I have a 1994 LT1, I am running some old school perimeter valve covers with a pcv on the passenger side valve cover on top and running the a vacum line to the passenger side of the intake manifold, but on the other side I don't remember how the pcv worked on the driver side, I think there was a gromet with a pcv valve and a U shaped 3/8 hose to a fiting on teh intake on the same side (drivers side).What is the point of the way the pcv is run on the drivers side of the manifold.... I am wondering if there is a better way to run it, the motor is all aftermarket...

 

The "U" shaped hose was used on the 93 and 94 engines. The port/grommet that the PCV valve sticks into has a passage that goes to slots in the bottom of the intake manifold, open to the lifter valley. That passage is not exposed to the intake plenum at all. The other end of the "U" hose is into a port that goes directly into the intake plenum, with its vacuum. PCV valve pulls from the lifter valley, the vacuum comes from the intake manifold.

The 95-97 engines ran the outlet side of the PCV valve to a port on the front of the intake, under the throttle body. On your 94, there is a pipe plug in that hole. I've found the 94 setup to be more than adequate, and that's with an engine that is "all aftermarket".

 

I know exactly what you are talking about! Thanks so much for the help!!!

Mark Tisdale

 

why dont u just put a breather on there.........

or is there some reason as to why we shouldnt???

 

The system is designed to work as it is, when you change it its no longer working as designed. When you put a breather on it you are essentially creating a vacuum leak because air is getting into the intake through the breather and bypassing the mass airflow sensor.

 

im talking about caping off the tube going into the throttle body with a vacuum cap and then putting a breather element on the valve cover where the hose went too.

I mean, tons of BBC and SBC have done this for a while......is this not good for us??? i mean the tube is there to let air into the heads fromt he throttle body, what is the difference in putting it in through a breather???


IM not trying to argue.........just trying to figure out if i need to put my hose back on and take my breather off

 

Don't get smart, I meant by all aftermarket that I running all different stuff and had my intake manifold all taking apart, and I was trying to remember where some of the ports on the intake manifold were used...

 

Sorry you interpreted my attempt to help you as "getting smart"..... I just wanted to assure you that the stock system, using the U-shaped hose was compatible and adequate for a highly modified engine. It was not intended in any way as an insult, getting smart, whatever. You have an "all aftermarket" engine with a lot of mods, and I was simply trying to help by explaining that the stock system would work on highly modified (800HP with the 300-shot of nitrous) engines.

Sorry... it was an honest attempt to help, which you have totally misinterpreted. I won't make that mistake again.

 

The stock system (94 and up) pulls in air that has been measured as part of the total air flowing through the MAF. They did that, because the air ends up in the combustion chamber. It has nothing to do with capping off the port on the side of the throttle body - although that is required. It happens because the air that get pulled in through your breather has not been measured by the MAF, and is in effect a small vacuum leak. It isn't anything that the long term fuel corrections can't compensate for, so its no big deal.

 

Regardless of the target recipient, I appreciate the info. I'll be running an LT4 intake shortly (with Lt4 style heads), and was wondering what I was going to do about that tapped hole in the front of the intake. Sounds like I'll be fine plugging it and running my old 93 LT1 hose setup.

 

I am sorry for the misunderstanding, thanks for you help!

Mark

 

Seems to be a great debate on the svt boards. Most people there end up getting oil sep kits.

 

would you think i should put it back on even though its no big deal?????

 

I seriously doubt it will make any difference. To me the stock system works great (even with an 800HP nitroused stroker). But I can see where the problem of oil getting back into the TB could be a concern on some engines. I've thought about going to a breather, just to simplify the plumbing, and I don't use an MAF any more, so it really doesn't make a difference where the air for the PCV system comes from.

If your tune is good and the engine is running fine, leave it alone.

 

k thx