tsmale
10-23-2005, 10:59 PM
I saw this on the Newsgroups: rec.autos.rod-n-custom
"Holley is misrepresenting their HP carb sizes, a HP 950 is really a
830, a HP1000 is about a 870 if measured the same vac as a 47-- series.
The industry standard for cfm ratings was 1.5"Hg vac for a 4 barrel.
holley may have decided to follow the deciptive lead of it's
competitors and use 28"wc which is 2.06" hg.
Holly has all their carbs listed with flow spects. They make no
distinction between a HP type and a older 4781 type. Unless you
actually flow a carb, with holley's listings, you can't tell what flow
it may be since the listed flows of the 4 barrels are not made with the
same test standard. Their all listed together by flow ratings. I'm just
for the truth in advertising, if holley actually told the test vac for
carbs it would be better, Esp if they use different test spects for
different 4 brl carbs. It looks like Holley uses a 1.5"HG vacuum
standard for the 47_ _ series carbs and for the HP series they use
2.06"hg vacuum test standard. The result is a false comparison between
the two carbs. I got tricked and many others will be also. Spread the
word about this .
The bottom line --- I paid $700 for a HP950 thats smaller than my 4781
850 carb.
The HP950 has a 1 3/4 base plate and a 1 3/8 venturi.
A older 850 has a 1 3/4 base with a 1 9/16 venturi
A HP830 has a 1 11/16 base and a 1 9/16 venturi"
http://www.thecarburetorshop.net/bigger2.html
"Holley is misrepresenting their HP carb sizes, a HP 950 is really a
830, a HP1000 is about a 870 if measured the same vac as a 47-- series.
The industry standard for cfm ratings was 1.5"Hg vac for a 4 barrel.
holley may have decided to follow the deciptive lead of it's
competitors and use 28"wc which is 2.06" hg.
Holly has all their carbs listed with flow spects. They make no
distinction between a HP type and a older 4781 type. Unless you
actually flow a carb, with holley's listings, you can't tell what flow
it may be since the listed flows of the 4 barrels are not made with the
same test standard. Their all listed together by flow ratings. I'm just
for the truth in advertising, if holley actually told the test vac for
carbs it would be better, Esp if they use different test spects for
different 4 brl carbs. It looks like Holley uses a 1.5"HG vacuum
standard for the 47_ _ series carbs and for the HP series they use
2.06"hg vacuum test standard. The result is a false comparison between
the two carbs. I got tricked and many others will be also. Spread the
word about this .
The bottom line --- I paid $700 for a HP950 thats smaller than my 4781
850 carb.
The HP950 has a 1 3/4 base plate and a 1 3/8 venturi.
A older 850 has a 1 3/4 base with a 1 9/16 venturi
A HP830 has a 1 11/16 base and a 1 9/16 venturi"
http://www.thecarburetorshop.net/bigger2.html