I have a 67 coupe Deville with a 429, I have done this intake manifold 4 times now and it still leaks. The motor has about 6000 miles but it did sit for 16 years. The heads were redone by Wayne's engine rebuilding about 150 miles ago and i have 180 psi on all 8 cylinders. I had just recently (before this install) had the intake resurfaced. I had it magnafluxed by another place and they said there were a few minor cracks and didn't seem to go all the way through, they did seem a little shady. I shimmed the heat riser ports on this install with 24 gauge stainless steel. I was having problems with fuel boiling over in carb due to too much heat. I have ran it and drove it and it seems to run actually better than it ever has but there is still a constant shake in the motor. I have the timing set at 8 degrees btdc, there is a modified cam in motor. No matter what I do with air mixture screws I cannot get it to level out. I sprayed starter fluid at ports that connect to head and it almost dies, same thing it has always done ever time I redo the gaskets. Is there any manifolds that will bolt to this engine with spacers of any kind? Is there anyone who builds manifolds for this motor? I'm willing to try anything at this point, any help would be greatly appreciated.