The 'E' Type Forum

Does anyone know why the vacuum pipes on my ex.US 2+2 (with twin Stromberg carburettors) have been blanked off by a previous owner?

If you view SNG catalogue for Reservac vacuum pipes

https://www.sngbarratt.com/uk/#!/Englis ... %20-%20RHD

https://www.sngbarratt.com/uk/#!/Englis ... %20-%20LHD

It will show the vacuum pipes and differances between RHD and LHD

might help anwer your question

Hi
I think you will find that a PO will have got rid of emission control gear. On the stromberg there is a temperature controlled bimetallic device on the side that can be vacuum controlled on some carbs there is also an overrun enrichment device also vacuum controlled that is often blocked off.
If you do a google search for buckeye triumph they have a brilliant article on repair and overhaul of strombergs.
Cheers

They do, this is the link:

https://www.buckeyetriumphs.org/carburetors

but be aware that the Strombergs fitted to E types only had fixed needles. Removing the emissions gear is the right thing to do along with holding the secondary manifold permanently open.

Thanks folks.............all helpful stuff.
My question relates to why the ignition vacuum advance/retard take off point on the front carb manifold flange has been blocked off?

Most/many of the Stromberg fitted US emissions engines had distributors with no vacuum advance so if a Stromberg had been fitted at some point which had a vacuum advance take off it would need to be blocked.

Or if the vacuum advance mechanism had failed, a common complaint, then some owners just blanked it off, and the pickup on the carb.
Cheers
mark

I must confess I thought all Lucas distributors had a vacuum system. Mine has. I'm not sure that U.S. cars were any different, in that respect, and I don't see how they got around the problem of advancing the ignition under acceleration without a vacuum.
The last posting, from Mark, is more feasible, but in my case the pickup has been soldered closed so it was a permanent modification. The car seems to run very well without the vacuum system so perhaps it's something to do with big capacity engines in that you don't notice anything is amiss!

There was certainly a significant period when cars destined for the US had no vacuum advance capsule. They still had mechanical advance and that is sufficient to let the engine run seemingly quite well but your mpg will suffer considerably without vacuum advance. I think some of the later cars had a vacuum capsule but it was configured for vacuum retard. You can tell by which side of the diaphragm on the vacuum capsule the take off pipe is mounted if it's a vacuum advance or retard capsule.

Lucas distributors without vacuum advance capsules were fitted to Mini Cooper S's and Lotus Esprits as standard from the factory to name two other examples.

Bigcatfrankie wrote: ↑

Wed Aug 14, 2019 4:28 pm

... I don't see how they got around the problem of advancing the ignition under acceleration without a vacuum....!

The opposite applies, in that light cruise vacuum advance is *abolished* under hard acceleration.

Not sure I'm quite with you there, Peter..........my understanding of the system is that under any sort of acceleration you need to advance the ignition timing so the fuel/air mix is ignited earlier because the pistons are moving faster, but the time it takes for the fuel mix to ignite and cause a bang doesn't change.

Peter is right, vacuum is biggest at part throttle (and max at idle), and advance used for fuel economy. Vacuum is immediately lost during acc and not present at wide open throttle.

Thanks............most helpful, everyone.