Post by PHAT69AMX on Feb 20, 2019 15:16:39 GMT -8
The Captains comment in that other thread reminded me about the old forum KP Carb Flow Test thread...
The Wayback Machine allowed finding the 1st of 2 pages of that 2008 thread, but not page 2.
Saved all the KP text from page 1, posted about it in a good old gAyMCer Head Flow thread with KP posts.
Hoping that maybe the rest of the KP text and Carb Flow Test info can be had, we'll see...
Here's what was saved from page 1:
Ken_Parkman
Carb flow test
02/09/08 at 22:39:45
For various reasons there seems to be a lot of carburetors
around here right now, so I decided to put them
all on the flow bench for comparison.
My flowbench cannot effectively measure a carb cause to do it right
you need to have a bench that will suck the roof off the shop and
has a direct power supply from the generating station.
But what I can do is run the bench wide open and then put on different carbs
and measure the pressure drop, and then I can compare one to another.
I could check an individual barrel, but that takes fixtures
I don't have and can't be bothered making.
As you know there is way more to carbs than flow - a point that
has really been hammered home to me with some dyno and track testing.
Also as you know factory ratings are pretty much meaningless
cause they are marketing more than anything. So this is an effort
to see how much some manufacturers are exaggerating. Do not use this
data to say one will make more or less power; it's only for interest.
So here is the list of different carbs and their ranking
flow wise, smallest to largest:
Rank/Carb/Part Number/Rating/Comments
1 Edelbrock 1405 600
2 Holley 1850 600 Significantly more flow than Edelbrock 600
3 Q-Jet ? ? Secondary air flap has a stop to limit opening
4 Holley 4777-2 650
5 Edelbrock 1407 750 Slightly more than 650 Holley
6 Edelbrock 1813 800 Big improvement over 750 Edelbrock
7 Q-Jet ? ? Secondary air flap opened noticeably more than above Q-Jet
8 Holley 4780 800 Same dimensionally as a 750,
but this carb had a slight TB mismatch.
9 Holley 3310 780 Factory GM original 3310, down leg booster
10 Holley 3310-2 750 Strait booster than above, flows a little better but close
11 Pro-Systems XC ? Built for a mild 327 Chev,
noticeably more flow than above Holleys
12 Holley 4781 850 No choke plate
13 Holley 80514 1000 Annular booster carb, very small flow difference from 850
14 Pro-Systems XE ? Down leg booster, very significantly more flow than 1000 Holley
A couple of comments:
The Edelbrocks flow significantly less than the same rated Holley
Holley plays games with flow ratings.
Yes a 750 Holley flows more than a Holley 800.
I've heard it before, but this seems to confirm
a 850 Holley is a lot bigger than a 950.
Dimensionally the 850 is bigger.
The 850 with no choke and a StubStack
was essentially identical to the Annular Booster 1000.
Stubstacks noticeably improve the flow.
A fancy CNC milled 2" spacer slightly improves the flow.
The Q-Jets were flowed with an adapter that slightly restricted the flow,
but calibrating with a Holley says the restriction was not much.
I'm going to try to get a few more carbs to add to this list,
including a factory AFB and MotorCraft.
-------------------------
Ken_Parkman
Re: Carb flow test
Reply #6 - 02/10/08 at 17:10:59
Trying to find some stock AMC stuff, just don't have any here!
I hope to score a stock AFB and a 4300 to test, I'll post if it happens.
What Reagam said is important. A high flow carb is no good
if it can't properly atomize fuel at a low delta pressure.
Only take this data as an interesting comparison.
Of course a really good carb is both high flow and
can properly control the mixture at a wide rpm and load range.
A simple flow test cannot tell this.
--------------
Ken_Parkman
Re: Carb flow test
Reply #8 - 02/16/08 at 18:22:16
Those were 2 different Stubstacks, both K & N.
One is very old (been through a carb fire)
and has been modified to better fit the 850,
which seems to have a different height air horn
then the Stubstack was designed for.
The other is an almost new one made from
a different plastic and fit the 750 very well.
Both noticeably improved flow,
but clearly the bigger 850 really liked it, the flow was well up.
The spacer is a really trick CNC milled 4 hole
translating to an open with a nicely flaired 'bullet' in the center.
But now that I am carefully looking I find it has slightly small bores
on the 4 hole part. I'm gonna fix that and try again.
Just scored a couple of Demons, a good prepped dyno 750 Holley,
and a stock AFB. Hope to have a MotorCraft
and a few more Holleys tomorrow. Will post info
-------------
Ken_Parkman
Re: Carb flow test
Reply #14 - 04/28/08 at 02:32:16
I FINALLY managed to score some stock AMC carbs
and get all the data together. I've had 29 carbs
across the flow bench and it is an interesting exercise.
I've learned carb flow numbers are a game.
Do not assume a carb is bigger because it it rated higher.
The highest flow 750 carb was 150 cfm better the lowest flow 750.
A surprise is the stock MotorCraft 4300.
I scored a OWA4-S, and it's surprisingly good flow wise.
It looks crappy, but flows a tiny bit better
(not enough to give a number)
than a Demon 625 or an Edelbrock 600, both of which are pretty much the same.
A Holly 600 is about 40 cfm better than the BG and the Ed.
The stock AMC AFB (tested # 4664) is about 40 cfm less
than the same BG and Ed Carbs. The Ed 600 is an AFB and is basically
the same carb as the stock AFB. It has the same bore's and venturi's,
but the Ed has 1/2 throttle shafts and a little aerodynamic fairing
to account for the 40 more cfm.
The 4350 MotorCraft is the same as the stock AFB.
I scaled the carbs on a 0-100 scale, and here are the small carbs:
Edelbrock 750 (1407) - 71
Holley 700 (4778) - 71
Holley 650 (4777) - 69
Rochester Q-Jet (xxxx) - 67 (small one)
Holley 600 (1850) - 65
MotorCraft 4300 (xxxx) - 61 (OWA4-S)
Barry Grant 625 (xxxx) - 61 (Road Demon)
Edelbrock 600 (1405) - 61
Carter AFB (4664) - 57
MotorCraft (4350) - 57
---------------
(4) MORE POSTS ON PAGE 2 -> BUT NOT ON WAYBACK MACHINE !
-------------------
The Wayback Machine allowed finding the 1st of 2 pages of that 2008 thread, but not page 2.
Saved all the KP text from page 1, posted about it in a good old gAyMCer Head Flow thread with KP posts.
Hoping that maybe the rest of the KP text and Carb Flow Test info can be had, we'll see...
Here's what was saved from page 1:
Ken_Parkman
Carb flow test
02/09/08 at 22:39:45
For various reasons there seems to be a lot of carburetors
around here right now, so I decided to put them
all on the flow bench for comparison.
My flowbench cannot effectively measure a carb cause to do it right
you need to have a bench that will suck the roof off the shop and
has a direct power supply from the generating station.
But what I can do is run the bench wide open and then put on different carbs
and measure the pressure drop, and then I can compare one to another.
I could check an individual barrel, but that takes fixtures
I don't have and can't be bothered making.
As you know there is way more to carbs than flow - a point that
has really been hammered home to me with some dyno and track testing.
Also as you know factory ratings are pretty much meaningless
cause they are marketing more than anything. So this is an effort
to see how much some manufacturers are exaggerating. Do not use this
data to say one will make more or less power; it's only for interest.
So here is the list of different carbs and their ranking
flow wise, smallest to largest:
Rank/Carb/Part Number/Rating/Comments
1 Edelbrock 1405 600
2 Holley 1850 600 Significantly more flow than Edelbrock 600
3 Q-Jet ? ? Secondary air flap has a stop to limit opening
4 Holley 4777-2 650
5 Edelbrock 1407 750 Slightly more than 650 Holley
6 Edelbrock 1813 800 Big improvement over 750 Edelbrock
7 Q-Jet ? ? Secondary air flap opened noticeably more than above Q-Jet
8 Holley 4780 800 Same dimensionally as a 750,
but this carb had a slight TB mismatch.
9 Holley 3310 780 Factory GM original 3310, down leg booster
10 Holley 3310-2 750 Strait booster than above, flows a little better but close
11 Pro-Systems XC ? Built for a mild 327 Chev,
noticeably more flow than above Holleys
12 Holley 4781 850 No choke plate
13 Holley 80514 1000 Annular booster carb, very small flow difference from 850
14 Pro-Systems XE ? Down leg booster, very significantly more flow than 1000 Holley
A couple of comments:
The Edelbrocks flow significantly less than the same rated Holley
Holley plays games with flow ratings.
Yes a 750 Holley flows more than a Holley 800.
I've heard it before, but this seems to confirm
a 850 Holley is a lot bigger than a 950.
Dimensionally the 850 is bigger.
The 850 with no choke and a StubStack
was essentially identical to the Annular Booster 1000.
Stubstacks noticeably improve the flow.
A fancy CNC milled 2" spacer slightly improves the flow.
The Q-Jets were flowed with an adapter that slightly restricted the flow,
but calibrating with a Holley says the restriction was not much.
I'm going to try to get a few more carbs to add to this list,
including a factory AFB and MotorCraft.
-------------------------
Ken_Parkman
Re: Carb flow test
Reply #6 - 02/10/08 at 17:10:59
Trying to find some stock AMC stuff, just don't have any here!
I hope to score a stock AFB and a 4300 to test, I'll post if it happens.
What Reagam said is important. A high flow carb is no good
if it can't properly atomize fuel at a low delta pressure.
Only take this data as an interesting comparison.
Of course a really good carb is both high flow and
can properly control the mixture at a wide rpm and load range.
A simple flow test cannot tell this.
--------------
Ken_Parkman
Re: Carb flow test
Reply #8 - 02/16/08 at 18:22:16
Those were 2 different Stubstacks, both K & N.
One is very old (been through a carb fire)
and has been modified to better fit the 850,
which seems to have a different height air horn
then the Stubstack was designed for.
The other is an almost new one made from
a different plastic and fit the 750 very well.
Both noticeably improved flow,
but clearly the bigger 850 really liked it, the flow was well up.
The spacer is a really trick CNC milled 4 hole
translating to an open with a nicely flaired 'bullet' in the center.
But now that I am carefully looking I find it has slightly small bores
on the 4 hole part. I'm gonna fix that and try again.
Just scored a couple of Demons, a good prepped dyno 750 Holley,
and a stock AFB. Hope to have a MotorCraft
and a few more Holleys tomorrow. Will post info
-------------
Ken_Parkman
Re: Carb flow test
Reply #14 - 04/28/08 at 02:32:16
I FINALLY managed to score some stock AMC carbs
and get all the data together. I've had 29 carbs
across the flow bench and it is an interesting exercise.
I've learned carb flow numbers are a game.
Do not assume a carb is bigger because it it rated higher.
The highest flow 750 carb was 150 cfm better the lowest flow 750.
A surprise is the stock MotorCraft 4300.
I scored a OWA4-S, and it's surprisingly good flow wise.
It looks crappy, but flows a tiny bit better
(not enough to give a number)
than a Demon 625 or an Edelbrock 600, both of which are pretty much the same.
A Holly 600 is about 40 cfm better than the BG and the Ed.
The stock AMC AFB (tested # 4664) is about 40 cfm less
than the same BG and Ed Carbs. The Ed 600 is an AFB and is basically
the same carb as the stock AFB. It has the same bore's and venturi's,
but the Ed has 1/2 throttle shafts and a little aerodynamic fairing
to account for the 40 more cfm.
The 4350 MotorCraft is the same as the stock AFB.
I scaled the carbs on a 0-100 scale, and here are the small carbs:
Edelbrock 750 (1407) - 71
Holley 700 (4778) - 71
Holley 650 (4777) - 69
Rochester Q-Jet (xxxx) - 67 (small one)
Holley 600 (1850) - 65
MotorCraft 4300 (xxxx) - 61 (OWA4-S)
Barry Grant 625 (xxxx) - 61 (Road Demon)
Edelbrock 600 (1405) - 61
Carter AFB (4664) - 57
MotorCraft (4350) - 57
---------------
(4) MORE POSTS ON PAGE 2 -> BUT NOT ON WAYBACK MACHINE !
-------------------