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Broken rocker arms
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langer74
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Joined: April 24, 2017
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Location: Lebanon Oregon PNW
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PostPosted: Sun Jul 16, 2017 12:36 pm    Post subject: Broken rocker arms Reply with quote

Hey all.... first time asker long time reader.
Working on a 74 bay window. Barely ran when I got it. Turned out to be 3 broken rocker arms. All on exhaust ports. 1,23. Tig welded and it held for a few revs. Then broke again. Any thoughts as to why??? And where to buy replacement parts of the same pitch degree and angle.
1800cc dual carb. Solex 32/34 pict.
I adjusted following the spec listed on the engine.
.006 intake and .008 exhaust
Thanks in advance
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Tcash
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PostPosted: Sun Jul 16, 2017 1:26 pm    Post subject: Re: Broken rocker arms Reply with quote

Type I or Type IV engine?
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bugguy1967
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PostPosted: Sun Jul 16, 2017 1:41 pm    Post subject: Re: Broken rocker arms Reply with quote

Well welding them makes them softer than before. They need to be re-hardened after welding. The reason why they broke in the first place could be a number of things: seized valves, retainers bottoming out, coil bind, rockers seizing to shaft, valve float...
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williamM
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PostPosted: Sun Jul 16, 2017 1:44 pm    Post subject: Re: Broken rocker arms Reply with quote

X2- what are we talking about here?-- but in either case not much to choose from.

1 Embarassed seized valves in the guides.- After reading lots of samba- was surprised to hear of people NOT reaming guides on a new valve job. (most common)

2 Mad rockers Not oiling thru the push rod tubes. A dry rocker will run a while, but sooner or later will "blue up and die." as they don't have a bushing they just freeze solid and if opening a valve, will be bound up and broken when the piston hits the valve- look for bent push rods and color on the rocker. (rare- as there is a bit of oil flying round up there.)

3 Crying or Very sad meaty double strong valve springs- Not a problem with normal build but if spring bound or just to damn strong, they can be an issue. Would watch the compression of the valve spring and see if there is room between the coils when compressed by the cam lobe.


Laughing see what happens when you type slow.
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raygreenwood
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PostPosted: Sun Jul 16, 2017 3:33 pm    Post subject: Re: Broken rocker arms Reply with quote

You do not weld rocker arms. They should be easy to find.....then again...no one knows where you are located. You need to post your location in your signature line.

Several sets are in the classified ads....including one set machined for swivel feet.


https://www.thesamba.com/vw/classifieds/search.php...ds=Rockers

He has.....as he noted an 1800 with twin carbs. In a 1974 bay.....that would be a 1.8L type 4....but again posting it would help.

Ray
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langer74
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Location: Lebanon Oregon PNW
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PostPosted: Sun Jul 16, 2017 5:27 pm    Post subject: Re: Broken rocker arms Reply with quote

Woops.
1.8l I'm guessing type 4?
I'm in oregon.
As to replacement ones. I've heard not to change to a 1.4 without Changing other parts at the same time. There are several available but aren't the 1.1 ratio. I have pulled a set of a spare parts bus. 76 2.0l. Mine now seems to run like a champ. But I'm not doing any road driving. Just up and Dow the 1000 ft driveway
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Tcash
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PostPosted: Sun Jul 16, 2017 10:14 pm    Post subject: Re: Broken rocker arms Reply with quote

Engine Type ID T2

Type IV rockers are beefy and not prone to breaking.
I am not aware of any place that sells new Type IV rockers. Used is all you can get.
The new rockers you are seeing must be for a Type I engine. Type I rockers will not work on a Type IV engine.

As posted check that the valve spring coils are not binding at full lift.

Since the rockers broke. Check for bent pushrods. Pull them out and role them on a piece of glass to check them for straightness . Keep track of which hole they came out of, so you can put them back in the same location.
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Wasted youth
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PostPosted: Sun Jul 16, 2017 10:36 pm    Post subject: Re: Broken rocker arms Reply with quote

Do you have the Bentley service manual yet? You are very near the edge of a slippery slope. Having an immediately accessible printed book at your side can be a wonderful thing. Technical specifications, weights, measurements and exploded parts diagrams are complimented by written procedures. Every entry is indicated by chapter, page and figure number so the entire community can reference this and provide insight and guidance for many questions and comments.
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langer74
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Location: Lebanon Oregon PNW
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PostPosted: Mon Jul 17, 2017 10:36 am    Post subject: Re: Broken rocker arms Reply with quote

thanks all.
I've ordered the Bentley service manual...
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