Fast idle after lean backfire through manifold

[Motorhogman]

UPDATE:
Note to self.. and others. When donalds makes a suggestion pay closer attention.

Installed the lower manifold.. Installed the upper manifold.. Thread stripped out on 3 of the wood screw holes at 40 inch lbs..

I assembled these manifolds on the bench and torqued to spec. 62 inch lbs.. Seemed solid. Must have been the last life those plastic holes had..

Picked up a new manifold.. $110.00 out the door. Came with $27.00 worth the seals already installed. I didn't use them. Used the new Fel Pro ones I bought.

All back together. Fired right up and still idling around the 1000 - 1100 rpm at operating temp..

Smoke test again.. Yep smoke puffing in paces that can hardly be seen, front of manifold below lower T stat housing.. Same place as before.

Disconnect the Evaporative Y tubing from the manifold and put vacuum caps on the ports.

Smoke test again.. NO sign of any smoke from any where.

In fact when I pulled the transfer pump hose off the power booster hose it blew smoke back out. It was pressurized

Start engine and let it run until up to temp with Y tube still disconnected and vacuum ports capped.

Idle comes down to that 650-700 rpm area..

Take it for a test drive. Runs good.. Made a few stops and starts.. Everything good.

Get back to the house put it in park and the idle is back up.. Not as high now, around 900 rpm now..

Going to look into using the BAFX OBII reader and the ForsScan Lite software I down loaded.

Learning is good.. LOL geeesh !

 

[donalds]

The hose that goes down the front of the engine is for the Evap system it goes to solenoid under the battery you can have a leak anywhere between there all the way back to the gas tank
Follow that black hose it's starts behind the thermostat housing tees off goes all the way down the front of the motor

 

[Motorhogman]

I did follow it to under the battery. Just about impossible to see a lot of that line the way it runs. I have it disconnected from the vacuum ports on the upper manifold. It was definitely puffing smoke from just below the T stat housing in the front of the engine.
No smoke with that disconnected. I'm sure there is a break in that line.

What makes no sense to me is the idle returned to normal for at least 20 minutes minutes when I disconnected that hose and capped those ports ?

I'm thinking of making up my own lines and rerouting them down to that solenoid.

 

[donalds]

I did follow it to under the battery. Just about impossible to see a lot of that line the way it runs. I have it disconnected from the vacuum ports on the upper manifold. It was definitely puffing smoke from just below the T stat housing in the front of the engine.
No smoke with that disconnected. I'm sure there is a break in that line.

What makes no sense to me is the idle returned to normal for at least 20 minutes minutes when I disconnected that hose and capped those ports ?

I'm thinking of making up my own lines and rerouting them down to that solenoid.

You can remove the Alternator bracket and get right to it

 

[EB4X]

As a NON SOHC owner...what in the world is >> "wood screw holes" on this engine ?!?

 

[Lee's Automotive]

As a NON SOHC owner...what in the world is >> "wood screw holes" on this engine ?!?

the screws from the upper intake that screw into the lower are wood screws of the T30 variety

 

[Motorhogman]

As a NON SOHC owner...what in the world is >> "wood screw holes" on this engine ?!?

It's called "planned obsolesce"

 

[Motorhogman]

You can remove the Alternator bracket and get right to it

Thanx

I'll give that a look. May be easier than making my own red neck concept. Just seems everything is Crammed together on this truck. I miss my 60 Chevy and 79 GMC P/U.. lol.