Adjustment of carbs on 65 BJ8

[steveg]

David,
The large screw is called the "slow running valve" or "slow running screw"; the one on the linkage is the "throttle stop adjusting screw" or "throttle stop screw".

If you remove the slow running screw, you should see a spring, a brass washer and the remains of the o-ring. You could use the brass washer to determine the size o-ring you'd need.

The Brooklands book: "SU Carburetters Tuning Tips & Techniques" is highly recommended and has a very good section on rebuilding the HD carb with pictures showing how to install the flexible plastic bushings. I found this process to be easy with the book.

Using this book, when I disassembled my HD8s, I found the plastic bushings had worn and the brass shafts were excellent.

After the rebuilds, my car idles at about 500 rpms with the slow running screws only; if I add just a hair to the throttle stop adjusting screws it idles around 800.

 

[John Turney]

If the O-rings are disintegrated and there is leakage around the throttle shaft bushings, it sounds like time for a rebuild. Fortunately, replacing the plastic bushings on HD8s is relatively easy - no reaming required.

 

[steveg]

Suggest buying a couple of extra of the plastic bushes as they're easy to bung up on installation.

When I rebuilt mine last year, I replaced the following:

Float pins & levers -- floats were OK and grose jets were OK -- otherwise new float jets/needles

Main jets/diaphragms & needles

Throttle shaft bushings per above

Slow running o-rings and their brass washers

Main springs (large coils inside domes)

I bought the jet-centering tool which made that process a piece of cake.

The book mentioned above is a good guide for rebuilding.

 

[DavidThorn]

Great thanks very much didn't realise when you all said `O rings` that`s what there were, just plain O rings , stupid me. I will be able to find those easily enough.

This is the throttle shaft bushings repair kit, its available locally to me at a reasonable price - https://sucarb.co.uk/throttle-spindle-kit-26331.html

Is this the easy fit one that you are referring to? If sounds sounds like a little winter project for me

David Thorn

 

[steveg]

The brass bushings don't look right for the BJ8.

I was referring to item 63 in the Moss page below, which is a parallelogram flat piece of PTFE plastic which you roll around the shaft and insert into the carb body.
Unable to find these at AH Spares, but they probably have them.:

 

[Bob_Spidell]

Agree with Steve, although this might be some sort of replacement using new bushes and rubber seals instead of the teflon wrap. HD8's were used on different makes--including Jag E-Types, I believe--and I think there is some variation between specific carbs (I don't have my BJ8 handy to check, but IIRC the part on the carb body where the shaft enters is flush/flat, and the Burlen picture shows it recessed). Usually the brass bushes, if replaced, have to be reamed to fit the shaft/spindle.

 

[DavidThorn]

OK so I have successfully fitted the O rings and there is a significant improvement at tick over - great.

There is a recess on my carbs just as shown in the Burlen Fuels picture so these seals would seem to fit, I will check with Burlen before ordering. Presumably it cannot be done with the carbs in place so I will tackle it as a winter job. Is it a simple task? If so what is the basic procedure ?

David Thorn

 

[mgtf328]

David,
I too have a later BJ8 which is fitted with Jaguar HD8's. To fit the bushes you show in your pic you need to get the body reamed part way into the body for each bush with a special tool to fit them. I've just had mine done and we nearly made the mistake of reaming straight through the body . The bushes are not the wrap round teflon as the one's shown in Steve's drawing. It's not an easy job. Make sure you know what you're getting into as it's a specialists job. If you need any more info send me you're email.
AJ

 

[Bob_Spidell]

The carbs have to be pulled off simultaneously. The hardest part, IMO, is getting the nuts off/on the bottom studs, esp. on the rear carb. The nuts are 1/2", a 'stubby' end wrench works best for me. I get to the rear by reaching under the front carb (it may be possible to get to them from underneath). I assume your car is right-hand drive, so it should be easier to get the carbs off without the steering shaft in the way

Once the carbs are off, disassembly is straightforward. There are two small, split screws holding each butterfly; pinch the split end together, unscrew the screws and slide the butterflies out then the shaft (spindle) can be withdrawn.

 

[BJ8Healeys]

Re: Adjustment of carbs on 65 BJ*

Because I became confused from the existing SU tuning procedures and conflicts with the workshop manual, Glenn's, and Chilton's I decided to write my own procedures for my own use. The problem with the published procedures is that they change nomenclature of a part in the middle of the procedures, refer to other section of the manual for tuning dual carbs that mention parts not on HD8, etc. I illustrated the ones I wrote with photographs. These have worked well for me and for others, and they are available to anyone who wants them. My e-mail address is below. The procedures are in a Word document, which is an invalid file for uploading here.

Steve Byers
HBJ8L/36666
BJ8 Registry
AHCA Delegate at Large
Havelock, NC USA
sbyers@ec.rr.com

 

[steveg]

Steve - is the document you're emailing different from the one on John Sims' site?:
https://www.healey6.com/Technical/HD8.pdf

 

[BJ8Healeys]

Steve - is the document you're emailing different from the one on John Sims' site?:
https://www.healey6.com/Technical/HD8.pdf

I have continually revised the procedures as recommendations have been submitted to me, and as I have used them myself on my car and others. The latest version is dated 18 June 2018.

 

[RAC68]

Hi Steve,

I have your original document and have found it to be the best. Could you post your latest document as a PDF attachment here for all to use?

All the best,
Ray(64BJ8P1)

 

[BJ8Healeys]

Thanks for the kind words, Ray. The PDF version is 858.6 kb. The limit to post it here is 48.8

 

[John Turney]

I read the maximum pdf attachment size is 976.6 KB.

 

[BJ8Healeys]

I read the maximum pdf attachment size is 976.6 KB.

When I tried to post the .pdf file by browsing to it and clicking on UPLOAD, it wouldn't go. The message I got is that the .pdf limit is 48.6. Right or wrong, the file wouldn't upload and I tried it twice.

 

[John Turney]

I would try posting my copy, but it is shown as 1,177 KB, over my limit. I guess people will just have to send you a PM with their email.