Discussion
Loctite 504 is an old (1970's) Lotus spec for sealing the 9XX cam carriers and such. It's an old technology sealant, but it works and it's still available. However, it's expensive, not readily available (usually only through industrial supply distributors), and it has fillers that result in a film thickness of about .0015". The film thickness is enough that you need to allow of it when shimming valves. Trial-shim .0015" tight with a dry joint, then when you apply the 504 the film thickness will open up the clearances the last little bit so they end up on-target.
Modern anaeorbic sealants have a film thickness of only .0005" or so... negligible. Ignore it when shimming.
Lotus replaced Loctite 504 with Permabond A136 as their specified sealant for cam carriers. A136 is one of those thin-film anaerobics, it works great, but it's not readily available everywhere. Not in the USA.
Here are a few interchangeable sealants...
Loctite, Permabond, Holdtite, .....Truloc
504 ...... A129 ..... S50 Orange .. 742
515 ...... A136 ..... S55 Purple ... 755
574 ...... A129 ..... S74 Orange .. 742
518 ...... ?
In the Loctite family, 515, 518 and 574 are very similar and work well for our 9XX engine applications. 515 is most similar to A136, but it is generally sold through industrial supply outlets and doesn't show up on retail shelves regularly. It's just not as conveniently available.
Loctite 518 is very similar to 515, but it's a little thicker gel out of the tube, and it's red instead of 515's more purple color. Once cured, you won't notice a difference between 515 & 518 for our Lotus applications. Like most Loctite products, it won't be readily available in neighborhood stores.
However, Permatex Anaerobic Gasket Maker is Loctite 518 private labeled ("518" shows up in the fine-print model number). In the USA, Permatex markets more to the automotive and retail outlets so it's much easier for private parties to find. It's usually in a blue tube on the sealants & adhesives rack in most auto parts stores and in the automotive section of better hardware stores.
574 is another member of that Loctite family (? quick set-up variety ?), but it's another industrial product that's not readily available in local stores. It will work if you have it, but if you have to go looking for it, you may as well look for 515 or 518.
In the UK, Permabond A136 might be more readily available (?) than Loctite products.
Regards,
Tim Engel
Modern anaeorbic sealants have a film thickness of only .0005" or so... negligible. Ignore it when shimming.
Lotus replaced Loctite 504 with Permabond A136 as their specified sealant for cam carriers. A136 is one of those thin-film anaerobics, it works great, but it's not readily available everywhere. Not in the USA.
Here are a few interchangeable sealants...
Loctite, Permabond, Holdtite, .....Truloc
504 ...... A129 ..... S50 Orange .. 742
515 ...... A136 ..... S55 Purple ... 755
574 ...... A129 ..... S74 Orange .. 742
518 ...... ?
In the Loctite family, 515, 518 and 574 are very similar and work well for our 9XX engine applications. 515 is most similar to A136, but it is generally sold through industrial supply outlets and doesn't show up on retail shelves regularly. It's just not as conveniently available.
Loctite 518 is very similar to 515, but it's a little thicker gel out of the tube, and it's red instead of 515's more purple color. Once cured, you won't notice a difference between 515 & 518 for our Lotus applications. Like most Loctite products, it won't be readily available in neighborhood stores.
However, Permatex Anaerobic Gasket Maker is Loctite 518 private labeled ("518" shows up in the fine-print model number). In the USA, Permatex markets more to the automotive and retail outlets so it's much easier for private parties to find. It's usually in a blue tube on the sealants & adhesives rack in most auto parts stores and in the automotive section of better hardware stores.
574 is another member of that Loctite family (? quick set-up variety ?), but it's another industrial product that's not readily available in local stores. It will work if you have it, but if you have to go looking for it, you may as well look for 515 or 518.
In the UK, Permabond A136 might be more readily available (?) than Loctite products.
Regards,
Tim Engel
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