Monday, July 6, 2015

Rebuilding The Rockers

<This post is part of the 'New Engine Rebuild' project>
In the previous post I got the head checked over and painted up ready to go onto the block, but what use is a head without the rockers? None I hear you shout, and you'd be right, well maybe apart from using it as a door stopper for a very large door, say a barn door for example or even a paper weight for use in stormy weather! Anyway, back to the rockers, time to sort them out...

Over the last year or so, I've acquired a number of rocker assemblies in a variety of different conditions, some obviously better than others. The set that came with the last engine seemed to be in a decent enough state but were a little stiff and were coated with some kind of black muck. For this reason I decided to strip them down and make sure the oil-ways were clear.

Taking the rockers apart is a fairly straight forward job. Once the split pins are removed from the two ends, almost everything apart from the locking post just slides off the main shaft. There are 5 rockers on one side...

... and 3 on the other.

This leaves just the locking post left to do...

Once the small grub screw is removed though, it too can be slid off the shaft, which at this point looks more like a flute.

When everything was in bits all the parts were soaked in diesel to remove the grease and grime, then scrubbed with hot soapy water and rinsed and finally dunked in oil and left them to drain.

While I was checking the rockers, I noticed that some of them had wear marks where they make contact with the top of the valves. Most weren't too bad, but some were a bit more noticeable.

This is one I took off the car last year. Thankfully none of the rockers I have in this set are that bad.

Any wear on the underside of the rockers is hidden when they are in the car so you never really know how good or bad they are. The problem come though when you need to set the gap between the rocker and the valve, the so-called 'tappet clearance'. When you slip the feeler gauge in to check the gap, you think it's correct, but what the feeler can't measure is the depth of the wear. That extra gap means that the rocker arm needs to travel further to make contact with the valve and that will alter the valve timing making it open late and close early.

Because of this, I wanted to make sure that my rockers were free from wear in order to get the best performance from the engine. Trouble is though new items are a bit pricey and all my spare rockers were showing some signs of wear. So what to do? Some Hooliganism is what's needed here I think!

I had the bright idea of picking out eight of the best rockers I had available and polishing out the wear from the surface. When I say polish, I actually mean file/grind past the wear marks with a hand file and some emery paper and then polish the surface as much as possible. Would this work, I have no idea at all, but it's worth a try.

Polishing the Rocker Tips.
With the rocker held in a vice, I started out with a hand file to try to get past the wear marks. On the whole, this worked very well, but due to the fact that the tips of the rockers are hardened, it did take a very long time and quickly became on of those jobs you wish you hadn't started.

After 8 to 10 minutes of none stop filing, the wear marks were starting to become less noticeable.

And then another 10ish minutes to get past the wear mark.

Now I wrapped the file in some 800 grit emery paper and spend the same time again polishing the scratch marks out left by the file.

Once I was happy that the 800 grit had done its job, I moved onto some 2500 grit to get a really smooth surface and when that was done, it was polished up with some metal polish to leave a nice lustrous surface.

As you can imagine, this is a long and very tedious process that requires a mountain of patience. I also discovered later that day that my hands were ruined as they didn't want to work properly due to the pain of holding the file for so long. As I progressed through the rockers over that week though, the pain did start to get less and less as my hands got used to the work.

It's worth throwing in at this point that some of the rockers had hidden problems that didn't come to light until after a little filing forced them to reveal their secrets. Two of the rockers had suffered a little lamination damage where the tip pushes on the valve resulting in the surface pealing away.

Here is a quick video of the process...

After about a weeks work (on and off), all the rockers were ready for final assembly, which to be honest is really easy if you took lots of pictures beforehand, so I won't go into it here. This article I wrote last year goes into more details if you are interested further.

Well was all that work worth it? I have no idea! Will it give me a problem when setting the valve clearances? I have no idea! Will the fact I have removed metal effect the valve lift height? I have no idea! Could I have damaged the hardness of the rocker arm by filing it away? I have no idea!

You get the picture here, I really have no clue if any of this was worth the effort or even if it will have a positive of negative effect of the future wear of the rockers. The only way to find out is to put them in, run them for a while and check them again in say 500-1000 miles or so.

I'll stick an update on here at some point in the future after the engine has been running for a while and we will see what the effect has been.

In the short term, I'll also let you know how it goes when they have been installed and I can check the valve lift height with my dial gauge.

None of that can happen of course until I stick the head on the block, so guess what's coming next ...

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