Hi , sorry if this has been discussed before ( tried a search but couldn`t find anything ).
The distributor on my car ( 1968 1.5 roadster ex-US ) does not have a vacuum capsule ( that end of the unit has an alloy blanking cap/plug fitted ).
Fuel economy is poor , so maybe fitting a vacuum advance would improve it.
Would it be possible to just buy the vac. capsule and fit it onto the existing dist. or would it be better to buy a new dist. with the vac. already in place .Also , would a dist. calibrated for a s. 1 4.2 be ok ? ( my car has the Strombergs and a different inlet manifold to the SU set-up ).
Hoping someone has been through this already. Thanks
I bought two from them a couple of years back for my XK120 and Mark V, and BTW I discovered that the threaded studs were not BA thread. You may not have that problem with the E-Type.
I see that they also sell what they call an adjuster blank, for '68 E only.
Is that what you mean by an alloy blanking cap/plug?
They do not explain the usage of this, so you might want to check with the E-Type forum for enlightenment there.
You should also check that the fitting on the bottom of the carb, where the copper tube would normally connect, is not open to atmosphere, or that would certainly lead to poor running.
The distributor for a series 1 1/2 is specific to that carburetor set up. It works very well, if properly lubricated. I would remove it and clean and lubricate it. Check to see if the centrifugal advance springs are in good shape and not broken, and that the weights move freely. Contrary to popular belief Series 1 1/2 E’s moved pretty damn good for the beginning of emission controled vehicles.
RR thanks for those pics - I think the second photo shows the arrangement I have ATM . I will check with XKs Unlimited as to the fitment of a vac, unit and how easy it is to remove and re-fit.
The car starts and runs ok , nice steady idle easily adjustable via the screw .I had a look ( using a mirror ) at the under side of the carbs but could not see any opening where a tube might fit , so one less thing to worry about.
Had a close look at the internals of the dist. and they appear new ( shiny ) also the wires are new , so it was probably overhauled by the p.o.
Longer term ( ie . when finances allow ) maybe the best option would be the 123 tune plus fuel injection plus big valve ( s. 3 ) head.
No fitting at all, capped or open? I am not familiar with the S-1.5 so perhaps they eliminated it altogether, in which case a vacuum unit would not work. You would have to drill and tap a hole for a vacuum fitting on the bottom of the carb. Better get some S-1.5 experts to advise there.
The mechanical advance system operates by weights turning the cam assembly - advancing it as rpm increases. It should have enough advance, if working properly to give you reasonable fuel ecomomy, so as suggested you need to first determine it’s actually operating - that is does the cam move radially on the dist. drive shaft.
The vacuum advance system works by have the internal plate the points sit on rotate relative to the distributor body, and relative to the motion of the cam caused by the weights. So for the vacuum to work you need to have a working two part plate in the distributor. I don’t know how the later no vacuum distributors were configured but I suspect that they either don’t have the two part rotating plate or if they do it’s immobilized. You can probably buy these parts used.
The distributor and more importantly the particular advance curve in your distributor was not developed to be used with vacuum advance.
The most straight forward action might be to buy a brand new Series 1 Pertronix distributor with vacuum capsule for under $200. You get rid of points, a Series 1 advance curve, a vac advance, and the copper tube for vacuum, and new tight shaft bushings so your dwell is consistent.
What is your fuel mileage? A vac adv. will add a few mpg if you are driving at a steady speed with light load (as in highway). But if you’re driving around town not so much.
Do you know if your mechanical advance is working properly?
Hi DA My distrib. looks like a standard type ( as seen in the above photos ) except for the vac. capsule. In its place is a blanking/adjuster connected to the base plate via a spring.This allows a small amount of advance/retard by turning the knurled screw.
The internals of the dist. look shiny , so I`m guessing the PO may have overhauled/rebuilt it.AFAIK the weights and springs inside are functioning ok although this has not been tested.
The car starts and runs ok , mpg is around 17 with gentle highway driving ( this is probably the best that can be achieved ).
Your idea about a new Pertonix dist. sounds excellent ( and I agree on your point about the advance curve maybe not being optimal ) - just what I`m looking for , thanks. I had considered one of the 123 type , but would prefer a more conventional set-up.
17mpg is a typical mpg for mixed driving. A 60’s V8 muscle car is lucky at 10mpg.
Its Smiles per Gallon that count.
If you are knowledgeable and capable of using a timing light, you can check your ignition timing to see if the mechanical advance is properly working. The specs are in the Bentley shop manual.
If ignition timing is not within your abilities, do not try to install a new distributor. Find a competent Jag mechanic. Its not a big job for a qualified individual.
