| Re: [GMCnet] Low pro carb hat. What's a good lowpro hat? Want my hatch flush again [message #362504 is a reply to message #362503] |
Tue, 23 February 2021 15:54   |
James Hupy
Messages: 6806
Registered: May 2010
Karma:
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Senior Member |
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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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