T4 Tear Down / Rebuild in Jax FL

[wreck]

Just google" Ray Vallero pushrod sprinkler " , you drill a .5mm hole in the end of the pushrod ,just past where the Hardened insert finishes , I'd angle the hole slightly so it sprays back towards the head/ valves .

I don't have flaps in either engine , One has a 911 shroud so impossible to do , the other is a totally custom set up that could have a flap system fabricated if you lived in a cold climate .

Florida on the other hand has close to the same climate as Brisbane where I live.So I really believe a bit of extra cooling on the heads is worth this simple mod , maybe next time when checking the valve lash .

[Clatter]

Glad to see your head temps are stabilizing a bit.

Without a wideband, you are kind of guessing at what is going on..

Back in the old days you could tune by reading plugs,
and with race gas, you still can,
but the additives in fuel make it impossible with pump gas any longer.

Google innovate LM1 that is the old one they don't sell any longer,
and you can get them cheap.
There are others.
You can get a wideband so cheap now. And they are cheaper than heads, or wasted gas, or especially a rebuild.

On TOS there is a post called "Wideband Results" in the engines forum, where John Connelly of ac.net goes ahead and holds everyone's hand through wideband tuning.

One of the techniques he uses is pulling the main jet stacks out.
Drive it around (town obviously) and feel where the idle jets finish working, and the mains kick in.
(Or not, if they are missing).

You get a feel for this, and then you know if your hesitation is taking place at 'transition', where idles quit, and mains take over.
This way, you can tune your idles, and mains, knowing where they 'are', so to speak.

Tuning with a wideband, plus knowing your transition area, and tuning it correctly, is all part of setup.

I know how you might feel right now; just about sick of all this.
It's a cruel joke that tuning is so hard, and no necessary, right as you are thinking you are done.

Often, it's good to get some time off from cars, make the family and spouse happy, study up, get some jets and whatnot, and return later.

The good thing about all of this, is that once you have it dialed in,
You can just leave it like that, and run it!

Are your valve adjustments holding stable yet?

Usually one way to know your break-in is coming along, is that the valves won't need adjustment, just checking..

[analogtherapy]

I know how you might feel right now; just about sick of all this.
It's a cruel joke that tuning is so hard, and so necessary, right as you are thinking you are done.

Often, it's good to get some time off from cars, make the family and spouse happy, study up, get some jets and whatnot, and return later.

You nailed it.

Thank you for the very insightful and kind reminder. And it just so happens that today, we'll be heading to a local fair (instead of me working on the bus)

The good thing is that I've got a friend who may still have his LM1. While he's looking for it, I ditched the old exhaust system (which had an exhaust leak), and picked up one of those new EMPI stainless systems. A total gamble for sure, but it's really quite nice, and it fit well. Flows MUCH better, sounds great too. Waiting on a set of 60 idle jets now. My mains are 115, so those may be a bit small too, but we'll see. I'm also waiting on a new, longer linkage hexbar. My previous bar became too short after I added thicker gaskets to the intake manifolds and fell off while I was driving the other day...but that's another story...

[analogtherapy]

All parts have arrived for the wideband test so we'll see soon where it's lean/rich.

In other news though, head temps have finally come down!

Today I gave it a real test. Sustained highway speeds between 60 and 75, and long bridge incline. Head temps reported never got higher than 390, and that was when flooring it, doing about 70-75 up the incline of the bridge. The rest of the way temps hovered around 380 or less. I will also add that the new stainless EMPI 4 to 1 style header/muffler setup seems to have made a big improvement in temps.

[analogtherapy]

Aaaaaand it looks like the image hosting site I was using vanished without a trace, so now all of my images are gone. Sorry folks.

[analogtherapy]

Alright, I've fixed most of the images. Hope they stay that way...

[Clatter]

This is a great build.
I love your tenacity, and how you followed through.

Here's the final follow-through ---> https://www.thesamba.com/vw/forum/viewt ... p?t=293837
TOS is still alive and kicking, and this is my favorite thread over there.
I often re-read through it every so often, just to 'own' the info, dig?

If you throw bigger and bigger jets at it, you run the risk of washing down your cylinders.
It might run cool, and run well, but your top-end life will suffer.
(Plus you'll be wasting money on fuel and polluting everything).

I'd start with timing at 28 total, all in, 3500RPM, hose off.
Adding the hose should give you a 'bunch' more timing, like 6-8-10 degrees or so.
Let the idle fall where it may..
If you need more idle timing advance, you can bend the stops 'in' inside your distributor.
Because you are running big carbs, this might be needed, vs. the stock setup the distributor was designed for.
FWIW, Jake went all the way to 12 degrees BTDC at idle with his bigger-cammed bus motors..


Also just re-read this one. Thanks for fixing the pics.
It's been really good to see the 'holes' in my cheap junk thread,
Where I assumed something was already known, or skipped over important stuff entirely..

Keep us posted. Happy tuning!

[raygreenwood]

This is a great build.
I love your tenacity, and how you followed through.

Here's the final follow-through ---> https://www.thesamba.com/vw/forum/viewt ... p?t=293837
TOS is still alive and kicking, and this is my favorite thread over there.
I often re-read through it every so often, just to 'own' the info, dig?

If you throw bigger and bigger jets at it, you run the risk of washing down your cylinders.
It might run cool, and run well, but your top-end life will suffer.
(Plus you'll be wasting money on fuel and polluting everything).

I'd start with timing at 28 total, all in, 3500RPM, hose off.
Adding the hose should give you a 'bunch' more timing, like 6-8-10 degrees or so.
Let the idle fall where it may..
If you need more idle timing advance, you can bend the stops 'in' inside your distributor.
Because you are running big carbs, this might be needed, vs. the stock setup the distributor was designed for.
FWIW, Jake went all the way to 12 degrees BTDC at idle with his bigger-cammed bus motors..


Also just re-read this one. Thanks for fixing the pics.
It's been really good to see the 'holes' in my cheap junk thread,
Where I assumed something was already known, or skipped over important stuff entirely..

Keep us posted. Happy tuning!

This is correct...but the 12* at idle really has nothing to do with "big cammed" motors. I have worked on what must be just under a couple of thousand type 4's....and NOT ONE that I have found (most especially the stock injection system driven engines)....does not benefit from slightly elevated idle timing.

The biggest myth is that you should time the type 4 to its maximum "all in" timing at 27-28 BTDC (this part is absolutely correct as a starting point)....and let the idle timing fall where it will......that last part is bullshit.

Its BS thats been propagated over decades ...simply because there is no simple "turn the screw" method of fixing that idle timing issue. The masses decided since they cant SEE a button to push to fix it....that it cannot and therefore ....should not be fixed...so they pass it on to everyone by gospel by word of mouth.

However....it can be fixed very simply and easily on stock distributors with a little judicious work with the advance springs and weights...and even easier on a vacuum advance unit by installing a simple set screw for the retard side of the can (the factory already installed a STOP pin...on virtually every vacuum can ever made for type 3 and 4).....and...its even easier to install a set screw on the advance side of the vacuum can. The factory even had these on certain Porsche 914 models VW 411 and 412 models (advance can arm # 917).

Its not rocket science to understand how having too low of an idle setting affects off the line performance. That little extra nudge of advance required to prevent a flat spot off the line is what vacuum advance is created to do. However vacuum advance can reestablish at part throttle at high rpms...over advancing.

So ...owners limit their max advance with the distributor position....which screws up their idle timing...giving a flat spot and making idle and off the line fuel mixture adjustments suffer.

The "partial" answer to that was to put a set screw on the advance side if the vacuum can and limit how much total vacuum advance it was capable of....which "helped" the idle timing issue.

This combination of off the line and maximum advance is why Jake initially was looking at the Mallory distributor because it gave better control over both ends of the range and allowed better tuning of fuel for off the line and throttle shift points. Ray

[Clatter]

OK, Ray, I guess I’m wrong, then..

I was all ready to start arguing,
But,
Couldn’t find where anything I said was different than what you said(!)

How did that not resolve as bull poop anyways?
The censors must be broken! LOL!

[analogtherapy]

I'm currently trying to wrap my head around the things I've read in the "Wideband Results" thread over at The Samba. So far, there are two comments by John C which I think paint the best picture for what I need to do.

Here: https://www.thesamba.com/vw/forum/viewt ... 51#5033051

"Copied from another thread, good stuff.

Glenn's 65 idles are too big, so your 70s are off by more than 5. How do you know his are correct or not? Did you help him tune his IDAs?

The progression circuit operates on throttle position, when the throttle is only open a little bit (<1/3) the manifold vacuum is very strong to the progression holes, and it pulls air/fuel out of the progression holes. This progression circuit is necessary because airflow at low throttle settings is insufficient to initiate the main circuit. You can prove this by removing the mains/emulsions/Airs (jet stacks) and drive around on the progressions to see how they work, and under what conditions they do and do not. I strongly recommend doing this for several HOURS (not blocks) to get a really good feel for how they function.

It is true that by using bigger idle jets the progression will be extended, but not the way most think it does. This is because the engine becomes too rich at low throttle settings, and as fuel metering tapers off it still stays above a "combustible" level. It makes no sense to make the entire progression circuit too rich just to fix a small lean hole at the end of progression/beginning of mains. Why fix a 500RPM band and ruin a 2500 RPM window, when you can fix the 500RPM band you are lean in, instead?

IF there is a lean hole between progression and main, MOST put bigger idle jets in to cover up the hole, but this makes no sense. This is because it richens up ALL OF PROGRESSION (to too rich), just to fix a lean hole right at the end. The proper solution is to make the mains come on earlier. That's why I recommend to do some extended driving on progression ONLY (Main stacks removed), to get a feel for the progression. Change jets as needed to get the lean cruise you desire (which is NOT 13:1).

Then you put in a "too big" main jet, so that when the mains come in you see it on the A/F or 5-gas, because it swings way rich (it's very obvious). Change airs to get the transition (lean hole) to just disappear. Start with a small air jet, as the lean hole will be biggest and most apparent. As you go bigger on the airs, the mains come in earlier and earlier. You stop with the air jets tuning once the transition has NO lean hole. Then you change the main from the one that's too rich, to the one that's just right. DONE.

If you can't get main tip in correct with air jet tuning, you have to mess with the emulsions, which sometimes requires emulsion modification (it's easy), not just changing them. Float level also changes when the mains come in, and these are not properly adjusted out of the box, you MUST do this.

I have done a lot of weber/dellorto tuning, and can simply say that 65s are too big for IDAs, UNLESS you have installed a much larger than "normal" idle air, like a 135+ (stock is 120), because what matters in the progression circuit is the ratio of idle fuel to idle air. You can use a 50 or even a 45 idle fuel if you have a small idle air, like an 80, to maintain the ratio. This is not easily adjustable on IDFs or DRLAs because they have a fixed orifice, but IDAs it's adjustable and tunable, which USUALLY means enthusiasts screw it up because they don't know what they are doing.

But my point is that if you have 48IDAs with 37mm venturis and change to 40 or 42mm, the idle jet tuning will not be affected AT ALL. You WILL have to change the mains and airs, since the mains will come in at a later time with the larger venturis, since the signal is weakened. So air jet tuning will have to be done to keep the mains coming in at the right time.

This is why the size of the venturi changes the size of the air jet needed, the bigger the venturi the bigger the air jet. That's why 28mm venturis use smaller airs than 32-36mm venturis with the SAME F11 tube and same 45mm Aux Venturi."

...And here: https://www.thesamba.com/vw/forum/viewt ... 09#4828209

"the question is "what is the load?".

If you insist on driving 70-75mph in a bus, you have a significant LOAD and will never run on progression, so you'll be on mains and should be 13:1.

That is why it's so important to KNOW where your progressions are, by driving around with the mains removed (deactivated). Progressions are for LIGHT LOAD (lean tune), mains are heavy load (Power tune). Do not confuse them.

However, I will say the most common problem is people tuning progression for 13:1, which is a huge mistake (even in a bus). If you jet the carbs like I recommend, the carbs will adjust the A/F for the load you give it. Load = throttle position."

Phew!

So we got the O2 bung installed at the crossover, right before the muffler, this past Sunday. Once the wideband wiring is done I'll be able to start collecting some numbers. It's a bit of a bummer to know that I've been going about this all wrong (throwing larger idle jets at it in an attempt to fix my flat spot) but at least I have a decent set of idle jets now in case I need them.

As a starting reference, I'm currently running 60 idle/120 main/175 air.

I'm curious about the distributor adjustments you guys have mentioned, but I'm pretty sure either way, I'm still running an overly rich jet configuration.

[raygreenwood]

OK, Ray, I guess I’m wrong, then..

I was all ready to start arguing,
But,
Couldn’t find where anything I said was different than what you said(!)

How did that not resolve as bull poop anyways?
The censors must be broken! LOL!

...sorry....I was not aiming my "BS" at you.....just the general tired concept....and I usually always get caught by the censors!
The reason I call it BS.....is because not one manual....not even Bentley manuals.....tell you that whatever you happen to get as an idle timing setting....no matter what it is or whether its working or not.....is what you should HAVE....when you set your timing by the factory method.

The problem is that 300 years ago or so when wll of these cars were brand new, the distributors were jice and tight, carbs or EFI were at factory nominal running condition.....they did not have to mention what your idle timing setting was because it typically ended up within spec.

Cut to 300 years later.....and I have been seeing this for quite some time.....a decade or more.....you have hoards of owners running around following the Bentley manual word for word....like it was the origibal copy of the old testament.
While the Bentley IS the bible......all of the "characters" in the book are now 2000 years old. Sh*ts worn out. It does not all just work like the book says...simply because you assemble it just like the book says.

Unless one does a stellar Glenn Ring level of distributor restoration...and that means new factory springs and stripped down to the weights and correcting wear in the pivots....and new factory Vac cans.....and all else the same as factory.....cam, compression, complete fuel system...etc.....your idle timing will likely not fall back to the original 300 years ago factory setting.
And....that would be ok....since a large part of it will be that your engine while it may be brand new with a superb....better than factory build quality....is no longer factory.

So my point with that in mind.....is to fix that idle timing issue.....instead of just saying the book shows no alternative to it....ao it must be fine.

Ray

[Clatter]

OK, thought I was missing something, or something..


That wideband thread is a real bear.
It goes off in a bunch of different directions no doubt.

It also focuses on a tuning technique of going clear way over to lean - like 16-17:1 at cruise,
And that's not necessarily the best way to run your bus.
You might try doing so if you are brave, and are having fun tuning.
You kind of have to commit do doing so, because you go clear way lean, past the 'death zone'.
At first, you want to just tune out your stumble, and get idle and WOT right.
You might lean the idle jets and pull timing as a final 'icing on the cake'.
The whole 'lean cruise' thing can be done after you 100% own the rest of the process.

Anyways,
You are 100% right in modifying your way of thinking in fixing the stumble you are trying to tune out;
Using a different air jet vs. throwing bigger idles at it.
Don't feel bad, almost everyone does exactly what you were doing. I did, too.


Always write down exactly what jets you have in at any given time.
Check every jet you install for correct size.
You can buy a tool from CB, or get a set of very small drill bits.
So many times they are marked wrong..

Might just go ahead and bite the bullet and get a few jets, and airs especially.
If I'm not mistaken, ac.net will buy unused jets back if you got from them.

I'd be throwing your smaller idles back in, and see what AFR it gives you.
See if it still runs hot - it might, but might not. Bet you it was just breakiing in.
Your stumble will probably come back.
You want to be sure you aren't washing the cylinders down with raw fuel, the rings might not be breaking in correctly if so.
Go ahead and drive it around with the main stacks out like John says, to learn where the idles quit working.
It's best to have some (good, not washed-down) break-in miles on the motor before going for final tune.

Make sure it has a fresh valve adjustment and triple-check your timing at full advance, both hose on and hose off, plus idle.
I like to write down what the timing shows and keep track, to be sure it's not changing over many miles.
Plus, it can help when you start pulling timing out of it as well, if you go that far with tuning..


So, get that wideband hooked up,
Get some air jets, and those BIG mains,
And see if you can't fix your stumble with airs instead of idles..

Wideband tuning can be really fun.
When things work like they are supposed to, and changes happen as predicted,
it's a real gas, no doubt..
With your motor all fresh and sweet and hotted-up like it is,
You'll be able to make it howl!

[Piledriver]

I have been guilty of telling folks to set max timing at 28 and letting base timing fall "where it way" as a starting point.
(I suspect it was a Jake-ism)

I also posted how-to pics of how to easily mod most stock distributors and 009s etc for more initial timing , but the pics were long ago eaten by bitworm.

I can personally attest that setting the timing curve up per the Bentley/stock specs will result in just about the hottest possible cht. That was likely done for emissions reasons.

Folks are under some delusion that >17:1 afr results in higher cht/egt...
That is only true if you don't also set the timing for the much slower burning mixture.
To do it right really requires programmable ignition and efi.

12.3-13:1 burns much faster and requires far less timing.

[analogtherapy]

Does anyone have suggestions on what AFR I should be aiming for for idles/mains? Wideband wiring is almost complete, and I'm not really sure what numbers I should be shooting for.

[wreck]

I'd go by what John has mentioned . "do the no main stack first" , take the bus for a free way drive and work out when the progression circuit ends . As John has mentioned ,once off the progression circuit you need to get the mains to be down to mid to high 12s .