Hi guys,i've found the turkey tray intake gasket on my recently rebuilt 455 has been leaking at bottom of port areas into engine causing low vacuum and a slight exhaust leak from the crossover ports into the engine.
Have removed the 1972 factory cast iron intake manifold and with a straight edge along ports have found the centre exhaust ports on it aren't quite flush(can get a 10thou feeler gauge between straight edge and intake manifold at exhaust ports)
Have bought a Felpro 1356 intake gasket set instead of a new turkey tray,my thinking being as these composite gaskets are 60 thou thick they should seal better than the thin metal factory one and eradicate the 10 thou gap in middle.

Few questions re fitting the Felpro 1356 gaskets - I thought from pics they would have the blue printoseal around ports on both sides but they each only have it on one side,so which side do you have the blue printoseal facing,intake or heads ?
I'll be using thin bead of silicone around both sides of gaskets at water ports and be junking the rubber end seals for bead of silicone.
What sealer should I use around the intake port areas of gaskets to get a good seal ?
And finally,what should I do at the centre exhaust crossover ports ? The 1356 gaskets come with no ports cut out in them at centre exhaust ports,is it ok to cut holes in them and use like that or will the edges of the composite gaskets around exhaust ports burn away and cause problems ?

 

I recently removed my intake as well to give it a thorough cleaning. I don't use the OE turkey tray. IMHO, it just creates problems. Of course, there are others that say you should retain the turkey tray. Once I removed the intake and saw that the underside was cleaner than the top side I was convinced (there were 2 years of grime on top of the intake and practically nothing on the bottom).

I use the Permatex "Form a Gasket" to seal the front and back of the intake.


Like you said, it's better to ditch the end rails. I also use RTV to adhere the intake gasket to the heads before I put down the bead of Permatex on the front and back.

If your intake gasket doesn't have the center exhaust divider cut out you can cut it out with a razor. You can also leave it in tact, cut a piece of metal from a soda can and fold it over the gasket. I've never done this but others say it will prevent the gasket from burning out. Seems logical but I would worry that it would create a spot for a leak.

Good luck, let us know what you do.

 

I found much success using Permatex Ultra Copper. Until I used it I had to take that intake off a couple times to get it to seal and as you know taking that heavy thing off is no fun.
https://www.permatex.com/products/ga...-gasket-maker/
I also found out the hard way not to use the front and rear rubber seals. I built up a nice bead of the Ultra Copper and I have no leaks.

 

I use spray copper (K&W or Permatex) sealer on the port areas of the turkey tray, and RTV instead of end seals. I use a thin film of RTV at the water ports. If the surfaces are warped, get the heads and if necessary the intake resurfaced with a very fine finish.

 

The gaskets you propose will work well. And you can retain the function of the turkey tray by cutting off the gasket portions on your old tray and trimming it so it fits snugly in the valley.

 

The first composition intake gasket I used didn't have cutouts for the exhaust crossover and I thought good, I have the exhaust crossover blocked off. They were burned through the next time I removed the intake. Don't know how long it took to burn through but I suspect it didn't take very long.

 

What permatex is everyone using. Blue, grey, black, or copper??
I have grey and black and the right stuff at home. I'm gunna put on my intake soon
I used grey when putting on my oil pan

 

Hi guys,thanks for your replies/advice. I fitted the composite intake gaskets,silicone along end seals and around water ports and VHT spray copper gasket cement on both sides of gaskets around intake ports. That cast iron intake sure is heavy ! Anyway,fired up engine expecting new intake gaskets to have solved my low vacuum at idle readings but no,exactly the same ! Engine has a Comp Cams XE262H camshaft in it but i'm only getting around 10inches of vacuum on vac gauge at idle. How much vacuum at idle would you guys expect to see with that camshaft ?

 

I am not sure but it seems that 10 is a bit low. Your initial timing will have a big impact on the idle vacuum: lower initial = lower vacuum.

My 350 with the UD 217/221 cam had a very bouncy 14" vacuum at idle. At that time, the distributor was set up with 10º initial and 24º mechanical (Moroso HEI Advance Curve kit). I changed the weights and center bar back to the factory HEI parts to bring the initial up to 18º and the vacuum smoothed out and increased. I also have the vacuum advance connected and the vacuum is a steady 16" at idle. Without it, the idle gets rougher.

 

Have HEI with initial timing at 18 with ported vac advance and rough idle. Was going to try it with vac advance connected to full manifold vacuum next time I fire it up. Am guessing you have yours connected to full manifold vacuum if your idle gets rougher without it ?