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MG MGB Technical - crankshaft bolt washer

OK I replaced the head gasket with the help of ARP studs from Brit-tek. No white smoke from the exhaust, no leaks. While adjusting the valves I noticed that the lift on one of the valves was considerably less than the others. Typical valve was .48", one valve was .23" lift. Time to replace the cam? If so the timing chain has to be removed. The crankshaft bolt has a washer with one side bent up. Does the washer have to be flattened out to remove the bolt?

George
G.E. Bulwinkle

Yes, you'll have to flatten the washer to get the socket on. Then use a powerbar, lay it on the nearside chassis rail and operate the starter to slacken the bolt.
Iain MacKintosh

Or just put it in first with the handbrake on and use a breaker-bar as normal.
Paul Hunt

You cannot say 'nearside' unless you know whether the car is LHD or RHD... get it wrong and you make a big dent in the bonnet (hood) at best!

Neil
Neil

Neil is correct. I should of course have said Left Hand.
Iain MacKintosh

And that's facing forwards, not as you are looking into the engine compartment from the front :o)

But what 'nearside' means depends on whether you use the traditional version or the more recent one. Nearside originally meant the left-hand side of a horse (and still does to riders) i.e. the side you mount it from, and that is irrespective of which side of the road *cars* drive on. It just so happens that *is* the kerb side in the UK, and so people have assumed it does refer to the kerb side regardless of which side of the road one drives. The problem with that is, if you take your RHD UK car to a country that drives on the left and have an accident, when making your report to the insurance company which side do you use 'nearside' for? Sensibly of course you don't and use left or right as approppriate. Another confusion is when people talk about 'drivers' and 'passenger' side without thinking that many people with the 'other' configuration also read the posts
Paul Hunt

Daniel Wong had a sensible approach when he replied to another post regarding flasher position - he described it as being on the starboard side.......
David Overington

ok its a locking tab washer. To remove the tab do I flatten it or cut it off?

George
G.E. Bulwinkle

It helps to carefully read Haynes before asking questions.
G.E. Bulwinkle

George,

If you replace your cam, be sure to replace the cam followers or the old ones will most likely ruin the new cam. You should read up on breaking in a new cam.

Also, consider the condition of the cam bearings. And, did you check the condition of your rocker shaft and rocker bushings?

Charley
C R Huff

George..
If you install a new cam you have to install new lifters. On doing so I suggest that you go to your local GM dealer and buy a bottle of EOS- engine oil supplement. This is a break-in additive that is 100-% necessary.
There are plenty of horror stories about camshafts with FLAT lifters that wear (GALL) out prematurely. sometimes less than 1000 miles of use.
Look in archives for reasons as they are numerous.
All MG's up to the latest MGB's have flat lifters.
Sandy
conrad sanders

You just have to flatten the tab to gain full access to the crank bolt. RAY
RAY

I pulled the radiator, flattened the tab on the washer and put a 1/2" drive breaker bar with a 3/4" 1-5/16" socket and about 3 feet of pipe extension. The bolt actually came loose. Thanks to all for your help. The rest of the disassembly is a job for this weekend.
G.E. Bulwinkle

No one has mentioned the need to over tighten the bolt / use loctite on the key / balancer to prevent the balancer from rocking back and forth on the crank, and damaging the crank beyond repair.
Len Fanelli

OK I got the cam out. Measued the lobes as best I could. They are from #1 through #8 are: 1.386", 1.284", 1.239", 1.387", 1.372", 1.327", 1.346", 1.384". Question is: what causes the extreme wear or is it just age and milage?

George
G.E. Bulwinkle

George,

Looking back through the posts, I don't see that you have told either the age or the miles, so it is kind of hard to offer an opinion based on that.

The short story is, if the cam is worn, you need to replace the cam and cam followers.

Charley
C R Huff

If you measure the base circle, they most likely are not uniform, measure base circle, then subtract heel to nose, you will have lobe lift. Rocker ratio is 1:42-1. Most of the time, the soft lifters, or a lifter not turning wears first, before any damage is done to the cam.IMO.
Len Fanelli

The car is a 78 roadster with 130,000 miles on it. It doesn't burn oil and when I had the head off there didn't appear to be any ridges at the tops of the cylinders. Subtracting the base circle and multiplying by 1.42 I get calculated valve lifts of .364", .318", .298",.361",.376",.158", .224",.368". Needless to say I've ordered a new camshaft and new lifters. When I get to the point of installing the tab washers how do I set them so they will line up properly with the lands of the bolt and nut once they are tightened?

George
G.E. Bulwinkle

George,

By tab washers, I'm thinking you are talking about the safety washers that go under the cam and crank bolts?

It's been a few years since I had one apart, but IIRC, they only go on one way. They lock into the cam or crank so that they can't spin along with the bolt/nut. That is the only part you line up. New ones are flat. It helps to bend them just a bit before installing so that you have something to grab onto to bend them up on the head of the bolt/nut after you have tightened it. It's generally a good idea to get new ones.

Have you checked your rocker shaft and rocker bushings yet?

Charley
C R Huff

George
Charley and the guys are giving you good guidance here.Just lateley there seems to be a slight variation in the outside diameter of new followers . It's very important for cam and folower life that the folowers are free to spin in the block. If you happen to get a tight one try it in another bore or another bore till you get the combo all free spinning. I think someone mentioned this earlier but it IS important to make sure they are free spinning. Cheers Willy
WilliamRevit

I'm not sure I'll be able to spin the followers. The engine is an 18V with short lifters. I had to remove the existing ones slowly with a magnet tool. Haven't had a chance to examine the rockers. What should I look for?
G.E. Bulwinkle

George,

I don't mean to be insulting, but the tone of your questions suggests that you are teetering on the edge of your knowledge base.

Do you have a knowledgeable friend nearby that could come to your aid? The friend would not necessarily need to know the MGB. They would just need be engine savvy, say perhaps on a Massey Ferguson tractor.

Regarding the rockers and rocker shaft, you should be looking for wear. I have a lot of machinery, so I can't keep all of the details of each in mind. But, if I remember right, the rocker assembly on the B is spring loaded in such a way that you can slide a rocker down the shaft so that you can see the portion of the shaft that the rocker normally rides on. I'll bet dollars to donuts that if you do so, you will see a ridge in the rocker shaft where the rocker has been riding.

The bushing in the rocker can also be worn. The issue is how much play there is between the rocker and the shaft. If you can move the rocker to a portion of the shaft where it does not normally ride, and it is firm there, then the rocker bushing is okay and maybe you only need a new shaft. If the rocker is loose on an unworn portion of the shaft, then you need both a shaft and bushings. With good luck you will need neither, but I doubt that is likely.

With a lot of play between the rocker and shaft, valve adjustment becomes somewhat meaningless.

Charley
C R Huff

Willy, thanks for the advice. All the tappets move freely. The new cam is in and lubed with cam lube along with new lifters and new timing chain and the valves are adjusted. Still have some work to do but the critical part is done. Charley, sorry if my questions have revealed my ignorance but this is the first MG I have worked on. Engines I have succesfully rebuilt: Water cooled VW (2), VW deisel, Ford V6 (2), Chevrolet V6. By the way my brother in law has a 79 MGB but it is in perfect condition - no work needed. I did consult with a former Chevy employee and GM Institute graduate who recommended a weeks worth of penetrating oil on the crankshaft bolt, which I did and it worked. Just trying to get as much input from knowlegable sources. Thanks for all your advice.
G.E. Bulwinkle

Now all you need to do is correct the cam timing with an earlier double row timing chain & sprocket set, or offset key.
Len Fanelli

Len, I replaced the cam with a stock one. The rest of the engine is stock 78.

George
G.E. Bulwinkle

Done. In the 9 years I've owned this car it has never run this well. Thanks to all for your help.
G.E. Bulwinkle

Good news George. Glad it all worked out for you.

Charley
C R Huff

This thread was discussed between 13/01/2009 and 08/02/2009

MG MGB Technical index

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