Burtz Block Spring Update

[JRLampl]

Update on Burtz Block Manufacturing May/June 2023.

I went to China a few weeks ago and thought I would provide a general update on the manufacturing situation there. China only opened up to foreign visitors just recently. This is the first time I have been back since November 2019. Those of you who do business in China and go there with some frequency to check on manufacturing etc., know this is really a long time to be away from the process. Overall, I was very pleased with the way the factories maintained communications over the Covid period and operations remained very smooth.

In my meeting with the cylinder block and head factory, I told them that hundreds of new engines are running and there have been no problems. I praised them on the quality of their QA and how their attention to detail was very good and that they have been doing a good job.
I asked them to make a few minor adjustments going forward.

1) On the bottom of the valve chamber cover machined surface, they will tap the center hole to 3/8-16 UNC to accommodate a set screw that can be used to retain the distributor drive gear housing, or the setscrew can be used to plug the hole. If you already have a block, this is a very simple job you can do yourself. We have explained it in the updated Builder’s Guide.

2) They will be making a UNC 1/2 – 13 button head hex drive rear oil-galley plug with a copper washer which will be added to the small parts kit with each block.

3) They will add an O-Ring groove to the #1 & 3 Main Cap studs for a 1.5 mm cross-section x 10 mm ID O-Ring that will prevent oil leaks from coming up through the castle nuts. We recommend the McMaster-Carr, Viton O-Ring 1295N162 for the studs.

The 3 changes above will be implemented in future production runs. The new grooved 1 & 3 studs and the oil-galley plug with washer will also be available fairly soon. We expect to have them in stock within about 45 days from now. If anyone is interested to receive any of these, please email me at: [email protected]

Regarding the High Compression Head, they will increase the diameter of the water pump shaft thrust surface to 1 inch. This change will also be implemented in future production runs.

I visited other specialized factories making the crankshaft, connecting rods, camshaft and flywheel for the "New Engine" and again commended them on their QA and attention to detail.

The engineering and QA at all factories are good and we don't anticipate any future changes, but if there is a change, I will make an update describing the change.

[ModelA29]

Will it be possible to get un-grooved main cap studs. I'm not a fan of cutting a groove in a stressed part. Maybe if it was radiused to match the o ring rather than the hard corners I'd be ok with it.


Mechanical seals – improving design reliability

Clifford Matthews BSc (Hons), CEng, MBA, in Case Studies in Engineering Design, 1998
Remove ‘stress-raisers’

Stress-raisers are sharp corners, grooves, notches or acute changes of section that cause stress concentrations under normal loadings. They can be found on both rotating and static components. The stress concentration factors of sharp corners and grooves are high, and difficult to determine accurately. Components that have failed predominantly by a fatigue mechanism are nearly always found to exhibit a crack initiation point – a sharp feature at which the crack has started and then progressed by a cyclic fatigue mechanism to failure. Techniques which can be employed to reduce stress-raisers are: • Use blended radii instead of sharp corners.........

[Bob4banger]

I concur, O-ring grooves should have a radi in the groove corners.
See attached Parker design guide.

Maybe John has advised the chinese plant to include radi in the oring groove, but not shown on the drawings.

[CT Jack]

John you have not mentioned adding an oil seal to the block surface where the camshaft bore ends. This is an area that needs sealing and can be easily incorporated during block machining. Adding an O-ring groove for an O-ring will solve the potential problem of oil leaking between the engine block and flywheel case mounting surfaces. The use of a thin paper gasket does not provide 100% assurance against an oil leak. Once the engine has been installed this problem can only be resolved by removing the engine.

[Terry Burtz, Calif]

Originally Posted by ModelA29

Will it be possible to get un-grooved main cap studs. I'm not a fan of cutting a groove in a stressed part. Maybe if it was radiused to match the o ring rather than the hard corners I'd be ok with it.


Mechanical seals – improving design reliability

Clifford Matthews BSc (Hons), CEng, MBA, in Case Studies in Engineering Design, 1998
Remove ‘stress-raisers’

Stress-raisers are sharp corners, grooves, notches or acute changes of section that cause stress concentrations under normal loadings. They can be found on both rotating and static components. The stress concentration factors of sharp corners and grooves are high, and difficult to determine accurately. Components that have failed predominantly by a fatigue mechanism are nearly always found to exhibit a crack initiation point – a sharp feature at which the crack has started and then progressed by a cyclic fatigue mechanism to failure. Techniques which can be employed to reduce stress-raisers are: • Use blended radii instead of sharp corners.........

The studs are well supported and are in tension only. There are no bending loads. The small diameter created by the o-ring groove is very close to the diameter of the section before the 7/16 UNF threads are rolled. Stress at the o-ring groove is nearly identical to the stress in the unrolled section for the 7/16 UNF thread.

[johnneilson]

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Originally Posted by Terry Burtz, Calif

The studs are well supported and are in tension only. There are no bending loads. The small diameter created by the o-ring groove is very close to the diameter of the section before the 7/16 UNF threads are rolled. Stress at the o-ring groove is nearly identical to the stress in the unrolled section for the 7/16 UNF thread.

Not to mention that the groove is substantially larger in diameter than the minor diameter created by the 7/16-20 thread.
The highest tension load is still under the nut to the end of the thread.

John

[Terry Burtz, Calif]

Originally Posted by CT Jack

John you have not mentioned adding an oil seal to the block surface where the camshaft bore ends. This is an area that needs sealing and can be easily incorporated during block machining. Adding an O-ring groove for an O-ring will solve the potential problem of oil leaking between the engine block and flywheel case mounting surfaces. The use of a thin paper gasket does not provide 100% assurance against an oil leak. Once the engine has been installed this problem can only be resolved by removing the engine.

We have heard of a few leaks at this location.

There is not enough room for both a camshaft bushing and an o-ring groove, so I chose to incorporate the bushing.

There is no oil pressure at the rear of the camshaft because that cavity is vented to the crankcase.

If the surfaces are cleaned with acetone and the paper gasket is glued with Indian Head Gasket Shellac to the cylinder block, there will be no leaks if the flywheel housing is flat.

Some builders have had leaks because they used diesel, kerosene, or mineral spirits as a solvent for cleaning, and these solvents have too much oil in them for an adequate bond.

If you insist on an o-ring, the rear camshaft bushing could be removed and the rear outside diameter can be beveled at a 45-degree angle, This small bevel area will provide space for a 1 mm x 44 mm OD o-ring like McMaster Carr 9262K209.

If the flywheel housing is not flat, the rear camshaft bushing could be driven towards the rear to protrude beyond the cylinder block and compensate for the flywheel housing not being flat.

[Synchro909]

Originally Posted by Terry Burtz, Calif

We have heard of a few leaks at this location.

There is not enough room for both a camshaft bushing and an o-ring groove, so I chose to incorporate the bushing.

There is no oil pressure at the rear of the camshaft because that cavity is vented to the crankcase.

If the surfaces are cleaned with acetone and the paper gasket is glued with Indian Head Gasket Shellac to the cylinder block, there will be no leaks if the flywheel housing is flat.

Some builders have had leaks because they used diesel, kerosene, or mineral spirits as a solvent for cleaning, and these solvents have too much oil in them for an adequate bond.

If you insist on an o-ring, the rear camshaft bushing could be removed and the rear outside diameter can be beveled at a 45-degree angle, This small bevel area will provide space for a 1 mm x 44 mm OD o-ring like McMaster Carr 9262K209.

If the flywheel housing is not flat, the rear camshaft bushing could be driven towards the rear to protrude beyond the cylinder block and compensate for the flywheel housing not being flat.

I have seen it done. I saw no such vent when I assembled mine. Is that only so on later engines?
All of that said, I enjoy driving my car even more now than I did with the old engine.

[Dodge]

I put the O-Ring groove in the flywheel housing. On the stock motors also.

[Synchro909]

Originally Posted by Dodge

I put the O-Ring groove in the flywheel housing. On the stock motors also.

That's the way to go and maybe bolt near the end of the cam shaft to hold the flywheel housing hard against the back of the block. It need only be a small bolt - maybe even as small as 1/4" so that the head doesn't cause a problem.

[Lawrie]

there is very little room for an oring as the flywheel housing has barely enough room for a .070 oring
lawrie

[Synchro909]

Originally Posted by Lawrie

there is very little room for an oring as the flywheel housing has barely enough room for a .070 oring
lawrie

It surprises me that it is so thin. Do you think the bolt I spoke of (and another with epoxy) could be used to also hold some re enforcement on the inside of the cover?