I am installing a stock 305 tbi intake, I heard we should use silicone in the wells in the back & front,
do I need to let the silicone dry before installing the intake?

 

dont let it dry. lay it down then put your intake on and try not to move it once set down the first time. then tighten your bolts and itll dry to both pieces to make a complete seal.

 

most like me prefer mr gasket right stuff silicone, they are in a sort of cheese whiz can so it's easy to dispense too.

i love the stuff, hell i was even able to reseal the top plate on my throttle body on my tpi car with it instead of using the intricate gasket, leak free 2.

 

you can seal lots of parts with black silicone trust me i know.

 

May be too late for you, so if it leaks later, try again - EXCEPT - this time let it dry! Put gasketmaket on the sides (small amount), spread, and lay the side gaskets on. Put a bead on the front and back, and let it dry. Then, put more on all around, especially front and back (another bead on top), then lay intake on, put in bolts, and tighten. I did mine with no drying, 3 times it still leaked - last time I let it dry (as above) and it worked fine.

 

it shouldnt leak if you do it right w/o drying. trust me ive done maybe 20+ cars with not letting it dry and not one of those cars has leaked one drop. you mustve not put enough on or made it stick right by smoothing and edge or you missed a spot. i do it for a living wet is the correct way to do it.

 

i agree with the above. + gasket maker works better than your standard silicone too......

but, yah 3/8 bead was always my rule of thumb when i was working with the old timers at a local shop, worked fine on the couple i did. Don't forget to run a dab at the corners where the china walls meet the intake to head gaskets. if not it will probably leak at the corners. Just make sure you drop the intake on where you want it the first time, don't move it much after you have it in place (take your time putting it in in otherwords).

i usually keep 1 bolt in mine to easily locate a hole but, it realy doesn't matter just look at it close.

 

Good advice here. I also like to use some pieces of broken pencil (around 2" long) to stick in the first and last intake bolts to keep the gasket in place as I lower the intake down. I then start at least two bolts, pull the pencil stubs, and install the remaining hardware. A little overlap at the china walls is important.

 

next important thing to putting it in the corners where the heads meet the block would be to clean your surfaces well and remove all the old gasket, silicone, etc that was on there and use brake cleaner or something to wipe the metal down before applying new stuff.