Retorquing cylinder head nuts

[Eric Aldcroft]

Today was the day to get awake my Javelin from its winter hibernation. Since my car has now travelled about 1,000 miles since its engine was assembled, I had decided that based on advice given earlier in this discussion forum by KC, I should re-torque the cylinder head nuts. I knew it wouldn't be straightforward based upon my prior experience, but it was interesting to go through the process again! Firstly of course, I have always wondered how Nut #1 can possibly be tightened with a socket and a torque wrench! I've haven't found this issue discussed anywhere in the Jowett literature that I have. Because Nut #1 is inaccessible to anything but an open ended spanner with the rocker assembly in place, my approach in the past has been to tighten the nuts in reverse order, putting Nut #1 and the rocker arm assembly on last. However, this time, I didn't want to lift the rocker assembly, because I've had problems with properly locating the push rods afterwards, without removing the tappet covers. So I decided to ignore Nut #1 at the start, and first work my way through the others. Now, despite the fact that I have a ground down a 5/16" BSF socket for this very purpose, I still can't get it on Nuts 3 & 5 with the rocker assembly in place. Nuts 2 & 6 are iffy for clearance also! However, since I originally assembled the engine, I've added to my BSF/BSW spanner collection with the help of eBay. My collection now includes a set of double ended box spanners, and one of the set solved the problem. I was able to get it on Nuts 3 & 5 as long as I moved the applicable rocker arm aside. I could then apply the torque wrench to the other (hexagonal) end using a suitable metric socket as the interface. This just left Nut #1 to be torqued using an open ended spanner and my precisely calibrated wrist!

I would be most interested to hear how others accomplish this deceptively problematic task!

Cheers,

Eric Aldcroft

[Chris Cole]

Eric, Nice to hear from the Canadian division of the JCC! I found the sockets fouled the rocker arms. I too have puzzled over this nut tightneing. I could see no other way than the following. I torqued up all the nuts, in sequence, but with the rocker assembly off. Then I whipped off the middle nut, replaced the rocker assembly and did the center nut up with, as you say, an open ender and a calibrated wrist.
I had no problems with the push rods. It helps if you can hold them back / slightly up-hill, so that they don't try to disengage at the cam shaft end. However, I admit to not having re-torqued the nuts after driving a distance yet, but can see no other sensible way. Regards, Chris.

[Eric Aldcroft]

Thanks for the response Chris. Maybe, my problem with locating the pushrods is due to a difference between hydraulic and solid tappets. My engines have hydraulic ones, and I have never seen a solid one, so perhaps the cup at the end of the tappet is different. When I did remove the rocker assemblies to re-torque the nuts, I think I had difficulty with locating three or four pushrods by feel and so resorted to removing the covers.

[Keith Clements]

Many years ago a travelling Snap On salesman saw me working on the Jowett and came up with the tool for the job. It is called a "claws foot wrench". This is an open ended spanner with a half inch square hole at one end to take an extension connected to the torque wrench.
This works; but quite frankly I have become used to using an open ended spanner as there is a better feel. I distrust the torque transmitted through the device. Torquing nuts up is a skill which needs feeling as well as quantitative measurement. By the way this message comes from the start of the Australian Rally.
Also I use a thin socket for the nuts where a normal one does not fit. You may need to use a bit of gentle force to separate the push rods.

[PAUL BEAUMONT]

Keith, yours may be a dialect term, but I believe that these are more commonly called "Crows foot Wrenches" I have to confess that whilst I have used them I have never bought same. They need to be used with care as they can alter the torque readings or settings on your torque wrench beacuse of the extra offset caused by the wrench itself. Probably not relevant for torques like are discussed here, but for smaller torques it can be significant.
Most tool dealers sell them - how available in BSF/WW sizes I don't know.

[Keith Clements]

You are right. suffering from Aus translation disease.

[Robin Fairservice]

Whilst in Australia I obtained a copy of a detailed Jowett tool kit list. This included a description of the cylinder head spanner. This is described as a "Square Drive socket style to suit 3/7" BSF nut (0.595" A/F). Overall 5-9/16" long". Would it be possible for the club to get some of these made, seeing as people are having problems trying to adapt other tools to do the job?

[Andrew Henshall]

Apartently I am guilty of passing Robin info on Javelin tools that contained the line "Square Drive socket style to suit 3/7" BSF nut (0.595" A/F) Overall 5-9/16" long" for the Jav/Jup cylinder head spanner.

Now we sometimes do things a little differently down here, and often have to adapt items due to poor availability, but I can assure everyone that we have not replaced the 3/8" BSF threaded studs in the Jav/Jup crankcases with totally unique 3/7" BSF studs, although I'm sure that a backyard Aussie mechanic somewhere out there beyond the black stump amongst the mulga has already fitted M11 nuts onto his 3/7" BSF studs!

Regards to all my Jowett friends,

Andrew Henshall
JCCA Secretary

[Robin Fairservice]

Oh dear, my lack of typing skills caught up with me. Of course our down under friends probably have 8/3" bolts! Thanks anyway to Andrew for his research work on this subject.

[Mike Allfrey]

Dear Eric,

I note your question about the cylinder head nuts.

Personally, I never torque the No 1 of the sequence. I just hand tighten with an open end spanner. Great care needs to be taken with this nut, because the stud is not screwed into the crankcase far wnough. In addition, it is screwed tight against the copper oil feed pipe flare, not against the shank of the stud, like the other studs, as it really should be.

I never tighten the cylinder head nuts beyond 37 lb.ft.

I now use nuts that are 1/2" thick and are 1/2" across the flats. I think they are 3/8" BSF aircraft nuts. Being slimmer across the flats, they need good quality washers under them.

After assembling an engine, I run it to 75 degrees operating temperature, switch off, let it stabilize for twenty minutes and then torque the nuts. I tioghten, very carefully the No. 1 nut with an open end spanner of good quality.

Hope this helps your dilemma.

Mike Allfrey - E0 SA 42R.

[Mike Allfrey]

Dear Eric,

I have now noted comment about the type of socket to be used to tighten the cylinder head securing nuts.

We have to go back fifty-eight plus years to when the Javelin tool kit was designed. My Javelin is a 1951 PC model and, its tool kit is close to complete. In it there is a socket-like tool with a tommy bar hole at the opposite end to the socket. This is a Britool socket and appears to be genuine. It also uses the tommy bar from the spark plug and other box spanners in the kit. In those days there was not as great a proliferation of dubious Asian torque wrenches as there is now. We, in the trade, took as Gospel the Britool torque wrench settings!

The Jowett supplied Britool socket had the dimensions, at the socket end, of a 3/8" drive Britool standard socket. These are probably extremely rare now in the name of so-called progress. There were also some slim walled Britool sockets that employed a hexagonal drive and could now be driven by a 1/2" drive Allen type socket of appropriate size. Gedore of Germany also made a good thin wall 5/16" Whitworth socket.

Truthfully, I can not see much use for manufacture of the Britool socket, unless it is made with a 3/8" square drive facility. The tommy bar hole could be kept for the sake of authenticity.

Maybe, the Britool socket supplied by Jowett Cars Limited, was the cause of some distorted crankcase faces, due to unskilled use during roadside head gasket repairs? The socket made by Britool can not be blamed though.

As stated in my previous response, probably it is best to go the 1/2" deep, 1/2" AF, 3/8" BSF nut way. I know that it will upset the purists at your local Concours, but my reasoning is that Javelins and Jupiters were built to be driven - reliably.

I now use stainless steel cylinder head studs that are 3 mm longer where they screw into the crankcase, and are 5 mm longer at the thread where the cylinder head nuts screw on. Again, the purists will be upset - but why not, in the interest of reliable service life?

By the way, I still have the 5/16" BSF, 1/2" square drive socket that I ground thinner to cope with the bottom row of nuts forty-three years ago and it still works OK on all other 3/8" BSF hardware on the car. I also use small rubber wedges to hold the push rods in place while torquing the cylinder head nuts with the rocker shafts removed.

Kind regards,

Mike Allfrey - E0 SA 42R

[Eric Aldcroft]

The last message was from me -- it seems I was logged out at the time.

Cheers,

Eric Aldcroft