307 with a factory aluminum intake would you use factory type metal gasket or use aftermarket gasket

 

I like the factory intake gaskets myself.

 

You can actually use either, but the factory all metal ones will create galvanic action and erode the manifold at the water jackets. I had to replace the intake gaskets on an 85 442 I owned about every 8 to 10 months. Got tired of doing them and replaced the A4 intake with a cast iron one from a 350.

 

In 40 years of owning Oldsmobiles (40 YEARS!?!?! ), I've never had a problem with the factory steel intake gasket on iron, factory aluminum, or aftermarket aluminum intakes. If you apply an RTV bead around the water ports, as directed in the Chassis Service Manual, there is no galvanic corrosion. Never had a leak (water or vacuum), either. I do throw away the rubber end seals and use RTV instead, however.

 

So do you happen to have a thread here on your proven techniques? What kind of RTV do you use?
I have just recently been looking at the need to replace the intake and VC gaskets on my 86 just because of the constant weeps of coolant and oil. Are there pressured oil passages in the intake or is it from splashing? As you can tell I've never pulled one from an Olds...

 

My technique is the one in the CSM. I use Permatex, but most brand name RTVs are comparable. There are no oil passages in the intake, only the air, exhaust crossover, and coolant. The oil leaks are from the rubber end seals, which is why I toss them. Of course, be sure the aluminum intake sealing surfaces are flat and be sure you get the four locating flanges around the outboard bolt holes in the gasket properly located in the recesses in the heads. Note that some aftermarket gaskets have been found to have these locating features formed incorrectly.

 

I do as Joe does but also use Permatex Aviation sealant around the other ports. Intakes need to be completely straight with the thick fiber gaskets or good luck getting them on.

 

Good advice - thank you.
Any preferred gasket vendor? Felpro perhaps? I have had good luck with their other gaskets, esp the rubber or silicone VC gaskets (which will be used on the 86 also).
I just dread excavating through the emission crap to get to them (and hope this does not turn into a complete engine bay resto)...
Have you done any partial restricting of the exhaust crossover ports? I have heard of some folks doing that to keep from cooking the carb but allowing enough heat for the choke to work.

 

Every replacement gasket set I used were installed just like you said, RTV around the water ports. I never figured out why I had the problems that no one else seemed to have with the galvanic corrosion. Used both GM gasket sets and Fel-Pro, both would go away with regularity. Used distilled water with antifreeze mix every time. The solution was the cast iron intake.

 

Interestingly, the CSMs from the 1960s and 70s only call for RTV around the water ports (even on the aluminum W-car manifolds). The 1980s CSMs call for RTV around ALL ports on the intake gasket (even with the iron #14 intake on the 307). I don't know if this is due to the thinner wall castings moving around more thermally or a relaxation in manufacturing tolerances, or just a lesson-learned, but that's what they say.

 

I would hesitate to use RTV on the intake fuel/air passages due to poor experiences with RTV vs fuel or ATF. I prefer Permatex Aviation #3H for the air/fuel passages. End rails, and water passages, sure. Molecular thin coating at water passages so that excess does not squeeze out in a string and go clog the radiator. Maybe "Right Stuff" would be OK for fuel/air ports?

Joe, in a rare moment of inaccuracy, states: "be sure you get the four locating flanges around the outboard bolt holes in the gasket properly located in the recesses in the heads. "

The locating pierces are near but not around [at or surrounding] the mounting bolt holes. Yes, during your dry test fit, you will ensure that these all enter and reside properly in their respective holes. Bending the gasket/ tray may be required. When it all fits perfectly and the intake has been test fitted also, THEN apply the sealants and do the actual final install.

 

Making sure the locating bosses set in the holes is very important. With some of the gaskets this task is very challenging. So many gasket failures are due to not getting this right.

 

The Felpro sets locate nicely, the Victor Reins worked well too. I bought a Cortecto dirt cheap close out from Rock Auto. Very tough to locate, more of a pain to put on. RTV doesn't like fuel much, weird they wanted it put around all the ports. Pretty sure I got into habit when a friend of mine did an intake and used the aviation sealant around the ports. His Dad and Uncle owned a shop. Jason had a 455 powered 78 Cutlass, blew multiple motors with nitrous. They were GM guys, not just chebbie guys. They had multiple 455 powered Cutlasses and a 68 Firebird with a 400 Pontiac. Jason told me they got the used 455's for $50 a piece at their shop price. Boy are those days gone, $700 for smoggers or knocking early 455's nowadays.

 

I have an edelbrock Performer, RPM manifold on 330. ( Probably overkill). Edelbrock sells a cast iron block ( solid) that needs to be fitted (i.e., ground down to fit properly) into the crossover ports to block the heat. On mine, it cooked the gas residue on the crossover resulting in ugly brown coating that couldn't be removed. Result was re-powder coating the manifold. ( Removed it due to vacuum leak). Have not put back together yet to see if it has been sealed.
Using Fel-pro with valley pan.

 

My ex-wives would suggest that they weren't that rare...

Chris is correct. Memory is the second thing to go and I can't remember the first. Here's a photo that shows the locating features adjacent to but above the bolt holes.