For those of you that do not have IAC runner port holes. I would try to see if you can thread the TB and put a threaded pipe in the TB as opposed to trying to port the IAC to the side of the manifold. When I did the mod I removed my PVC breather from the side of the LT1 manifold and placed it to the port on the TB below the crankcase breather to bring that in front of the plenum. I did not want any of the ports on side of the manifold to breathe any air. My thoughts were that if it does it will still favor that side of the manifold. All my ports on the manifold now are strictly pulling a vacuum for whatever is needed. IE power brake booster, and vacuum canister for heater A/C duties, etc.

 

Hmmmm.... that actually sounds like a pretty good idea. Only problem is you're now putting oil vapors (and some oil) thru your TB and plenum. That can be messy, but maybe the oil lining the walls will help the air move quicker......

 

If you look at the stock LT1 setup the PVC uses a solenoid that attaches to the IAC port anyway. The LT1 adaption on the conversion shows it going to the plenum on the drivers side. TB's with airfoils have a tendency to suck oil because people don't realize the crankcase breather hole in the top of the TB isn't breathing enough air. Either way I would not be so concerned about that especially with the centerbolt valve covers if you are using them. Supposedly GM baffled those pretty good to keep that from happening.

 

A stealth ram has the PCV port up in the plenum as well. It's unavoidable.

 

Unfortunately my Sportsman IIs are perimeter bolt and the VCs I have aren't baffled all that well. May go to a breather type fitting with a built in PCV valve if I can find one with some steel wool type baffling. Other wise I may have to rig up a "catch can" type of arrangement....

 

Your sportsmans will accept both types of covers unless they are a real old set. I had a set of SR torquers with the centerbolts. They are worth it. Get the rubber gasgets and you have no leaks at all.

 

Guess they're the older style ones. They're not tapped for center VCs. They do require the older (pre-86 or so) intake config.

 

Are you sure? All the World product heads came with both bolt patterns for the valve covers since I believe the early to mid 90's. If you bought them in the last 10 years they should have both: http://www.worldcastings.com/docs/05_cat_pg17.pdf

 

I'll check again next time I have to pull the covers, but I'm pretty sure. According to the PDF file I found you had to do some machining to them yourself.....

 

That would explain the little step my Brodix heads have on the perimeter holes. To bad the hole didn't line up for my centerbolts.
I got spoiled with my solid cam and the CB's.
I always try to get VC's with a stock style baffle.

 

Don't know where you got that info from but the pdf I linked is directly from World. If I was smart I would have gone with the Sportsman and not the SR Torquers but then again I guess I needed an excuse to get some AFR's. I can tell you this I ran the centerbolts on my SR's no problem and if you look at the picture in the link I sent it shows the center bolt holes. The only thing I had to do was buy shorter bolts as the stock bolts for the center covers were too long.

 

Yeah, I got my PDF from them too, but it's from 2004 (not the 2005 catalog you used). Could be I'm having a "Senior Moment" and it's just the required machining down for the center bolt covers to fit that I'm thinking of.....

 

Pull a cover and look at them. The centerbolts holes will be there and you can use them as is. They look exactly like the SR's on top. If you have to flatten the inside of the covers by the bosses but I say you don't need to touch them. My AFR's have line machined throught the bosses on the perimeter. If you get a set make sure you get what you want as the covers have changed over the years. They fit on only 1 way but will fit on both sides. I ended up getting a new set when I went to the LT1 intake. One side is conpletely sealed because the PVC was moved to the intake. The passenger side has the oil fill and the crankcase breather. Older sets vary the oil filler location, etc. Yards are full of them. I think I paid $10 for the set.

 

I'll definitely check them out, thanks!

 

FIgured out how I can do this. I just ordered a 1" throttle body spacer. WIth that, I can try this pipe thing.

In any case, I'll get 50 hp from the helical throttle bores...

 

Note that those gasgets are the early style without sealing the IAC area! Good luck seems like at least 1 person that is logging both sides is split by about 1 volt even while driving.

 

The miniram is just one big opening for the throttle body. There is no IAC port in the manifold. So in this case, the gasket doesn't really make a difference.

 

One volt in AFR is almost exactly what I'm seeing. I see 1.0 - 1.2 at idle, and .75 - 1.0 when off idle. Passenger's side is richer.

69_Ghost - what do you mean by "moved the PCV to the intake and sealed the VC"? Could be I'm just slow this early in the morning, but I'm having trouble picturing that one..... (sorry!)

 

VC -the valve covers. On the TPI units the valve covers on both sides have holes. They have oil fill, crankcase breather, and PVC. Depending on the valve cover you will see different configurations. The center bolts are offset. They fit both sides but only one way. On the LT1 intakes GM moved the PVC to the intake. The LT1 valve cover setup accomidates this by having the oil fill and the crankcase breather on the passenger side. The driver side has no holes in the valve cover. That is why I said make sure that you get the set of covers you want. LT1intakes shows the PVC hose going into the intake right by the PVC -on the drivers side. I moved that breather to the TB port under the crankcase breather port. I also made sure that my crankcase breather was getting enough air by grinding my airfoil to make a breather hole in the top and opened up the IAC breather hole in the airfoil. Next I opened up the crankcase breather hole some more to make sure the wedge that mounts the airfoil does not restrict the crankcase breather hole in the TB. In effect all the air going into the intake has to go through the TB.

 

I hate to disappoint you about the gasget but if you don't get the right one it will still breath air out the sides in the area that there is no gasget. So putting in a pipe to try to fix your issue will not work unless you fix the gasget problem. Note this only for the gasget between the spacer and the TB.

 

So the LT-1 intake has a port for the PCV to draw from the crankcase? That's the part I didn't know or realize. Thanks for the education! Sounds like all the more reason to consider an LT-1 conversion....

 

Yes. Actually the air is routed from the PVC to a solenoid controlled switch that then goes to a port hole at the bottom in the front of the intake which is part of the IAC port. I don't have a lot of room there so again I put routed my PVC to breathe through the port in the TB just below the crankcase breather hole.

 

Hey Ultm8z can you pm or email me some info on your setup? Thanks - Justin

 

Just to clarify some info.
The LT1 intakes for the 5.7 & the L99 both have IAC air passages to each individual runner.
7 of the IAC ports are ~0.235" in diameter.
#1 cylinder is smaller at ~0.156 in diameter.
So it appears that even GM tried to mess with the IAC/EGR air distribution.

 

So, is the EGR fed back into these same ports that the IAC uses on an LT1 intake? IF so, that would mean the heads would not have to be drilled for the EGR to work doesn't it?





Don't know what I was thinking....


The heads are drilled so you have a source of exhaust gases to feed back into the intake, right?

 

the lt1 intakes use an external EGR tube coming from the exhaust manifold, on the passenger side. Whether the IAC passage and EGR passages share the same holes in the casting, I dunno, never looked. I can inspect the one at home and let you know.

is that what you were asking? the heads do not need an egr crossover, if I think thats what you were asking, you need to plumb it in remotely(if you even use it)

 

You cannot use the EGR on a converted LT1 intake. The distributor is in the way. And yes you are right the LT1 heads do not have an EGR port. The EGR is routed from the exhaust manifolds to the EGR port in the back of the intake. Vortec heads do not have a port either. Look at Scoggins they make some kind of EGR conversion when using the heads on older trucks to make them smog legal. I don't think you can use that on a LT1 intake though. You may be right about the EGR using the same port as the IAC I could not tell but assumed it was the case as I could not see any area the opened into the plenum from the back of the intake.

 

IIRC, the LT1 intake routes the EGR through a channel in the base and exits at two small ports behind the TB flange.

Z69, good to hear that the intakes you have looked at have the #1 runner with a smaller IAC passage. I had been wondering if GM had mis-drilled the one I was working on.

RBob.

 

Yep, that answers the question - thanks! Sounds like the EGR source with the LT1 intake is sorts like the Vortech TPI manifolds. My Sportsman IIs are drilled for EGR, so I'm not using EGR now anyway, but have considered drilling them since I'm running 10.5 compression.



So - RBob, you're playing with an LT1 intake now? GREAT!!! Does that mean we may be seeing some Lockers development for $8D in the near future?

 

There are two ~5/16 (by eyeball) holes on the plenum floor just inside the TB flange.

I'll have to run some water through one to verify.

The PCV inlet to the plenum on the front below the TB and the lower left side vac port are tied togethor also.


You can run egr on a converted intake also.
You just have to make adapters to put the valve on the outside of the fuel rail & FPR. I haven't had time to make one up since I found the pics. link

 

Is that where you are showing the hookup in lt1intakes? I did some tests by ruinning water through the holes when I had my intake off but can't remember. The dual holes below the TB would be like the TPI units also.