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Has anyone used these guides in their rebuild? I bought a set for a customer's engine and have a question about fitting them. As you know, the original guides are secured by a circlip which fits into a recess machined into the head. The improved guides don't utilize the circlip, instead having a flange. The flange is too large to fit into the recess for the circlip. Question is are the guides just installed until the flange seats and the spring seat modified to fit over them (nothing actually securing them from up-and-down movement then), or does the head need to machined so that the flange sits flush in the head? Neither is particularly optimum IMO.

Early engines use guides with circlips, part number 16.02.15

Later engines use the flanged guide, part number 16.02.19

I ordered 16.01.15 and the appropriate circlips, but apparently the only guides available from NLM are the "improved quality" with the flange, so that's what Stuart sent.

Early style guide with circlip.



Early style spring seat



Later style guide, recessed in head



Later style spring seat



Since the majority of heads are going to take the later type guide (that presumably at least Morini thought was an "improved" design), it makes sense that NLM have only commissioned that type (in an "improved" Bronze material). NLM are probably the largest customer for these guides themselves.

The spring seats are two part with a ground shim in a pressed steel cup. Morini don't appear to have changed the part number for the seat.

Thanks Paul. I really don't want to modify the heads to accommodate the later type guides, so may try machining the flange off and cutting the circlip groove in the new guides.

Just as a follow-up - I machined the flange on the "improved" guides down to just over 12 mm in diameter and .85 mm wide. They now fit into the head and spring seats without alteration to either.

The customer is glad he hired the right guy to rebuild his engine.

Mepstein wrote:The customer is glad he hired the right guy to rebuild his engine.