What are these intake doohickies for?

what are these two outlets for and can i remove the brass one, it makes the clearance between the intake and engine bay way too close.

there for the manifold water jacket dont worry about them and yes you can remove the fitting

I reckon they're essential!

Water regulates the manifold temperature. Australia has negligible icing of carbs, so it's clearly not designed for cold temperatures. Nor is hot coolant going to "cool" a manifold specifically.

It just helps maintain a stable temperature during operation. You might see if the brass one can be re-routed with a pipe thread fitting, or tapped at the base adjacent and the original hole welded shut.

If you're fitting a Holley 2300 series, are you aware of the "trick" where the original carb pad is milled down at the same angle, to add about 5/16" clearance?

i personaly never hooked water upto any i had.if you dont want to use water plug the end with those rubber end caps that way you not butchering a perfect manifold.if you not worried just cut em off.

This shows my limited experience. I never heard of a water jacket in an intake manifold. Seriously, how hot could the intake air be?

The manifold, being light alloy, "wicks" heat from the head, and absorbs radiant heat from the headers. The water jacket acts to regulate the maximum temperature it may reach under most operating conditions.

IIRC some Ford V-8 intake manifolds have water passages, too.

i have often thought to pump ice water through the water jacket on the manifold to help drop intake temp.
but on all my race engines ive never ran it

thanks for the info. guys. it's helpful. as quite usual addo deviates from the conventional thinking (one of the things i like about him)!

adam, please elaborate on the "trick" for the clearance with the holley carb. thanks.

addo":37f868lx said:

I reckon they're essential!

Water regulates the manifold temperature. Australia has negligible icing of carbs, so it's clearly not designed for cold temperatures. Nor is hot coolant going to "cool" a manifold specifically.

It just helps maintain a stable temperature during operation. You might see if the brass one can be re-routed with a pipe thread fitting, or tapped at the base adjacent and the original hole welded shut.

If you're fitting a Holley 2300 series, are you aware of the "trick" where the original carb pad is milled down at the same angle, to add about 5/16" clearance?

Click to expand...

If you look at the carb mount pad, you'll see it's milled at an angle to the horizontal. Set the adapter on top and trace neatly around the perimeter.

Next, the intake needs to be tilted when clamped on the mill table so this angle is parallel to the flycutter. Then you just go down until the cutter starts skimming the runner surface. Check the adapter still mounts neatly, and you have picked up a good quarter inch of clearance; sometimes more.

good tip adam, i still have to check my clearances. i have been waiting and waiting for Mike to get my holley adapter in.

It's there to keep the manifold temperature steady and is especially helpful when it's cold out. Liquid fuel doesn't burn, and the manifold heat helps to vaporize the fuel that bounces off the bottom of the manifold.

Generally the better the carb atomizes the fuel, the less manifold heat you need.

http://www.gofastnews.com/board/technic ... t-3-a.html

how do i get the brass fitting out? is it threaded?

It's just pressed in, from memory. Plenty of meat around it.

seems like maybe it has been cemented in with something. i tried to twist it out and it is just bending.

Cut it flush, then use a hacksaw blade on the pull stroke to chafe through the remaining thin wall of brass. I think you could TIG weld in an undersize alloy pipe plug or cut a little "blank" then drill/tap the base immediately below where it was (see crosshairs below), and use a 90° elbow.



This was Bryce's intake. Note how the elbow had already been replaced with a threaded one, but in the stock position.

Thanks Adam,

That is a really good idea. I will chop it off for now and see how she runs without the water. But if I decide to hook up water again I will do it from the bottom.

Trust me, your climate is very similar to ours - and it was deemed to need the water fittings. Easier to unhook it later and experiment, than tear down and start welding/tapping later...

I had the water fittings on my 2V manifold cut off and welded up. Also had a fitting for the brake booster connection tapped into the center on the side to equalize the load on all cylinders.

skeet3r":8o4lyqzi said:

I had the water fittings on my 2V manifold cut off and welded up. Also had a fitting for the brake booster connection tapped into the center on the side to equalize the load on all cylinders.

Click to expand...

Sounds like a great idea.

I can't see airflow being affected by vacuum take-off point. There's no airflow to speak of through the vacuum port - just the tiniest "puff" as brake is released.

And again - IT DOESN'T GET COLD IN AUSTRALIA - people need to stop considering the manifold water jacket a heater. It's an aid to reliable (predictable) operation, just like a cup of coffee in the morning.

I believe that discarding the water jacket would only work reliably (in terms of tuning) on a speedway engine. The WOT operation and fairly volatile fuel would work as a cooling device. In a normal motor, your intake water jacket is a 95% guarantee that the plenum won't exceed thermostat opening temperature.

Anyone who considers it unnecessary on a DD probably considers expansion joints in a bridge as surplus to requirement...