Georgia Fiero Club Forum

All Things Fiero => Tech Tips, Tech Questions => Topic started by: f85gtron on May 01, 2015, 05:44:12 am

Title: lower intake possibilities
Post by: f85gtron on May 01, 2015, 05:44:12 am

Which lower intakes fit on the 2.8 from other motors?
Mine needs replaced or repaired and I thought this would be a good time to explore alternatives while it's off the car. 

Title: Re: lower intake possibilities
Post by: Fierofool on May 01, 2015, 07:45:48 am

The 3.4 V6 intake is almost identical. The only difference is that it doesn't have the port for the cold start injector, which you have already deleted, anyway.  You would need to transfer the thermostat housing over from the Fiero intake.  The 3.1 might be, but I have no experience with that one.  If it's aluminum head, the 3.1 won't work.

Title: Re: lower intake possibilities
Post by: f85gtron on May 01, 2015, 03:13:28 pm

It appears to be missing the iac passage as well. I suppose I could run it back up into the plenum through the egr hole. Right?

Title: Re: lower intake possibilities
Post by: Fierofool on May 01, 2015, 08:52:12 pm

The IAC is on the throttle body, not the lower intake. 

Title: Re: lower intake possibilities
Post by: f85gtron on May 02, 2015, 10:04:55 am

Correct me if I'm wrong, but, me thinks the iac passage originates in the throttle body inlet, via the hole in the bottom of the passage before the butterfly, then travels under the butterfly to the iac plunger, past it, then through to the big black pipe that exits from directly under the rear of the throttle body and under the upper plenum. The pipe then juts out about three inches, then does a 90° down and into the lower-most intake manifold, just to the left and above the cold start injector.
I'm thinking i could simply tie back in at the egr hole, instead of traveling all the way down to the intake manifold?

Title: Re: lower intake possibilities
Post by: Raydar on May 02, 2015, 12:46:52 pm

Ron,
You are correct about the routing of the idle air circuit. (I didn't notice it at first, but the 3.4 manifold is missing that fitting, as well as the CS injector.)
You probably could route it to the EGR fitting on the upper plenum. I've tried to think of a reason why it wouldn't work, and I keep coming up empty.

Title: Re: lower intake possibilities
Post by: Fierofool on May 02, 2015, 01:13:01 pm

While Raydar was posting, I was out looking at my manifold set and there isn't a port on the manifold.  I wonder where the 3.4 got their vacuum from.  Remember that the Camaro/Firebird throttle body was on the end with the thermostat housing, so there might be something up there that we can't see.  I'd pose the question on PFF or pull up the 3.4 project install thread.  I believe it's still on our website. 

Title: Re: lower intake possibilities
Post by: Raydar on May 03, 2015, 11:57:44 am

Speculation...
I'm guessing that the 3.4 idle air circuit is entirely contained within the throttle body. Instead of being routed to a pipe in the lower intake, I'm guessing the idle air "re-entered" the main air stream behind the throttle plate. Or else was routed to the upper plenum as Ron was describing doing, with the Fiero plenum.

Title: Re: lower intake possibilities
Post by: Fierofool on May 03, 2015, 02:22:01 pm

I just looked at an exploded view diagram of the engine showing the throttle body, gasket and upper intake and the only passages in the gasket or manifold are bolt holes and air intake.  The gasket I have in my set matches the diagram. 

Title: Re: lower intake possibilities
Post by: f85gtron on May 03, 2015, 06:59:48 pm

I wonder if I could plug the hole on the back of the throttle body and drill a passage to after the butterfly?

Title: Re: lower intake possibilities
Post by: Fierofool on May 03, 2015, 11:02:57 pm

Easiest way to do it---Meet me in Greensboro one day this week and I'll bring my manifold. 

Title: Re: lower intake possibilities
Post by: f85gtron on May 04, 2015, 06:32:59 am

That sounds easier! 

Title: Re: lower intake possibilities
Post by: f85gtron on May 04, 2015, 10:53:30 am

There's a couple 3.4 at the junk yard, but I didn't know that they're shoved into those camaro like a van!  I didn't have the will power to tear them out, just to experiment on, so if the offer still stands, I'll make arrangements convenient to you, Charlie, to buy the one you have already.
I did find an 84 in there. Good shape, but almost gutted. Gray and silver.

Title: Re: lower intake possibilities
Post by: Fierofool on May 04, 2015, 12:32:25 pm

I'm free all week except Friday.  Just as long as I get on the way back by 2:30-3:00 so I can pick up my Granddaughter. 

Title: Re: lower intake possibilities
Post by: f85gtron on May 04, 2015, 08:31:20 pm

My schedule is unclear until Saturday. It'll be day by day. I'll call with much notice as possible....say 24hrs.

Title: Re: lower intake possibilities
Post by: Fierofool on May 04, 2015, 09:17:44 pm

I may be able to meet you in Greensboro after the club meeting, but you'd need to be available on a moment's notice.  It would take me about an hour and a half to get there from the meeting.  I could call you when the meeting's over. 

Title: Re: lower intake possibilities
Post by: f85gtron on May 07, 2015, 05:57:14 pm

Update:
I've managed to drill out the remaining easy out and surrounding dirty metal. Took it to a shop where a guy I know it's skilled at welding aluminum and he filled the hole back in. Now I just have to drill, then tap a new hole. He was surprised at how soft the aluminum was...whatever that means. 
I tried to use alumiweld, but I could not get the manifold hot enough. I think that stuff is better suited for smaller work, like brackets and such.

Title: Re: lower intake possibilities
Post by: f85gtron on May 15, 2015, 06:41:04 am

The finished product.
Drilled and tapped, hand filed flat, then studded so I don't have to go through this again!  What an ordeal!  All this over a stupid bolt!