Guys, What would be wrong when the head lights intermittently go up and down by themselves under hard acceleration? Car is a 1969 BB. Thanks
1969 head lights bob up and down under hard acceleration
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Re: 1969 head lights bob up and down under hard accleration
A little study of how the vacuum system works (CSM is a good place to start along with a search on here) and some troubleshooting and repair will make your engine run a whole lot better. If you want to see how much better quickly, disconnect the vacuum system from the intake and plug the port. Then tune the engine as it should be and go for a drive.Terry- Top
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Re: 1969 head lights bob up and down under hard accleration
Your vacuum system has a large leak, which can not make the engine run well, and the vacuum system check valve (second item from the vacuum port on the intake) is AFU.
A little study of how the vacuum system works (CSM is a good place to start along with a search on here) and some troubleshooting and repair will make your engine run a whole lot better. If you want to see how much better quickly, disconnect the vacuum system from the intake and plug the port. Then tune the engine as it should be and go for a drive.
how exactly will this make the engine run poorly? Rough idle?
if I pull the vaccume line off the intake then wha t should happen? What if I put my finger over the fitting and plug it. What should happen?
thanks for any education on this subject
Regards
don- Top
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Re: 1969 head lights bob up and down under hard accleration
Terry
how exactly will this make the engine run poorly? Rough idle?
if I pull the vaccume line off the intake then wha t should happen? What if I put my finger over the fitting and plug it. What should happen?
thanks for any education on this subject
Regards
don
Yes, you can hold your finger over the opening once you pull the vacuum system hose off the intake fitting, but driving the car will be difficult with you trying to run beside it. I would encourage you to get a plastic or rubber cap to cover the fitting. These are available at your FLAPS (Friendly Local Auto Store) in an assortment of sizes. The cap will allow you much more flexibility in operating your vehicle.Terry- Top
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Re: 1969 head lights bob up and down under hard accleration
Terry;
You're a crack up!
Thanks for the response. Personally I've been trying to diagnose a rough idle and have done everything on the outside of the engine to correct it but nothing has. I did unhook the intake Vacuum line and put my finger over it but don't recall anything changing. So I was asking for more details so I could test again. I guess if I take off and plug and that does not improve my idle I know I have to keep looking.
Regards- Top
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Re: 1969 head lights bob up and down under hard accleration
Terry;
You're a crack up!
Thanks for the response. Personally I've been trying to diagnose a rough idle and have done everything on the outside of the engine to correct it but nothing has. I did unhook the intake Vacuum line and put my finger over it but don't recall anything changing. So I was asking for more details so I could test again. I guess if I take off and plug and that does not improve my idle I know I have to keep looking.
Regards
The fit of the carburetor(s) to the intake manifold is another source of vacuum leaks. If you are blessed with a Holley there can be internal vacuum leaks due to poor or deteriorated gaskets and material warping. Not that other brands of carburetor don't warp, but they are less sensitive to it.Terry- Top
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Re: 1969 head lights bob up and down under hard accleration
Russ my 1970 Corvette headlight on the passenger side would come up under heavy acceleration and go back down when the acceleration was ended. I disconnected the hose going to the 70's vacuum tank and plugged the vacuum fitting on the manifold. Don't usually drive at night in my 1970 any more, the headlights pull up so easy when I have and I am very familiar with how they operate and just pull on the elbow linkage to lower the headlights when I through with night time use.
When my 1970 was new I remember how I could go to my car two days after driving it and the vacuum was so good that there was enough stored to raise the headlights without starting my 70.- Top
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Re: 1969 head lights bob up and down under hard accleration
I'm thinking that this might be more of an adjustment issue at the headlamp actuator than vacuum. It is not low vacuum. The up and down motion is based on vacuum being applied to one side of the diaphragm or the other. The mechanism that opens the doors has an over-center design that, along with an adjustable stop, locks the headlamps into a fixed position. If properly adjusted, once up and locked, you cannot simply push down on the door to make it go down, you have to pull it down using the actuator rod.- Top
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Re: 1969 head lights bob up and down under hard accleration
I'm thinking that this might be more of an adjustment issue at the headlamp actuator than vacuum. It is not low vacuum. The up and down motion is based on vacuum being applied to one side of the diaphragm or the other. The mechanism that opens the doors has an over-center design that, along with an adjustable stop, locks the headlamps into a fixed position. If properly adjusted, once up and locked, you cannot simply push down on the door to make it go down, you have to pull it down using the actuator rod.
We should also remember we are troubleshooting this issue over the Internet. There is no substitute for hands-on diagnosis. Troubleshooting over the Internet is not a whole lot better than throwing parts at a problem, and in some cases may even be worse.Terry- Top
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