BrawnyMan

Hello All,

Last night I finally got the stock 2-barrel intake manifold off of my '71 Cutlass Supreme 350. This weekend, I intend to install a refurbished cast iron 4-barrel manifold but thought I would seek some advice while I have access to the lifters and area underneath the manifold. Is there anything I should inspect, measure, check besides the lifters? Also, if anyone has any tips for replacing the manifold gaskets that would be helpful as well. I will not be using the "turkey tray" style gasket that I removed but the separated gasket style along with main seals.

Thanks in advance,
BrawnyMan

Olds64

Do you plan on disassembling the valve train? This would allow you to check the pushrods for straightness and the lifters for abnormal wear. However, valve train parts need to go back in the same spot they were removed from and if one of the lifters or pushrods is bad then the entire set SHOULD be replaced.

olds 307 and 403

Are they the shim or composite gaskets? Not sure why you wouldn't use the Turkey tray with an iron intake. Ditch the end seals, tall, 3 layer beads of RTV but not too wide and beads on both sides of the gaskets around the 4 corner water ports. I also use Permatex Aviation sealant, similar to Gaskasinch, around the intake ports.

BrawnyMan

Found the gaskets below at Autozone
https://www.autozone.com/external-en...0_825029_12080

tru-blue 442

Unless your blocking off the exhaust crossover, I would use the valley pan gasket. It keeps hot oil off
the bottom of the intake. If you don't, it will cake up and fall into the lifter valley over time.

https://www.pepboys.com/intake-manif...-350%20%205.7L

Olds64

I would use the gaskets you found over the turkey tray. Put RTV around the water ports at the corners and hi temp RTV around the exhaust crossover in the center. Like Olds307 mentioned you can ditch the end rails and use RTV or form a gasket instead.


Make sure you let everything setup overnight before you fill it with coolant and start it.

BrawnyMan

Is there a requirement or advantage to blocking off the crossover? I was not aware of it.

BrawnyMan

Three layer as in a pyramid? Or three layers right on top of one another.

oldcutlass

Dry fit the intake and measure the gap, you want the bead thicker than what you measured. Did you check the lifter bottoms and cam lobes?

olds 307 and 403

Three layers right on top of one another. I have used those gaskets with a pan cut off the Turkey tray since Summit couldn't ship the Turkey tray to Canada.

Olds64

Don't bother with this. It's a PITA. I tried to use aluminum beer/soda cans in the past to block the exhaust crossover port and the heat of the exhaust blasts right through the aluminum. I recently tried to block it using metal cut from a tin can and all I succeeded in doing was causing a vacuum leak. The exhaust crossover is properly blocked in the heads when rebuilding the engine. It only needs to be done for guys running their cars at the drag strip. Blocking the exhaust crossover will NOT register on the butt dyno.