ride height

[max-it-out]

Just this last week I noticed the car seems to be lower on one side than the other.

N/S ( also driver`s side because its LHD ) is 2 cm lower than O/S ,this is more or less uniform along the length of the car , although maybe a bit more pronounced at the rear .Doesn`t sound like much but it is noticeable and spoils the look of the car.Could it be that due to the extra weight of the fuel tank and also the driver , both being on the same side , that the suspension has sagged more on that side ?

Is there an easy fix , or am I looking at new springs ?

[rswaffie]

Hi,
Front adjustment is via the torsion bar and rears via the springs - although there maybe something you could do with collets/spacers at the rear? I’m sure I’ve seen this discussed in other posts.
Does the ‘sag’ increase when someone sits in the driver’s seat? If not, I’d be inclined (no pun intended) to get the front adjusted first.
Where in South Lincs are you?

[mgcjag]

Hi....whats your name...please try to put it in the signature area......a quick search or look at similar topics below will find lots of info on ride height......what tyres do you have......look at your service manual on where to measure your front ride height and what it should be.....S1/2 cars do not have a documented rear ride height in the service manual....best to measure from the lowest point of the IRS tie plate to ground in general your looking for about 7 1/4 in ..hope this helps...Steve

[max-it-out]

Hi , I`m in Holbeach.Adding spacers to make the rear higher is something I had thought of , but 2 cm is a fair bit so not sure if that would be the best option.If it was just the rear springs that had sagged , would that affect the height at the front as well ?

Its off the road now for the Winter under sheets and a polythene cover,just wiping the chrome bits over with oil to protect them then that's just about it for this season.Next year I plan on taking it up to Doncaster to M+C Wilkinson for an RHD conversion and 2.88 diff change plus a bit of rot in the sills needs dealing with.That might be a good time to get the ride height sorted as well.

I wondered about ditching the Strombergs and replacing with triple SU s , although it seems to run fairly well as it is , more so now I have removed the secondary throttles.The only downside is the mpg - only 17 at the moment.The last E used to do 20-24 on a run , but that was a 3.8 - don`t know if they are slightly more economical.The exhausts ate a sooty black colour although the plugs are a nice pale grey/light brown

[rswaffie]

If M&C are doing some work on it, getting the ride height looked over at the same time seems a good plan.
I’m in Market Deeping so not far from you.
Looking at some of the posts re springs, getting the correct size seems to have been a problem for a number of members, leaving them too high. Glad I kept my originals and just got them powder coated, with new shocks.

[mgcjag]

SNGB adjustable height rear spring/shock...as used on their demo car 50EE...... talk to them about....Steve

[johnetype]

The only downside is the mpg - only 17 at the moment.The last E used to do 20-24 on a run.

Have you changed your distributor for one with the UK advance curve and the vacuum advance operational? When I did that on my Stromberg set-up the mpg improved considerably.

[max-it-out]

Interesting , thanks for that idea , AFAIK the distrib. is the original US one without any vacuum capsule.

Am I correct in thinking that the vacuum capsule retards the ignition when cruising on small throttle openings leading to more efficient burning of the fuel ?

Any idea why the US spec had a different advance curve ?

One advantage the Strombergs have over the SU s ,at least in my ( limited ) experience is ease of starting .Hot or cold it`s instant.The 3.8 I used to have was fine when hot , but a real ba****rd when cold.

[Tom W]

Advance or retard depends on the distributor you have. Most advance the timing under part throttle, high vacuum conditions. This is beneficial, and improves part throttle response and fuel consumption, though won’t improve maximum power.

Some US cars use a vacuum retard distributor in order to meet the emission regulations of the period. This doesn’t offer any performance benefit, it’s more to minimise performance loss whilst still being able to pass the emission test.

[PeterCrespin]

"...it’s more to minimise performance loss whilst still being able to pass the emission test."

"...Am I correct in thinking that the vacuum capsule retards the ignition when cruising on small throttle openings leading to more efficient burning of the fuel ?"

No, and no, sorry.

Vac retard has nothing to do with 'performance up or down - not least because it doesn't operate once the engine is at running temp.

The retard vacuum operates from cold to speed warm-up (when emissions are at their highest). Once up to temp the vacuum is cut off by a thermostatic valve.

[Tom W]

Not entirely true Peter. The S3 had the temperature valve, the S2 with the vac retard didn’t.

[PeterCrespin]

Fair enough Tom. Mine has a thermostatic valve but it’s to do with the hot air blend apparatus. There are also different vacuum take-off points on the varied S2 emissions systems.

Any chance you could clarify how and when 6 cyl vac retard works? Is it different in principle from the S3 if it operates at all times? How does it minimise performance loss? My temptation is always to remove it as a cause of performance loss, not a preventive?

Thanks
Pete

[Tom W]

I’m open to being corrected on this, as I’ve only had the kit in the box, the car’s converted to Webers, but my understanding is as follows. My car had the 3rd gen Stromberg setup with the flat airbox and the vac capsule on the distributor.

The US had a requirement for NOx emissions. Retarding the timing allows this to be passed, but if this is achieved by using a distributor with only mechanical advance, then the performance will be poor as the timing is retarded at all driving conditions. The NOx test isn’t performed at all driving conditions, so the trick (fudge) was to use a distributor with a short mechanical advance curve and a lot of initial advance. The vacuum present under small throttle openings pulls the timing back to where it needs to be to pass the NOx test, and it doesn’t affect the timing under full throttle where the performance is expected. If you remove the vacuum source, and make no other change, I expect you’ll end up with an advance curve that’s over advanced at certain points, though I’ve not plotted it to see exactly what it is.

The heat valve in the air box allows hot air into the intake until the engine is up to temperature. Heating the intake promotes better mixing of the fuel and air, and ensures best atomisation. This helps the car pass emissions requirements from cold. This valve is operated by vacuum. Once up to temperature, the heating can be covered by the intake manifold. The secondary butterflies direct air through a heating chamber, to ensure best optimisation. At wide throttle scenarios, the secondary butterflies open and the intake becomes straighter, restoring some performance. Heating the intake is good for emissions, mixture burn completeness and driveability from cold, but it reduces the volumetric efficiency of the engine as it expands the intake charge.

There was also a vac circuit to draw fumes from the crank case and fuel tank evaporative circuits.

So in essence, the emissions setup is designed and tuned to pass the emissions requirements. It then has a couple of short cuts built into it to improve performance in scenarios where the the emissions weren’t tested, or the requirements were lower.

I’ve not worked on an S3 so no idea how that works, only that it’s more sophisticated/complex.

[PeterCrespin]

Thanks. Para 2 was the new bit I was after. Mine's a flat airbox (i.e. thermostatic vacuum valve) but no vac capsule.

Somewhere in my mind I associate NOx with high burn temps, which I haven't quite reconciled as being cured by raising exh temp via retarding timing. It'll do for me though, until/unless someone comes along to correct or verify.

The S3 used raised exh temps as a rapid warm-up/hydrocarbons solution, not NOx (I think). I'd have to read up to be certain. The thermo switch was in the back of the right side coolant rail and just switched the retard vac off at running temps. Lots are left in situ but isolated via two short loops of hose across the four spigots. That plumbing schema at least saves the car from overheating if the switch fails open and vac retard remains in operation.

The US air injection on sixes and 12s was also to burn off excess hydrocarbons. 'I'm not sure if it helped NOx. I do know that in the late sixties Jaguar had something like two-thirds of their engineers tied up in emissions work, so it's no wonder one or two other areas like S2 rear bodywork around the lamps etc. look a touch rushed.

Regards
Pete

[Tom W]

I did find this on it http://georgiajag.com/Documents/Vacuum% ... Retard.htm

[bitsobrits]

Wow. Serious thread drift.

[abowie]

Jack the car up at the front in the centre of the picture frame so that the front is level. Use a wooden block to protect it. Now look at the rear and see if one side is lower than the other. If so, swap the springs and shocks from one side to the other and see what happens.

Similarly, jack the car up level under the diff and see if the front heights are different. If they are you could readjust the low side TB to give it a little more height and see how you go.