great news chris. if you can set it up and you don’t get any ‘funny’ issues at tickover I wouldnt worry too much about the spindles
Read in Viart’s book “XK120 Explored” that the early XK120 engines had no insulating spacers between carbs and manifold, which caused fuel evaporation from the float bowls due to heat soak. To cure this, they started fitting the 1/4" spacers with slightly longer studs. This seems to fit in with what Chris said earlier in this thread.
Chris
The eight studs you want measure 4.75 inches in length. I found it is cheaper to purchase a complete set of inlet manifold studs than to purchase the eight studs individually.
However, I also found that a complete set of XK120 studs typically come with the eight shorter studs.
I ended up purchasing a complete set of XK140 studs, which will always have the eight longer studs, although only some of the other XK140 studs can be used with the XK120 inlet manifold.
I had that problem with my early 120 engine, no spacers, heat soak or vapor lock when I shut off the engine and 5 minutes later the carbs were really hot and it wouldn’t start for a half hour.
I put on the 1/4" thick spacers with an extra gasket and longer studs and it seems to have cured the problem.
The studs are 1/4-20 UNC thread on one end and 1/4-28 UNF thread on the other end.
I bought 6" long bolts with 1/4-20 UNC thread on the end, not full threaded. I cut off the heads to the right length and threaded the other ends 1/4-28 UNF with a die.
Thanks, guys. I have ordered the complete intake manifold stud set from Coventry Auto Components. They do a set for the later XK120 with the longer carb studs.
Looking at it again today, I can see that I cannot use thicker spacers than 1/4" because the jet assembly on the rear carb would foul the steering column on this RHD car. Wouldn’t be a problem with LHD, of course, and LHD owners can get at everything on the carbs so much more easily!
Chris
RHD 120 had a spacer under the RH front engine mount, for that very reason. Is yours missing?
Hi Rob:
The depth of your knowledge of things XK never ceases to amaze me! It has been said before, but may I repeat how fortunate we all are by having your expertise available to us on this forum. Thank
you!
Chris.
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Never thought of that, Rob. But I see from Viart’s book that RHD cars had an extra spacer on the right side. How thick are they, do you know. Should there therefore be one spacer on the left and two on the right?
Thanks for the kind words, Chris.
RHD cars are not often seen in my part of the world, so hopefully someone in the UK, NZ or Australia will respond.
The SPC shows one part 1350 on the right and one on the left, which I think is probably wrong, but that is a draftsman’s mistake by someone who was not really familiar with how a RHD car was assembled.
He has drawn what appear to be two of the lower steel part of the normal C428 rectangular rubber mount.
Viart shows two on the right, which makes sense, would raise up the right side.
As to the C6790 for later cars with the round mounts, if I had to guess it would be the lower steel plate from a C4303 mount. The no. per unit is not given, so guess 2?
A good use for old mounts with bad rubber, save the lower plates. 
the XK140 with button type engine mounts has oval shape alloy spacers or at least one at each point space or cushioning from mount to plinth?
I’ve now looked at my 120 again, and there are no spacers on the front engine mounts at all. However, they would have to be really thick to make much difference to clearance between rear carb and steering column. Maybe the rubber has settled a bit and new mounts would help. I’ve also noticed that there is a line of weld across the engine mounting plate on the RH side (and presumably the left, though I haven’t checked) - could someone have shortened them in the past for some reason, I wonder…?
from my knowledge the spacer is quite tick and only fitted under the right hand side engine mount
Porter mentions that there were two packing plates on the right side of RHDs but does not give a thickness. Urs does not mention them.
Unless we hear from a RHD owner, I would try slipping in a few big washers and see what difference it makes.
By mounting plate I presume you mean the boomerang cross plate as shown as part 158 in the screen shot above. The line of weld could be a repair of a stress crack. Mine had a stress crack that began at the lower right hand bolt attaching it to the timing cover, and was progressing upwards toward the nearest upper bolt hole. I welded it and it has not reappeared.
Stress cracks occur where there is a combination of a sharp notch, stress loading and cyclical vibration, and they progress across the metal until it suddenly gives way. This is often why bridges fall down.
I will try and see if any suppliers stock the mounting shim(s) and how thick they are supposed to be.
As Rob suggests, I might also try jacking up the right side of the engine a bit after undoing mounting nuts to see how much difference it makes to clearance between rear carb and steering column. I’m slightly concerned that this might put unwanted strain on the rubber sandwich mount under the back of the gearbox… Might have to put in a couple of washers under the right side of that mount to take the strain off the rubber. By the way, this is an original RHD car, not a LHD conversion.
Chris,
Just had a look at my early 120 and same as yours there is no spacer. Also the spacer would have to be quite thick to lift the carbies above the steering column. See photos below. I don’t think mine has been modified but who can be sure.
Hope this helps,
Matt
Thanks for the pics, Matt. Yours looks much like mine. I think a thick-ish spacer would have some effect, maybe at least allowing the jet not to touch the column with a heat spacer fitted (though probably not the full 1/4"). I think the jet assembly would always have to be removed to take the rear carb body off altogether.
I’m just about at the stage of removing and overhauling the carbies and I’m going to make gaskets out of heat insulating layered carbon gasket material, need to speak to one of my boiler sub contractors to get the right material. Also have new engine mounts to fit. Slowly, slowly it is all coming together.
Here’s mine, later C.6805 type with added struts.
If that is say a 50 degree angle, then 1/4" of spacers under the C.428 rubber mount would raise the carbs 3/8" up.
Thanks Rob, that’s interesting. I think Viart mentions 3 different part numbers for the engine mounting plate, but doesn’t really explain the differences. I didn’t know about a later version with struts, but it makes sense, helping stiffen up what is apparently a slight weak point. I couldn’t fit struts to mine, as my early block does not have the threaded bosses later used for brackets for the round type engine mount rubbers.
I will try some spacers on the right at some stage and just see what difference it makes.