'58 Sq 4 Head removal

[paul.sammut]

Decided to disassemble my 1958 Square Four as it has not run in several years and have read enough disaster stories about engine blow-ups because of sludge in the crank oil pathways. The only handbook (owner's manual) is particularly unhelpful so thought I'd ask the experts since this is my first attempt at working on a Sq 4 engine.
The book shows a diagram containing 18 head bolts and suggests a tightening (thus, I assume, the reverse for loosening) sequence, but my head appears to have only 10 bolts visible on top and 4 nuts on studs underneath the head. I know there have been various iterations of the heads over the years and wonder whether mine is different or am I just blind? Also, the bolts that hold in the rocker spindles - do they go deep into the barrel and therefore must be removed to lift the head or can they be left in place as they come out with the head?
Hopefully, these questions are not too stupid and someone can help - I'd rather be safe than sorry.
Thanks in advance,
Paul.

[phil.auldridge]

Hi Paul,
Unless you have some strange aberration, no doubt your engine has the 18 studs just like all the MK II engines. Here's a good head/block explosion on the Draganfly website, which may be similar to your manual: https://www.draganfly.co.uk/ariel/4-str ... nd-1953-58
Note that while the rocker tower studs do NOT extend into the block, you do have to remove the external oil transfer lines at the rocker mechanism to get to the bolts/nuts underneath.

As far as loosening sequence of stud nuts, I'd likely not be too concerned with that, however, with the chart there, certainly no downside in following that procedure.

I have completely rebuilt my engine, but it's been 18 months now, so my memory of how that head looks is a bit fuzzy. However, I did document much of the process on my own personal blog, and you might find some useful tidbits there: http://blog.auldridge.org/2018/01/16/th ... s-revenge/

If you remove the rocker covers and the front engine mount plates, you can remove (and reinstall) the entire engine in one big hunk, then build some sort of stand/fixture to work on the baby. I don't know why they don't mention that technique in the manual, which had me worrying the frame would interfere, but it really came out pretty easily.

sometimes that head can be a bugger to separate from the block, and of course, the last thing you want is to break off a cooling fin or two by prying on it. one suggestion: remove the exhaust manifolds, then fashion a lift bar on each side from 2" x 1/4 or 5/16" bar stock. Make the bar a good 3 feet in length or so, then drill holes to slip the bar over the 4 exhaust studs on each side, and cinch the bar down with nuts and spacers. Now, with the block secured to the floor, get a friend to grab the bar on each side, while you do the same on the other side, just pull and rock the head until it lets go!

Get a MORGO pump (expensive, I know, but probably the cheapest insurance you can get for your engine's health.. there are other UK sources for the Morgo significantly less cost than Draganfly) have your crank oil galleys drilled out slightly oversized. Order replacement "sludge trap" plug/screws, as they will most certainly get buggered with removing them.

Good luck, and keep us posted on your project. If you have further questions, feel free to either PM me, or use the CONTACT tab on my Blog.


Phil A.

[paul.sammut]

Good for you Paul,
Glad you discovered those issues before further damage could happen. I learned a long time ago that so-called owner "overhauls" can range anywhere from mechanically perfect, to nothing more than a Krylon spray job on the fins. My own engine was supposed overhauled "just 1,000 miles ago" and I wound up suffering blocked crank oil passages and a thrown rod after less than 100 miles of riding.

At this point in my life, unless I know the engine was done by a reputable, well-known professional in the community, I would take any claims of owner "overhaul" with a grain of salt!

I consider myself to be a pretty decent amateur wrench, and have overhauled more engines than I can count, ranging from a Vespa to twin turbo double overhead cam car engine. nevertheless, I soon learned that this Ariel engine, despite their apparent simplicity, do have lots of unique aspects to them that I would never have known to address without professional guidance.

For this, I must give a shout-out to Paul Ackerman, in Maine (he advertises his gaskets in the club news bulletin), who provided expert guidance; oversight of the machinist (also in Maine); and lower-end assembly for my engine. It was a long process, and not cheap (although Paul's hourly rate is very reasonable), but I am so glad I left the intricate details to him. My engine now has about 1,200 miles on it, and I couldn't be more pleased with the final result. It is smooth as butter, runs about 60PSI oil pressure at cruise speed, starts easily, and pulls like a freight train.

Of course, hopefully your engine hasn't suffered the catastrophic damage mine did, so I trust you'll have it all back together in good order and on the road again.
Phil

Phil,

Thank you so much for very kind response.
As it happens, it doesn't matter as I figured it out and feel a bit silly - all I had to do was remove the rockers and that included the extra 4 head bolts I was looking for.

Also, thank goodness I'd decided to disassemble the engine as I was headed for disaster - as I removed the push-rods, I noticed that numbers 5 & 6 (my numbering system, counting from right across to left) were deeply gouged. In the push-rod tunnel there was a broken tappet bolt and nut sitting on top of the cam followers! I checked all the valve adjusters and all 8 are intact. The broken part must've fallen in at the time of a previous build and not been noticed by the p.o. or whomever the builder was. I hate to think of the swarf circulating in my oil and I will inspect the entire engine very carefully.

Cheers, and thank you, again.

Paul