The car's running pretty good, so I've begun my quest to fiddle with it enough to make it run worse. I've been data logging my air fuel ratios at various speeds and engine loads and decided it was pig rich. It is set up with dual Kadron 40s with 130 main jets and 55 idle jets. As I'm sure you all know, but it was news to me (most of my tuning has been fuel injection), the Kadrons run on the idle jets up to 2500-3000 rpm and then on the main jets up to around 4500 rpm and then pretty much depend on the air jets above that. I was seeing low 11s with the 130 mains at full throttle and 11-12s on the idle jets at lower rpm. So, time to play around with smaller jets.

Cheapskate that I am, I checked around for an assortment of jets that didn't break the bank. Thesamba said that Mikuni motorcycle jets were the same as the Kadron/Solex/Brosil jets, and you can find a good assortment of identical jets in smaller sizes than the 130 on Amazon for less than $10. You can also get a kit for PWK Keihin OKO CVK PWM carbs that include "air jets" for the same price. I decided to give the latter a try.

The kit included 10 main jets from size 100 to 140. The PWK Keihin OKO CVK PWM jets have the same threaded part as the Kadron/Mikuni jets but the heads are a bit smaller. I tried the 125 jets and the 120 jets and both worked well. Switching from a 130 to a 125 raised the full throttle AFR by .9. I'm running the 120s right now and seeing full throttle AFR of around 13 at 4000 rpm.  solex vs PWK Keihin OKO CVK PWM

The idle jets in the kit are useless for the Kadron - they are very much the wrong size to replace the originals. It's not worth buying the PWK Keihin OKO CVK PWM kits to get them. Doing it again, I'd just buy the Mikuni assortment.

kits

I looked around for a replacement for the idle jets and there are some on eBay for about the same price that John at aircooled sells his but with free shipping. I figured John has contributed so much of his grumpy expertise to the aircooled community over the years that I'd order the idle jets from him even though it almost doubled the price for shipping (Hawaii problems). I ordered 50s for the idle circuit, we'll see how it goes.

Mike

 

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That's really cool. Thrifty and smart.

I have a customer with an 1835 sandrail I work on from time to time. It had a badly worn single progressive carb on it. I replaced that with a dual Solex 35PDSIT kit from John Connelly, among other parts. He jetted them for me and honestly they ran awesome out of the box, all I did was synch them and set the idle mixture.

I bought my recent rebuild parts from him, Mahle P&C, Total Seal rings, etc.....I love the Total Seal tapered ring installation tool. SO EASY to get the pistons installed. Used that on my motor and Brian's 2332.

The shipping is sometimes excessive but the parts are always right. Thanks John.

A couple of small updates:

- Some of you may remember me complaining about crunchiness in the steering. We conjectured about bearings, etc. I finally disassembled the steering to install a new turn signal switch and to rebuild the top steering bearing. When I got it back together, it still had crunchy spots when turning the wheel. I had a "doh!" moment and took a look at the lower end of the steering tube. Sure enough, the column was rubbing on the upper edge of the steering tube. The tube alignment was off because the steering tube, where it attaches at the top (near the steering wheel) needed a spacer to lower the steering wheel. This is one of those things that happens when you buy a speedster completely disassembled by the previous owner or by the forces of nature after sitting near the ocean for 14 years. One small rubber spacer later, all of the crunchiness disappeared! Huzzah.

- I'm getting closer on the jetting for the Kadrons. I've dropped the idle jets size down to 50. This gives me much more reasonable air fuel mixtures during normal low speed driving. Unfortunately, I had changed the main jets to 120s.  This gave me full throttle AFRs in the 13s between 3000 and 4500 rpm, but gave me a huge lean spot between 1800 and 2500 rpm on partial throttle.  It's obvious that main jets can have a big impact on Kadrons below 2500 rpm under certain conditions. I swapped the mains up to 125 and then again back to the stock 130s before the flat spot at partial throttle went away. While I was in there, I slightly bent the accelerator tube tips out of the venturi space (up roughly 1/4 inch) and pointed the spray towards the joint where the butterfly touches the wall. I re-positioned the tubes slightly again to make sure they fit well under the carb tops. Once I had them set up so they wouldn't dribble gas at high venturi speeds I tapped the tube base using a screwdriver and a small hammer. That made sure the tubes wouldn't swivel and were sealed to the carb. 

So, I did a rough sync and set the accelerator linkage a little bit richer and took it out. It's running really nicely. I can't feel it with my buttometer, but the AFR logs say I need to dial the accel pumps back just a hair (getting a drop down into the 6-8 range right after I punch the throttle).  

With the alignment (THANKS for the help with specs), the front and rear sway bars, oil shocks up front and the engine losing its flat spot, I'm grinning like an idiot most of the time. 

Mike

 

Mike, dial those accel pumps back until it falls on it's face, then open them a tiny amount. You want the minimum accel fuel spray until the fuel gets drawn from the well by the speeding-up air. That's how I set them.

According to John Connelly from aircooled.net, it's OK for it to run lean at part throttle, up into the 15-17 range. There are some AFR threads on thesamba.com. Good reading. Cheers, glad you got it running well.

mppickett posted:
ALB posted:

Glad to hear! What did the alignment specs end up at?

Al, sorry we're on a quick trip to NC for a funeral and I got away without my phone or any of the spec info. 

No rush, Mike.

At home in Durham, NC for a funeral and staying at my brother's house. Our mother grew up in the mountains of NC. Real hillbilly country with some of the finest people I've known. She grew up without electricity or telephones. Her first encounter with the"civilized" world was in the mid 40's when she enrolled in school at Duke University.

A few of our Possum Trot relatives had a hand in the moonshine trade and I always enjoyed seeing what kind of car my uncle Grover was currently driving. On one visit, he took us for a spin in his new 1970 Superbird. It was one of 16 produced with the 440 six pack engine. Uncle Grover had an infectious cackle which commenced every time we would come out of a corner and he would floor it. Here's a picture of my little brother Walt and Grover's long-gone Superbird :-)IMG_20200222_081041~2

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As I noted in a separate thread on how to modify the Holley 12-804 fuel pressure regulator to reliably work in the 1-2 psi range, I took the speedster out yesterday to test for fuel starvation and the stability of the output pressure. Those parts appear to be working just fine. However.... (see next post)Holley 12-804

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Tales of the Exploding Cooling Fan 

A Plea for Good Advice, General Uninformed Opinions, and Thread Drifting Comments

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Alternator stand broken cleanly off at the base all the way aroundIMG_20200303_074534

BANG! While checking for fuel starvation around 5600 rpm (hmmm, thought I'd set the rev limiter to 5200), I heard a large bang and saw my oil filler cap take off across the road behind me. The engine was running fine but the generator light came on so I knew it had to do with the fan belt. Pulled over and looked in the engine bay to see the alternator sitting at an angle, the alternator stand broken in half, a nice 2 inch hole in the top of my shroud and the alternator belt completely untouched (gee, I saved $10). Evidently I did not have one of the balanced, TIG welded fans in this engine.

So, anyone who has gone through this, I could use some advice. I need to buy a good doghouse shroud and replace at a minimum the fan and the alternator stand (and maybe the alternator). After reading about alignment and balancing woes, I'm wondering if there's a magic purchase of a pre-balanced alternator/fan set to be had. I don't plan on super high revs although the engine seems to really like the 5000s. I don't have the valve train to support more than that. However, I don't want to have another exploding fan adventure so a 7000 rpm fan would be welcome. Any suggestions on sources for good parts?

Many thanks,

Mike

 

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Whoa, that's nasty Mike! I've never heard of a fan coming apart at that low an rpm. Let's hope the head/cylinder fins and the cooler are all ok. Gene Berg does a welded/balanced fan

http://www.geneberg.com/produc...php?products_id=1254

and while it's not cheap, you know it's done right. I have heard of guys using tig to melt the blade ends (and not add any rod) so the balance is not affected (great if the fan was already balanced) but if you have to buy a fan and then pay for it to be done I'd go with the Berg piece. I've heard of blades coming through engine lids (on bugs) so take a good look around to catch all the damage and I'm glad no one was hurt. Al

PS- pics of the alternator and stand! We need to see the carnage!

 

Last edited by ALB

@ALB, thanks. I'll check out Gene Berg. This engine was freshly rebuilt in 2003 but sat unturned until I bought it a year and a half ago. It was in a garage but the door was mostly open and just a few hundred yards from the North Shore surf. I suspect the ubiquitous salt air corroded the little twisted ends that attach the blades. I'll know more when I get things apart. Thanks again for the tip.

Wow!  I've wondered about this before.  I had the rotating assembly of my engine balanced, but never did anything with the alternator/fan assembly.  What speed are the fans typically rated?  Aren't they turning 1.5 to 2 times the RPM of the engine?

Last edited by James

@James the only post I saw on thesamba said 2x the engine RPM. Several folks were talking about regularly going to 8000 RPM with balanced and aligned fans. General wisdom is that the original German fan assemblies are best (with TIG welding).

Again, I suspect mine was a fluke of over a decade of close exposure to mist from the surf. Our house is 1/2 mile up the hill from the beach and still have to wire brush and repaint outdoor steel items every 2 years.

Mike, you should be able to pound that out with a hammer and braze it closed, then maybe a touch of bondo and paint. And a new welded/balanced fan and a new stand. Check the alternator shaft, keyways, keys, etc. carefully though.

& you should invest some money in a smaller pulley to reduce the fan speed. The original 175mm is way too big for 5000 revs.

usually for more than 4000 you need a smaller one, I would go at least to a 146mm.

and don't worry about the cooling this will not be affected or even better because the stock fan can't handle the high revs anyway.

And check the alternator before you reassemble, usualy after a fan crash it's not in line anymore and ready for the trashcan

27026

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Last edited by Jan Peter Stahl
Jan Peter Stahl posted:

& you should invest some money in a smaller pulley to reduce the fan speed. The original 175mm is way too big for 5000 revs.

usually for more than 4000 you need a smaller one, I would go at least to a 146mm.

and don't worry about the cooling this will not be affected or even better because the stock fan can't handle the high revs anyway.

And check the alternator before you reassemble, usualy after a fan crash it's not in line anymore and ready for the trashcan

Great tips, thanks Jan!

Mike

DannyP posted:

Mike, you should be able to pound that out with a hammer and braze it closed, then maybe a touch of bondo and paint. And a new welded/balanced fan and a new stand. Check the alternator shaft, keyways, keys, etc. carefully though.

The directional vanes inside may be damaged as well; it may just be time for a new shroud.

Panhandle Bob posted:

Would damage to the fan blades be from stuff getting sucked into the shroud or is there something else, like bearings wearing out that would cause that?

I don't think it has to do with anything like that, Bob; it's my understanding that even a new stock fan in perfect shape will come apart after being subjected to enough higher rpm bursts. There doesn't seem to be a set number- rev the engine significantly higher than stock often enough and it will come apart. Some last longer than others, but it's enough of a certainty that you can count on it happening eventually.

The good elves at Wolfsburg never envisioned engines running at more than 4500 rpm, and to be honest I don't think I've ever heard of a fan coming apart on a stock carbureted engine. Remember, we're taking properly engineered parts that almost never fail when run within their original operating parameters and subjecting them to way more stresses than they were ever designed for. IIrc, the common thought is that for a fan to survive above 6,000 rpm with any regularity it needs to have no wear on the center where it fits on the collar (it will round out if the nut that holds it onto the shaft isn't torqued properly) and it needs to welded/balanced.

Mike seems to have got the short end of the stick.

 

Ouch.

Now I know why Tony insisted the fan blades on my new (six years ago) engine be welded.

At the time, I asked the engine builder how many revs the engine was safe to. He said about 6200. But, somehow, I've never had it over 5000.

Deep inside me (I think it may be somewhere between my shoulder blades), there's a rev limiter. The engine revs easily to 5000, and starts pulling really well over 4000, but it's MY rev limiter that kicks in around there.

It just doesn't sound right to me winding the thing up that high. It sounds like I'm tempting fate. Like something very well might let go.

None of my modern cars have done that. They sound the same at 5000 as at 3000, only a little louder. My old 2002 would hum along all day at 5000 (about 85 mph) and sounded, well, purposeful doing it.

This Briggs and Stratton is of another era, though, and - to me at least - sounds that way. I respect its age.

And just where are you going in such a hurry, anyway - marooned as you are on that tiny, little island? You're going to careen around some corner and fall into the ocean.

You'll shoot your eye out.

 

 

Panhandle Bob posted:

Would damage to the fan blades be from stuff getting sucked into the shroud or is there something else, like bearings wearing out that would cause that?

Nope.

The fan wheel flies apart because unwelded, unbalanced, unaligned fan wheels of all types tend to blow apart when they exceed their design RPM. Carrier package HVAC units are notorious for doing this. When they go, it's pretty manly-- shrapnel everywhere

...unfortunately, it's the same deal with a VW Type 1 (only the parts are heavier).' 

Get a welded/balanced fan-- for the children.

Mike-

Really, really sorry man. I'm pretty sure there is zero difference between the EMPI and Scat 36 hp doghouse shrouds. I'd bet a latte that they come from the same place. This is one of the EMPI parts that has nothing wrong with it.

If it were me, I'd get the full-meal deal: shroud, welded/balanced fan, backing plate, alternator, stand, and a pair of cylinder tins, just to be safe. Hopefully, the cylinder and head fins are OK.

Since you’re about to be the father of a new alternator stand, is it possible to change the mount from case studs to bolts?  (I saw your current nuts and looks like they’re function specific for something else).  If you can change them, it makes it a lot easier to get the fan/alternator off without pulling the shroud if you ever need to service it later on.

Gordon Nichols posted:

Since you’re about to be the father of a new alternator stand, is it possible to change the mount from case studs to bolts?  (I saw your current nuts and looks like they’re function specific for something else).  If you can change them, it makes it a lot easier to get the fan/alternator off without pulling the shroud if you ever need to service it later on.

Good idea, Gordon. I'm sure I can figure out a sleeve for the linkage mounts.

Mike, I slotted the two holes on the back (shroud side) of the pedestal and ran studs back there with beefy washers under the nuts, then went to bolts on the bumper side of the mount.  That way I can pull the two bolts and slide everything right out.

Try to keep the slots tight-ish to the back studs to keep the fan straight.

Last edited by Gordon Nichols

Reposting - Ok, we now have a better view of the scene of destruction. Overall, very little damage to the most important things.

Alternator stand sheared off cleanly at the base. No debris observed outside or inside the base. The backing plates are trashed.

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Elvis and all of his most loyal fins have left the building...

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Anybody still alive in there?

IMG_20200303_141746IMG_20200303_141818

And where did all the fins go?

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Aha. Cylinders 1 & 2 were hiding quite a few fins. Some surface gouges but nothing serious (1/8" at most).

IMG_20200303_143748IMG_20200303_143920IMG_20200303_143936

Oil cooler and cylinders 3 & 4 are fine

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Every fin is deformed. They are thick steel so that explains the bang and makes me grateful that the damage was contained by the shroud.

IMG_20200303_144523

I spotted circular scrape marks on the shroud towards the flywheel side of the engine. It's possible that that it wore one of the fin tabs enough for it to let go and then it took out the rest. Or, it just may have been badly balanced. I didn't see significant amounts of corrosion so my first guess was probably wrong.

Next steps: order a good doghouse shroud, welded/balanced fan, backing plates, alternator, stand and pulley. 

Darn, I was THIS close to Pachitto heads...

Mike

 

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Mike: my heart sank when I saw your first posts about this. All that work! You deserve better luck!

Thank you for posting all this here though. As others have said already, most of us have only ever heard rumors of Type 1 fans exploding, and never seen any direct evidence. It's really helpful to read your detailed description (5600 RPM! Not "over 5,000," or "5500" or "5700") and well-composed photos. 

Here's hoping it's but a minor bump on the road to smooth and twisty pavement.

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