| Re: [GMCnet] Low pro carb hat. What's a good lowpro hat? Want my hatch flush again [message #362505 is a reply to message #362504] |
Tue, 23 February 2021 16:19   |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma:
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Senior Member |
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Many years ago, when I first put a snorkel on the 455, I used a
"corrugated" rubber hose, taken off of something in the junkyard 'cause it
looked good and fit where I needed it. May have been off of some 2L
engine, for all I know. It really worked out nicely -- until the first
time I was doing about 50 mph and stepped into "passing gear". Suddenly,
beside the passee, my engine died! After that happened a few times, I
tried it with the hatch open. When that 455 ci air demand went high at
full throttle, that convoluted rubber collapsed, acting like a fully
closed choke!
Now I use "picker hose", designed to suck cotton bolls out of their shells
and deliver them to the baler. :-)
Ken H.
On Tue, Feb 23, 2021 at 4:55 PM James Hupy via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Any abrupt turn in an inlet tract will SEVERELY negatively effect
> horsepower production at high airflow. As will right angle turns in the
> inlet. The seemingly inconsequential "flow bumps" in small block chev 202
> heads were developed after endless flow bench and dyno testing. They
> account for a significant boost in flow at certain rpms when coupled with
> the correct compatible carbs, intake manifolds, compression ratios, cam
> shaft profiles, gaskets, and header diameter and tube shapes.
> When we drag raced small block chevs back in the late '50s and early
> '60s, we kept 302 cubic inch motors alive at 9000 rpms, when no one else
> seemed to be able to keep one alive for long much over 7500. Had lots of
> guys peeking over my shoulders any time I had an engine apart to learn how
> we did it. Hard earned secrets, kept mostly in my head, now as then.
> Jim Hupy
> Salem, Oregon
>
> On Tue, Feb 23, 2021, 1:30 PM Larry via Gmclist
> wrote:
>
>> Thinking back on this Jeep snorkel, someone out there had it on their 455
>> and ran it on a chassis dyno. Above 3K rpm it fell flat on its face.
> Whoever
>> it was running the dyno speculated that the Jeep snorkel was the cause.
>> The air coming in at 3K did not have time to straighten out after making
> the
>> right angle turn and the turbulence of the flow was interrupting the
>> effectiveness of the venturi effecting the FA mixture. They placed a 1"
>> spacer
>> between the snorkel and the carb to give the air time to straighten out.
>> That took care of the problem, and engine pulled strong to 4K. Wish I
> could
>> remember who that was, but might be worth considering that you have an
>> extra 1" there in case you have power issues. JMHO
>> --
>> Larry
>> 78 Royale w/500 Caddy
>> Menomonie, WI.
>>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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