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Opeler
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850 Posts
Discussion Starter · #1 ·
My cam didn't fit!!!

I ordered a combo cam from OGTS and the lifters. The weekend was mine to do a cam swap. The cam slid in thru the inner bearings just like every other cam I've installed. The last or end cam journal was very snug going in. I knew it wasn't right, but I tapped it into place thinking that it would wear in after start-up. But now that the head is torqued down, the engine won't turn. I don't know if the cam was fat at the end, or if my cam bearing had been sized to fit the previous cam, but I am screwed either way. I have to replace the head gasket ( Felpro no-retorque ) and most likely the cam with the possibility of needing head work. Man, doing my own tooling is kicking my ass.
 

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What year is the cylinder head you have? It might have the 'delta' cam bearings, which would make the bearing ID/cam OD smaller than most later heads.
 

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RallyBob said:
What year is the cylinder head you have? It might have the 'delta' cam bearings, which would make the bearing ID/cam OD smaller than most later heads.
I thought that the "delta" head had a BIGGER (not smaller) cam bearing journal diameter, such that the bearing wall thickness was greater, but the bearing inner diameter was the same as every other Opel CIH cam. At least that was the case in my '69 three-bearing "delta" head. I had to get "OP3" cam bearings, as the stock OGTS three-bearing sets were too small. They just slid right through the holes. Or is there another "delta" head...?
 

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Old Opeler
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5,564 Posts
Rule #00

Measure stuff before fitting it together!

Another of Opel's little "joys" is that some cam bearings are different sizes - some on the inside (smaller journals on cam) and others on the outside too (bigger holes in the head where the cam bearings go).
The off-sized heads are marked with a stamped on triangle near the rocker cover gasket rail surface.
All is not Beer and Honeys' with Opel Heads ..... :mad:
 

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Opeler
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850 Posts
Discussion Starter · #5 ·
Well, there doesn't seem to be any triangle stamp on either of the heads I have. I don't know how else to identify the head. The head I tried to install into was from a '71. The other head is from a '70. I used the '71, because it looked fresher and cleaner that the '70. I'm just going to take the head with the stuck cam to my machinist and have him get it right. I may even have the chevy valves installed while I'm at it.
Thanks for your feedback,
Wes
 

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Delta Head

I first heard about the Delta head or cam bearing issue from Dennis at OGTS today. Sure got me thinking before I have the machine shop start any porting or valve work to check... head...cam bearings...cam for proper fit! For once in my life I've heard about a possible nightmare BEFORE I'm living it! My head is going up there as soon as my cam arrives. I also was not aware that a 4 journal Opel camshaft will work in a 3 journal head but not vice versa.

PS- Gary- the Google site search feature is awesome!
 

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Can someone post a picture of the dreaded "Delta Triangle" (just as scarey as the Bermuda Triangle in Opel-dom) which is stamped on the head so we'd have an idea of what to look for and how to identify the Delta head?
 

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1971 GT
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636 Posts
Can someone post a picture of the dreaded "Delta Triangle" (just as scarey as the Bermuda Triangle in Opel-dom) which is stamped on the head so we'd have an idea of what to look for and how to identify the Delta head?
Gordy - Don't know if you are still interested after 3 months, but since I'm dealing with this right now, here you go.
 

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I would be good to get this issue clarified once and for all.

If I understand what I was told:

ALL Opel CIH cams have the same bearing journal OD's. Unless they are worn down!

SOME older three-bearing CIH heads were marked with a "delta" (triangle, like the photo) and the OD of the HEAD cam bearing journal was a bit larger than the "normal" head. As a result, the non-OP3 cam bearings had the correct ID, but were too "thin" and won't fit inside the larger hole (they just slide through). The correct OP3 cam bearings are thicker-walled.

Later CIH heads use the OP5 bearings. These fit all non-delta heads, even the three-bearing head, but you just use three bearings.

MANY cam bearing sets come "unfinished", as in they need to be line-bored to the correct ID AFTER they are installed. Perhaps this is what happened to krewzer's head? Or perhaps "delta" thick-wall bearings were PRESSED into the smaller non-delta head journals? My machinist was VERY concerned about using non-finished bearings, as he didn't think he had the correct boring equipment to properly size them.

RallyBob recommended using the "finished" and "solid" (non-split) cam bearings to me. Many brands (Glyco for example) are "split", although my machinist still thought that they would have been fine. But he was able to source Durabond DUR OP5 bearings for my '71 4-bearing head, and the DUR OP3 "Delta" bearings for my '69 3-bearing head. Although still not running, I did check the cam fitments in both head and they seemed fine. The machinist also did and concurred.

CDN OpelNut, you showed in another thread how your cam bearings were "worn". Was the head hot-tanked? If so, the bearings are almost ALWAYS destroyed by the solution (unless they used a gentler "aluminum" tank).

Any corrections needed to my statements above?
 

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1971 GT
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636 Posts
Keith - Yes my head was tanked and that was likely the culprit. The old cam did not show any wear that one would expect with bearing damage like this.

Here is some info from the Dura-bond catalog regarding Opel bearings:
 

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Old Opeler
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I would be good to get this issue clarified once and for all.

If I understand what I was told:

ALL Opel CIH cams have the same bearing journal OD's. Unless they are worn down!

My machinist was VERY concerned about using non-finished bearings, as he didn't think he had the correct boring equipment to properly size them.


Any corrections needed to my statements above?
Keith, Since the non-finished bearings are well undersize a cam that is worn on the journals (not the lobes) can be ground under-size and the cam bearings bored to fit - hence it is possible, after 35 years, that cam journals can turn up that are undersized - always worth checking!

Standard Sizes:

3-bearing cam journals are:
First (front) - 1.9266"-1.9272" (48.935-48.950mm)
Second - 1.9167"-1.9173" (48.685-48.700mm)
Last - 1.9069"-1.9075" (48.435-48.450mm)

4-bearing cam journals are:
The same on three journals but with the
Third (extra) - 1.9118"-1.9124" (48.560-48.575mm)


There IS a 0.004" (0.1mm) Production undersize journal listed
AND a 0.020" (0.5mm) Service undersize journal listed also.

"Camshafts with 0.004" (0.1mm) undersize installed in production are marked with a violet paint dot between the 4th and 5th cam lobe. Cylinder heads with 0.004" (0.1mm) undersize (cam bearing ID) fitted are also marked with a violet paint dot at the first camshaft bearing."

Then there are the 3-bearing "Delta" heads with oversize OD cam bearings !!

LOVE OPELs



HTH
 
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