R&T Lost Art: The Valve Adjustment

I just found this issue in my locker at work (Road & Track, July 2014) and thought this was a really nice little article.

http://www.roadandtrack.com/car-culture/a8289/lost-art-the-valve-adjustment/

Twenty five years ago, I feared my Honda's 15,000 mile valve adjustment intervals. It was a mysterious and expensive jobs. Now I love doing them myself and I adjust valves any time I get the chance.

Strangely enough, I just picked up that exact same magazine at my British car cub meeting on Saturday. I wasn't sure how the heck you adjusted the bucket and shim setup. Sounds like a pain in the arse.

You had to push down the cup and pull the shim out, measure it, select the correctish shim, push the cup down, install the shim, and remeasure it again.

I am not sorry to see them in the rubbish bin of history.

Manually adjusted valves are still fairly common in industrial engines.

Nissan engines wear loose usually, and can go a long time between adjustments.

Mazdas wear tight, and do so slowly.

Mitsubishi engines wear tight, and should be checked and adjusted first thing every Monday morning.

Donebrokeit wrote: You had to push down the cup and pull the shim out, measure it, select the correctish shim, push the cup down, install the shim, and remeasure it again. I am not sorry to see them in the rubbish bin of history.

Then you float the valves and bounce a shim out and all SORTS of money falls out of your wallet.

So you go to shim under buckets, which require that you measure everything, then remove the camshaft, juggle shims, reassemble, and remeasure...

They aren't in the rubbish bin of history. Some new engines are shim over bucket. When I scrapped a '06ish Jag X-type engine, I saved all 24 of them because they are the same diameter as VW but a bunch lighter.

There's an article in the latest Hot Rod magazine about the Offenhauser engines they used to use in Indy cars. To adjust valve clearances you actually had to file down the valve stems - go too far, and the valve has to be replaced.

Routine maintenance for us Honda owners. Not hard at all, I just take my time and measure each valve several times to make sure each one is dead on.

Shims are a pain though. I had the cams in my SR20 in and out a half dozen times before I got them all right. Funny story, the guy who bought it pulled the head off to rework it. The machine shop did a valve job, but didn't shave the top of the valve stem to compensate the height. He put it back together with the same shims which were now too big, holding every valve open just enough that the car had zero compression.

Checking clearances to .0005", in this case its an exhaust and we want final clearance of .012"

pick through the shims, and get your clearance set

Shim tools make the job easier

stuart in mn wrote: There's an article in the latest Hot Rod magazine about the Offenhauser engines they used to use in Indy cars. To adjust valve clearances you actually had to file down the valve stems - go too far, and the valve has to be replaced.

Actually, we do that with our Miata valves. Ever priced a full set of shims? A good machinist can measure how much is needed and take just that exact amount off.

My first car was a Capri with the 2.8L V6 and it had solid lifters. Easy to adjust, you just had to do it in the correct order as you rotated the engine over. I also owned Capri's with the 2.0L I4. That also was required valve adjustment. I never found it a pain once I learned how to do it but I also can say I don't miss doing it.

A while back I rebuilt a Mazda 1.8L BP engine out of a Escort GT for a guy. It had hydro lifters. Later he bought a later version of a cylinder head off a Miata that had solid lifters.

I had to assemble the head, measure clearances, measure the shim thickness, figure out what I needed and then buy the required shims. Afterwards I figured out why that early '00's Miata was in the pick-n-pull that the guy got the head off of. Someone had worked on the head in the past and totally F&&ked it up by putting random shims in instead of the correct size ones. The engine must have run like crap.

On some of the late model bucket style Toyotas there is no adjustment or shim. You have to replace the lifter.

The late BPs from Mazda all seem to run very similar shim sizes, they're pretty close to that already.

Ahh, you all adjusted valves from the top. On a 914 you adjust the valves from underneath. For two of the eight valves, you have one hand around one side of the trailing arm and your other arm going around the other side of the trailing arm.

Just a reminder: don't adjust 914 valves while lying on the ground with whiplash from a recent rear-ending or you might not be able to ride in a car without stabilizing your head with both hands. Just sayin'...

Scared to death about adjusting the CM200's valves. But with a little help from the manual and YouTube, easy as pie.

In reply to Zomby Woof:

Seems they never really need adjusting though, along with most of the bucket over shim designs, thankfully.

jimbbski wrote: My first car was a Capri with the 2.8L V6 and it had solid lifters. Easy to adjust, you just had to do it in the correct order as you rotated the engine over.

Exhaust opening, intake closing, and follow the firing order. If you're smart, you have an underhood momentary switch to bump the starter hardwired into the car.

I understand Porsche did this, small wire in the harness near the generator. Tap it to the battery feed on the generator to bump the starter.

Our 2005 Honda Element would not run from cold starting at about 125,000 miles, after numerous dead end fixes it ended up being the valves. Not the intake, they were spot on, it was the exhaust valves. They had tightened up. Now at 153,000 miles and no issues.

Had to check vakve clearances in the 3208 before taking Moby the Road Condo on ta rect trip, the job kinda took me back a ways, to when I had the hotrod 510 in the... when was that? gad. the 80's?

So this is why some of the new cars cost $200-300 for a valve adjustment instead of $30-40 my Nissan truck used to cost?

The DOHC 907 in my Jensen Healey is shim under bucket. You have to run down both the intake and exhaust sides and record the existing valve clearance, then remove the cam towers without popping the buckets off of the valves, that's not easy when you are trying to make sure all 8 buckets stay with their valves! You then measure the existing shim and add/subtract as necessary, we Loti typically run them about .002 loose. That's because as the valve face and seat wear the valve 'grows' up out of the head, setting them to spec means you'll be doing it again before you want to. The 9xx engines are interference so you have to be really careful when you put things back together. Not only that, but where the cam tower seals to the head you use Loctite 518 and that will add about .0015 to your valve lash; at least it's not like the early 907's that used paper gaskets. Yeah, it's a royal pain in the ass. The best part is that Saab valve shims work perfectly, you don't have to rely on Lotus shims ($$$$). If you get really lucky you can just swap the existing shims around to achieve proper settings.

Be prepared to spend several hours doing this and for the car to be down a few days as you wait for the shims to show up. Or spend cubic $$$$ on a selection of shims.

Both my X 1/9's had shim over bucket. As long as you had the right tool and compressed air to blow the shim out of the bucket they were easy to adjust. My WR400 Yamaha had the same setup (5 valve Genesis type engine) but it was necessary to remove the cams to do it, the best thing about that bike was every time I checked the valves they were within spec! I never had to actually adjust them.

Knurled wrote:

jimbbski wrote: My first car was a Capri with the 2.8L V6 and it had solid lifters. Easy to adjust, you just had to do it in the correct order as you rotated the engine over.

Exhaust opening, intake closing, and follow the firing order. If you're smart, you have an underhood momentary switch to bump the starter hardwired into the car. I understand Porsche did this, small wire in the harness near the generator. Tap it to the battery feed on the generator to bump the starter.

You mean that you don't do it with the ENGINE RUNNING?

Amateurs ...

slantvaliant wrote:

Knurled wrote:

jimbbski wrote: My first car was a Capri with the 2.8L V6 and it had solid lifters. Easy to adjust, you just had to do it in the correct order as you rotated the engine over.

Exhaust opening, intake closing, and follow the firing order. If you're smart, you have an underhood momentary switch to bump the starter hardwired into the car. I understand Porsche did this, small wire in the harness near the generator. Tap it to the battery feed on the generator to bump the starter.

You mean that you don't do it with the ENGINE RUNNING? Amateurs ...

Don't laugh

Knurled wrote:

jimbbski wrote: My first car was a Capri with the 2.8L V6 and it had solid lifters. Easy to adjust, you just had to do it in the correct order as you rotated the engine over.

Exhaust opening, intake closing, and follow the firing order. If you're smart, you have an underhood momentary switch to bump the starter hardwired into the car. I understand Porsche did this, small wire in the harness near the generator. Tap it to the battery feed on the generator to bump the starter.

MGBs conveniently have the starter solenoid signal wire very close to the 'fuse box' (if you have ever looked at an MGB you will know why I put fuse box in quotes). Pull the signal wire off its connection, and touch it to the hot side of any of the fuse posts to bump the starter.

MAKE SURE THE CAR IS IN NEUTRAL FIRST...

In reply to spitfirebill:As mentioned in the article, I lot of the labor time on newer cars is dealing with all the electronics and wires. Not just adjusting the valves alone. But many older cars, such as Jaguars. were hugely expensive for a valve adjustment.

You had to measure and record all the valve gaps. Then remove the cams & check to see what shim was under each bucket. Then calculate what size shim you needed. After all the "new" shims were in place you reinstalled the cams, remeasured, & hoped you got it right.

The shims were marked with letters. So there was another chart to tell you what size shim each letter designated.