Just wondering what people have done for the pcv valve on the lt1 intake conversion to sbc1. Did you just buy the one for an LT1 intake or can you use the one from the tpi?

Anyone?
I am putting the motor together hopefully next week.

I would use the pcv routing of the tpi,in the valve cover

So from this diagram, which one goes to the valve cover?, the bottom left or right? What do you do with the other?
http://www.lt1intake.com/images/LT1locations1.jpg

lb9gta,

Did you get that resolved? Have you eliminated the egr as well?


Rabi C.

I will eliminate the EGR.

No, the problem is not resolved yet

lb9gta,

Well my pcv set up consists of the following;

Driver's side valve cover having 2 orifices one being one inch in diameter and the other being 1 1/4 inch in diameter.

Passenger side valve cover has one orifice being 1 inch in diameter.

I took my old pcv from my tpi set up and stuck it into the front driver side valve cover 1 inch ori fice. The rear driver valve cover orifice i plugged up. Its not a good idea to use a breather here as the idea of this is to create a sealed system. I had a breather on there and it just ended up getting soaked up in oil not a good idea so plug it up. So that Pcv valve should be plugged into a vacuum port in your mani which it seems like you have.

Passenger side valve cover--- You can either put a breather on it or route a vacuum tube up to the port on the side of your throttle body.

Heres the idea ---> fresh air is supposed to come into the passenger side valve cover either from a breather or from the air coming into the motor.
Then the gases coming up on the driver side need to be routed back to the manifold and it needs to be a sealed system so a breather on the driver's side would defeat the purpose.

Hope this helps man I had to deal with the same thing just recently. Do post how things work out

Take care,


Rabi C.

Thanks for your reply!

Do you have a pic?

lb9gta,

A picture is worth a 1000 words ...
So here we go now the first picture (I know its tough to see but just follow the hose back) the pcv is on the front of the valve cover and routes to the manifold. I have white silicone tape rapped around the base of the nipple on the vacuum port. Thats where i have it routed to. The plug i have on the rear orifice on the valve cover is to ensure that the pcv system is properly sealed.

To test the pcv valve just shake it and it should click back and fourth. If it doesn't click its not functioning correctly.

2. This is a picture of my breather on the passenger side. Now instead of a breather you can have a vacuum line going from this port to one of the 2 ports on the tps side of the throttle body. You can see the two ports plugged up on my third picture.
The idea here is to allow fresh air in either from one of these ports or by a breather. Either one of these methods would be satisfactory.

3. This picture is of the tps side of the throttle body and both of my plugged up ports. One is for the charcoal canister and the other for this vacuum line if you deem it fit.

Do post if you have any questions. Hope it works out


Rabi C.

lb9gta,

Heres one more of the passenger side if you wanted to go up to the throttle body but its a tpi setup. But the idea is the same. Thanks to Vader once again for this one.

Good luck bro,


Rabi C.

sorry to bring this one up again....but if the drivers side valve cover PCV valve goes into the one smaller port location on the LT1 manifold, what goes into the BIG PCV hole on the LT1 manifold as shown in this pic? they label it as PCV valve. how to go about this?

Orr89RocZ,

Well, according to Scott over at lt1, you can use either the method. Mounting and routing a pcv valve to the small mani vacuum connection or route a hose from the pcv connection on the mani to the vacuum port just behind it. You will still need a breather or use the port under the tb or the port on the side of the tb.

Hope that makes ,

Rabi C.

Wouldn't you have to have the reverse operating PCV valve if you put it in the manifold vs. putting it in the valve cover? In one case the vacuum is at the top of the PCV valve lifting the little internal cylinder. On the other case the vacuum is coming in the bottom of the valve and pulling the cylinder downwards (towards the intake). So I would doubt a regular SBC PCV would work on an LT1 intake. What am I missing here? It's got to be something...

Either way will work fine. I used the lt pcv and welded a round piece of sheet metal in the hole on the valve cover. After grinding smooth and painting You can't tell there was ever a hole in the valve cover.

Vern,

Dont worry ... either way would pull gases back in. Just Plug up the valve cover or the mani port which ever you dont use. I think the valve in the mani is of a diffrent design than the one in the mani so it would still work as its designed if you route a u hose to the vacuum port just behind it. Did you pull the mini ram off your motor for the lt1? Anyhow they are both viable methods.

Rabi C.

Nope, I'm sticking with the MR, have my PCV in the passenger's side VC with the hose routed to a vac port on that side. Used the vac ports on the driver's side for the brake booster and AFPR (put a breather on the driver's side VC). Looks a lot cleaner to me with the hoses routed like that.

I was just trying to point out that a standard SBC PCV valve needs to go in the VC and if you put a PCV in the LT1 intake it needs to be an LT1 PCV, not the "standard" SBC version from what I can see on these.

Vern,

You are right. I think that the LT1 has a different style of pcv though the traditional in the valve cover style will work. The one you dont use has to be plugged up.

Rabi C.

The car that I took the PCV off of was a 1997 Caprice. It had both a pcv in the manifold routed from the port below the throttle body, and one in the rear of the valve cover routed to the PCV port on the drivers side of the manifold. I was going to use both. As long as the PCV valves operate properly there should be no vacuum leak. The passanger side would go to the side of the throttle body so it will draw air from that point. This way he system is sealed, and you are drawing only filtered air in. I think it will allow better evacuation of any blow by gasses, which is what the system is designed for.

psy4s,

It seems that this is what the lt1 motors do to compensate for the lack of an egr valve. They dont actually have an egr valve in the traditional sense but what the stock lt1 motor does do to compensate for this is by adding more overlap in the cam. At least this is the case in the '96 and '97 lt1s. I was investigating this to see if I could get my mini ram to pass smog with out an egr but instead with extra overlap in the cam. In the end it might pass the sniffer but would fail visual (damn those overly strict smog laws!). So in terms of building a more efficient motor vern, you could hook up both pcv valves. Its up to you. If both pcv s are hooked up then the passenger side valve cover needs a breather then. Thanks for the input psy4s.

Rabi C.

Thanks,
Rabi C.
I am in the process of making a Vacuum diagram to list to actually show what I am doing with mine. I will post it this evening when I get home from work.
It explains the double PCV, If it workes efficently, it could (I guess) help to cool the inside of the valley. Just a guess. But to flow enough air to do that it would have the adverse effect of a vacuum leak. So I was going with better scavaging.

psy4s,

I am curious to see your vacuum routing. Well as I see it the pcv is using engine generated vacuum so as long as its sealed it shouldn't cause any adverse effects. This is the way it was set up from the factory so I'm sure there is something to it I'm just learning about this type of system myself so how this all works together is new to me. Thanks again psy4s for your input.

Rabi C.

A is the Crank Case Vent tube to the large port on the top of the Throttle Body

B is the Vacuum line to the Fuel Pressure Regulator

C is the PCV line from the manifold to the Valve Cover

D is the line that hooks to the Vacuum port below the Throttle Body to the PCV on the center of the Drivers Side of the Manifold

E is the line from the Manifold to the Power Brake Booster

My Engine is in a 1967 Camaro, and does not have the charcoal canister. This is the most simple way to connect the major Vacuum lines. You can use the small vacuum port on the drivers side for the fuel pressure regulator, but my regulator is pointing the other direction, so I used one from the passanger side. Any unused port should be plugged, or capped. The MAP sensor of course gets its vacuum from the hole in the top of the manifold.

you guys are making this way too complicated. The LT1 intake uses the same type of PCV valve as a TPI. It vents into the valley, just like the valve cover would, it's just in the manifold. If you have this on an engine with valve covers with holes, you can either plug one, or put a breather on both, or run both to the fresh air port on the throttle body/air intake, etc. Then just hop a shorty hose from the vaccuum port to the pcv.

I don't know how this changes with the LT1 manifold mods, however, if the mounting bolts get in the way of the PCV valve. If so, just plug it and use the valve covers as a standard tpi/tbi.

psy4s,

Thanks for the diagram. This way people in the future can reference it if they need to reroute their vacuum lines. Makes sense.

Rabi C.