Mustache bar adapter strength?

[ccowx]

I am putting a small stroker motor into a 1970 Westfalia and I just got word from the machine shop that the bus case I had hoped to use for that engine is possibly not going to work. I don't seem to have immediate access to a suitable bus case and might end up needing to use a standard bug case. I have an adapter for the mustache bar that attachs to the oil pump bolts and also has the mount on the case bolt. I am looking at around 100 hp in a stock westy with a full interior. Will the adapter hold that engine?

Thanks!

Chris

[metz]

Yes. But if you're planning to run full-flow you will need to modify the adapter.
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[richparker]

If it’s at a machine shop, why not just have them drill and tap the bug case to accept the mustache bar?
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[ccowx]

Because it doesn't have the bosses in place to drill and tap them into. I can try to get another case that does have them but I was hoping to not have to buy a new case.

Thanks!

Chris

[telford dorr]

Remember, ALL of the engine torque is going thru that adapter and those 4 little 8mm oil pump studs. Do you really want to do that? Just asking...
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[ccowx]

True, I don't. However, looking at the world I live in, I don't appear to have immediate access to a good used bus case that has a dual relief oil system and late dog house oil cooler. I also don't have $2000 for a new one, even assuming it was available.

Good news is that I might be able to save my old case after all. It is a 1600 dp case with dual relief and everything I need. The machine shop is looking it over now.

Fingers crossed!

Chris

[metz]

[Earl Bay]

Interesting subject.
My engine builder refused to build me a 2074cc with such a bug case.
Allthough he never tried it before he wasn't willing to take the risk.

[busdaddy]

Much of it depends on your driving style, smooth easy clutch work and civilised throttle won't be a problem. But dumping the clutch for burnouts at every light will likely twist it off in no time at all.
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[ccowx]

I am getting the sense that, as I suspected, it is an "OK" solution, but not ideal. Here is a few thoughts:

-The wider spacing of the mounts is more important that the strength of the fasteners in my mind. Less leverage to twist and move.
-Strength wise, probably fine if you are not shock loading it, as BD says. I have other vehicles for drag racing, so no problem there. Long hills and freeway merging are my concerns.
-Leaks are a thought. That kind of flexing could be an issue, though I am not hearing it.

Thanks for the input guys! I have used one in the past with a very mild 1835 for years without problems, but I am upping the horses by about 40%, so it needs a re-think.

Chris

[busdaddy]

The farm fabricator in me wonders if you could add braces between the rear exhaust port studs and the bar?, something that sandwiched between where the gasket goes and runs down and back to clamp or bolt to the bar.

Food for thought......
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[SGKent]

if your case does not work out for you, ask Mike in Wasilla, AK if he has a bus case like what you need. his member name is BigBore
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[ccowx]

Definitely food for thought. I did find a picture somewhere of an adapter like what you describe.

And if I don't get good news from the machine shop, Bigbore might be my next phone call!

Thanks!

Chris

[Abscate]

What’s the shear on an m8 bolt? About 15 kN?

What’s the torque * moment arm/4 on the motor? I’ll bet it’s pretty comfortable
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[Earl Bay]

for an M8 8.8 18.100 N, 10.9 26.600 N, 12.9 31.100 N

I had to look that up. Not an expert in this. I wouldn't use 8.8 in that place.
However sometimes the more flexible 8.8 is preferred over a 12.9 because 12.9 doesn't flex but breaks.
You certainly wouldn't use 8.8 to mount disc brakes. But I can't remember if they are 10.9 or 12.9

[Abscate]

[Earl Bay]

I'd love to have a profound reply to this.
I'm sure the math behind it isn't just "engine torque divided by 4 bolts that can each take 18kN so no problem"

I still have such a spare case but only a bus.
Maybe this would get more attention in the performance forum

[germansupplyscott]

Some crankcases have one boss that can be drilled/tapped, so in this situation you have the existing case boss, the through-bolt on the parting line below and the oil pump studs. It's still not ideal but sometimes you make do with what you have. Having the case boss drilled/tapped is a big plus.

One tip to using these case adapters is to weld nuts to the adapter plate so the fastenings can be blind, makes installation or removal of the hanger bar smoother.

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SL

[ccowx]

Thanks Gentlemen, as always a lot of good responses and points made! My ultimate conclusion was that I could use the mustache bar adapter if I had to and likely it would be fine. However, me being me and the bus being my last and best of several, I decided to at least TRY to get a bus case, and I did. I got lucky and found a a nearly complete 1600 dual port, dual relief case. It even has 8mm studs. I plan to have it bored to fit the 92mm TW cylinders.

I have a question though. It is coded AES728699. It looks like it may have been planed and re-stamped at some point. What is the "S"? I also am not sure if the case savers and 8mm studs are original or not. If it was an "AE" code 71 bus engine it all makes sense, but I didn't think they had 8mm studs this early on. Could the "S" be some sort of waranty/re-issue block?

Thanks!

Chris

[Abscate]