What ports are these...smog maybe?

This is my first big block, its a 454. I am cleaning up this motor and in the process of replacing the intake. In the center of the heads there are some (what I am assuming) smog related ports that are full of a thick oily carbon build up. What are these? I am cleaning them out as best as I can but am afraid of where the residual crap I cannot get may fall in to. My edelbrock performer intake has the smog block off. How critical is it to get these perfectly cleaned out?

Here is some pics:
http://img91.imageshack.us/img91/1062/454head1xm8.jpg
http://img91.imageshack.us/img91/4971/454head2gy1.jpg

Heat cross over passages. Designed to warm up the intake manifold. Olden day style manifolds had a corresponding passage to flow thru underneath. Some apps with old style choke stoves used them to warm up the choke for proper operation. Some apps also used it to pick up exhaust gases for the E.G.R. I would prefer them clean but it does also connect to the exhaust port and will push the excess out the exhaust manifold. Be cautious though, if one of the exhaust valves are open, the carbon can fall into the engine and can also hang up the valve off of it's seat and create a miss and make you scratch your head wondering why.

Depending on where you live and the time of year you will be driving this engine may allow you to just block them off. Using an aftermarket gasket without X-over passage is an option.
This passage area as mentioned already allows hot exhaust gas to heat the fuel charge by keeping the floor if the intake right under the carb heated. This does help a cold running engine become more drivable until up to operating temp and feeds the gas to the EGR valve also dumping raw ex. gas into the intake fresh fuel charge BUT the down side is it is always heating the fuel charge and that is not good for power or mileage.
If you can either live with allowing engine to warm up before driving in cold country or pass any smog check without EGR function BLOCK that baby off with a solid gasket. Ex gas entering fresh fuel charge and hot gases under the carb are never good for performance and even worse when using an aluminum manifold as they xfer heat to fuel charge better anyway. If local laws allow then go for it.

If you will be using a alu intake its not needed.The alu intake absorbs heat better than a spong in water.:LOL:

What are the numbers on the heads? That will tell us how big of a cam you can use. They kinda look like the bigger oval ports from the pictures but I can't really tell with the paper towels stuffed in there.

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Originally Posted by nitrowarrior

I would prefer them clean but it does also connect to the exhaust port and will push the excess out the exhaust manifold. Be cautious though, if one of the exhaust valves are open, the carbon can fall into the engine and can also hang up the valve off of it's seat and create a miss and make you scratch your head wondering why.

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And because of the above mentioned..if it was me...it doesnt cost toom uch for a top end gasket set...your already needing intake gaskets anyway..Id pull those heads..do the cheapy way of cleaning them by power washing them, the soaking them in degreaser and power wash them again...blow em out best you can with compressed air to dry them ( and while the wife is out and if the rack inyour over can handle it bake those sucker dry) . Of send them to a shop that still uses tank method of celaning which should cost you more than $30 or so.

By the way..without #s nobody can say for sure...but if I had to guess Id say those are the small peanut port heads.