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88v8
Ivor Duarte
Gloucestershire UK
(472 posts)

Registered:
02/11/2010 04:29AM

Main British Car:
TR6 74 2.5 injection six

Which 4bbl
Posted by: 88v8
Date: June 05, 2017 02:51PM

Time to change the engine in my Lightweight Land Rover.
The well worn 3.5 RV8 will be retired and replaced by a younger sibling, which is standard other than a Piper 270 cam, not an ideal cam for a 2800lb car with an auto box but that's what's in there so I'll give it a try.

At the same time I plan to install a 4bbl on a JWR Offenhauser dual port manifold.
It is a Land Rover so torque is more important than top end, hence that choice of manifold.

I have two 4bbl options, acquired some years ago.
A Carter AFB 1404, and its Edelbrock descendant the 500cfm 9511.
The Carter comes with a manual choke which I would prefer, but that needn't be the deciding factor.
Both are pre-loved, but look pretty decent.

I have an overhaul kit for the Carter, it contains an alarming number of parts.

All things being equal, which of these carbs would you recommend that a 4bbl virgin should use?

Ivor


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5240 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Which 4bbl
Posted by: BlownMGB-V8
Date: June 05, 2017 11:45PM

Ivor, unless I'm mistaken both carbs are really very similar in that the Edelbrock is derived from the Carter and a near identical copy in many respects. However, the old AFB used a phenolic or plastic fuel bowl/body and in some cases that could lead to cracking and fuel leakage. For that reason alone the Carter is probably the safer choice.

The AFB had it's enthusiasts, and was especially popular with the MOPAR crowd.

Jim


DiDueColpi
Fred Key
West coast - Canada
(1198 posts)

Registered:
05/14/2010 03:06AM

Main British Car:
What if the Hokey Pokey really is what it's all about?

authors avatar
Re: Which 4bbl
Posted by: DiDueColpi
Date: June 06, 2017 02:13PM

To me the 1404 is probably your best bet Ivor.
It's got the manual choke that you want and you have a rebuild kit for it.
It is the simpler carb to tune out of the two as well.
Jim must have gotten into some of my Scotchy scotch.
The 1404 AFB (Aluminum Four Barrel) is an all aluminum carb so no phenolic issues.
The phenolic ones were the ThermoQuad carbs that were also an excellent carb when set up correctly.
The Edelbrock 9511 is an AVS carb (Air Valve Secondary) that was made for dual 4 installations.
It is an excellent carb that is more tune-able than the AFB but it is more complicated to set up.
At the end of the day they are both good choices.
The rebuilt kit is actually quite straight forward. It has enough parts to service a wide range of carbs. You will find that many of the pieces will be left over when you are done. Just match up old parts to new, follow the directions, keep it all clean and you're good to go.

Cheers
Fred

On a side note. The lovely Lynne and I will be in England some where around the 20th. We were planning to go to the Borough Market. How are things there now?

Thanks
Fred



Edited 1 time(s). Last edit at 06/06/2017 04:11PM by DiDueColpi.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5240 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Which 4bbl
Posted by: BlownMGB-V8
Date: June 06, 2017 10:49PM

Coulda been the Rye. Thanks Fred.

Jim


88v8
Ivor Duarte
Gloucestershire UK
(472 posts)

Registered:
02/11/2010 04:29AM

Main British Car:
TR6 74 2.5 injection six

Re: Which 4bbl
Posted by: 88v8
Date: June 07, 2017 04:42AM

Thsmkyou.
Glad you mentioned that there will be parts left over. My wife had a new hip yesterday - wonder if surgeons ever have that problem.

Haven't been glued to the Borough Market situation, but I heard people who work there saying that things are already getting back to normal. The George in Boro Market was pretty good back in the 90s when I worked across the rover, and I dare say still is.
[drinks.seriouseats.com]

I'll give the Carter a go. Although I love SUs, the pair on there has been giving me grief with not holding a mixture, ever since I bought the car. Could buy two new SUs and I already have a replacement manifold, but anyway.

I see there are a few people who keep parts for the Carter, needless to say none of them are over here.

Ivor


roverman
Art Gertz
Winchester, CA.
(2854 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Which 4bbl
Posted by: roverman
Date: June 08, 2017 04:33PM

Ivor, I'm not sure of the cfm. rating of the 1404, but 400 cfm should be adequate unless maybe high altitude or your hedging on HP ? The Edelbrock dual plane, will likely out-perform the Offy dual-port. Begs the question: What HP. at what co$t ? art.


DiDueColpi
Fred Key
West coast - Canada
(1198 posts)

Registered:
05/14/2010 03:06AM

Main British Car:
What if the Hokey Pokey really is what it's all about?

authors avatar
Re: Which 4bbl
Posted by: DiDueColpi
Date: June 08, 2017 11:16PM

SU's incapable of holding a tune.......whats the world coming to Ivor?

In all seriousness they would be the better off road choice. Their off idle throttle response is superior to any 4bbl, low speed torque is generally better, they have the ability to pass trash though the carb without plugging up and they work very well off level.
They do give up a little on full on HP but that's generally a manifold problem and not the carbs fault. (throw four of them on an engine to level the playing field and you'll see what I mean.)
Mixture wandering problems on SU's fall into three categories.
#1 and the most prevalent, but ignored problem is fuel level control. The needle and seat assy's are garbage. They are a steel on brass design (generally) that will leak faster than grandpa after his afternoon tipple. Convert them over to viton units from a nissan and enjoy the absence of fuel leakage.
#2 is ovaling of the fuel jet. Early SU's never had this problem but later ones with the sideloaded needles did. Way back when emissions became an issue. (as it should.) SU decided to make their carbs a little more idiot proof. Apparently the average mechanic of the day was incapable of centering a metering rod. Which is true, I've seen lots of it.
The fix was to spring load the metering rod to give it more forgiveness to the adjustments of less adept technicians of the time.
This worked well, the down side was that the side loaded metering rod now rubbed on the side of the fuel jet.
This caused the rod and the jet to wear every time that you moved the throttle. The fuel mix became increasingly richer every time you hit the gas. Kinda like an STD, it gets worse every time you touch it.
So, get a new fuel jet, grind off the little stud that offsets your metering rod, (this applies to strombergs as well) and live a long and happy stable life.
#3 is the most talked about and yet has the the least effect on the engine. this would be throttle bushing wear.
Worn bushings will affect your idle. Period!
Worn bushings will not allow the throttles to return to the same spot every time. And leak unmetered air causing mixture instability.
Once off idle the amount of unmetered air drawn through them amounts to nothing.
Kinda like fido peeing on the lawn in a rainstorm..... nobody noticed.
So like any other carb put in some new bushes, replace the shaft seals and idle on !

There's my misc. ramblings for the day.
Live like you mean it.
Fred



Dan Jones
Dan Jones
St. Louis, Missouri
(252 posts)

Registered:
07/21/2008 03:32PM

Main British Car:
1980 Triumph TR8 3.5L Rover V8

Re: Which 4bbl
Posted by: Dan Jones
Date: June 09, 2017 07:01PM

> The Edelbrock 9511 is an AVS carb (Air Valve Secondary) that was made for dual 4 installations.

Like the AFB, the AVS was originally a Carter design. Carter supplied AVS carbs to Chrylser and other car companies but never sold them as aftermarket carbs. They are very similar to the AFB on the primary side but, on the secondary side, they use an adjustable spring loaded secondary flap (AVS = Air Valve Secondary) and nozzles like a ThermoQuad. The AFB's non-adjustable weighted counter-balance. IIRC, the Edelbrock AVS design isn't a copy of the Carter AVS but is essentially an AFB with AVS flapper.

> Ivor, I'm not sure of the cfm. rating of the 1404, but 400 cfm should be adequate

In the United States, 1404 is an Edelbrock part number for the manual choke version of the 500 CFM AFB carb. In Europe, I believe they were marketed as Webers as Weber USA manufactured them for Edelbrock. The 400 CFM Carter AFBs were the 9400 and 9410 were only available from Carter as Edelbrock did not reproduce them. The 400 CFM AFBs are arguably a better carb than the 500 CFM Edelbrock AFBs.

Dan Jones


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