The Stovebolt Site Forums The Shop Area Engine Shop Loctite RTV won’t set up on intake

I mounted a 4 bbl intake on a 283 last night. I used a unopened tube of “Loctite” copper RTV gasket maker. I put small dabs of the stuff where instruction tell you too. I was putting on other stuff around engine today and noticed the RTV was still like it just came out of the tube. Temps in the high 50’s and around 60% humidity. I thought the stuff would ‘harden’ within 20+ hours. Phone call to company was no help. Has anyone else had this problem? And if the stuff doesn’t harden,any real harm? Thanks.

RTV doesn't set up well in low humidity situations- - - -not sure if 60% is enough or not. Try squeezing a bead of the same sealer out on a piece of cardboard on the workbench and see if it sets that way. You might have gotten a bad batch of sealer in that tube. On very dry days, I've had to use a sprtiz bottle of water to get RTV to start curing.
Jerry

Whenever I use RTV, I let the surface skin up before I assemble the parts. Its still gooey underneath, but it is less prone to smearing out of place while joining the parts. If you had done that before putting the intake on, you could have noticed the problem. My hindsight is 100% flawless, ain't it?
If it were mine, at this point, I would leave it alone for another 2-3 days to see if it sets up. If it doesn't set up after that, then I'd take it back off and buy some Black or Gray High Heat RTV (my two favorite go to products) and reinstall the manifold. I am not suggesting that the copper RTV is not a good product. I am saying that I would now be superstitious about it after it failed on me. Superstitions, while scientifically invalid, make me feel better about myself so often that I succumb to them from time to time. This would be one of those times.
Give it a couple more days, don't walk under ladders, nor let a black cat cross your track. It may set up.
Carl

Loctite 5920 takes 7 days to cure. At 50% humidity and 70 deg F. Do not use motor for 7 days. Assemble within minutes. Wait 7 days.
It is moisture curing, so your 60% is perfect.

I know nothing about “Loctite” 5920. I have never had a RTV product that didn’t harden within 24 hours, or at least start to. As suggested, I will let it cure, if it’s going to, for several days as I complete the assembly in the engine deck. I have no plans to remove the intake. I will run it failed or otherwise and toss all my “Loctite” products as far as these old arms can toss them. Thanks.

No No no, you didn't do anything wrong and Loctite is good stuff. I was assuming that you got the 5920. If you got some other Loctite copper sealant, could be a different cure. All the companies sell RTV. It just means Room Temperature Vulcanizing. It's silicone. There are MANY types of RTV. Indeed, the Loctite RED cures in 24 hours. Loctite Copper 5920 RTV is 7 days. Only 6 more days. I try not to use ANY RTV.