RE: Dual exhaust, side thread to what 4bbl

[<stevec@xxxxxxxxxxxxxxxxxxxx>]

I think of the engine as a pump - it can put a set volume of fluid (in this case air and fuel) through it depending on the limitations of the "pump" - be it exhaust, port size, valve lift, carburetor, air filter, etc.  For any given combination, one of the aforementioned parts will be the bottleneck, restricting further flow.  Upgrading that particular component improves flow (performance) and the next most restrictive part becomes the bottleneck.

Looking back at dual quad and six-pack options, the factory definitely made those intakes and carbs capable of flowing more than the rest of the combination.  But being as how they ran (at low throttle openings) on either the primaries of one carb (normally the rear) or the center carb in the case of a six-pack, low speed driveability was not compromised.  At WOT, the engine took what it needed, limited only by the exhaust, port size, valve lift, etc. of that particular combination.  That's why cars equipped with those induction systems responded well to exhaust and camshaft upgrades - the induction system was ready!  

So really, the engine isn't forced to accept the 1000-1200 cfm of the multiple carb systems, it simply takes whatever it can take - could be just 600 cfm, maybe 800 or 900, but since the fuel is metered in relation to the air flowing at WOT, it all works, which was good enough for most folks, and allowed the cars to perform well even with production tolerances and tuning variances.

So could a well-tuned 650 or 750 cfm carb outperform a dual quad?  Probably, unless the dual quad was properly matched and as well tuned as the single carb.  If you're running a dual quad, be sure to read Dan Dvoraks' treatise on multiple carburetor tuning linked from here:

http://www.dvorakmachine.com/carb_sync.shtml

If you don't already have one, by all means get one of his synchronizers - you won't believe what you've been missing without it.

SC

 Dual exhaust, side thread to what 4bbl

Dodger7998@xxxxxxx Jan 14 11:05AM -0500  

Looking for opinions here, several days ago Gary H. made a
statement,,,,,dual exhaust will not change (carb) air flow needed , this got me
thinking,,,,,,, please correct me , in my opinion dual exhaust will increase the
amount of air flow especially during WOT, the benefit of a dual exhaust other
than sound is it's ability to flow more exhaust fumes, that being said
during that split second when both exhaust and intake valves are open the
scavenging effect will increase the HP, by clearing the cylinder better and
drawing more air and fuel into the cylinder,,,,,,,,,,so my question,,has it
changed the needed size of CFM carb needed?

-- 
-- 
--
Please address private email -- email of interest to only one person -- directly to that person. That is, email your parts/car transactions and negotiations, as well as other personal messages, only to the intended recipient. Do not just press "reply" and send your email to everyone using the general '62-'65 Clubhouse public email address. This practice will protect your privacy, reduce the total volume of mail and fine-tune the content signal to Mopar topic. Thanks!
 
1962 to 1965 Mopar Clubhouse Discussion Guidelines:
http://www.1962to1965mopar.ornocar.org/mletiq.html and http://www.1962to1965mopar.ornocar.com/general_disclaimer.html.
-- 
You received this message because you are subscribed to the Google Groups "The 1962 to 1965 Mopar Mail List Clubhouse" group.
http://groups.google.com/group/1962to1965mopars?hl=en.
 
--- 
You received this message because you are subscribed to the Google Groups "The 1962 to 1965 Mopar Mail List Clubhouse" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 1962to1965mopars+unsubscribe@xxxxxxxxxxxxxxxxx
For more options, visit https://groups.google.com/groups/opt_out.