Been trying to google this one for years to no avail.
Here are things I remember about the movie:
1.) The monster had long arms/tentacles
2.) The protagonists kill it in the end by using some form of gunpowder fuse that they light with a cigarette. The house it was in explodes, and you hear it wailing as it burns up. I think you even see the tentacles moving around in the flames.
3.) Earlier in the movie a girl falls down into a cavelike basement area. Her friends above say they will go for help, and while she waits you see the monster emerge from the shadows. Then I frantically changed the channel, so unfortunately can’t say what happened next.
Without Warning (1980)?
http://www.imdb.com/title/tt0081764/
or, could also be The Boogens (1981)
http://www.imdb.com/title/tt0082094/?ref_=fn_al_tt_1
“The Strangeness”(1985)?
http://www.imdb.com/title/tt0234817/?ref_=fn_al_tt_1
Wow. That’s the one! Good pull. It’s amazing how different those scenes feel seeing them now 25 years later. They scared me to death as a kid and I had the image of the monster burned into my memory, but now it’s quite laughable. I can now move on:)
Thanks Livinghead (and GG and Ron Marshall for your suggestions)!
Thank you bpack, glad you found it!
Here is a picture of the creature, don’t look too long at it.
https://horrorpediadotcom.files.wordpress.com/2013/07/strangeness3.jpg
There’s a movie called Tentacles from the late seventies
Solved!