HS8 AED removal?

[alan-87]

Im in the process of rebuilding my HS8 carbs and wondered if anyone had any info on removing / bypassing the AED?

The carbs are on a 4.2xk engine which the previous owner has put a manual choke control onto the top half of the aed in place of the metal strip. Im not convinced it works overly well, so looking at removing the whole lot. Cold starts wont be an issue as its anweekend car and only used if the sun is shining.

Would also be interested in any info on manual choke conversion.

[a8hex]

You can convert to using the manual choke arrangement from the E-Type.
My XK150 has a 4.2 engine conversion with triple carb setup with the manual choke arrangement on just the middle carb.

[alan-87]

Thats interesting ill have to have a look. Does it still run the aed or is that removed?

[Mopar440]

The manual choke just pulls the jet down to give a richer mixture.

[Jaguar steve]

There was a manual choke kit to convert the AED to manual operation available. It replaced part of the AED unit and operated the cold mixture enrichment by replacing the bi metalic strip controlling the cold and warm up mixture and aux air bleed with a couple of manually operated cams running off a normal choke cable. I fitted one to my first XJ. Carefully set up it worked well.

I guess the original AED unit has ruined many, many XK motors, it wasn't uncommon to find that the carbs had been adjusted so far out of tune to compensate for a failing AED that the net effect was the engine was running really rich most of the time diluting the lube oil and washing the bores.

[alan-87]

Jaguar steve said:

There was a manual choke kit to convert the AED to manual operation available. It replaced part of the AED unit and operated the cold mixture enrichment by replacing the bi metalic strip controlling the cold and warm up mixture and aux air bleed with a couple of manually operated cams running off a normal choke cable. I fitted one to my first XJ. Carefully set up it worked well.

This is exactly what i have currently. The lobes on the cams have become warn and it doesnt operate very well. Ideally id just like to lose the whole lot.

[Piersman2]

Maybe try and repair the AED you have, does this kit have eveything you need?

http://sucarb.co.uk/aed-repair-kit.html

I vaguely remember one of my previous jags having AED issues and I think I ended up fitting the manual conversion, worked well enough, I seem to recall the AED unit being about £250 to buy a new replacement at the time so the manual conversion was a far better option.

[richw_82]

The only thing the cam arrangement does is to give a manual override to the AED and remove the necessity of heated air and a bimettalic strip. Most people with one of these conversions are convinced it can't go wrong despite there being two diapraghms in the unit further down that can - and will - perish and split.

Unless you're a purist or concours entrant, get rid of the AED entirely. Its best use is a doorstop or paperweight.

Edited by richw_82 on Friday 23 January 09:27

Edited by richw_82 on Friday 23 January 09:27

[alan-87]

Thanks Rich. Appreciate the extra info over on RR. Im going to have a proper look over the article tonight and see what is needed to convert it. At a quick glance i couldnt work out where the new parts linked to on the carbs

[richw_82]

The bolts that hold the jet assemblies are replaced with two that have an elongated head, with a recess in it. The link bar then fits between them, with the lever arms fitted on it operating both jets in sync. Give me a yell on here or RR if you get stuck.