops off as you push down the go-pedal.
If it was hooked to manifold vacuum, when you timed it at idle to a "normal" range, it would idle OK. But hit the go-pedal it would RETARD the vacuum and cause a complete bog.
There are times, when band-aiding a very radical cam, where you would want that behavior, but in your case, probably not so much.
--
The low-end power might be timing related. You might not have enough initial timing now. It would be a good thing to check what the mechanic set it to, and report back with what you find.
Anyway, ported vacuum:
Ford's distributors, when you apply vacuum, ADVANCE the timing. So, what you want is, at idle, no vacuum. Touch the gas, the vacuum is applied, and advances the timing a bit.
Manifold vacuum is exactly opposite of that. It's high at idle, and drops off as you push down the go-pedal.
If it was hooked to manifold vacuum, when you timed it at idle to a "normal" range, it would idle OK. But hit the go-pedal it would RETARD the vacuum and cause a complete bog.
There are times, when band-aiding a very radical cam, where you would want that behavior, but in your case, probably not so much.
--
The low-end power might be timing related. You might not have enough initial timing now. It would be a good thing to check what the mechanic set it to, and report back with what you find.
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Senior User
Joined: May 2010
Posts: 280
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From: ROCKVILLE, CT.
Questions
13.5 is pretty low, 14 is about right, especially by "todays" standards.
Anyway, ported vacuum:
Ford's distributors, when you apply vacuum, ADVANCE the timing. So, what you want is, at idle, no vacuum. Touch the gas, the vacuum is applied, and advances the timing a bit.
Manifold vacuum is exactly opposite of that. It's high at idle, and drops off as you push down the go-pedal.
If it was hooked to manifold vacuum, when you timed it at idle to a "normal" range, it would idle OK. But hit the go-pedal it would RETARD the vacuum and cause a complete bog.
There are times, when band-aiding a very radical cam, where you would want that behavior, but in your case, probably not so much.
--
The low-end power might be timing related. You might not have enough initial timing now. It would be a good thing to check what the mechanic set it to, and report back with what you find.
Anyway, ported vacuum:
Ford's distributors, when you apply vacuum, ADVANCE the timing. So, what you want is, at idle, no vacuum. Touch the gas, the vacuum is applied, and advances the timing a bit.
Manifold vacuum is exactly opposite of that. It's high at idle, and drops off as you push down the go-pedal.
If it was hooked to manifold vacuum, when you timed it at idle to a "normal" range, it would idle OK. But hit the go-pedal it would RETARD the vacuum and cause a complete bog.
There are times, when band-aiding a very radical cam, where you would want that behavior, but in your case, probably not so much.
--
The low-end power might be timing related. You might not have enough initial timing now. It would be a good thing to check what the mechanic set it to, and report back with what you find.
What would be a good example of band-aiding a radical cam?
I still am wondering why it has the OEM voltage reg still hooked up and an aftermarket one on the alternator itself? Could this be why the charge reading is low?
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 423
From: Long Island USA
I doubt the regulator on the fenderwell has anything to do with that. It's probably not even hooked up anymore. But, check it - where do the wires from the stock regulator go?
If that alternator is not stock, the pully size might be too big compared to the crank pulley and it's not spinning fast enough to keep the full charge. But - who knows. 13.5 volts is "not bad". I would just leave well enough alone at this point.
As for the band-aid, well, radical cams, the more radical they get, the worse the idle vacuum gets. So brake power booster, or anything else that runs on vacuum, starts to get weak.
If you advance the idle timing, and adjust the carb idle to compensate, the vacuum gets better. The band-aid comes when you would have very high compression, a very radical cam, and need to advance the timing at idle to get any decent vacuum, but also need to keep the engine from pinging when you hit the gas. So, you hook the vacuum advance to manifold vacuum. That pulls the timing way up at idle, drops it when you hit the gas, and retards the timing when starting so it starts easily. It's NOT recommended to do it that way, the engine should be built right from the get-go. I personally did it with the 390 I built for my highboy, because I was trying to get as much low-end torque as possible with a radical cam, and 11:1 compression. And it worked great. But I was unwilling to fore-go the low-end torque and the huge cam and high compression
If that alternator is not stock, the pully size might be too big compared to the crank pulley and it's not spinning fast enough to keep the full charge. But - who knows. 13.5 volts is "not bad". I would just leave well enough alone at this point.
As for the band-aid, well, radical cams, the more radical they get, the worse the idle vacuum gets. So brake power booster, or anything else that runs on vacuum, starts to get weak.
If you advance the idle timing, and adjust the carb idle to compensate, the vacuum gets better. The band-aid comes when you would have very high compression, a very radical cam, and need to advance the timing at idle to get any decent vacuum, but also need to keep the engine from pinging when you hit the gas. So, you hook the vacuum advance to manifold vacuum. That pulls the timing way up at idle, drops it when you hit the gas, and retards the timing when starting so it starts easily. It's NOT recommended to do it that way, the engine should be built right from the get-go. I personally did it with the 390 I built for my highboy, because I was trying to get as much low-end torque as possible with a radical cam, and 11:1 compression. And it worked great. But I was unwilling to fore-go the low-end torque and the huge cam and high compression
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Senior User
Joined: May 2010
Posts: 280
Likes: 0
From: ROCKVILLE, CT.
Wow
I doubt the regulator on the fenderwell has anything to do with that. It's probably not even hooked up anymore. But, check it - where do the wires from the stock regulator go?
If that alternator is not stock, the pully size might be too big compared to the crank pulley and it's not spinning fast enough to keep the full charge. But - who knows. 13.5 volts is "not bad". I would just leave well enough alone at this point.
As for the band-aid, well, radical cams, the more radical they get, the worse the idle vacuum gets. So brake power booster, or anything else that runs on vacuum, starts to get weak.
If you advance the idle timing, and adjust the carb idle to compensate, the vacuum gets better. The band-aid comes when you would have very high compression, a very radical cam, and need to advance the timing at idle to get any decent vacuum, but also need to keep the engine from pinging when you hit the gas. So, you hook the vacuum advance to manifold vacuum. That pulls the timing way up at idle, drops it when you hit the gas, and retards the timing when starting so it starts easily. It's NOT recommended to do it that way, the engine should be built right from the get-go. I personally did it with the 390 I built for my highboy, because I was trying to get as much low-end torque as possible with a radical cam, and 11:1 compression. And it worked great. But I was unwilling to fore-go the low-end torque and the huge cam and high compression
If that alternator is not stock, the pully size might be too big compared to the crank pulley and it's not spinning fast enough to keep the full charge. But - who knows. 13.5 volts is "not bad". I would just leave well enough alone at this point.
As for the band-aid, well, radical cams, the more radical they get, the worse the idle vacuum gets. So brake power booster, or anything else that runs on vacuum, starts to get weak.
If you advance the idle timing, and adjust the carb idle to compensate, the vacuum gets better. The band-aid comes when you would have very high compression, a very radical cam, and need to advance the timing at idle to get any decent vacuum, but also need to keep the engine from pinging when you hit the gas. So, you hook the vacuum advance to manifold vacuum. That pulls the timing way up at idle, drops it when you hit the gas, and retards the timing when starting so it starts easily. It's NOT recommended to do it that way, the engine should be built right from the get-go. I personally did it with the 390 I built for my highboy, because I was trying to get as much low-end torque as possible with a radical cam, and 11:1 compression. And it worked great. But I was unwilling to fore-go the low-end torque and the huge cam and high compression
The real downside is not knowing what this engine is all about. I need to sit down with the paper work. The problem is from what I have perused is there is not much explanation as to what the cam or compression is. I highly doubt the cam is radical and you got me on comp. ratio.
Like I said. I intend on talking to the mechanic and hopefully he can help.
As far as the voltage reg goes. It looks like the OEM one is still wired into the harness and connects to the solenoid on battery side. I don't have it in front of me right now but from memory it is like this.
The aftermarket is wired to the field, stator, power and ground connections on the alternator and the " power " wire goes from the alternator to the battery side of the solenoid. Total of 5 wires comes out of this voltage reg. w/ one wire ( orange w/ female connector ) not attached to anything ( just like the one I replaced ).
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