Jump to content

L20 intake and exhust manifold


thebucketslider

Recommended Posts

im looking for a new intake manifold for my L20. i herd of using a L16 intake manifold, and i have yet to find any aftermarket applications. also i cant find a header that will fit the 620, they are all for the 510. basically i want to eliminate all the emissions controles and vacume liines. any suggestions are vury much appericated. thanks.

Link to comment
  • Replies 10
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

I just did that to my 77 620 K.C. It has the U67 head with the square-port exhaust holes. I wanted to use an older exhaust mani with the square-port holes but could not find 1 in good enuf shape so I used a round-port ex mani I had from another L20 and just plugged all the smog holes with bolts or plugs.

I then put on an L20 mani that I had layin around and did the same pluggin off the smog crap!

 

Here is a pic with the smog crap

 

manifolds002.jpg[/img]

 

And after

 

manifolds004.jpg[/img]

Link to comment
im looking for a new intake manifold for my L20. i herd of using a L16 intake manifold, and i have yet to find any aftermarket applications. also i cant find a header that will fit the 620, they are all for the 510. basically i want to eliminate all the emissions controles and vacume liines. any suggestions are vury much appericated. thanks.

 

Stick with the stock L20B intake. If you are expecting to find a miracle 5-10 extra hp by removing the emission controls, forget it. The biggest problem with emission equipment is people not looking after them properly or tearing it off and cobbling a block off plate together and causing more problems than they fix. This is lots of needless work for no gain.

 

IF, however, you don't want EGR, it's best to disable it than the bother of removing it and making a block off plate. To disable: on the valve cover side of the stock carb are two vacuum lines, disconnect the rear one and plug the port on the carb. No vacuum... No EGR, it's that simple.

 

PCV: never run without it. It's function is benign and improves long term engine life.

 

A.I.R. Injection: The ONLY effect on performance is the power used to run the pump. To disable, cut or remove pump belt. It's hard to remove the injection tubes without cutting them, but if you just have to, use pipe plugs to fill the holes in the exhaust manifold.

 

Carbon Canister: Has absolutely no effect on performance. Check that hoses are tight and not leaking.

 

BCDD (on carb): No effect on performance. Only operates on deceleration.

 

ATC (carb warm air): Improves driveability when engine is cold. Prevents carb icing in areas where temps get down to just above freezing.

 

AB (anti backfire valve) : no effect on performance works on deceleration only. Check that hoses are tight and not leaking.

 

Some provinces and states require working 'smog' equipment. If you disconnect, you can re-connect later. If sold, the new buyer isn't going to want the expense of finding all the missing parts and hoses and hooking it up. If your truck runs fine, leave it, or you'll be back next month with questions.

 

To-days cars are controlled by the emissions equipment and prevent (limit performance) the engine from straying into areas where it pollutes excessively. In the time of the 620s it was the other way around. The motor produced pollutants and the emissions equipment dealt with it as best it could, but only after they were produced.

  • Like 1
Link to comment

DatDoug: nice clean job but where is the PCV valve? It's function is to remove fuel, oil and water vapors caused from blow by, from inside the block. Without it, these vapors will condense when the engine cools and contaminate the oil leading to shorter oil life, corrosion, rust and gummy deposits. What about the fumes you're breathing?

Link to comment

Hey DatzenMike thanks for the info. I always wanted to know what all that stuff did. As for the PCV I have another manifold with one on it and I think I will change it over. Again thanks for your great info and the main reason I took all that crap off is to simplify my engine so a amateur like myself can keep it running good. The carb was having the Hitachi hiccups and I got a killer deal on this new weber so I did the change over.

Link to comment
looks like egr man strikes again. he hates it when people remove the smog stuff completely.

 

:lol: Thanks for going easy on me. Except for the PCV this is a good example of how to do it right.

 

DatDoug: on your picture of the plug offs, I can see there is a hose going to the thermal switch in the thermostat housing, if you still have a vacuum source connected to it, it should be disconnected at the Weber and the port on the carb sealed off. Hard to tell in the picture whats hooked up or not.

 

I would find a way to mount an elbow on your block off plate and connect to the PCV valve with a short length of hose and some clamps. Your set up is clean so you should be able to 'get it right'. Keep in mind that a back fire will exert lots of pressure on this so keep it 'tight'.

Link to comment

I use the L16 intake cause they are FREE in most cases!!!!!

 

If you want a header Top End performance sell a short tube(square exhaust port) one that fill all the car/trucks. But shoud get ceramic coated $$$$$

 

Its a clean and simple set up.. The L20 instake is not bad, it already match poerted to the bigger intake of the L20 So you take a Felpro gasket and put it up to the L16 intake and HOG it out. Dremel tool or what ever turns you ON.

then rig a hose to the PCV valve since the L16 and L20 ones are routed different.

photo below is a L16 intake and a Top End perf short tube header.

If you have a L20 block cut the L20 PCV tube short then cut a L16 tube and pound it on there to the correct size then you can use the stock rubber PVC tube that goes to the loer part of the intake to PCV valev since both ends ARE a DIFFERENT size!!!

lseries17_thumb.jpg

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.