Medium riser dual carb suggestions.

[sideoilercat]

Stock stroke 427 side oiler, medium riser heads, Ford "D" cam, tunnel wedge intake. It currently has 2 780's converted to rear metering plates to make them shorter. I still have the 652 body's and throttle plates. Should I go back to 652's? Will it be enough. I am now living at 5,000+ feet. It's been sitting since the early 80's. Will be coming back to life soon after freshening up. It's been so long ago I don't remember weather the switch to bigger carbs made a difference or not back then.
Thanks.
J.K.

[BH107]

When you say 652 I am assuming you are referring to C8OF-AC/AD carbs? Those were a drag race only carb that won't have good manners except at WOT.

If you don't like your current converted carbs Barry can build you some trick QFT carbs, or you can by reproduction carbs from Carls.

[sideoilercat]

These are the C3AF-BK and C3AF-BJ. No choke on either one. Thanks.
J.K.

[cjshaker]

The factory carbs would be plenty for your stock displacement engine. You'd be looking at plus/minus 1200 cfm, and that's plenty of carb to feed a pretty healthy engine.

[GJCAT427]

I`m running BJ-BKs on my 427 with the "B" cam in my 427. I have also run 1850s with no problems.  The AC-ADs are not streetable because of the no power valve plate. You need the powervalve on the street for transition rpms.  I have 2 "D" cams which I will put one of em in my tunnel port this yr. More radical but still streetable .

[427LX]

I`m running BJ-BKs on my 427 with the "B" cam in my 427. I have also run 1850s with no problems.  The AC-ADs are not streetable because of the no power valve plate. You need the powervalve on the street for transition rpms.  I have 2 "D" cams which I will put one of em in my tunnel port this yr. More radical but still streetable .

Just curious...do you remember your jetting on primary and secondary with the 1850's?

[BH107]

These are the C3AF-BK and C3AF-BJ. No choke on either one. Thanks.
J.K.

BJ/BK carbs would be 600cfm each, not 652cfm.

What is it going in and what are your goals?

[Barry_R]

Interesting enough is that Holley list numbers 2804 and 2805 are shown as 510 cfm in the hand written Holley part number assignment book.  This is genuine first source data from the guys that built them.  No way for me to know what changes were made after the part numbers were assigned, but changes to the list numbers were usually accompanied by a "-1" or "-2" type of suffix.  They show a 1-1/4 and 1-5/16 venturii and a 1-9/16 bore.

I made a photocopy copy of this document when Holley moved out of the Warren, MI headquarters because it looked like they were just going to throw it away.  Don't know whether the original still exists, but I really ought to post this copy on the web for future reference.

[GJCAT427]

427LX as I remember they were stock out of the box, some minor tweeking of the idle screws and away I went. Barry I would be very interested in a copy  that Holley sheet for my holley archives.

[sideoilercat]

These are the C3AF-BK and C3AF-BJ. No choke on either one. Thanks.
J.K.

y

BJ/BK carbs would be 600cfm each, not 652cfm.

What is it going in and what are your goals?

Wow, all these years I thought they were 652, thanks for that info.
 It is going back into a 67 Cougar with an 8" torque converter. very limited street use and occasional 1/4 mile for fun memories.

How about spacers, I have none now?

[cammerfe]

My own experience with '652s' was a pair of the sort of center-squirters that were used on the LeMans 427 TPs. I got a set that had come back from testing in France and we used them on the TP engine we put in Brother Lon's '67 Mustang. They worked just fine. They were only one set of several we used on that engine. We finished-up with a pair of Holley EFI throttle bodies. They worked much better than ANY of the carb pairs once we sorted them out.

KS

[sideoilercat]

I'm back on these carbs, found this mod I did back in the day to the metering plates (drilled and tapped so I could change jets). I don't remember how it worked. Has anyone seen this done and should I put them back or replace them? the jets say 84 but I think I remember drilling them bigger omg! They were on the 780 bodies last but originally on the C3AF BK/BJ's. Wonder what jets to run if I install them back in the BK/BJ 600's.
Thanks
JK.

[My427stang]

This is a copy of an old post from an FE Forum member, Chipmechanic.  It doesn't have measurements for the rear "jet" size but I would expect 72-74s in your case with the modified plate?  Hope it helps

BJ carb...List 2805

Primary main air bleed .030"
Primary idle air bleed .062"
Secondary main air bleed .025"
Secondary idle air bleed .028"
Squirter .025"
Primary Jets 66
Transition slot width .025" all 4 corners
emulsion jets .029" ...both sides both jets
kill bleeds .028"
idle feed restrictors .042"
Power valve channel restriction .043"
balance of jets on primary metering block unrestricted
secondary metering plate same as 600 holley
PV not marked but seems to be same as 85. Pretty stiff.
straight leg boosters, standard 600 holley sized plates and venturi
yellow squirter cam position 1

BK Carb...List 2804

Primary main air bleed .030"
Primary idle air bleed .060"
Secondary main air bleed .025"
Secondary idle air bleed .028"
Squirter .025"
Primary Jets 66
Transition slot width .025" all 4 corners
emulsion jets .029" ...both sides both jets
kill bleeds .028"
idle feed restrictors .042"
Power valve channel restriction .043"
balance of jets on primary metering block unrestricted
secondary metering plate same as 600 holley
PV not marked but seems to be same as 85. Pretty stiff.
straight leg boosters, standard 600 holley sized plates and venturi
yellow squirter cam position 1

[sideoilercat]

Thanks Ross, good info. I thought by the original specs maybe about 70 on primary and like you say 72-74 secondary. I do live in a vacuum here a little over 5,000 feet so staying on the lean side considering the bigger D cam, tunnel wedge etc? I'm kind of looking for a starting point.
JK.

[Russ67Scode]

When you say 652 I am assuming you are referring to C8OF-AC/AD carbs? Those were a drag race only carb that won't have good manners except at WOT.

I can tell you this my car has a set of AC/AD carbs on it and I have no problem driving it on the street. Maybe I got lucky with my combination, but it works just fine I have tried it with a different primary metering block with a PV didn't really notice a difference in street manners , I did it to run a smaller jet in the primary
People told me the same thing about a dominator carb on the street drove one of those all the time also
my 2 cents Russ