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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 631139 times)
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wobblywalrus
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« Reply #2985 on: January 01, 2018, 12:05:11 PM »

That kitchen counter is Rose's territory.  Those parts were gone without a trace in minutes after the foto.

The conversion from 360-360 to 270-450 firing order was accelerated after Noonan's crash.  The engine has a lot of power now and the back end like to kick out to the side in the lower gears.  This conversion should make that issue more manageable and reduce the risk of highsides.  The expensive parts like the crank and balancer were free.  A new alternator rotor was $220 on e-bay.  Good used 270-450 cams could not be found so I ordered some new ones for $650.  Then, the last task was the electrics.  This always is my weak area.  New racing coils were needed.  The wiring harness was 15 years old and ratty and lots of mods would be needed for the conversion.  A new one was bought.  None of the 360-360 ignition modules could be reprogrammed so five new ones were bought for the advance curve tuning.  The electric things, other than the rotor, cost over $2,000.

My next land speed engine will be a diesel with mechanical fuel injection and a kickstart.  There will be no W.Walrus attempts to control and channel those wild and uncooperative electrons. 
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wobblywalrus
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« Reply #2986 on: January 04, 2018, 11:18:06 PM »

The journal to compressed bearing shell clearance is OK with one coated shell on the rod big end and one uncoated shell on the rod cap.  The clearances are too small with any combination of two coated shells.  Has anyone used a combination of coated and uncoated shells?  These shells have the coating done by Polydyn.


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wobblywalrus
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« Reply #2987 on: January 07, 2018, 11:15:39 AM »

The new Shoei X-14 helmet has slightly better visibility under the eye port than the helmet that was bought a few months previous.  That is with standard pads in the X-14.  A thicker front pad and a thinner rear pad are ordered from a racing supply store and fitted.  This moves the helmet higher at the front and lower at the rear.  It makes a big difference.  Now the X-14 provides the best eye port height of any helmet I have tried on.


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wobblywalrus
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« Reply #2988 on: January 08, 2018, 09:06:39 PM »

The Triumph rod big end shells are classified by thickness using a color code.  There are blue, red, and white coated shells.  The white ones are the thinnest.  The clearance was 0.0015 on both journals with them fitted.  This is OK for a production motor.  Racing clearances between 0.0017 and 0.0023 are recommended by Mahle.

The crank was set up in the lathe using this aluminum tab that is bolted to the face plate.  It keeps the crank from spinning.  This aluminum tab and harness setup holds the rod up against the crank.


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wobblywalrus
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« Reply #2989 on: January 08, 2018, 09:24:02 PM »

The clearance is checked with plastigauge.  The best for this is Triumph part # 3880150-T0301  It makes nice and fat spreads that are easy to measure.  Toothpaste is put on an old bearing shell and the journals are carefully lapped to the correct size.  The plastigage stuck to the bearing caps, sometimes.  Acetone and a clean rag was used to wipe it off.  The toothpaste lapping and shell wiping eventually increased clearances 0.0005 inches to 0.002 inches, total.

The coatings subtract 0.0006 from the big end bearing diameter.  That requires lapping the journals down 0.0006 inches or lapping 0.0003 off of each shell thickness.  Does anyone have any experience with lapping shells to get clearance for coatings? 
 


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« Reply #2990 on: January 08, 2018, 10:40:09 PM »

The bad thing about plastigage is it only shows you what the clearance at the exact spot on the crank is relative to a matching spot inside the bearing ID. Usually when you fit bearing clearances, you confirm the rods are a specific ID size and round within a tenth or less with no taper. I have had to recon hundreds of brand new Carillo, Crower, Oliver and the whole alphabet of billet rods because they didn't fit our specific size needed to achieve our desired bearing clearances. Coated bearings also added more challenges because it makes the clearances tighter, obviously. You often have to switch several sets or even mix extra clearance bearing shells with standard size to get your desired clearances. So you may find that opening up the housing bores will help, even aftermarket rods rarely come the size that provides the optimum clearance. Polishing the journal's can often make them v-shaped and tapered which isn't desirable for a race engine.
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wobblywalrus
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« Reply #2991 on: January 08, 2018, 10:57:35 PM »

The rods were checked by a machinist a couple of years ago.  They big ends were round and the right size.  I have a micrometer that reads in tenths. I will check the journal roundness to make sure there I did it correctly and there are no high spots.  It seems like I should quit now and not keep lapping to give clearance for coatings.
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wobblywalrus
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« Reply #2992 on: January 08, 2018, 11:49:18 PM »

Will enlarging the rod big ends reduce the the crush on the shells to an unacceptable low amount?
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wobblywalrus
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« Reply #2993 on: January 09, 2018, 01:03:16 AM »

The journals are measured in nine places, each.  All measurements are within plus or minus 0.0001 of the average. 
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CNC-Dude
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« Reply #2994 on: January 09, 2018, 02:12:49 PM »

Connecting rods have a +/- tolerance, usually a .001 from the high to low spread. So as long as the housing bores stay within that spread the bearing crush will be fine. But it does give you a .001 to play with if you need to tweak the bearing clearances.
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wobblywalrus
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« Reply #2995 on: January 09, 2018, 08:13:38 PM »

Thanks for the advice.  The local engine machinist can hone rod big ends.  He will need to enlarge them 0.0006 for room for coatings.  The upper shells give me trouble if I have it.  Can just the upper shells be coated?  That way, a 0.0003 hone should work.
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WhizzbangK.C.
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« Reply #2996 on: January 09, 2018, 08:44:54 PM »

Thanks for the advice.  The local engine machinist can hone rod big ends.  He will need to enlarge them 0.0006 for room for coatings.  The upper shells give me trouble if I have it.  Can just the upper shells be coated?  That way, a 0.0003 hone should work.

Bo, I don't know if it's directly applicable to your question or not, but the latest generation of Detroit Diesel truck engines have upper and lower rod bearing shells made from different materials with different coatings on them, and the engines are designed to last for over a million miles with very heavy usage and high duty cycles. Seems that the engineers have decided that the upper and lower shells see different loading conditions and can benefit from different material specs. The upper shells get a lot more force applied to them than the lower ones do, so the bearings material is harder and also designed to retain oil film better under loaded conditions. Apparently it's also much more expensive so using a lower spec material on the bottom shell saves money without sacrificing performance. The take away to me is that it should not matter if you only coat the top shell, but ultimately you need to make that call. Hope this info helps. Keep plugging away at it.
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wobblywalrus
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« Reply #2997 on: January 11, 2018, 01:08:13 AM »

Thanks for the info.  Do you know someone who can hone rod big ends?  The plan is to add 0.0003 to the ID and use coated upper shells and uncoated lowers.

The weak link on these engines are the fasteners that hold them together.  This fretting gets worse when the horsepower increases.  I do not know how to fix the issue.  I manage it by minimizing the runs down the salt to just what I need to do the job and tightening the bolts every off season.  The 107 HP the engine makes now looks to be the limit until I figure out a solution to this problem.


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WhizzbangK.C.
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« Reply #2998 on: January 11, 2018, 10:36:50 AM »

Thanks for the info.  Do you know someone who can hone rod big ends?  The plan is to add 0.0003 to the ID and use coated upper shells and uncoated lowers.

The weak link on these engines are the fasteners that hold them together.  This fretting gets worse when the horsepower increases.  I do not know how to fix the issue.  I manage it by minimizing the runs down the salt to just what I need to do the job and tightening the bolts every off season.  The 107 HP the engine makes now looks to be the limit until I figure out a solution to this problem.

I would think that just about any GOOD automotive machine shop could hone them to your spec. The Sunen hone has been a shop staple forever, and it's really not rocket surgery.

On the fretting issue. Do you find that the fasteners are actually loosening, as in the nuts or bolts backing off? Or is it more a matter of stretching fasteners or creeping threads in the case? Do you use torque indicator stripes on the nuts/bolts and if you do are they moving? When I worked on airplanes every torqued bolt had a "torque seal" applied to it by the inspector after he witnessed the torque. This type of stuff.

 http://www.mrochemicalsupply.com/product-p/dykem-crosscheck-1oz.htm?gclid=Cj0KCQiAs9zSBRC5ARIsAFMtUXE3OxebyDJZV3wxNDO_cnaslucGAZn9NOPtWKw6E8FngDPA3vxabZsaAopwEALw_wcB

A stripe of it laid on the side of the fastener and run down onto the part. It dried hard and made it possible to visually inspect whether the fastener had moved, as it would crack if that did happen.

One often overlooked cause of loss of clamping force it thread creep. It can happen during torquing  if the applied torque is more than the base material can stand. It can also happen during operation when heat expansion and engine vibration combine to increase the actual load on the threads, especially if the static torque was already close to the max they could stand. Some designs (later model Harley engines with aluminum cylinders and studs that run from the heads, through the cylinders, and into the cases are one example) cope with this by specifying cold assembly torque specs that are shockingly low, but once everything expands they provide correct clamping force without over stressing the threads in the cases.

One way to check if this is what's happening would be to make a "thread creep gauge". This would be nothing but a short bolt with a line inscribed on the head at one point of the hex, and a hardened washer. Before assembling the engine, lubricate the threads and put the bolt into each hole and torque it to a very low but repeatable number. Make a small scribe line or punch mark (not enough to causing sealing issues) on the case surface to line up with the line on the bolt head. Do this exactly the same way to each hole. Keep the bolt and washer in a safe place. The next time you tear the engine down, perform the same torque sequence with the tool and see if the marks line up. If they don't, The threads are pulling in the case and need attention. Thread inserts can help to hold more torque by spreading the load over a larger surface area of the case, or in some cases actually lowering the assembly torque could be beneficial.

Another thing that can happen is fastener stretch. Test this by documenting the overall length of each bolt or stud prior to assembly, and then checking it when you take the engine apart. On some of the big diesel engine the head bolts have a maximum length that is allowed for re-use. The are known to stretch every time they are used and can only take so many uses before they fail.
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« Reply #2999 on: January 11, 2018, 11:03:44 AM »

WBKC;

I have sometimes used my wife's red nail polish on a fastener to indicate that it has been torqued to spec and as an indication that it has not moved. Cheap & easy but not as good as those brittle lacquers.

Regards, Neil  Tucson, AZ
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Regards, Neil  Tucson, AZ
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