Air filters on a pair of DCOE 40 Webers

[Stevensonjr]

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[jbcollier]

And what is it like where you live: lush and humid, dry and dusty, or?

Edited March 25, 2024 by jbcollier

[Stevensonjr]

Lush and Humid, South Louisiana Cajun country

[Stevensonjr]

I sent 4 photos that seemed to disappear. Bill

[jbcollier]

Well, in that case, there really isn't anything to fix or improve.  Drive it and enjoy.

[JohnCh]

1 minute ago, Stevensonjr said:

I sent 4 photos that seemed to disappear. Bill

 

Do you mean the 4 photos on the last post of the previous page or something else?  If it's not those photos, please send me a PM and I'll help you troubleshoot.

[MV8]

You could fit hardware cloth/mesh to the scoop opening to catch anything big short of dirt/mud doubers in the garage.

Maybe a new bonnet with a repositioned forward clamp and a notch for clearance instead of an opening where the air filters would need to be removed to remove the bonnet.

[MoBoost]

Shorter air horns would provide more room for filtration.

[Stevensonjr]

2 hours ago, JohnCh said:

 

Do you mean the 4 photos on the last post of the previous page or something else?  If it's not those photos, please send me a PM and I'll help you troubleshoot.

Yes, the 4 photos on the last post of the previous page. Found them feeling like an idiot!

[JohnCh]

Just now, Stevensonjr said:

Found them feeling like an idiot!

 

Always happy to help   

[Christopher smith]

I recall hearing that the short velocity stacks are optimum for high rpm while tall ones are more for torque at lower RPM.Not sure if this really matters much.

[jbcollier]

It's the total length of the intake tract that matters. This is already quite restricted in Seven derivatives.  The main thing the horns do in our case is smooth the flow into the carb, significantly reducing turbulence and thus increasing total flow.

 

Long way of saying, yes, shorter stacks would probably be fine.

[Stevensonjr]

Just ordered the short stacks from Pegasus. They are almost an inch shorter than the air horns the Webers came with. I did some measuring and they will fit with just a bit of grinding. Low profile filters will work. Thanks everyone for the info.    Bill

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[SCse7en]

Can you tell me how long your original  air horns are vs the new ones from Pegasus?   And when you get them what filters do you plan on using? Thanks!

[Stevensonjr]

The original air horns were 1.54” high and the new horns are .63” high. A difference of .91” shorter. Going to use the metal mesh filters that attach with a plastic/rubber ring around each horn.

 Not the best filter, but sufficient for our high humidity weather in South Louisiana.

These filters add about 1/2” to the horn length so I will end up with just over an inch total as opposed to just over 2” with the original horns.  Cheers, Bill

[jbcollier]

You will have to re-jet the carbs.  These mesh screens block a minimum of 40% of the air flow wide open.  This effect is biased: full at wide open down to negligible at idle.

Edited March 26, 2024 by jbcollier

[SCse7en]

Where did you get that figure of 40% from?  First time I ever heard of that.

[Christopher smith]

Does anyone have any dynamometer or other actual flow data on the stainless mesh or for that matter any air cleaner types? What were the cars out front for all those years in D Production using for their 1340 and 1500 cc powered pre-crossflow cars?

[JohnCh]

I don't have data on the stainless mesh screens, but when I had my old Westfield with a 1700cc crossflow on the dyno, we did a run with the ITG air filter removed and lost 1.5hp.  I didn't expect that.  I wouldn't read that as ITG filters make power, but rather they do a good job of not losing power.   Given the limited under bonnet space, the Webers were fitted with a short JC50 (or JC40?) filter and the Stubby bolt-on radiused air horns from Pegasus.

 

[Stevensonjr]

3 hours ago, jbcollier said:

You will have to re-jet the carbs.  These mesh screens block a minimum of 40% of the air flow wide open.  This effect is biased: full at wide open down to negligible at idle.

That’s the beauty of Webers, I can play with them if I’m not happy with what the filters do. Anyway there’s not much call for 6000 rpm on the street at 80 years old. Thanks again for the  info.   Bill