Click Here -> Please Consider Making a PayPal Contribution to the FordSix Forum!
2019 Contributors:
NJwpod, 1strodeo, mightynorseman, maxtrux, 6d7coupe, broncr, Phase3, 68Flareside240, bmbm40,
mustang6, WorldChampGramp, justintendo, BigBlue94, ags290, motorsickle1130, Rooster, ousooner919, ethanperry
rzcrisis, DoctorC, jamyers, Motorboy, fastpat, Silverback280, chad


<<< New Site Update >>>

F250 300 AFR / Vacuum Reading With Holley 2300 350 cfm Carb

Moderator: Mod Squad

User avatar
old28racer
Registered User
Posts: 623
Joined: Wed Apr 12, 2017 3:27 pm
Location: Camarillo, CA

F250 300 AFR / Vacuum Reading With Holley 2300 350 cfm Carb

Post #1 by old28racer » Fri Oct 04, 2019 10:24 pm

The following information is from my latest road fest with a AFR & Vacuum gauge inside the cab. My truck is a 1971 2WD F250, 300, C4, 3.73 stock fresh rebuilt motor (5,600 miles). Carb is a Holley 2300 350 cfm 2 barrel mounted on a 300 log intake with a 2x1 adapter (very restrictive).

Today I was able to make another road test ( all the same places ) with quality vacuum hose. Before I post numbers let me say that the vacuum reading are very close to the first ones I got back a few months ago.

The AFR & Vacuum reading were taken at the same time. Both idle screws are set at 1 turn open. Idles very smooth at 650-700 rpm.

Idle in gear with motor up to running temp -- ( AFR = 14.7 - 15.2 ) --- ( Vacuum 19" )
35-40 cruise -- ( AFR = 14.6 - 14.8 ) --- ( Vacuum 16" )
55-60 cruise -- ( AFR = 14.2 - 13.9 ) --- ( Vacuum 13" )
WOT in drive, just rolling to 60 mph -- AFR = 11.2 ) --- ( Vacuum -0-" )

I would stand beside the numbers as being accurate. When I change jets I have a new 6.5 PV to replace the 8.5 PV that is in the carb now.

With the cruise and WOT number I feel like I should go from a pair of current 61 jets to a pair of 57 jets for the first change, don't think 59's will make that much difference.
Bad Day Racing Is Better Than A Day In The Stands :mrgreen:

Who is online

Users browsing this forum: No registered users and 32 guests