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Super Moderator
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Not likely. That’s would be a massive misfit.

Stock Chevy keepers fit the Opel retainer taper but they are the wrong overall diameter. This means that only about 50% of the taper is in contact.
Bob, I assume that if Chevy-style valves are used, then the complete valve assembly:

1) valve
2) spring
3) retainer
4) keepers

Must be kept all Chevy. Is that a fair assumption?

Gordo, perhaps ask Charles to confirm what parts of your valve assembly were "Chevy" , and what was "Opel".

The valve is Chevy, presumably w/ 11/32" stems. That is ~8.73 mm, so smaller than the OEM Opel 9 mm valves.

Were the springs and retainers "Opel", but the keepers Chevy?

I am working on a 1.9 CIH w/ 11/32" Chevy valves, and Opel springs are slightly smaller than the Chevy retainers. So I doubt the shop would have mixed Opel retainers and Chevy springs, but perhaps?

On the subject, also ask Charles what spring pressures (installed and open, and at what lift) the shop built the head to. Should have figured that out when the head was built, as changing to Chevy valves is NOT plug and play. The valves pressures, spring installed height and open height should be in the build sheet.
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Just Some Dude in Jersey
15,689 Posts
Discussion Starter · #104 ·
Woop! Woop! A new, slightly used, 2.4 piston arrived from Rally Bob today to replace my damaged one! Of course, Bob just had to polish it. 🤪 It's pretty darn new looking, even after the polishing the patination marks are still visible on the top and sides. He said it came from his Dad's 2.4 in the early 90's. 2.4 pistons have full floating pins that don't need to be pressed in, they are held in by spring clips instead. Interesting: There seem to be strips of steel with markings that are stamped in place inside the pistons. I'm one step closer to fixing my dropped valve mishap! Thanks Bob! 😍

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Super Moderator
14,056 Posts
I think that the 96.76 number on that piston is its diameter. Your damaged piston looks like it is 94.97.
What's the clearance, Clarance?
The piston I sent is 94.96 mm.
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