Wideband Results

[tzepesh]

Thank you very much for your suggestions John. I get from your replies that you would recommend the 48s and have ~16AFR till 3000rpm.
I will try the new ignition map, but only in about two weeks when I come back from vacation (today it might rain). It is so good to have this programmable ignition and be able to tune that too.
If I can get those 48s to work without pops, I would be happier: lower CHT, better MPG.
_________________
'74 1303S, L98B Viperngrun (extra glitter), German Look
'64 1200, Sea Blue, under restoration

[sallittjob]

1968cc
8.5:1 Compressor
Dual DRLA 40s @ Sea Level
52 idles
148 Mains
200 Airs
34mm Vents
3-4 PSI Mechanical Pump
Mallory Unilite Dizzy 4 BTDC @ Idle 30 BTDC @ Max Cent


Hey guys,

I've gotten really close to dialing my new motor in but wanted to ask for some help before ordering more jets.

Right now at LBI I'm sitting around 13.5:1 AFR

Once I get into the skinny around 10% throttle (light cruise) I get a reading right around 16:1 afr. If I accelerate gently I getting a lean spike around 3,000 RPM (19:1 or so) before the mains kick in and then it goes from around 15:1 down to 13:1 once I pin it @ WOT.

I'm assuming I need to up the Air Correctors to a 220 or so to bring the mains in sooner to fix the lean hole then bump the mains to keep the WOT AFR at 13:1?

Also feel like I should be able to knock the idles down to 50s to improve my MPGs on the idle circuit. I did briefly try running the 50s with the main stax out and found it very hard to drive as the car would choke out quickly at the top of progression. If I stayed below say 15% throttle with the 50s I could drive it around with my AFR around 16.5-17 until I got into it a little more (never above 20-30 mph though).

Any help is appreciated... Thanks!
_________________
57' Beetle Deluxe
1192cc SP

71' Super Beetle
1968cc DP

73' 412 Sedan
1679cc FI

75' Westy
1800cc FI

[[email protected]]

to me it sounds like you are close with the 52s. Maybe 51s?

For the airs, try 210s next.

I think you'd find an improvement if you'd change your cent curve to be 8 at idle and 30 total, in other words 4 degrees LESS in the curve. 4 at idle will be lethargic for sure.
_________________
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[sallittjob]

[[email protected]]

but your timing of 4/30 shows too much cent advance.

Proper idle timing will almost always be in the 7-8 range. If it's idling too fast, back the idle speed screws off, then re-set LBI.
_________________
It's just advice, do whatever you want with it!

Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net

"Like" our Facebook page at
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[deanbradford]

Hi guys need some advise please.

1600c
stock heads, mild port
stock crankshaft
Engle W100
1:25 ratio rockers
dual Weber40 IDF's
Bosch 009 set to 31 degrees
Fuel pressure 3.2


Idles 18 to 20
WOT starts at 11.8 then quickly rises to 13.3
Part throttle 16

Pulls very well but have a very slight stubble when I floor the accelerator but didn't do it when I had 50/120/170.

Jets are
Idles 50 (tried 47's but engine popped and was really not happy)
F11's
Mains 115 (had 120 in but ran rich)
Airs 180

Cheers
Dean

[sallittjob]

Adjusted timing per John's recommendations to 7 idle 29 max and reset LBI. Idle circuit is much better! Lean hole in the top of progression is almost gone at this point. Only problem I still notice is when I down shift (let's say from 3rd to 2nd) the engine goes lean when I get into the throttle and it sputters for a few seconds until everything stabilizes. Is this something that I can remedy or is it just normal?

Thanks again.
_________________
57' Beetle Deluxe
1192cc SP

71' Super Beetle
1968cc DP

73' 412 Sedan
1679cc FI

75' Westy
1800cc FI

[modok]

Are you sure it is going lean on downshift? it could be rich too, but, the wideband is probably right if your eyeballs are fast enough to read it. what size acc pump squrters?

[[email protected]]

it's completely normal for a lean spike to occur during a gear shift change, but recovery should be quick (like .25-.5sec).
_________________
It's just advice, do whatever you want with it!

Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net

"Like" our Facebook page at
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and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net

[modok]

When you downshift quick, you get all the enrichment from evacuating the main wells. I found on smaller engines it could be too much, it's partly why, (talking IDF terms) why a LITTLE engine uses f-16 and a BIG one uses f-7, because of the acceleration enrichment, but the DRLA only have basically one kind of e-tube........and it's quite a puzzler of a tube too. Bigger air jets and or smallish venturis will make the acc enrichment faster and sooner. What kind of accelerator pump adjustment you can get away with is interrelated to this too.
the problem is probably simpler than all this, sorry for straying too deep, but it is food for thought!

[sallittjob]

Not sure what size the pump jets are anymore; I do remember they were the stock starting point for those carbs. I'll confirm on the weekend.

I haven't spent anytime adjusting the accelerator pumps to be honest. I backed them off a lot so they wouldn't get in the way while tuning and they are still at that setting.

So the idea here is to counter the lean spike at downshift I want to provide more accelerator pump squirt? It does go away to some extent if I quickly open the throttle after the downshift (pumps add the shot of fuel) and is worst when I gently and gradually get into it after the shift.
_________________
57' Beetle Deluxe
1192cc SP

71' Super Beetle
1968cc DP

73' 412 Sedan
1679cc FI

75' Westy
1800cc FI

[modok]

[deanbradford]

[sallittjob]

[tzepesh]

I am adding a small update to my configuration: 1584cc engine, W100 cam, 4-in-1 exhaust, Megajolt ignition based on MAP, Dellorto DRLA36, 30 vents, 48 idles, 180 airs, 9164.2 emulsion tubes, 122 mains.

I used the 48 idle jets that used to pop through carbs and increased the ignition advance between 2 and 8 degrees below 80KPa. the pops disappeared, and I also have some logs. But I feel the vacuum read by Megajolt could lead to improvement: I see that right after acceleration, while cruising, the MAP is around 93-96KPa, not 80 as I expected. And it stays around that value on cruise. The ignition advance seems a bit low, around 23-25 degrees because of the high KPa values.
In the logs, the purple trace is AFR and is 10 time the real value (147 means 14.7 AFR; I had to trick the Megajolt to show the AFR correctly).

Can you please suggest improvements in the ignition map?

Here is the ignition advance I started with:

This is the increased ignition advance:

And here are two logs:

_________________
'74 1303S, L98B Viperngrun (extra glitter), German Look
'64 1200, Sea Blue, under restoration

[tzepesh]

I'm bringing up the topic, maybe i can get some suggestions. Shall i increase the advance more, and if yes where and how much? Cruise seems too low at 23-25 at 92 kpa. I would have expected higher vacuum an more than 30 degrees.
_________________
'74 1303S, L98B Viperngrun (extra glitter), German Look
'64 1200, Sea Blue, under restoration

[[email protected]]

Having just tuned a MS converted Waterboxer, this advice will likely help you. I'm hardly a MS expert, but I try to pay attention to cause/effect, and this comes from what I've directly experienced.

Note that your map you jump up 7 degrees of timing from 1200 to 1500 RPM (300 RPM), but only 1-3 degrees from 1500-2200 RPMs, yet only 3 degrees from 1000 to 1200 RPMs.

Think of the RPM range in a %, rather than absolute. 1000 to 1200 is a 20% increase. 1500 to 2200 is a 50% increase (roughly).

In your map, your advance is too fast at 1200-1500, and too slow at 1500-2200. My opinion.

On my engine, if I increased the ignition timing too quickly, I got a stutter on the logs which I could only SOMETIMES feel.

I think your engine would run a lot better if you'd simply back off the 1500 RPM timing ~2-3 degrees. That will also increase it's rate of advance in the 1500-2200 range. Both regions will drive better in my experience.

It will also help to look at the MAP in 3D view, you'll see where it's advancing too quickly, or too slowly, and you can edit it. Save smoothing for later on.

Lastly, how fast the ignition advances will depend a lot on the A/F mapping. On my engine I have basically 3 types of cells. Stoic for around idle, 13.2:1 for WOT, and 16.2:1 for everywhere else. With a stoic row for transition between the 13.2 and 16.2.

At the 13.2 areas (WOT), you will effectively be at high load, and don't need any vac timing addition. Once I went to 16.2 I could add in heaps of vac timing, since the lean tune burns very slowly.

YMMV

[TinCanFab]

[TinCanFab]

So, what I would like to know is, what do I do next?

I haven't fiddled with anything, just swapped exhaust so I can see the immediate change.

What HAS changed:

- smoother driving experience in every gear and RPM
- the accelerator pumps are still backed off, but when I stab the throttle it goes like stink with no hesitation. Almost like I had engaged the acc pumps
- I can hold a speed much better
- when I come to my lean hole (that my AFR gauge reads) I can just hold the gas steady and powers right through it. Previously I had to feather the pedal to keep engine from stumbling and popping

What has NOT changed:

- idle AFR (mid 13's)
- WOT AFR (high 12's to low 13's)
- constant dead zone AFR of 14.5-15 cruising in 4th on the highways

I am thinking now is the time to try F2 emulsions and rejet all over? Suggestions?
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http://www.thesamba.com/vw/forum/viewtopic.php?t=658092

[[email protected]]

I'd go back to try the 50 idles next.

Just repeat the tuning process, you have a new engine to tune now with the exhaust change. Don't skip steps. Now that you know what/how to do it, it will go faster.
_________________
It's just advice, do whatever you want with it!

Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net

"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
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