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@ALB Hi Al, before I did any adjustments, the wrist pins in grams were, 132.2, 132.6, 132.4 and 134.2. To reduce the weight, I used a small diameter grinding wheel that would fit inside the pin and took material off both sides. 

Speaking of reducing weight, about 15 years ago one of my Pelican forum buddies was converting a 911SC into a 934 relica. He had done a body off pass through the chassis and drivetrain replacing bolts and nuts or cutting them down to the exact length needed to reduce weight. After doing that and some of the other things you described, he got his car under 2000 lbs. My frankenporsche (also a converted SC) weighed in at 2700 lbs to give you a sense of how serious he was.  Just curious, do you know how much your 356 weighs after all of the things you've done to it? 

Mike

mppickett posted:
Carlos G posted:

One way of making a car lighter that is often overlooked, is looking at oneself in a mirror.

Hey, don't make Al start to think about getting a lot of piercings. They're really not becoming at our delicate age.

Stan Galat posted:
Carlos G posted:

One way of making a car lighter that is often overlooked, is looking at oneself in a mirror.

Now that's just hurtful/hateful. 

Don't worry, Mike, I'm not one for any piercings, whether they be for decoration or ink (which I guess is decoration as well). I'm not a fan of pain...

And Carlos, I'm with Stan on this one 

@Michael Pickett- did you notice the inner diameter of the pins being especially hard?

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aircooled posted:

Mike....Maybe I missed it in your comments but how did you weigh the large end and the small end of your rods ? I know you recorded the total weight difference but then how did you determine which end (or how much of the total) you removed from each end ?  I was surprised how much difference there was in the wrist pins !...............Bruce

I'm sure Mike will explain what he did in more detail, but you have to build a fixture to hold the other end of the rod so it is level with your scale to get repeatable results.

Last edited by ALB
aircooled posted:

Mike....Maybe I missed it in your comments but how did you weigh the large end and the small end of your rods ?

Bruce, I took a small 4x4 block and drilled one hole for the big end and another for the small.  With a 1/8" bit positioned in either hole (smooth end out) the rod arm was level and I could weigh the big and small ends consistently. I marked squares in pencil around the scales and the block to make sure they didn't shift position and marked a landing zone on the scale for consistency. Rinsed and repeated until I could get the same readings. 

This harebrained scheme was the third approach. The first two showed a lot of weight drift because there was too much surface area on the block side. In this case, smaller was better.IMG_20191214_091720

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My first attempt to build the pulley end of the crank wasn't successful following the instructions in the VW Service Manual (178* oil bath). The cam timing gear scootched down about 1/8" and said "that's about right." I pulled it off and put the crankshaft in the freezer overnight (suffering through smart ass comments from Marianne about "What's for dinner?"). This morning I heated the oil until it smoked and it dropped right into position like it knew it was going home. Applied the spacer and the brass timing gear fell right into place, too. Had to buy the expensive  retaining ring expanders to get the locking ring in place without scratching the #4 bearing surface. It only bit me once before agreeing to slip into place. Now onto piston rods and bearings.

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Last edited by Michael Pickett
mppickett posted:
ALB posted

@Michael Pickett- did you notice the inner diameter of the pins being especially hard?

@ALB - it was definitely hardened compared to the rods. I tried a drill bit inside one of the pins that needed a little bit removed and it just skipped around and didn't remove much. That's when I went to the little grinding wheel.

I knew the outside surfaces of the pins were hard but wasn't sure about the insides. A carbide drill bit is probably what's needed to remove larger amounts of material. I guess even the grinding wheel took a little while?

Thanks Mike...It sounds/looks like you were right on. I recall finding the balance point between the big end and the small end and marked this on the rods. This became the index distance between the pivot point of both ends when weighing the ends.  This changed when I ground off some so I re-indexed that center point each time until I got what I wanted.  I have to say that "blueprinting" an engine is one of the more interesting and exciting parts of engine technology. It doesn't cost much to do except time and produces significant results too !......Good on you Mike !.......Bruce

ALB posted:
I knew the outside surfaces of the pins were hard but wasn't sure about the insides. A carbide drill bit is probably what's needed to remove larger amounts of material. I guess even the grinding wheel took a little while?

It went very quickly on the two pins that were a few tenths of a gram out. The other one took about 10 minutes of grind, blow out, weigh, switch sides and repeat. About 2 minutes in, I had to go find my welding gloves to prevent my fingers from cooking.

I did my top end over the summer. I didn't bother splitting the case, great oil pressure, no knocks, and 0.005" endplay. When Jake built the engine 45,000 miles ago, it was fully blueprinted and balanced. I replaced the pressure plate(as it had some bent fingers) and crank pulley(JayCee with hidden spark trigger wheel from the Dub Shop, machining and fabrication by me). So the whole assembly of pulley/crank/flywheel/pressure plate was no longer a balanced/indexed unit. Some people gave me flack for not splitting the case and re-balancing. It runs like a top, and I can discern no imbalance whatsoever, as smooth as it always was.

However, I did change the pistons and cylinders. New Brazilian Mahle 94mm "B" pistons for mild stroke(78mm). They were off a bit, I ended up removing 2 grams from one piston, and almost 6 from another to get them all the same. I used a grinder then a flexible small disc sander to smooth on the 2 gram heavy piston. On the 6 gram heavy, I took it to my friend Mike's and removed the 6 grams on a Bridgeport mill. All material was removed from the underside of the crown. 6 grams of aluminum was better than 1/16" deep and about 2 square inches and included the grinding boss.

Rods were already end-balanced when Jake built it, and all my piston pins were right on the money, no weight to remove there. Also had the heads redone so I'm basically back to a new engine again.

Keep going Mike, you got this! I really enjoy your posts.

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Just thinking about what Danny did on his pistons gives some credit to  balancing each component on an individual basis.    ie balance the pistons separately from the wrist pins , balance the rods separately too. VS  mate a piston with a wrist pin etc. to get everything balanced as assembly (piston, pin,rod) that equals the other three assemblies. If that is done and a piston change is necessary, the. other components of the assembly will no longer be in balance..............Bruce

mppickett posted:

@ALB Hi Al, before I did any adjustments, the wrist pins in grams were, 132.2, 132.6, 132.4 and 134.2. To reduce the weight, I used a small diameter grinding wheel that would fit inside the pin and took material off both sides. 

Speaking of reducing weight, about 15 years ago one of my Pelican forum buddies was converting a 911SC into a 934 relica. He had done a body off pass through the chassis and drivetrain replacing bolts and nuts or cutting them down to the exact length needed to reduce weight. After doing that and some of the other things you described, he got his car under 2000 lbs. My frankenporsche (also a converted SC) weighed in at 2700 lbs to give you a sense of how serious he was.  Just curious, do you know how much your 356 weighs after all of the things you've done to it? 

Mike

Hi Mike- The info I've read states that the early (pan) Intermeccanicas  weigh in at 1700-1750 pounds when done. After I'm finished I expect the thing to come in at somewhere around the lower end of those numbers, and if it hit the 1600 lb. class I'd be thrilled. This is, of course, with a functional roll bar on board which will add 75? 85? 95? lbs.

And yeah, getting any 911 into the sub 2,000 lb club is quite the feat! And I know all about shortening bolts to exactly the length needed...

@aircooled- How much work you put into it depends on how high you want to rev it (balance requirements for 5,000 rpm are different than for 6500 rpm), how smooth you want it to be and last (but not least) how anal you are.

@DannyP- I agree with you- with it's condition there was no reason to touch the bottom end, and certainly no reason to question the amount of work that went into the balancing, given the original builder's reputation. Glad to hear it's up and running well! If I make it to Carlisle this year I expect a ride, and you have permission to try to scare me silly!

Yoda out for now (I don't know why write that I do, we all know it's not true!) 

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I moved on to looking at the 043 Mexico heads and the intakes. The heads, as described by the previous owner were "racing heads." They indeed, had been massaged. Porting swirls down the intake and exhaust, 40mm and 35mm valves. Otherwise, nothing special. I decided to just make sure I was getting good flow from the intake manifolds into the heads.

The Erling gasket overlapped the rockers side of the ports. Plus, it was way too big for the Kadron manifolds.

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Gasket trimmed to fit the intake.

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I then flipped the trimmed gasket and put it on the intake manifold and trimmed it to not block the openings. I made a thin paper replica of the trimmed gasket, cut holes to fit the studs, attached (blue masking tape) 2 positioning bolts on intake and made sure the paper gasket fit. I sprayed some paint onto a paper towel and coated the contact surface of the Kadron manifold, pulled it off and let it dry.

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I labeled the orientations on the blue gasket and slid it into place on the head.IMG_20191215_153434

 

I rubbed the edges of the ports on the head with a pencil to get an outline. Using a dental pick, I followed the blue outline of the Kadron ports and put tiny indentations in the surface of the intake ports where the Kadron ports didn't overlap. Look closely on the lower side and you'll see a semi-circle of dots ranging up to 4mm outside the ports on the head.IMG_20191215_154623

 

The gasket had blocked the Kadron ports at the top and the port overlap had blocked them at the bottom. It had clearly gotten the full "race head" treatment. Hey, what do I know.

On a wild hunch that spinning a big drill would make me feel happy, I got out my porting burrs.

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I matched the head intake ports with the Kadron manifold and blended a smooth passage to the intakes. I didn't mess with the porting that had already been done inside the head, I just made sure there was a straight shot in and curved edges.

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I went ahead and cleaned up the Kadron manifold where it is welded to the coupling plate. There were areas where the plate edges intruded into the ports. I just smoothed those out.

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One side down and I'll finish up the other side tomorrow. I find this kind of work very satisfying. I guess it hits my OCD just right.

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Last edited by Michael Pickett

@edsnova- Just a 4 point, Ed, with the back braces going through the back of the passenger cabin and tying into the brace between the tops of the shock mounts. (Hopefully) It'll be a kafer bar type thing with a support on each side going from the top shock mount area to the frame horn end and another support going down to the torsion tube.

@Gordon Nichols- wouldn't that be cool!

@Michael Pickett-Looking good Mike! The further you can smooth those changes in flange shape up the manifold (so the change is more gradual) the better/more power it will make. And watch that the area between the intake ports doesn't get too thin or the engine may develop a habit of sucking that part of the gasket out, with rough running  being the result of an intake leak that you can't find unless you take the manifolds off. If you use Alan's method to flatten the manifold bases don't go very fine on the sandpaper- leaving it a little bit rougher will help keep the gasket in place.

@ALB, I've always subscribed to the theory that intake passages on carbureted engines should be be smooth to aid aid flow, but some texture should remain to create turbulence to more completely mix the gas and air. Too much polishing and too much texture is bad so finding a happy medium is what I've always shot for. My cardboard, duct tape, play dough and vacuum cleaner flow bench didn't get shipped out here from Rhode Island - since it didn't work...

Great point about the gasket between the ports!

Anyway, does that make sense? Thanks, everyone!

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As an alternative method to think about, If you make sure that both the head mating area and the corresponding flange on the bottom of the intake manifold are really flat (that sanding on glass trick mentioned above) and it still sucks the center of the gasket out over time, you could delete the gasket and use Locktite 510 flange sealant in place of the gasket between the parts (as recommended to me by Jake Raby).  Harder, but not impossible, to get them apart in the future, but they shouldn't leak.

Looking at your photo of the head, though, you've got about twice as much meat between ports as I do, so the gasket will probably be fine for you.

Progress report for New Year's week: all of the engine rebuild parts arrived and the fun began. Little things measured to 1/1000ths of an inch, cleaned, coated with assembly lube and torqued to the appropriate spec.

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First the crankshaft, then the case halves, the bearings, the camshaft and lifters, and finally the piston rods. Sealing the case around the parts yields a complete short block.

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The rings are installed on the pistons, the pistons gently inserted into the cylinders, the pistons/cylinders attached to each connecting rods using the wrist pins and the cylinders sealed to the case with aviation sealant.

The heads are bolted onto the cylinders and the valve train installed and adjusted to 5/1000ths of an inch gap. Valve covers installed and we've completed a long block.

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The flywheel, clutch, pulleys, crankshaft tooth wheel, crankshaft sensor, oil cooler and engine tin are installed and the engine is ready for installation.

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Oh, then I spin a heavy duty drill handle into my right hand. I've done it at least 20 times while building this car and escaped with bruises and very sore fingers. This time I heard a pop and while icing my hand, I figured that I'd broken a finger and maybe a wrist. Thirty minutes later the x-rays show a neat diagonal break on my 4th finger and that my wrist was just fine. A custom splint cast and wrapping later I was back at home taking ibuprofen and continuing to ice it. The strategy worked. No real pain and I was able to do a few low stress tasks before going out to pupus with friends at the beach. Here's a picture demonstrating how to measure 3 fingers of scotch. Could have been a lot worse!

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mppickett posted:

@ALB, I've always subscribed to the theory that intake passages on carbureted engines should be be smooth to aid aid flow, but some texture should remain to create turbulence to more completely mix the gas and air. Too much polishing and too much texture is bad so finding a happy medium is what I've always shot for. My cardboard, duct tape, play dough and vacuum cleaner flow bench didn't get shipped out here from Rhode Island - since it didn't work...

Great point about the gasket between the ports!

Anyway, does that make sense? Thanks, everyone!

I agree, Mike, the intakes ports need a little bit of texture and should never be polished. Interesting- you say your vacuum cleaner flow bench didn't work- any details?

Something you may want to consider- before I installed the 'back to the case' brass full flow fitting I spent a little time rounding the corners with a file (sadly, I didn't weigh it before and after, as this was before Bruce filled my head with perverted ideas of lightness), and then after getting it mounted as deep as possible (you need 2 taps, the 2nd cut down to thread deeper into the case) there was very little needed to be done to the under the pulley tin. A little heat, a little hammer work and the sheet metal clears both the fitting, the pulley and no cutting (with no hot pre-heated air able to enter the engine compartment) of tin was required. Btw- that's a full size Berg pulley and you can see nothing hits..

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Sorry to hear about your hand- we're at the age where things like this don't heal nearly as fast as they used to! Last June my oldest (he's 20, 5" taller) was chasing me up the stairs (don't remember exactly what I said but I knew if I got caught I was in trouble!). I was givin' it for all it was worth (I really didn't want him to catch me), slipped on the last stair and hyper extended the ring and little fingers on my right hand when I hit the wall. We both ended up on the floor laughing (he was close enough that he tripped over me) with Beth yelling "will you to cut it out! There's too much testosterone around here!".

The 2 knuckles on my hand blew up like a balloon. I'm still feeling it in the ring finger... Al

Sorry, I don't remember the details of the build- I know it has Kadrons. You did a great job on the Hoover mods, btw. 1776? camshaft/rockers? stock valve heads? compression ratio? 

                                           TELL ME EVERYTHING!!!

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ALB posted The details of the build- I know it has Kadrons. You did a great job on the Hoover mods, btw. 1776? camshaft/rockers? stock valve heads? compression ratio? 

                                           TELL ME EVERYTHING!!!

Thanks, Al. Good info! 

I couldn't get reliable test-to-test data on my vacuum cleaner flow tester so I decided it wasn't worth more effort considering I do heads every 10 years.

On the engine, 1776 cc, dual 40 Kadrons, modified intakes to open up insides and port matching, 8 to 1 compression, W110 cam, 1 to 1 rockers, slightly massaged Mexican 43 heads, Bosch high output ignition module triggered by Speeduino ECU and a CBR 36-1 trigger wheel and hall effect sensor. Just a nice little engine to putt up to the 10,000 foot summit of our volcano and to dodge people distracted by the breaching whales and island views (including tiny bikinis!). 

I got the engine installed today and should try to start it some time tomorrow. Keep your fingers crossed for me.IMG_20200104_124037IMG_20200104_180523

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Good morning @Michael Pickett- I've heard that about the vacuum cleaner flow  benches; there's no way of quantifying measurements and all you get is a more or less (than last time) thing. That engine combo is a fun little beast, will be reliable, and will provide close to Super 90 power. You do mean 1.1:1 (late 1300-1600) rockers? 1:1 rockers are from the 40hp series engines. If/when you get bored, a little bit of a flycut on the heads (to raise the cr to 9:1) and some 1.25 rockers and it will feel like a different beast...  Al

Time to go back to bed for an hour or so and then catch the World Juniors Hockey final- Canada's playing Russia for Gold, and hopefully they'll come out looking to avenge the loss from earlier in the tournament...

PS- car's looking sharp (but then I've always been kind of partial to Speedsters with alloys... Al

Last edited by ALB

I'm ok, just a lot harder to make the switch to my non-dominate hand than I thought. I spent a day refabricating the CBR trigger wheel sensor bracket. I like to use Hall sensors and CBR likes VR sensors. I got that wired up this afternoon and spun the engine with the starter to check for an RPM reading (yep, it worked) and oil pressure. I didn't see any oil pressure after spinning it for nearly a minute so I called it a day. Maybe something will occur to me overnight (added oil, attached hoses, ...).

Finished hooking up the engine wiring harness and added the manifolds and carbs. Upgraded the fuel pump to a quiet rotary and replaced all the fuel and vacuum hoses. Did a lot of burping the oil lines out to the filter and finally got the oil pump primed. Got over 30 psi running the starter and decided it was safe to try to start it. After a couple of ECU timing adjustments (since I refabricated the crank sensor bracket), it fired up and seemed to run just fine. Seemed like a good time to break for dinner and a glass of wine. Tomorrow will be installing the muffler, cleanup and road test.  

Safety Jim Buffalo NY. posted:

I'm impressed!  After the bunch of bug motors that I have built, rebuilt or gone through, this CB Performance 1716 kit has been a challenge for me.  I am hoping to have it running.....properly in the next week or so.  However, I am keeping my fingers crossed that I can solve the compression issue and move on to carb tuning soon.

Nice job MPPickett!!!!

Thanks, Jim. It seems like no matter how many you've built, der gremlins always find a way to surprise you. Keeping my fingers crossed on you solving the compression bug.

Mike

Mike:  Now that you’re on the road, my wife has sent your photo, above, to her friend who also moved to Kihei (small world, huh?) a year ago with her very young family (they love it there).  

So don’t be too surprised if a young woman wanders over in a parking lot and says, “Hi!  Are you Mike?  Do you know a Gordon Nichols?”  

Just reply, “Oh.....  Are you Lindsey?”

Unfortunately, neither Massachusetts nor Rhode Island would allow no bumpers when I was first on the road with my speedster, but they would allow Nerf bars so that's how we went.  I really like the classic bumpers on a classic-sided body, especially if they're pulled in close to the body, but the Outlaw style seems to look much better with either no bumpers or Nerfs (if ya gotta have sumthin out there).

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It was nice not to need a front license plate while in South Carolina, but the holes and mount were already there so plated it became.  The Palm and Crescent looked pretty good, though.....   Still have a Palm and Crescent decal on the rear of the car, white-on-white so it only shows up when the light's just so.  That's pretty cool.

Feels like I'm watching an episode of "Through the Glass, Darkly", only I'm not schizophrenic (at least the voices keep telling me I'm not - Can't tell whether the voices are but they sound nice...)

OK, so I got rid of the double post (and don't blame me, the forum server didn't like me for a minute or so, I think) and I'll try posting the photo again here, but you have all seen it enough, anyway;  Pearl, sitting on the show field at Carlisle, top up (yes, it was probably threatening rain) and Nerf bars prominently displayed.  Whoopie.  

Been working outside in freezing weather for over an hour sans-gloves (no, I do not envy Stan).  These fingers really don't want to type right now, so I'll go.

Car (and Nerf Bar) shot #2:

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Gordon.....I really like the paint on your car !  It's the color I have chosen for my Spyder.

Probably Burgundy leather upholstery with "Practical Black" carpet accented with some Burgundy . Frame will be Burgundy and so will the darts. The darts will be outlined in gold and the field in Burgundy. A couple other items (small ones) will be gold too.  Right now I'm thinking fake Fuch's with black spokes and polished rims.

All this could change but that's what I'm thinking today. Ha ha ............Bruce

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.

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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.

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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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.

@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.

& 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

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