Itinerant Air-Cooled

hambone wrote:Do you have another distributor to try?

We ran it at 28*btdc hoses off, and we ran it at 22* btdc hoses off, as well as vacuum advance hose on and off for both settings. I will certainly try anything at this point; Saturday is ball joints, and I will try several distributors and report if we would like that.

Robbie

Also wondering if you did any other measurements of temps, like with an IR gun or an oil temp gauge. Would you consider moving the CHT sender to another (or to each) cylinder and getting a measurement there before you tear down the engine?

Those are good questions Satch. I'm reminded of my temp travails in the air-cooled 82; to touch on Asia's questions about ambient, it was my experience that ambient made little difference. I drove out to Vegas during the day. Left OC around 10am, arrived in Vegas around 5 pm (I stopped a few times to rest, etc.) Ambient temps were north of 110, CHT was a steady 400+ reaching to 440 on the last long grade uphill headed towards Vegas.

I came back at night, leaving Vegas around 8pm, and arriving in OC around 2 am. Ambient temps were easily 20+ deg cooler, but I saw little or no difference in CHTs. Maybe a delta of 5-10 degrees at some point, but I was still 420+ going uphill out of the desert in the middle of the night.

It would be worthwhile to have more info; I was struck by the inverse relationship between oil and engine temp; as CHT went up, oil temps went down, and vice versa, generally. In the most stressful moment, it was both really; I went up the grade towards LV in 2nd gear, doing around 30 mph, maybe. CHTs were 430+, and oil temp was around 240 F I believe. I'll see if I can find the link.

I suspect either: CHT temp gauge is iffy; something is up with the oil movement and/or engine function. Dakota Digitals are good, but CHT gauges are not as accurate as they should be.

Until later; gotta sleep.

edit: Couldn't sleep 'til I found the link. Here 'tis:

http://itinerant-air-cooled.com/viewtop ... 3&start=15

ML

satchmo wrote:Also wondering if you did any other measurements of temps, like with an IR gun or an oil temp gauge. Would you consider moving the CHT sender to another (or to each) cylinder and getting a measurement there before you tear down the engine?

Oil temps with the IR gun were 212-220* measured at the camshaft curve on the case.
Valve covers were 215-ish (remember no sizzle Robbie, ewwww)
Exhaust pipe temps were 574* @#3 /520 #1
We were driving in such short bursts that we did not have an opportunity to heat-soak the engine much. The head temps were too high too quickly.

The engine seemed happy enough in almost very way but the vibration. Chloe was similar. Ran well, good power, good tune, nice oil temps, spot-on timing, a full range of carburetor jets and adjustments, and a terrible increase in CHT on the merest of hills. There was a problem. It eluded everybody until the last instant where there was nothing else to even look at . . . and there was that exhaust valve sitting flush in a seat that had not recessed in the slightest.
Colin

Can't sleep at night now because my bus is sitting in a garage 125 miles away and torsion arms won't get here in time for this weekend. So I'm going to get the flywheel/PP balanced, but a thought just hit me. Colin dutifully asked me about the gap between the fan and fan shroud (or was it fan and backing plate?) and it was one of the few things I genuinely couldn't answer. I know I LOOKED AT the fan last year to make sure it was filling the doghouse fan shroud in my dual-port doghouse engine straight out of a '71. And during my appointment, he enlightened me to the cast-iron generator pulley that the T1 buses would have come with to match the 38 amp alternator.

Now, I'm not sure of any of this, but I hypothesize that because my engine from a '71 bus was made with an alternator conversion and with a 30a bug generator, could I have a non-doghouse fan appearing to fit the doghouse shroud because I don't have the right generator? I know the backing plate for a correct 38a generator has an offset, but I haven't personally seen one so I don't know if it would fit.

And dang these cast iron pulleys are hard to find.

Robbie

I'm running an off the shelf German pulley, no issues.
The generator would be WAY off if you used the wrong backing plate.

asiab3 wrote:Colin dutifully asked me about the gap between the fan and fan shroud (or was it fan and backing plate?) and it was one of the few things I genuinely couldn't answer. I know I LOOKED AT the fan last year to make sure it was filling the doghouse fan shroud in my dual-port doghouse engine straight out of a '71. And during my appointment, he enlightened me to the cast-iron generator pulley that the T1 buses would have come with to match the 38 amp alternator.

Could I have a non-doghouse fan appearing to fit the doghouse shroud because I don't have the right generator?

Not likely, but we don't leave stones unturned. The non-doghouse fan is 32mm wide and blows 20 cubic feet per second, the doghouse fan is 35mm wide and blows 25 cfs.

The gap is a close 2mm max between the support plate and the fan.

If you balance the flywheel and the pressure plate, please index the two before you send them in, so you can ask the balancer if indeed they are grossly out of balance. This will apply to your forensic information-gathering. You still have the crankshaft and rear pulley serving as confounding variables.
The flywheel has four different possible positions on the crankshaft. It took me three placements to get the vibration minimized, 180*/90*CW/180* from there, and three separate 180/120*CW/180CCW on the pressure plate to find the best-for-the-meantime balance. That is a lot of twiddle-twaddle that a full balance could have helped me to avoid. I will be sending out everything when I tear down Chloe's engine for a refresh of bearings and maybe pistons and cylinders.
Colin

Could that tailpipe be the culprit? Looks kind of small diameter. Restricting the exhaust gasses and increasing temps?

brandt wrote:Could that tailpipe be the culprit? Looks kind of small diameter. Restricting the exhaust gasses and increasing temps?

HaHaaaaaa! Oh but I tried this monstrosity too:




And temps had their ups and downs. When I took it off for the STOCK tailpipe that I currently have, temps didn't change on the highway or around town. In fact, I went one main jet leaner and temps didn't change. Where with the Bazooka, temps went up a tiny bit with the proper main jet. The higher airflow through the pipe wants more fuel to match it I think. And I will try to paraphrase Colin: "Stuffing the LM-1 into Chloe's tailpipe through the Southwest desert did nothing to the engine except alter the sound bouncing off the canyon walls. That, and read the mixture ratio". So I don't buy that

Edited by the Society to Prevent Paraphrased Bus Confusion

brandt wrote:Could that tailpipe be the culprit? Looks kind of small diameter. Restricting the exhaust gasses and increasing temps?

A famous misconception. VW *selected* that small tailpipe to restrict the power output to within the cooling system's capabilities. As soon as you fall for those aftermarket exhaust sloganeers, "get up to 20% more power!" you have now a corresponding increase in heat generation. We managed to fire up those 430* CHT readings at 45 mph in 4th gear, nowhere near "exhaust restriction rpms".

Both Robbie and I heard the wheezy restriction of that LM-1 plugging up the damper, but he did not hear Chloe happily wheezing just as badly at 370* CHTs at 108* ambient. The BobD doesn't wheeze. The BobD shows not a difference between LM-1 installed and not installed.
Colin

Yeah this is a thread about Colin's travels, but I'm going to keep complaining about my engine. Sue me.

The McDonalds BBQ Sauce Tin Deflector was installed, much to Inspector Otto's dismay:



I have made the decision to keep digging.

Robbie

asiab3 wrote:Yeah this is a thread about Colin's travels, but I'm going to keep complaining about my engine. Sue me.

The McDonalds BBQ Sauce Tin Deflector was installed, much to Inspector Otto's dismay:
I have made the decision to keep digging.

Robbie

That's it! . . . . . . not.

Let's place the last few posts here into your own thread in the Engine Forum. Title it and I will transfer the salient posts. I am anxiously awaiting your findings.
Colin

1600 dual port, doghouse fan setup, stock 34/3 carb, stock exhaust, Mallory Unilite SVDA.

CHTs showed 360 cruise and 390 floored uphill for months. One day up a mediocre hill temps went straight to 430 and I heard pinging. A day and half with Colin, and we are no closer to getting this little engine back to where it once was.

(placeholder- forgot my Bentley in Oceanside, gotta adjust the thermostat DOH.)

While I'm waiting for the original technical threads, I'll post these issues here:

The Brazilian dual-port heads have a recessed spark plug well with grooves that royally screw up any CHT sender installations. We tried it twice, and both times we got crunching when torquing the plugs, and before that I had a few missed-installs too. The problem didn't end up being JUST the grooves, but the depth of the well compared to the thickness of the sender crimp. The crimp ends up hitting the side of the well, then the crimp can't scoot out of the way with a spark plug socket in place. See here? If you leave the plug socket in place, the crimp just pulls the sender into leaking and ovaling out:




Also, Colin was miffed that my engine builder ground off my head locating dowels, but I mistakingly said they were ground off. The heads have NO casting for the dowel. Talk about cheapening of later model VWs………

asiab3 wrote:1600 dual port, doghouse fan setup, stock 34/3 carb, stock exhaust, Mallory Unilite SVDA.

CHTs showed 360 cruise and 390 floored uphill for months. One day up a mediocre hill temps went straight to 430 and I heard pinging. A day and half with Colin, and we are no closer to getting this little engine back to where it once was.

(placeholder- forgot my Bentley in Oceanside, gotta adjust the thermostat DOH.)

While I'm waiting for the original technical threads,

Update us! Photographs!
Colin

Ah! I was waiting for my mistake to be moved to the Engine forum. I have photographs. I have MS Paint drawings. I have 63mph freeway cruise at 360-370*. I have FAR BETTER rotating mass balance. And I have full-throttle runs for HOURS topping at 404*. And a set of nice 70-79 torsion arms after REPEATEDLY STRESSING THE PART NUMBER BUS-BOYS. Posts to come when I need to kill time at work.