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[253] intake gaskets

DANNY8

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Need to change the intake gaskets over on the 253 in our race car. If the manifold is slightly out and requires machinging, could we just use 2 gaskets on either surface?

Or if we used the normal gaskets on the heads, could we just use the RTV silicone on the bottom? If so, wat's the best way to do it.....put the side gaskets on with sealant around the water galleries (wat's the best gear for that?), and lay a nice bead of RTV silicone on the bottom, front and back, then sit the intake on, do the bolts up a bit, but then allow it to sit for 24hrs b4 tightening the bolts up?

We're getting sick of pulling this bloody intake off, so hopefully we get it right this time haha.:bang:
 

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DANNY8

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Well after test fitting it with the side gaskets and leaving out the bottom ones it has a good gap under the manifold, so don't think it needs machining. Have used the cork gasket again, and used RTV slicone on both sides of the gasket, plus both sides of the side gaskets, plus used the RTV silicone around the water galleries on the gaskets.

Just sat it on, done the bolts up so they are nearly in, but they have no pressure on the manifold yet, just the weight of the manifold is holding it down, and will wait for the RTV silicone to dry b4 torqing it up 2morrow. Hopefully it works!
 

VR38

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Usually if a manifold requires machining it is because the inlet port faces are not aligned due to head and deck machining.
The gap under the manifold is irrelevant and usually filled with sealant.
 

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The gap under the manifold is far from irrelevent, when the heads/block are decked it effectively widens the V where the manifold sits. So, then the manifold drops down closer to the block at the ends, and worst case you end up with no gap between the block & manifold. This then holds the manifold off the head surfaces which either causes a massive vacuum leak or water goes straight into the block.
 

ari666

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The gap under the manifold is far from irrelevent, when the heads/block are decked it effectively widens the V where the manifold sits. So, then the manifold drops down closer to the block at the ends, and worst case you end up with no gap between the block & manifold. This then holds the manifold off the head surfaces which either causes a massive vacuum leak or water goes straight into the block.
holy crap i never thought of that...
 

VR38

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If the manifold was sitting on top of the block there would be NO gap lol.
 

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The gap under the manifold is far from irrelevent, when the heads/block are decked it effectively widens the V where the manifold sits. So, then the manifold drops down closer to the block at the ends, and worst case you end up with no gap between the block & manifold. This then holds the manifold off the head surfaces which either causes a massive vacuum leak or water goes straight into the block.
How about you learn to read.....Thats exactly what i said. ;)
 

DANNY8

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Well the intake is no longer leaking from wat I can see. I think half the problem was the bolts were a fraction to long. They were used on the same intake and heads on another motor and were ok, but when I done them up tight on the new motor, some washers were still loose.....so chucked another washer under each bolt and I think it done the trick.

Now the only issue is one of the waterpump bolts is stripped out and it leaks a bit....chucked some of that flakey crap down the radiator and that seems to have done the job.
 
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