I have a problem with my intake bolts on my ZZ454. They keep loosening up. I had to replace the intake gaskets because after just a few miles on the motor because they loosened up and I had an antifreeze leak. So now I keep tightening them because I worry it will happen again. I'm torqing them to 25ft lbs. But every few weeks I torque them again and they do turn slightly. Any ideas? Should I leave it alone and stop worrying if it is just slightly loosening up?

My tech manual says to torque the bolts down to 30-35 foot pounds in 5 pound increments. Hope this helps.

Could I ask what tech manual that is? Is this for aluminum heads?

Its an S-A design "how to build a big block chevrolet" book. I have the small block book also which has the same torque figure. I torqued the bolts like it stated on an aluminum edelbrock manifold with no problems. I had to put sealent on the threads though because some of the bolts would let oil up through even when torqued to 35 ftlbs.

I forgot to add that I use ARP bolts for the intake manifold because they have a high psi rating. I snapped a couple of cheap spectre performance products intake bolts because I tried to john wayne it when I misplaced my torque wrench. Darn thing was under some shop rags and didnt find it until I went looking for my bolt extractor.

The ZZ454 came with the ARPs. I must admit, I'd be afraid to tighten it that much with Aluminum heads. But this may be my problem why its loosening up.

su,
I hate to tell people to not do things the "correct" way, but I dont think I have ever used a torque wrench on intake manifold bolts except on the late model engines where it is very important. On a big block Chevy, I just tighten them until they are good and tight. Then check them again in a few days. I have never stripped an intake bolt. Grab a 8" long wrench and pull them tight, bet you will not have any problems.
Just my opinion,

WHOA, aluminum heads, hold off on the torque, I would call the place you got the motor from and ask them about the torque specs for aluminum heads to an aluminum intake manifold. I was under the inpresion you had iron heads.
I have never had aluminum heads, just intake manifolds. sorry about the confusion.

I think consistency is important. You know how easy it is for an aluminum intake manifold to warp. That is why I feel torquing them down is important starting from the middle of the manifold and working your way out. Its the amount of torque that I'm not sure of. If I didn't use a torque wrench, I would surely not go tight enough... Dealer told me 25-30. 30 just sound like too much. Maybe I'll leave it alone for a while and just make sure it doesn't loosen too much....

I used to have problems with my arp intake bolts loosening up on my vortec intake. I finally used blue lock tite, they sealed and stayed tight

I have a Ram Jet 502 with aluminum heads. Probably not much different than your application as far as the torque setting go. Here's the proper setting from my owmers manual....

First pass......10 ft.-lbs.
second pass...37 ft.-lbs.

Hope this helps....:waving: