Throttle return springs

[Treetrimmer]

Hi Folks,

As usual I'm slightly confused, and hope someone out there can help!

Firstly, how many throttle return springs should be fitted to the 3.8 litre engine? I appear to have 3, whereas the workshop manual (W.S.M.) shows only 2.

As found, I have two springs attaching to the actual throttle shafts, via little "bell cranks", (item 54 on page C4 of the W.S.M., and also item 55, which appears to be incorrectly identified.) On my car, spring 76 attaches to bracket 77, and then onto the carburettor nearest the windscreen, via the bell crank labelled as 55. I then have a third spring attached to item 83, (also on page C4), and then onto bracket 74.
The second part of my query relates to where Bracket 74 (74 0n page C4 ) attaches to the car. This was providing the lower fixing point for the unidentified throttle spring. As found, bracket 74 was attached via two of the nuts securing the inlet manifold, whereas recent information indicates the bracket should attach via the two lower studs securing the front-most carburettor. It doesn't help that the numbering in the parts book (plate 7) differs to that in the Workshop Manual (page C4) !

Can one of you kind folks please put me out of my misery!

Regards to you all in Jaguar land.

Richard Hinds

Regards, Richard Hinds

[Glyn Ruck]

You should have 2 throttle return springs. Long one to oil filter housing bracket. Short one to bracket attached to carbs.

throttle springs 1.JPG (164.02 KiB) Viewed 1310 times

Throttle springs.jpg (282.43 KiB) Viewed 1309 times

Front throttle spring bracket..JPG (167.13 KiB) Viewed 1307 times

Bracket-Assembly-on-Front-Carburetor-950x925.jpg (61.69 KiB) Viewed 1300 times

Carbs1.JPG (40.63 KiB) Viewed 1303 times

[cass3958]

As Glyn states just the two. The longer one hooks on to a metal bar that is like a washer on one of the bolts for the oil filter housing.
This is a very dirty picture showing the oil filter housing taken during my strip down and the bar that the spring hooks onto.

IMG_0354.jpg (1.17 MiB) Viewed 1276 times

[Treetrimmer]

A big "thank you" to Glyn and Cass for your replies and supporting photos.

I'm please to say I've now got the "Y" piece in the correct location, and both springs attached as per Jaguar's design.

The third spring I mentioned is obviously an addition by a previous owner. The lower end of this third spring is secured by a cable tie to one of the pipes to the inlet manifold, that form part of the A.E.D., system. The upper end of the third spring is attached to a bell crank on the extreme L.H.S. Of the throttle shaft, of the Carb., nearest to the windscreen.
I think I'll leave this light spring in place, as it makes it easier to ensure both butterflies are fully closed, before tightening the "inter-connectors" between both Carbs, thus assisting with synchronising the two carbs.

Other than this minor alteration, I'm gradually getting my car back to production specification.

Once again, thank you for your assistance.

Regards, Richard

[Glyn Ruck]

Just make sure your 3rd spring is an ultra light spring or you will accelerate wear on the butterfly shafts. Far better to check for alignment & lubricate every part of the accelerator linkage. People usually put a 3rd spring on to get the car to settle to the correct idle speed. More spring power is NOT the advised fix.

Good luck!

[minimeadow]

I took my carburetors off this week and realized that I'm missing both the short spring and the "Y" bracket. The long return spring that runs down to the oil filter housing exists, and seemed to do an adequate job closing the throttles. However, I'd like to have both, for originality and possibly as a safety backup in the event the other spring comes loose while the engine is running.

Looking for these parts online, I don't find the exact bracket, but there is a similar one for the E type:

https://www.englishparts.com/products/J ... 15963.html

I might have to try a couple springs to get the correct length. Any thoughts on how else to solve this problem?

[Glyn Ruck]

Modify one of the numerous brackets offered by SNG Barratt.

[minimeadow]

Glyn, thanks. The carbs are back on the engine, and this bracket worked with no modifications:

https://www.sngbarratt.com/English/#/US ... b480770063