Improving a 301 turbo motor

claudio

claudio

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Hello everyone
Thank you in advanced.....
My question today is about extra exhaust ports in cylinder heads.......
My car is a 1981 TURBO Trans Am
301 Turbo engine
On the heads there are 3 exhaust ports that I would like to block off......
Two on the front of each head and one on pass side head....
What are they for....???......and am I disturbing any thing by blocking them.....???
Any other mods or ideas.... Please let me know
Thanks
 
I cannt begin to image why the cylinder heads would have exhaust ports in the front. They would have an exhaust crossover passage that matches the passage in the intake manifold. Those are commonly blocked off by using an intake manifold gasket with a stainless steel plate covering the passage. Can you post pictures of the heads?
 
I think these ports he is talking about are threaded for an exhaust crossover tube part of the emissions system that feeds 02 into the exhaust helping the Catalytic converter work properly.

there are 4 holes not just three one may be currently occupied by a bolt holding a bracket in place.

They have four because the heads are not side specific.

Gm used to sell double sided threaded inserts that would be used on the front on the cylinder heads, these inserts would allow you to use these holes to mount accessories power steering alternator brackets etc.

you will not hurt anything by blocking these holes off however if you have a stock Catalytic converter and no air pump and no crossover tube or check valve you will harm the converter.

Do not just jam a bolt in these holes I think the threads are pipe threads.
Give me some time and I will see if I can find the correct threaded inserts. or check with any machine shop they should have a bunch of them laying around.
 
I have not found the inserts but for sure the threads will be pipe thread.

this is what is supposed to be on the back of the engine

Sorry I gave you the wrong part here

so I have removed the link.

if I remember correctly these ports have 1/2 NPT and the inserts provide 3/8 course threads on the inside of the insert these get screwed in with a special tool sometimes they can be removed with a large straight blade screw driver.
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Last edited:
EaOutlaw said:
take some picture of what your engine looks like and post them.

Is it all hacked to hell missing parts? or does it look like the one in this video?

https://www.youtube.com/watch?v=7ZbX5vBh5E8#action=share
Click to expand...


Yes motor in video is just like mine.....
A 1981 301turbo engine.....
There is currently a pipe on front that goes from head to head and I think connects to smog pump.... Also on right ( pass )side of intake is a large threaded hole that matches a port on head for exhaust.......
I've bin told that I can use earlier(I think 77-79) 301 non turbo heads because they don't have extra ports

I believe they are EGR ports..... Not sure.....
Also my engine is all stock.....
Thanks
 
if you want to improve performance, you must make sure the entire engine is operating at its peak performance, if you still have the factory converter without an air injection system your exhaust could be plugged up.

Connect a vacuum gauge to a central vacuum port and test the engine vacuum.
here is a video on what to look for, I did not watch the video to see if it is any good.
however this is a basic test. if you want to know better information buy a manual for your car. https://www.youtube.com/watch?v=d-jp1IIJVVk#action=share
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BTW be kind enough to confirm that the exhaust ports that you mentioned in this post are in fact the threaded ports that I mentioned.

the large threaded hole on the intake may be for the egr valve
 
Ok thanks
I'll check on the heads (I do know there's a pipe from head to head in front of engine at front of the intake behind alt and a/c comp. ) I'll do a vacuum check too...when I get some time ... Engine still in car and I have to go back to work......
Not worried about cat as I am removing all current exhaust and upgrading it and a full tune up as well....
If I plug all the "exhaust leaks" I should have better flow to the turbo right.....??
Thanks again
 
yes leaks are bad for a turbo, but they would have to be pretty bad to effect performance
 
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