7R case weldable

[pors1968]

Inside and out gone .half case broken rod broken probably crankshaft and oïl pump and cylinder head .Buy another one a lot cheppier.

[Rostrenner]

Originally Posted by Rostrenner

May I use this existing thread to ask for advise regarding my 77 RoW 7R that I have just aquires in Germany: after stripping down the CIS I found the right case to having been welded between two cylinders at some point. Neither proximate head stud nor case bolt seem to have been the problem.

As probably most I intended to build an RS replica performance motor, carbs.. The usual.

Frankly, previous postings worry me quite abit. Could somebody please advise on what best to do?

Thank you very much,

Regards, Jan

Here is what I am referring to:



Thanks, Jan

[Lapkritis]

Opposite of the rod for the other side... curious what the inside looks like.

[Rostrenner]

I "solved" the problem by returning the engine to the seller and collected my money. Thank god this worked out so smoothly.

Thanks a lot, everyone.

[Walt Fricke]

#2 rod my thought also. However, when things have gone sour on my motors, the rod did its damage on the same side as the piston, cylinder, and head area it inhabited. Such as sawing a slot in the case up to the crankcase breather area. externally the opposite case half was not damaged (interior damage basically cosmetic on that side).

Perhaps if a rod bolt failed, the crank could kick the big end up hard enough to bust out a chunk in the area shown? Sometimes a case sort of lucks out (some) after a failure, with the detached rod big end lodged somewhere so it stops flailing around.

[Rostrenner]

#2 rod my thought also. However, when things have gone sour on my motors, the rod did its damage on the same side as the piston, cylinder, and head area it inhabited. Such as sawing a slot in the case up to the crankcase breather area. externally the opposite case half was not damaged (interior damage basically cosmetic on that side).



Perhaps if a rod bolt failed, the crank could kick the big end up hard enough to bust out a chunk in the area shown? Sometimes a case sort of lucks out (some) after a failure, with the detached rod big end lodged somewhere so it stops flailing around.

@ Lapkritis & Walt: I share your opinion, thanks for pointing this out to me - it opened my eyes on cause and possible effects of this damage. On the upside, we saw that cylinders must have been renewed more or less recently due to no visible corrosion. On the downside, I realized that one CIS cylinder heads had a 1973 date stamp on it, with the inlet port looking a bit smaller in diameter at first glance.

Since the motor must have had an interesting life, I simply lost confidence in this buy in the end. Happy that this lesson was rather inexpensive, all in all...

[Walt Fricke]

Different port sizes would be quite a negative sign!