I need help to make sure parts match. Putting together a base manifold with no manifold heat cross over, left and right runners have the small tube blocked as purchase, the plenum is a 1985 the TB is 1985 also. My question is should the two small tubes of both runners be plugged. Are the triangle shaped opening in the TB and plenum EGR passages I have EGR removed and blocked. Is this a working setup?

 

If the plenum is a 85-88 if the egr has a block off plate no exhaust gas can go in to the 2 runners small tubes and up to the plenum y.

 

I believe the triangular shaped openings in the TB and plenum are for idle air. If you have the egr removed and a block off plate installed, there is no need to plug anything.

 

85 - 88 plenums have two separate passages cast underneath ,
the pass side tube takes EGR gases up , the drv side one takes IAC air down
The tube on the drv side runner is the air supply to the CSI from the IAC passage on the TB
89 + plenum shown on left only has the EGR riser

 

Thanks for your replies it also explains why I was having slow cold starts.

One more question converting a MAP Sensor and a MAP ECM...

If I converted to 1990 MAP with a 1990 ECM. WILL THE PARTS (85-88 plenum and TB) work with the plenum and TB that I have?

Thanks in advance!

 

You can use a map sensor on the older plenum just use a dedicated manifold vacuum signal .

https://www.thirdgen.org/forums/tpi/...tion-85-a.html

 

Thanks tuned performance! Is the MAP sensor sensitive to the orifice size?

 

I'm not sure about the orifice size being a issues unless you are going smaller than the stock fitting witch is the same size that you have right now for your fpr.
The length of the vacuum hose will effect the map sensor try to keep it a foot or less.

 

Ok Tuned Performance and thanks again guys for the help.

 

Last night I began installing the intake manifold, runners, and plenum. Noticed that that the cylinder head port opening was slightly larger than the intake manifold opening more so in height than width.

A Fel-Pro 1205 was trimmed to fit the cylinder head opening (basically trimmed back to the blue raised seal) the intake manifold port is close to the Fel-Pro 1205 opening.

Question how much will performance lost will I be looking at or will it matter that much?

Thanks in advance

 

Nothing you can do, if it seals up run it. Your intake is the bottle neck especially if this is a larger displacement engine.

 

How much hp will be added if the manifold was open to match the heads. Is it worth the effort to gasket match the manifold?

 

I'm really not sure you might pm this guy. I think he was going to have a few bases flow tested.

https://www.thirdgen.org/forums/member.php?u=45203

 

Thanks Tuned Performance

 

np, wish I could have given you a better answer .