427 Intake install

[Jack O.]

I posted previously about having oil in my intake manifold and head runners. I decided to do a "test fit" of my intake with new gaskets to check that it was torquing down properly. I went ahead and used the provided rubber end gaskets that come with the intake gasket set. I noticed that once I have the intake torqued down there is a full 1/8" gap front and back. Too much for those gaskets alone to seal. I've been advised to use a silicone based sealant there instead of the gaskets anyway but was wondering if this 1/8" gap is unusual and perhaps an indication of an overall fit problem with the intake. Also, since the intake bolts do not utilize a lock washer should I use locktite and check the torque periodically?
Thanks,
Jack

[Clem Z.]

Re: 427 Intake install

I posted previously about having oil in my intake manifold and head runners. I decided to do a "test fit" of my intake with new gaskets to check that it was torquing down properly. I went ahead and used the provided rubber end gaskets that come with the intake gasket set. I noticed that once I have the intake torqued down there is a full 1/8" gap front and back. Too much for those gaskets alone to seal. I've been advised to use a silicone based sealant there instead of the gaskets anyway but was wondering if this 1/8" gap is unusual and perhaps an indication of an overall fit problem with the intake. Also, since the intake bolts do not utilize a lock washer should I use locktite and check the torque periodically?
Thanks,
Jack

make sure to use "stock" type gaskets as most aftermarket "race" type gaskets are too hard a material to get a good seal on production engines. check the "fit" to the heads without any gaskets to make sure someone has not done a "bad" job of cutting the heads and the intake interface is not square to the manifold surface. silicone sealer will work BUT make sure you "rub" a thin layer onto the block and intake surface to make sure the "bead" will "wet" the surface for a good bond.

[Joe L.]

Re: 427 Intake install

I posted previously about having oil in my intake manifold and head runners. I decided to do a "test fit" of my intake with new gaskets to check that it was torquing down properly. I went ahead and used the provided rubber end gaskets that come with the intake gasket set. I noticed that once I have the intake torqued down there is a full 1/8" gap front and back. Too much for those gaskets alone to seal. I've been advised to use a silicone based sealant there instead of the gaskets anyway but was wondering if this 1/8" gap is unusual and perhaps an indication of an overall fit problem with the intake. Also, since the intake bolts do not utilize a lock washer should I use locktite and check the torque periodically?
Thanks,
Jack

Jack-----


In addition to clem's comments, the fact that you have a 1/8" gap between the manifold and the end seals with the side gaskets in place is definitely an indication of an underlying problem with something. There are 3 possibilities:

1) The intake manifold end rails have been machined down to accommodate a problem that existed on some other engine it was once installed on;

2) The cylinder heads have been machined excessively on the block mating surface. This will ENSURE that you will not have proper fitment of the manifold with the cylinder heads and MAY be a big factor in the oil wetting problem you previously reported;

3) The cylinder block machining is "off" in some way. This, in turn, causes the cylinder heads to be "off" and that, in turn, causes the manifold to fit improperly. As mentioned in (2), this MAY cause enough "misalignment" to cause oil leakage at the lower edge of the manifold.

You can easily solve the problem of the "gap" of the end seals just as clem described----use silicone sealer in place of end gaskets. This will seal better, anyway. The big problem is this will only solve the end-sealing problem; it won't solve the underlying problem, assuming there really is one. However, you may need to try this before moving on to the next step (whatever that step may be).

One thing to check carefully assuming the oil problem continues: after you've driven the car for awhile, if the oil burning and/or "smoking" problem continues, when you remove the intake manifold check for the presence of oil well "upstream" from the intake manifold-to-cylinder head interface. If there is significant oil there, it may well be that the oil problem is NOT coming from an interface sealing problem. I just don't see any way that oil drawn into the interface due to poor sealing could possibly find its way UPSTREAM. In that case, the only possible source for the problem would be excessive oil drawn into the PCV system. So, how does one stop this? I wish I knew. This is another area that I explored HEAVILY in my once-upon-a-time quest to get to the bottom of my small block problems. I never came up with any way to solve it, though. And, believe me, I tried. BIG TIME!!!