granprixweiss928

Anyone have any idea why my AFR swings so much?

granprixweiss928

Continued investigation.

Unplugged O2 sensor. AFR went steady and bucking went away. Super lean- in the 16s .

Opened up AFM and adjusted spring, loose 20 notches to test if Fuel will richen up.
and it did. Drove around, in the 12s. idle in the 10s. holy.

opened up again, (Im getting good at it) and turned back 5 notch tighter. Improvement in AFR, now driving in the 13s.

did again and went 2 notches. Now in the high 13s/low 14s. opened again today and another 2 notches.

AFR now in mid 14s. steady accell, no bucking, O2 still unplugged.

Then I got my hands on a smoke tester. Found pretty big leak on the Drivers side cam carrier, on top edge. didnt even look at underside, but I assume there maybe some there too.

temporarily plugged those top leaks with puddy weatherstripping, and then tested rest of intake. All was holding well, just a few wisps at the idle screw and throttle shaft. not going to worry about those.

So I need to change cam carrier gaskets, and while Im there Im going to pull the engine and do the head gaskets too.

Mrmerlin

wait what? the cam tower will not leak smoke no way no how
The cam towers will leak oil IF,
you have RnR the cam towers and used the later gaskets with the early style cam tower bucket bores,
as these take a special gasket to seal ,
and when combined will cause the edges of the cam tower to be unseated when its all bolted together, but smoke is probably leaking from the rubber gaiters or the intake manifold gaskets.

granprixweiss928

Stan, explain why cam tower at gasket to head would not leak air. Its clearly coming from there.

My theory: crank case gets pressurized, via the intake pipe thru the oil filler neck, and thus the oil passages as well up into the cam carrier.

Pretty clear hiss...and once plugged by my wad of putty, it stopped.

Mark

granprixweiss928

here is where the leak is and where the I put the putty to block it.

Ducman82

you would be getting smoke in the crank case, then some how getting it past all the oil galley gasket material to leak there... that would be odd unless it had a massive oil leak. if the intake its self is not leaking around the plenums or the throttle body, then its not leaking. this situation would be like pressuring a chevy 350's intake checking for leaks, and finding it coming out of the valve cover breather.

granprixweiss928

after returning the smoke machine to my friend, I made up the DIY kind using my compressor.

Here is my rig for the L-Jet intake.

the large end, was the closest fitting I could find at the hardware store, to the approx 3" opening in the part below the AFM (which I removed).

I wrapped that in some rubber tape that I had to make it fit tight into the seal from the AFM opening.

I found the leak in the cam carrier corner, right away.

Cant fix it right now so I got to live with it for now.

Ducman82

what are you using for smoke? or are you just looking for flow?

granprixweiss928

i used the smoke machine to make smoke. Once it was connected a for a while, then I could hear the hissing in that corner of the cam carrier.

then after a few minutes, the smoke came out pretty good.

all that stopped when I blocked it off with the putty.

The crank case was getting pressurized. via the pipe from the lower bowl of the intake, up thru the oil breather, and then into the crank case. when pressurized, the oil fill cap was holding. when I undid it, it make a big "poof" as all the pressure escaped. and same time the hiss at the cam cover stopped.

M

Speedtoys

Can we do the 85 this weekend?

Ducman82

sounds about normal to me. unless you have all the intake valves closed (no cams installed) you will be the smoke past the valves, in to the chamber, and past the rings into the rest of the crank case.

GregBBRD

The smoke machines have adjustments for how much volume of air/smoke is injected.

If there is smoke coming out of the crankcase (or cam carriers, it's turned up too high.

If you can actually hear a "hiss" it's definitely turned up too high.

BC

The barn door maf pieces are getting old. They are the last of the "mechanical" ways of tracking airflow. They have boards in them that swipe an arm across a resistance pad.

I'd drive it like you stole it this summer and work on it later.

granprixweiss928

yes, and I had it up on highest setting. the pressure built up, over a few minutes, and then it would start to hiss. I could feel the leak with my hand.

granprixweiss928

Just bumping this thread back up. I have NOT solved this.

What I have done is run the car without O2 connected to get around it.
It got me thru the rest of the show season.

This was not solved ad I want to continue trying things to figure this out.

Mark