• Registered: 2009-06-25
  • Posts: 554

Topic: Running better now ;)

Now that our VW is stopping well, it was time to work on making it go a little better. I had a performance intake that I was experimenting with, but the stocker got put back in so I could hunt down that elusive vacuum leak. My friend from the islands tipped me off to the throttle shaft seals on the 34 PICT, and that did the trick. I took 30 minutes and replace the intake manifold, but hooked everything back up to the factory air cleaner. With the stock cleaner, I did not have to rejet or adjust the carb. In this mode, the car ran smoother and quieter, and the powerband was wider and flatter. Freeway cruising was much easier, but I still did not have a lot of pickup when slowing back down and trying to get back up to speed again. It was better than before, but I could tell that there were restrictions in the intake system. Of course, I was also carrying 200 lbs of sound equipment and heading into a stiff headwind at 70mph, but it was not breathing all that it wanted to. The air inlet to the stock air cleaner is about the size of a thumb. Not enough for 1600cc at 5000rpm, and even more of  a problem for a 1776cc which I suspect is actually in there. After I got back home (at a more relaxed pace), I installed a high flow air cleaner, modified the oil breather port on the new cleaner so it was not being forced against the generator, and adjusted the idle mixture out one full turn. Just for the record, the stock air cleaner on the Ghia has a weighted flow damper that puts a consistent restriction on the intake air. The valve is large and opens enough to not be the bottleneck in the system, but if you take it out, you run leaner at idle and part throttle. Putting an easier flowing filter also leans the mixture. Putting a less restrictive exhaust on also leans the mixture. You get the picture, and that's why I had to richen the idle and hand-adjust the main jet. Don't worry, I can go back to stock in 45 minutes, but the stock intake manifold has issues because it was designed for economy and ease of manufacture. It's still too lean and I need to step up the main jet size one notch, but now it's breathing much better and you can actually feel it accelerating in 3rd gear as opposed to merely gathering momentum.

1st and 2nd gear are a thrill, 3rd is nice for a change (no pun intended), and 4th not bad. I do have a 135 main jet that was tried, and power above 3000 rpm is crazy, but it was too rich. The stock is 127.5 I believe, and the modified jet equals about 129, but I think a 131 would be about right. The problem with air cooled engines is that you have to let them get cold before you pull the plugs to check mixture, so it takes a lot longer to get the mixture right the old fashioned way. A wideband AFR gauge would solve that...

  • From: B.C.Canada
  • Registered: 2005-01-26
  • Posts: 2,586

Re: Running better now ;)

That's an interesting way to check the mixture. What do you do? Put in clean plugs I assume and drive for how long before checking them?

jim

'71 SB(DD only 79K(now 84K miles) & '78 FI Westy (project)
PO of '65 Beetle in '69, '70 Crewcab & '70 Ghia in '77
'71 Super inside rear vents now available
http://www.openroad.ca/volkswebbin/view … p?id=85915
  • Registered: 2009-06-25
  • Posts: 554

Re: Running better now ;)

jamesdagg wrote:

That's an interesting way to check the mixture. What do you do? Put in clean plugs I assume and drive for how long before checking them?

You can keep the same plugs as long as they are good. In just a few minutes of driving, the plugs get fired several thousand times, so any AFR (air/fuel ratio) changes leave their mark after a relatively short time. I usually drive for about 15 minutes and avoid idling for any significant time (like in a drive thru), and you want to shut down the engine when you pull back in the driveway. Reason for this is that the idle mixture can be set rich or lean and can affect the plug reading. The goal is to find the fuel mixture you get with the main jet(s).

The procedure I use is: Drive enough so that at least half of your drive is after the choke comes off, park without idling too much, then wait for the engine to cool for aluminum head engines, then remove the spark plugs. You should be able to find an on-line photo of different plug readings, but the ideal mixture will give you a ground electrode that looks relatively clean with a light tan or brown coating. For performance engines, light to medium brown is ok. White is too lean, dark brown is on the rich side, and black is way too rich. Note that driving style will affect the reading... drive like speed racer and they will show as being richer than if you drove gently. This is because most carbs and FI systems are calibrated to richen the mixture under heavy throttle, and you have the accelerator pump shooting raw fuel in as well. You can still read the plugs regardless of driving style, but you just need to realize it will look a little richer if you just drag raced a Lambo  :-)

This works much better on iron head engines simply because you can pull the plugs out immediately without waiting for the cool down. At the track I would coast into the pit area and check the reading between the first couple runs to make sure they were ok.

Paul

Last edited by Altema (2010-05-17 16:20:04)

  • From: Austin, TX USA
  • Registered: 2004-03-30
  • Posts: 240

Re: Running better now ;)

I use this method a lot for 2 stroke engines, it's a nice way to see what your mixture and/or jets are doing. I use
this chart for a plug read as well, nice and simple to follow.

Cheers,
-David

  • Registered: 2009-06-25
  • Posts: 554

Re: Running better now ;)

Not THAT, my friend, is the most complete chart I've seen! Thanks.

14 is about what I aim for, or just a hair lighter.
23 is what they look right now.
I'm not sure if I would classify # 12 as "good" though. It looks like high speed glazing which indicates that the deposits on the plug were melted due to a sudden increase in temperature, like under hard and long acceleration. The glaze usually burns off after an hour of use, so I guess "good" is still valid.

Paul

  • From: B.C.Canada
  • Registered: 2005-01-26
  • Posts: 2,586

Re: Running better now ;)

I bookmarked that site. Much better than the Haynes chart.

I suppose I could do the same for gas heaters. I'm restoring several BA6's and am not looking forward to the mixture setup. It's too hot to use a CO meter.

jim

'71 SB(DD only 79K(now 84K miles) & '78 FI Westy (project)
PO of '65 Beetle in '69, '70 Crewcab & '70 Ghia in '77
'71 Super inside rear vents now available
http://www.openroad.ca/volkswebbin/view … p?id=85915
  • Registered: 2009-06-25
  • Posts: 554

Re: Running better now ;)

jamesdagg wrote:

I bookmarked that site. Much better than the Haynes chart.

I suppose I could do the same for gas heaters. I'm restoring several BA6's and am not looking forward to the mixture setup. It's too hot to use a CO meter.

jim

Jim, you ever work on the optional Ghia gas heater? If I had one, It would only encourge me to drive the car in bad weather though! Not that the current system is a deterrent whne working well wink

  • Registered: 2009-06-25
  • Posts: 554

Re: Running better now ;)

Well, I put a 135 in for the main jet, and it's too rich. The car has good power and is very drivable and quiet, but it is making less power than it did with the hand-drilled 129 jet. The other downside is that gas mileage sucks: only getting about 20mpg as opposed to 35 to 40mpg. I swapped back in the 129, BUT, I also installed the heat risers for this intake manifold. They did not fit well (aftermarket parts), but I cut and bent the risers rather than anything else. For the record, the exhaust flow in the tubes is from the left site, to the intake manifold, then out through the right side tube which ultimately connects to the muffler. The only problem with this setup is that it warms the bottom of the intake center section, but air is flowing from the carb, so the carb stays cool until you shut the engine down and the carb warms up from heat soak. I had my air cleaner preheater wired so that it fed some warm air all the time to the system, and this was much more effective in keeping the carb in intake system warm. I may rig something up to use that to maintain a consistent temperature when needed since it worked better for me in testing.

I also ran some ignition timing testing with the new intake. The sweet spot seems to be 8 degrees BDC. This gives me good pickup off the line, and good power for freeway cruising as well. 5 degrees BDC resulted in sluggish low RPM performance, but good and very smooth hig RPM performance. Matter of fact, if felt like it LIKED going fast, 80MPH seemed like it was loafing.
The tables turned with the timing set to 10 degrees BDC: Low end performance was real strong, but top end hurt from being too far advanced, and high speed cruising felt strained. Best of both worlds would be to modify the dizzy mechanical advance to give 3 to 4 degrees less total advance.

By the way, before you pass this off as a waste of time, drivability is greatly improved, and I also beat a Chrysler 300M in a dash to the freeway ramp from a standstill. The Ghia left behind a pair of nice black stripes and some very surprised people in the other car.

Don't worry, I will not be doing this again in the forseable future, but it did make a good acid test.

Paul

  • Registered: 2009-06-25
  • Posts: 554

Re: Running better now ;)

Just a little update: I settled on 7 degrees BDC, the 129 hand drilled jet, and full heat to the manifold with no preheat to the air cleaner, and the preheater outlet from the engine blocked. I could get an extra horse or two by going to a 131 main jet, but that would not be worth throwing away a couple mpg in exchange. Everything feels about right now. City driving, highway cruising, startup,.. engine feels happy and I'm not gonna mess with that. Today after the rain dried up I took it for a long drive, over fifty miles at an almost steady 45-50 miles per hour along US-24. There were a few lights that stopped me, but not too many, and the fuel gauge stayed covering the upper half of the "2" at 1/2 marker the entire trip. It was not until I got on the freeway and pushed it a little to get up to 70 at the bottom of the ramp, and sped up to 80 to pass a car to get over to my exit, that the needle moved to the middle of the "2". Life in the air-cooled world is good  smile

Paul

Last edited by Altema (2010-05-22 18:21:15)