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vaccum advance
- Thread starter mtlman8
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HerronScott
Darth Vader
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Can you confirm that there's no boss in the casting as Jay and that it looks like it was added afterward?
I was about to say that I had never seen anything like it either until I recalled a posting here by someone in the UK that was looking at a TR4A which had a vacuum-assisted brake booster (possibly a factory option). The port for it was installed in the back toward the engine versus on top but in that same general area.
You can see the pictures here in this thread. First picture shows the brake booster and third picture shows the port in the intake.
TR4A with vacuum-assisted brake booster
And here are links to the pictures directly:
I don't suppose there was any chance that you car would have had something like this? That was a left-hand drive car so not sure where it would have been mounted on a right-hand drive car, but the brake line would have to have been routed to it.
I can't think of anything else that would have been vaccum-assisted and needed something like this.
Scott
I was about to say that I had never seen anything like it either until I recalled a posting here by someone in the UK that was looking at a TR4A which had a vacuum-assisted brake booster (possibly a factory option). The port for it was installed in the back toward the engine versus on top but in that same general area.
You can see the pictures here in this thread. First picture shows the brake booster and third picture shows the port in the intake.
TR4A with vacuum-assisted brake booster
And here are links to the pictures directly:
I don't suppose there was any chance that you car would have had something like this? That was a left-hand drive car so not sure where it would have been mounted on a right-hand drive car, but the brake line would have to have been routed to it.
I can't think of anything else that would have been vaccum-assisted and needed something like this.
Scott
HerronScott
Darth Vader
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poolboy said:
That's probably a more likely explanation!
Scott
poolboy
Yoda
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Yes, but more so with the ignition timing and troubleshooting.
https://automotivemileposts.com/garage/v2n8.html
And:
https://www.secondchancegarage.com/public/186.cfm
https://automotivemileposts.com/garage/v2n8.html
And:
https://www.secondchancegarage.com/public/186.cfm
poolboy
Yoda
Offline
It works like a champ for ignition timing.
The damper marks are probably way off due to stretching of the timing chain, wear of the sprocket's teeth, even wear in the dizzy drive gears. A little bit here and a little bit there, and pretty soon the timing marks don't reflect the actual ignition timing.
17 to 18 In-Hg on the Vacuum gauge will put you darn near the engine's sweetspot as far as timing goes.
You might find the section in this Lucas Training Manual informative as to the way timing was set. No mention of marks on the damper.
Check out "Timing: Final Adjustment" about midway on page 22.
https://mgaguru.com/mgtech/books/lts_otcc/Session3_CoilIgnition.pdf
The damper marks are probably way off due to stretching of the timing chain, wear of the sprocket's teeth, even wear in the dizzy drive gears. A little bit here and a little bit there, and pretty soon the timing marks don't reflect the actual ignition timing.
17 to 18 In-Hg on the Vacuum gauge will put you darn near the engine's sweetspot as far as timing goes.
You might find the section in this Lucas Training Manual informative as to the way timing was set. No mention of marks on the damper.
Check out "Timing: Final Adjustment" about midway on page 22.
https://mgaguru.com/mgtech/books/lts_otcc/Session3_CoilIgnition.pdf