Weber selection and initial jet tuning

[240260280]

I re-read the thread and checked on a few items.  Here are my thoughts:

 

1.  The 00 exhaust/spill/bleed-back jet could be the bug bear that has been on our back the whole time.  It would cause the rich high rpm tilt that we have been trying to tune out with very large air correctors.

2.  The 00 exhaust/spill/bleed-back jet could also be causing the rich dip when you start your run. The squirt of liquid fuel would be the reason.

3. The two above effects will cause the WOT run to always appear to have a hump in the middle and hide the subtle effects of the E-tube.

4. By adding a larger air corrector, to try and bring back the high end from its richness caused by the 00 exhaust, it also delays the E-tubes with the high holes from coming in early enough. The F16 is particularly affected by this due to its higher holes and it will come in later if the air corrector is too large. This will cause a flat spot between the progression circuit stopping and the main circuit starting.

 

I also ran Weber's formulas for your engine and rpm range.

- Ideal bore is 44.1mm so 45DCOE's are as good as it gets.

- Ideal Venturi is 35.8mm for 6500rpm redline so your 34mm or 36mm would be fine.

 

The carb and chokes you are using are well within the ideal range.

 

In the spring I think the first order of business is to do a run with the 00 Exhaust in place and another with the Exhaust valves replaced by screws. This will help us better understand what that beastie is doing.

 

 

[blodi]

Drove the Z into work today since it's the last day in sight for 50+ degree temps.   Ran great all the way until I was almost to work and then the tapping came back.   I'll see what happens on the drive home. Good point on checking for throttle plate screws..yikes. I'm also wondering if I'm getting a bit of knock due to timing since the temps have gotten colder. I am running a lot of timing so maybe I need to back it down a bit and see if that changes it. 

I will try the blocking of the accel jets in the spring and we will see what we get. 

[Patcon]

I would think cold temperatures would make it less prone to spark knock...

[blodi]

went from bad to worse...tapping turned to #4 cylinder not firing at all.  Got spark and fuel....compression test showed 90 psi on that cylinder.  So, I'm suspecting a stuck or bent valve....going to pull valve cover to inspect when I have a chance here.

 

[240260280]

Rats.... good luck finding out what is going on.

[Mark Maras]

 Any change in the engine performance when it was tapping?

[blodi]

7 minutes ago, Mark Maras said:

 Any change in the engine performance when it was tapping?

Not at all...still ran/started great.  Plenty of power. 

[Patcon]

Did you look at the throttle plate screws?

[blodi]

“That theres ur problem”. 

Broken lash pad.  The other small part that broke off it I cannot find so it probably dropped to the pan.  I’ll check the thickness tomorrow and order one. Do I have to remove the camshaft to install a new one? 

[240260280]

Good find!  Glad it is not lower end.

 

Sweep the head with a magnet (including springs) to try and find the broken pieces.

Also put a super magnet on the outside of the oil pan near the drain to try and localize any debris.   Remove the magnet when you drain the oil and hopefully it will be close enough to the drain to get carried out with the flow.

For installing the rocker, you just need to wind down the adjuster all the way.  Fit the rocker end between the cam and lash pad then pop the other end over the adjuster ball. Sometimes a long flat screwdriver helps as a lever to push down valve spring a wee bit.

 

Be sure to inspect the cam lobe and two rocker faces for wear or damage.

 

Excellent!

Edited December 6, 2017 by 240260280

[siteunseen]

Yes, good eyes.

 

Edited December 6, 2017 by siteunseen

[blodi]

I did run a magnet around the head last night, but no luck finding the small part.

Ordered new lash pad (.170") and got a couple rare earth magnets here at work.  Should be back up and running soon!