Thread: Please help I am racking my brain on this one.

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Originally Posted by aahx2011

They came with a small tube of black rtv silicone.

Use the Silicone Luke.

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Originally Posted by aahx2011

Since I have had this leak I have gone through three sets of intake gaskets and each time they did not even come with the rubber china wall gaskets at all. They came with a small tube of black rtv silicone. It is hard for me to use silicone at all, I was always taught that if it has a gasket do not use silicone as that is what the gasket is for. And I have seen what using to much silicone can do to an engine especially when it is used to excess.

Being a GM technician for too many years, I have to agree. Use the silicone. Not any silicone, but use the Ultra Black. Of the hundreds of intakes I have done on small blocks, I've only had one come back due to a oil leak. I always put a 1/4 inch bead down for the "China wall". Now are you sure it's the intake? Most blocks have a oil port in the rear along with the dist which can also leak. I have seen a few people forget to plug the oil port or not have the gasket on the dist.

On the few where the "China wall" fell into the block, GM released a Technical Bulliten years ago for how to keep that from happening. Basically you use a punch to create small indents to keep the "China wall" from falling in. I've only used that one time, and I really don't think it was needed. The customer asked for it.

350 intake valley 004.JPG350 intake valley 005.JPG350 intake valley 003.JPG350 intake valley 001.JPG

Originally Posted by autotec

Most blocks have a oil port in the rear along with the dist which can also leak. I have seen a few people forget to plug the oil port or not have the gasket on the dist.

I hope that it worked I tried to attach some pictures, the oil port I believe you are talking about is the one that I have my oil pressure gauge plugged into at this moment. Please let me know if we are on a different page on this as I have been known to miss an oil galley plug here and there.

Do yourself a favor and disconnect the oil line and move it out of the way until you have the manifold secured. They are much too easy to crimp and it will be easier to set the manifold on with it out of the way.

A couple drops of oil on the threads of the brass fittings will go a long way to guarantee a leak free fitting.

Keep us posted on the leaks, good thread with lots of usefull info. Personaly I've also had good luck with the black RTV for my 460 big block. Only time will tell though!

On the assembly line at the Chevy V8 engine plant in Flint MI we used a product called Threebond. I’ve never seen it sold in parts stores any place, but that’s what GM used to seal the "China Wall.” (Tech, thats the first time I’ve seen that term used outside the assembly plant! It takes it’s name from it’s resemblance to, you guessed it, The Great Wall Of China). We also used guide pins to align the bolt holes in the intake with holes in the heads. The pins also held the gaskets in place. As was stated earlier, this only works with intakes with vertical bolt holes. The Threebond was applied, intake gaskets were set into place with the ends set into the wet sealer and the intake was set in place immediately. Engines that sat for more than five minutes (such as when the line was shut down for break time or lunch period) had the already applied sealer, (applied by a robot) removed and reapplied by hand prior to dropping the intake manifold. The engines were in the test stands and being fired up within 2 hours after assembly.

Reset the intake and this time I used almost and entire tube of silicone on the "China Wall". Did not let the silicone set for more than five minutes and it was probably a good 1/2 inch thick. Once the intake was set and torqued down I let it set for a couple of hours while everything else was reasebeled. The best part is no more oil leaks on this engine. This one has deffinatley been a learning experience for me.

one time I tore down a sbc that had silicone on the China wall. there was a chunk of it stuck to the screen on the oil pump pick up. Not enough to hurt anything but if it is inside it will go to the bottom.

If you let the silicone completely cure (24hrs min.) before you fire it up, it will not chunk, flake or otherwise cause problems.

bringing this back from the past as it has some excellent info at the right time for us
cheers
Hank