first hotrod build

with cams for any given lift which is better, a cam with a higher lobe lift or a higher rocker ratio on a smaller lobe lift. I would think the higher rocker ratio would be better but would give higher pressures on cam and lifters.
 
purely from an engineering stand point, a larger diameter cam lobe with a lower rocker ratio, in theory,
produces less physical part to part,contact stress and wear.
one reason the cam bearings and lobes size were increased on the newer LS series engine vs the older first gen sbc.
 
good grief nothing goes right. torqued down the crank and spins smoothly by hand, checked end play and I have none, I cant get a feeler gauge between the crank and thrust bearing. so what now, do I get the 600 wet or dry and sand off a few thousands from the bearing face?
 
If you find you've dropped the crank into the new main bearings and theres less than the .006-.009 thrust bearing clearances,
thats totally normal until you beat the crank front to back in the bearings 4-5 times with a 3 lb plastic dead blow hammer,
give it several good wacks front to back, then back to front on the crank center-line,
too seat the thrust bearing clearances
20322a.jpg

READ THESE LINKS
https://www.harborfreight.com/3-lb-neon-orange-dead-blow-hammer-69002.html

http://garage.grumpysperformance.com/index.php?threads/thrust-bearing-wear.619/

http://garage.grumpysperformance.com/index.php?threads/thrust-bearing-wear.619/#post-37676

http://garage.grumpysperformance.com/index.php?threads/bearings-and-oil-flow.150/#post-68206

http://garage.grumpysperformance.co...nk-durring-short-blk-assembly.852/#post-39528

http://garage.grumpysperformance.com/index.php?threads/rotating-assembly-bearings.9527/#post-35037
 
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until you beat the crank front to back in the bearings 4-5 times with a 3 lb plastic dead blow hammer,
give it several good wacks front to back, then back to front on the crank center-line,
too seat the thrust bearing clearances
Don't you have to do that with the rear main cap loose??
 
To align the thrust bearing, pry and hold the crankshaft forward, pry the thrust bearing cap rearward,
and tighten bearing cap while holding crankshaft forward.
 
short answer ..no.
the crank takes far m0re stress and or abuse during a few power shifts,
changing gears at 6000 rpm, than anything you'll,
potentially do to the bearings or crank with a lead shot,filled plastic mallet,
driving that crank, forward and back in its bearings ,on the cranks center line axis.
naturally I assume your not trying to break or bend anything , your simply seating the thrust bearings shell upper and lower halves in the block.

http://garage.grumpysperformance.co...tion-of-crank-durring-short-blk-assembly.852/

http://garage.grumpysperformance.com/index.php?threads/thrust-bearing-wear.619/#post-37676
tru3.jpg


tru4.jpg


thr1.jpg

A simple modification to the upper thrust bearing may be beneficial in some engines. Install the upper thrust bearing in the block to determine which thrust face is toward the rear of the engine. Using a small, fine tooth, flat file, increase the amount of chamfer to approximately .040" (1 mm) on the inside diameter edge of the bearing parting line. Carefully file at the centrally located oil groove and stroke the file at an angle toward the rear thrust face only, as shown in the illustration below. It is very important not to contact the bearing surface with the end of the file. The resulting enlarged ID chamfer will allow pressurized engine oil from the pre-existing groove to reach the loaded thrust face. This additional source of oiling will reach the loaded thrust face without passing through the bearing clearance first (direct oiling). Since there may be a load against the rear thrust face, oil flow should be restricted by that load and there should not be a noticeable loss of oil pressure. This modification is not a guaranteed "cure-all". However, the modification should help if all other conditions, such as surface finish, alignment, cleanliness and loading are within required limits.
bearing41.jpg

trustbca.png

thrustb1.jpg

thrustb2.jpg
 
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will go back and do everything step by step as shown in the links, hopefully that corrects the situation as has happened so many times before. I know I am learning with this build but it seems that I am having an extraordinary amount of problems, is this average for a build or just mine, everything has worked out after your help. how did the kids I ran with build engines that held together when I was a teenager I know they didn't do all these checks just slapped it together with only an occasional excitement.
 
this whole forum.. is installed and maintained to make it easy for both the beginners and the very experienced hot rodders to find, or post information regarding various car and engine related subjects, youll find threads generally have links to related info,
no your not having anything extraordinary happen,
if your building your first engine and running into quite a few problems ,
with the assembly process or sloppy machine shop work!
slapping something together vs
"BUILDING AN ENGINE CORRECTLY "
are vastly different concepts
I look back on the first few engines I built when I was about 17,
and I'm amazed they even ran.
I had never heard of ring gaps,
yet in-spite of that the cars engine started and ran.
A great deal of the content in this whole web sites based
on the idea that readers can benefit from reading about how too ,
avoiding the expensive mistakes many of us older geezers made in the past,
and learning how things should have been done correctly
theres no possible way that I can know each particular problems cause, or suggest the best possible parts choice, or process to fix it, in every case ,unless you post detailed info and perhaps clear pictures. so I try to make it far easier to find answers to the more common problems and questions.
I try to give a good over view on how things work, how they can be tested and what commonly fails.
or I try to provide links to related sources to make your search for information related to any subject covered both easy to find and as extensive as you care to push into your research. I've been building engines and racing for 45 plus years and while I have done many things.
I've built well over a 170 plus engines in 45 plus years , but keep in mind thats only 2-4 engines a year most years, Im always learning and looking to learn from others in this hobby ,so if you can add useful links or information or just as questions to clarify an answer or question you read on the site,to clear up a question or find an answer too the info please do so.
 
I am having an extraordinary amount of problems, is this average for a build or just mine.

Welcome to the world of hot-rodding. There are no problems if you are not looking for them.
Some guys just get really lucky. The more you know, the more you are looking for, and the more
problems you will find - even with professional machine shop work.

It really sucks when you know you have done everything correctly down to the last detail and triple
checked EVERYTHING, and still have a failure. And then, there is the guy who just slaps parts
together without checking anything, and it runs, and runs, and runs.

Don't let it get you down - it's normal. Hang in there.
 
went through the five steps for getting crank run out and got 3 thou before torque down, after torque down it went to zero. crank now spins free as if it was on roller bearings but no run out. time to sand a few thousanths off the forward thrust bearing side? king bearings came with the rotating assembly. nothing about crank run out clearances in the box and have seen two different specs .003-.005 and .006-.010 will call scat tomorrow for their say on specs.
 
just talked with the tech rep from king bearing, he said they make the bearings to max spec because you can always remove a few thou but you cant add so just sand down to 4-8 thou. my thought is to aim for .005 and it will beak in about right, if this is wrong please say so.
 
youll be fine with .004-.006 thrust bearing clearance,
as the crank contacts and compresses the contact face surface,
on the thrust bearing in use.
and theres always going to be some additional clearance due too some wear over time.
 
http://www.4secondsflat.com/Thrust_bearing_failures.html

Crankshaft Thrust Bearing Failure - Causes & Remedies

For years both transmission and engine rebuilders have struggled at times to determine the cause of crankshaft thrust bearing failures. In most instances, all of the facts concerning the situation are not revealed at the onset of the failure. This has led to each party blaming the other for the failure based only on hearsay or what some "expert" has termed the "cause". Some of those explanations have led to an argument, that ends up in litigation while the truth lingers uncovered in the background. This document is a group effort of combined information compiled by the Automotive Transmission Rebuilders Association (ATRA), the Automotive Engine Rebuilders Association (AERA), the Production Engine Rebuliders Association (PERA), the Automotive Service Association (ASA) and bearing manufacturers. This group of industry experts has assembled the following information to consider and offers solutions that may prevent a similar thrust bearing failure.

Background:
Although thrust bearings run on a thin film of oil, just like radial journal (connecting rod and main) bearings, they cannot support nearly as much load. While radial bearings can carry loads measured in thousandsof pounds per square inch of projected bearing area, thrust bearings can only support loads of a few hundred pounds per square inch. Radial journal bearings develop their higher load capacity from the way the curved surfaces of the bearing and journal meet to form a wedge. Shaft rotation pulls oil into this wedge shaped area of the clearance space to create an oil film which actually supports the shaft. Thrust bearings typically consist of two flat mating surfaces with no natural wedge shape in the clearance space to promote the formation of an oil film to supportthe load.

Conventional thrust bearings are made by incorporating flanges, at the ends of a radial journal bearing. This provides ease in assembly and has been used successfully for many years. Either teardrop or through grooves on the flange, face andwedge shaped ramps at each parting line allow oil to enter between the shaft and bearing surfaces. However, the surface of the shaft, as well as the vast majority of bearing surfaces, are flat. This flatness makes it more difficult to create and maintain an oil film. As an example; if two gauge blocks have a thin film of oil on them, and are pressed together with a twisting action, the blocks will stick together. This is similar to what happens when a thrust load is applied to the end of a crankshaft and oil squeezes out from between the shaft and bearing surfaces. If that load is excessive, the oil film collapses and the surfaces want to stick together resulting in a wiping action and bearing failure. For this reason, many heavy-duty diesel engines use separate thrust washers with a contoured face to enable them to support higher thrust loads. These thrust washers either have multiple tapered ramps and relatively small flat pads, or they have curved surfaces that follow a sine-wave contour around their circumference.

Recent developments:

In the past few years some new automotive engine designs include the use of contoured thrust bearings to enable them to carry higher thrust loads imposed by some of the newer automatic transmissions. Because it’s not practical to incorporate contoured faces on one piece flanged thrust bearings, these new engine designs use either separate thrust washers or a flanged bearing whichis a three piece assembly.

Cause of failure:

Aside from the obvious causes, such as dirt contamination and misassembly, there are only three common factors which generally cause thrust bearing failures. They are:

    • Poor crankshaft surface finish
    • Misalignment
    • Overloading
Surface finish:

Crankshaft thrust faces are difficult to grind because they are done using the side of the grinding wheel. Grinding marks left on the crankshaft face produce a visual swirl or sunburst pattern with scratches - sometimes crisscrossing - one another in a cross-hatch pattern similar to hone marks on a cylinder wall. If these grinding marks are not completely removed by polishing, they will remove the oil film from the surface of the thrust bearing much like multiple windshield wiper blades. A properly finished crankshaft thrust face should only have very fine polishing marks that go around the thrust surface in a circumferential pattern.

Alignment:

The grinding wheel side face must be dressed periodically to provide a clean, sharp cutting surface. A grinding wheel that does not cut cleanly may create hot spots on the work piece leading to a wavy, out-of-flat surface. The side of the wheel must also be dressed at exactly 90° to its outside diameter, to produce a thrust face that is square to the axis of the main bearing journal. The crankshaft grinding wheel must be fed into the thrust face very slowly and also allowed to "spark out" completely. The machinist should be very careful to only remove minimal stock for a "clean-up" of the crankshaft surface.

In most instances a remanufactured crankshaft does not require grinding of the thrust face(s), so the grinding wheel will not even contact them. Oversize thrust bearings do exist. Some main bearing sets are supplied only with an additional thickness thrust bearing. In most of those instances, additional stock removal from the crankshaft thrust face surface may be required. Crankshaft end float should be calculated and determined before grinding additional material from the thrust face.

Crankshaft grinding wheels are not specifically designed for use of the wheel side for metal removal. Grinding crankshaft thrust faces requires detailed attention during the procedure and repeated wheel dressings may be required. Maintaining sufficient coolant between the grinding wheel and thrust surface must be attained to prevent stone loading and "burn" spots on the thrust surface. All thrust surface grinding should end in a complete "spark out" before the grinding wheel is moved away from the area being ground. Following the above procedures with care should also maintain a thrust surface that is 90° to the crankshaft centerline.

When assembling thrust bearings:


    • Tighten main cap bolts to approximately 10 to 15 ft.lb. to seat bearings, then loosen.
    • Tap main cap toward rear of engine with a soft faced hammer.
    • Tighten main cap bolts, finger tight.
    • Using a bar, force the crankshaft as far forward in the block as possible to align the bearing rear thrust faces.
    • While holding shaft in forward position, tighten main cap bolts to 10 to 15 ft.lbs.
    • Complete tightening main cap bolts to specifications in 2 or 3 equal steps.
The above procedure should align the bearing thrust faces with the crankshaft to maximize the amount of bearing area in contact for load carrying.

Loading:

A number of factors may contribute to wear and overloading of a thrust bearing, such as:

1. Poor crankshaft surface finish.

2. Poor crankshaft surface geometry.

3. External overloading due to.

a) Excessive Torque converter pressure.

b) Improper throw out bearing adjustment.

c) Riding the clutch pedal.

d) Excessive rearward crankshaft load pressure due to a malfunctioning front mounted accessory drive.

Note: There are other, commonly-thought issues such as torque converter ballooning, the wrong flexplate bolts, the wrong torque converter, the pump gears being installed backward or the torque converter not installed completely. Although all of these problems will cause undo force on the crankshaft thrust surface, it will also cause the same undo force on the pump gears since all of these problems result in the pump gear pressing on the crankshaft via the torque converter. The result is serious pump damage, in a very short period of time (within minutes or hours).

Diagnosing the problem:

By the time a thrust bearing failure becomes evident, the partshave usually been so severely damaged that there is little if any evidence of the cause. The bearing is generally worn into the steel backing which has severely worn the crankshaft thrust face as well. So how do you tell what happened? Start by looking for the most obvious internal sources.

Engine related problems:


    • Is there evidence of distress anywhere else in the engine that would indicate a lubrication problem or foreign particle contamination?
    • Were the correct bearing shells installed, and were they installed correctly?
    • If the thrust bearing is in an end position, was the adjacent oil seal correctly installed? An incorrectly installed rope seal can cause sufficient heat to disrupt bearing lubrication.
    • Examine the front thrust face on the crankshaft for surface finish and geometry. This may give an indication of the original quality of the failed face.
Once you are satisfied that all potential internal sources have been eliminated, ask about potential external sources of either over loading or misalignment.

Transmission related problems:


    • Did the engine have a prior thrust bearing failure?
    • What external parts were replaced?
    • Were there any performance modifications made to the transmission?
    • Was an additional cooler for the transmission installed?
    • Was the correct flexplate used? At installation there should be a minimum of 1/16" (1/8" preferred, 3/16" maximum) clearance between the flex plate and converter to allow for converter expansion.
    • Was the transmission property aligned to the engine?
    • Were all dowel pins in place?
    • Was the transmission-to-cooler pressure checked and found to be excessive? If the return line has very low pressure compared to the transmission-to-cooler pressure line, check for a restricted cooler or cooler lines.
    • If a manual transmission was installed, was the throw out bearing properly adjusted?
    • What condition was the throw out bearing in? A properly adjusted throw out bearing that is worn or overheated may indicate the operator was "Riding The Clutch".
How does the torque converter exert force on the crankshaft?

There are many theories on this subject, ranging from converter ballooning to spline lock. Most of these theories have little real bases and rely little on fact. The force on the crankshaft from the torque converter is simple. It is the same principle as a servo piston or any other hydraulic component: Pressure, multiplied by area, equals force. The pressure part is easy; it’s simply the internal torque converter pressure. The area is a little trickier. The area that is part of this equation is the difference between the area of the front half of the converter and the rear half. The oil pressure does exert a force that tries to expand the converter like a balloon (which is why converter ballooning is probably often blamed), however, it is the fact that the front of the converter has more surface area than the rear (the converter neck is open) that causes the forward force on the crankshaft. This difference in area is equal to the area consumed by the inside of the converter neck. The most common scenario is the THM 400 used behind a big-block Chevy. General Motors claims that this engine is designed to sustain a force of 210 pounds on the crank shaft. The inside diameter of the converter hub can vary from 1.5 inches up to 1.64 inches. The area of the inside of the hub can then vary from 1.77 square inches to 2.11 inches. 210 pound of force, divided by these two figures offers an internal torque converter pressure of 119 psi to 100 psi, respectively. That is to say, that depending on the inside diameter of the hub, it takes between 100 to 119 psi of internal converter pressure to achieve a forward thrust of 210 pounds. The best place to measure this pressure is the out-going cooler line at the transmission because it is the closest point to the internal converter pressure available. The pressure gauge must be "teed" in so as to allow the cooler circuit to flow. Normal cooler line pressure will range from 50 psi to 80 psi , under a load in drive.

Causes for excessive torque converter pressure:

There are two main causes for excessive torque converter pressure: restrictions in the cooler circuit and modifications or malfunctions that result in high line pressure. One step for combating restrictions in the cooler circuit is to run larger cooler lines. Another, is to install any additional cooler in parallel as opposed to in series. This will increase cooler flow considerably. An additional benefit to running the cooler in parallel is that it reduces the risk of over cooling the oil in the winter time—especially in areas where it snows. The in-parallel cooler may freeze up under very cold conditions, however, the cooler tank in the radiator will still flow freely. Modifications that can result in higher than normal converter pressure include using an overly-heavy pressure regulator spring, or excessive cross-drilling into the cooler charge circuit. Control problems such as a missing vacuum line or stuck modulator valve can also cause high pressure.

What will help thrust bearings survive? When a problem application is encountered, every effort should be made to find the cause of distress and correctit before completing repairs, or you risk a repeat failure.

A simple modification to the upper thrust bearing may be beneficial in some engines. Install the upper thrust bearing in the block to determine which thrust face is toward the rear of the engine. Using a small, fine tooth, flat file, increase the amount of chamfer to approximately .040" (1 mm) on the inside diameter edge of the bearing parting line. Carefully file at the centrally located oil groove and stroke the file at an angle toward the rear thrust face only, as shown in the illustration below. It is very important not to contact the bearing surface with the end of the file. The resulting enlarged ID chamfer will allow pressurized engine oil from the pre-existing groove to reach the loaded thrust face. This additional source of oiling will reach the loaded thrust face without passing through the bearing clearance first (direct oiling). Since there may be a load against the rear thrust face, oil flow should be restricted by that load and there should not be a noticeable loss of oil pressure. This modification is not a guaranteed "cure-all". However, the modification should help if all other conditions, such as surface finish, alignment, cleanliness and loading are within required limits.

bearing1.jpg


Other External Problems. Aside from the items already mentioned, there is another external problem that should be considered. Inadequate electrical grounds have been known to exacerbate thrust surface wear. Excessive current in the vehicle drive train can damage the thrust surface. It affects the thrust bearing as though the thrust surface on the crankshaft is not finished properly finished (too rough). Excessive voltage in the drive train can be checked very easily. With the negative lead of a DVOM connected to the negative post of the vehicle battery and the positive lead on the transmission, there should be no more than .01 volts registering on the meter while the starter is turning over the engine. For an accurate test, the starter must operate for a minimum of four seconds without the engine starting. It is suggested to disable the ignition system before attempting this test. If the voltage reading observed is found to be excessive, add and/or replace negative ground straps from the engine to the vehicle frame and transmission to frame until the observed voltage is .01 volts or less. Note: Some systems may show a reading of .03volts momentarily but yet not exhibit a problem. For added assurance, it is a good idea to enhance the drive train grounding with larger battery cables or additional ground straps.

A special thank you goes out to Dennis Madden of ATRA, Dave Hagen of AERA, Ed Anderson of ASA, Roy Berndt of PERA and John Havel of AE Clevite for their contributions to this article.

The AERA Technical Committee

March 1998 - TB 1465R
 
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