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Question about Jay Browns Intake Comparo. Book

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FERoadster:
Jay: From a discussion on the FEForum.  Your test of the Edelbrock F380 3X2 intake stated that at WOT there was still 2.2" of vacuum.

Is there a way to back into the amount of CFM that actually went through the carbs?  I got rid of all of my 94's and 81's and have standardized on Stromberg WW's since they are considerably larger,a newer (better?) design and have parts readily available.

I'm wondering CFM differences from the Ford-Holley 94's and the Strombergs. I have read that the WW's flow over 250 CFM where 94's flow someplace around 150 CFM. Your test is the only one I've seen that maxes out flow.

Richard >>> FERoadster

Heo:
I have one of those intakes and you could order
them for 2bbl Rochester so there is material
att the base to drill them for Rochester
and open upp the runners to match
if that make any difference i dont know
but im going to try that when and if i have
any spare time
Stromberg WW wich carb is that?
The early y-Block got a 3 bolt carb thats
look like the 94 but is much bigger ...well
over one inch throtlle blades ..1 inch and
some /16 dont remember now
Think 56 is the biggest one

jayb:

--- Quote from: FERoadster on December 06, 2013, 12:49:46 PM ---Jay: From a discussion on the FEForum.  Your test of the Edelbrock F380 3X2 intake stated that at WOT there was still 2.2" of vacuum.

Is there a way to back into the amount of CFM that actually went through the carbs? 
Richard >>> FERoadster

--- End quote ---

Normally yes, because the dyno measures the cfm taken by the engine.  However, in the case of that test I don't know if I had the dyno's inlet air turbines connected; it would have been difficult to fit them over the 3 small carb openings without leaks, so I would have had to make a box with three holes for the carbs, tape that in place, and then cut one or two larger holes for the air turbines to flow air into the box.  I probably still have the dyno data from that test; I will look it up and try to post what I find later - Jay

FERoadster:
Jay: Thanks for the reply.  My ides was that if you had some data on what the 428 pulled (CFM) at a certain RPM and the vacuum there you could relate it and make a SWAG about how much flowed thru the 94's. If vacuum on a certain carb-intake combo was say 1" and the 94's were say 3.5  it would be possible to calculate flow.

It's been 43 years since my fluid flow class in University but I did work for the natural Gas industry so I was exposed to the calculations. I'll have to check some of my books from the GasCo.

Heo: yes  my Edelbrock 3X2 has the Stromberg WW's  and was the 4 bolt base version of the F380. The larger Holley-Ford carbs were the 81 and I think the 48. 97 was the smallest then 94,81 and 48.

Thanks  Richard

jayb:
OK, I found the data for the 390 Stroker dyno mule and it looks like I did take the time to make up an airbox so I could get the airflow data on the F380 intake.  Here are two charts; the first chart shows the manifold vacuum over the course of the dyno pull, and the second chart shows the airflow.  Sorry about the graphs, they are a little difficult to read:





Just for a point of comparison, here is a graph of the airflow from the Blue Thunder 2X4 intake, which basically showed zero manifold vacuum:



Hope that helps, Richard.  If you come up with some kind of a calculation on this for the carbs, please post it here for interest - Jay

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