Weber selection and initial jet tuning

[blodi]

Yes, my cruise has been pretty nice- 14.5-16ish depending on the setup. 

I'll put the .35 exhaust back in. I did notice a slight stumble with the .65 when driving around. 

I did put copper spray on the both sides of the gasket. But, I used an OEM gasket this time and MSA says that's a no-no with their headers.

I could see two leaks when it was on the car  ,but there were 6 I spotted once I had it all apart.  So MSA gasket one should be here any day. That's what I had on there before and had zero issues. 

 

[blodi]

Replaced manifold gasket and drove 1/2 mile and once again I got a leak. Out of town for the next two weeks..I'll try to replace the gasket again when I'm back and we'll go from there. 

[240260280]

Good luck!  I heard of some people stacking two together. It may need more research. 

You may wish to  check side of head and manifold surfaces for bumps that could prevent sealing as well as flatness.

[blodi]

Welp, back from vaca and installed a new intake/exhaust gasket....still the noise. Got the bore scope out and the damn #4 intake valve seat came out again! Agh.  

[240260280]

That is a bummer. I guess a new head is needed.

[blodi]

Head is repaired. This time with some "staking" to hold the valve seat in place. So pretty much impossible for the seat to come out again. A new head would be really tough as this is a rare E31 that has also been ported/shaved/etc....

Hoping to have the car back up and running by this weekend. 

 

[blodi]

Car is back up and running. No noise.  ?

[blodi]

Ok, back in business. Here is F2 140/185 fuel level set at 29mm (the front carb I had to lower the floats further than the other two by a few mils to get the fuel at the right height) and .35 exhaust jet. 

The lean spike at the beginning, which can be felt as a stumble when I first hit the throttle, is that the exhaust jets not being 00? Its been that way the last few runs...wasn't  there before. 

8318 by blodi, on Flickr

 

[240260280]

Here is your second last run:

35 Choke
140 Main
240 Air
F2 Tube 

 

 

Here is your last run:

35 Choke
140 Main
185 Air
F2 Tube

  

Decreasing the air from  240 to 185  significantly lowered the a/f  in the first 3/4 only (It scooped the middle a bit too).  It seems the top end is controlled more by the fuel jet.

 

Please try the 225 air and 150 main.

 

For the lean spike, I am not sure if it is controlled by the 00 spill jet.  You can try a bigger accelerator jet to get more fuel to squirt earlier.

 

Edited August 9, 2018 by 240260280

[blodi]

I actually tried a couple different setups beyond that last one posted over the weekend. I took a log of one that was too lean up top and then tried a different setup that I didn’t get a log of but it looked really good just watching the readout.  I’ll try to get a log of it later this week if we get a dry day here. 

[blodi]

Took a couple of logs tonight...first one was down an entrance ramp. Second one was a flat entrance onto highway and engine was more up at temp.  The setup? F16 155/185 

8918-1 by blodi, on Flickr

8918-2 by blodi, on Flickr

[240260280]

Here is your F16 155/185 flat run from last night.

 

Here is the next previous F16 155/185

 

 

Here is your very first run with F16 155/185 and 34mm choke from last October

 

My thoughts:

• There is some variation due to the time being the x axis  rather than rpm  however the same max/min signature is seen. 
• It seems this combination of  155/185 gives nice results with F16 Etube. 
• A main jet in the 165 to 150 range seems to be where to hover.
• We were unable to change the high rpm tilt/drop off by opening the air corrector. When we tried, it leaned too much elsewhere.
• We were unable to change the low dip when the accelerator circuit kicks in.
• Due to the two items above, all of the runs had a lean hump in the middle for which the edges could not be modified to meet nor could we beat down this lean hump.
• The very low dip into the 10's and 11's when the main circuit kicks in is always present. It is independent of emulsion tubes, acceleration jets, bleed back valve, or fuel level. This gorilla in the room seems to be due to the 45mm carb as it appears in many other 45 applications that are not L28's.  I think the only way to deal with it will be modifying E tube tops. 
• Of all the runs, the F16 165/215 seemed to have the least dip at the start of the run. This may be the best compromise. Here it is:
  
• And here is your F16 155/185 run from last night where it dips below 11:
  

 

Going forward:

1.  A run with the 155/185 with the F11 tubes would be a "nice to have".
2. The low dip at the start may be due to the emulsion tube unloading liquid fuel at its onset (We proved it is not acceleration circuit or Etube or Main Jet or Air corrector, or fuel level).  If you are up for it, some modifying of the top holes of the F11 tubes would help confirm if there is a way to tune this region.
3. If the low dip at start can not be tuned with modified E-tubes then it is simply due to the 45 DCOE design being incompatible with the cylinder size.  A 40DCOE may be a more appropriate carb for tighter controlling a/f ratio.

 

Question:

1. Is the 45DCOE output diameter port-matched to the intake runner's opening or is there a step from a large 45mm dia carb to a smaller diameter intake port?