MG Sports Cars

Does anybody have a strong opinion on which carb to use?

Thanks,
Martyn

Great question... I hope lots of people chime in.

Larry Shimp has tried both, and he wrote a bit about it here.

Put on the Edelbrock and go driving.

Put on the Holley, go back to the parts store for all the do-dads you need to adjust it without spilling gas all over, back to the garage for more tuning, back to the parts store....

Granted, you might get 1 or 2 more HP with the Holley, when you get a chance to drive it....

Flame proof shorts on!

Hi Martyn,

If I was in your shoes, I would call Summit Racing's advice line and discuss your need with them. My understanding is that Holley has made some changes to their line of carburators. Some of these change are worthy modifications.

Jim is right by saying that if you go with Edelbrock "you put it on and just forget about it", however, Holley offers some adjustability for fine tuning that can help drivability. There's also the "Demon" by Barry Grant which looks just like a Holley and seems to perform quite well. The Edelbrock is a copy of the old Carter AFB which had a reputation of dependability and performance.

That you either call Summit or Jegs advice line, hopefully you'll get a mature advice technician and the beauty about buying from Summit (or Jegs, I prefer Summit) you can return your purchase if you're not satisfied.

My 2 cents

Not to change the question but Summit has there own carbs now, If i buy a new carb for anything I will give one of these a try. Lot of good features just not many options on sizes but I bet they have what you need.

As to your question I am not a fan of the Edelbrock, and the Holly if ordered correctly is just bolt on and drive as well.



Edited 1 time(s). Last edit at 11/26/2009 09:37PM by MGB SS.

I am now running a vacuum secondary Speed Demon 575 on my 302 and it is excellent (I put it on after the dyno session last June). It has annular boosters which cut in much earlier than the typical boosters on most other carbs. Jetting is more critical than with a Holley; even one jet size makes a difference. But once set up the throttle response is amazing. If you are interested, I can let you know how I set up my Demon.

The only other carb that has annular boosters is the Summit carb. I understand this is based on the Autolite (Ford) carb that was original eqipment on many 289's and early 302's. It has a reputation for being an excellent carb that is stable for many years (immune to dirt due to large fuel passages). I would recommend giving it a try but keep in mind that it is 1/4 inch higher than other carbs because it needs a spacer (included) to clear the power valve housing.

For hood clearance reasons I removed the choke plate from my carb. The plate hits the top of the air claener and causes fast idle problems. I left the electric choke module in place and use the fast ide function. This does about 80% of what the choke does and allows the engine to idle by itself almost right after start up; even in 20 wdegree eather. I use a 1 1/2 inch drop base K&N air cleaner base with a Mr. Gasket low-rider air cleaner lid. This allows a K&N 2 9/16 inch high filter element to be used with about 1/4 inch hood clearance. For holley carbs, it might be a good idea to cut down the choke tower to avoid an air restriction (but do not cut down the bowl vent tube!). The Demon has a smaller choke tower and I did not cut it.

Yes, great discussion and I am sure that it will be several valid opinions on the subject.
Harvey, first determine the type of use that the vehicle will see and what you want out of the engine.
A carter will give a false sense of driveability. the old saying,"Just put it on and go driving" Yes this is true. Now check the AFR (air fuel ratio) and you will see that is going to be close but not close enough.
Same with the Holley and Demon. I have all of them in different vehicles.
It is impossible to purchase a any carb and expected to be right one for your particular engine, all carbs need some tuning and changes to the AFR to produce the best results to that particular engine.

First mistake is purchasing a carb that is to big for your engine and then try to make it run with the correct AFR.
A street 302 ci engine with a 650 cfm carb is already a bit large but acceptable regardless of carb manufacture.

Holley carbs are the most popular carb due to the ease tuneability and response. Yes Holley carb takes a bit more work and the correct tools to do the work is not a mess. Great carb to tune at the drag strip. Same applies to the Demon and yes you can install different annular boosters to a specific set-up. Keep in mind that this will also gives a false sense of tuning. Just becasue is running smooth does not mean that the AFR is correct.

Carter/Edelbrock carbs are also tuneable. the myth is that they are easy to tune, "You just change the needles and that is is it" That is not true. Yes some small changes can be made with changing the needles, but then you will also need to change the jets and then you laso have the secondaries jets to adjust same as some Holleys. Then there is springs for the needles and idle etc it becomes a real test.

Keep in mind that not all engines are build the same, so the carb manufacure makes the best they can for the masses, one thing that helps is installing annular boosters to correct and to give a good feel due to the increase velocity of the mixture.

It is hard to advice anyone to whcih carb is the best for a particular set-up.
I can say what I have to give an idea.

Hot Rod ( sold it) had a small block Chevy 400 ci it ran with a 650 Holley vacuum secondaries for the street, 350 rwhp Had to change the secondary vacuun spring, change the metering secondary plate and jets 3 steps up.

MGB 3.4 525 CFM highly modified carb, had to drill the idle air bleeds and re-adjsut the secondary plate opening at idle plus other things. It ran great. Drove the B to TN in 2006 and got 26 mpg
It now has a special modifed Holley 650 set-up for centrifugal blower, no other carb works as good as the Holley for this set-up.

Jag MK II 3.8 Buick 10-1 compression and high lift cam. I am using an Edelbrock. Had to change jets, needles, springs and needle spring so that it accelarate smooth and with the correct AFR at crusising speed. This car is a cruiser.

MGB 2.8 Ford V6 I used a 390 cfm Holley with Webber plate in the primary to adjsut jets and air metering just like a webber. This was a most due to the manifold which it was a dual plane Offenhauser.

Yes manifold type will also determine which carb will work best and which boosters to use. Check with the manufacturer to see which carb they recommned using with their manifold.

Which ever carb you deicde to use, I would recommend buying a book for the particular carb. I would also recommend buying the correct kit for the particular carb you will be using. Also fnd someone who has an AFR meter or just buy one.
The one I would recommend is the LC1 by Innovate. This guage can be mounted on the dash or just use it as needed.
The gauge uses a heated sensor just like the ones used at the dyno. Then you can download the information into your lap top.

Gauge is $280 complete. Summitt has one with theri name, it the same as innovate and cheaper. It is also made by Innovated.
This is the only correct way to tune a carb. Another way is to read sparkplugs and a stop watch. Use the stop watch on a marked 100 yards until you get the best times and the correct color in the sparkplugs.
Do not forget your engine timing.

Well said Bill. If Martyn really wants to invest in something trouble free, I say go with E.F.I. as drivability, fuel economy and performance will make him forget about the money he had to spend on the system. If he buys a good system such as Edelbrock then he'll be able to record data and fine tune his engine himself without the expensive dyno tuners.

He'll also enjoy going through the mountains as the AFR will adjust itself for the higher altitude. I'm going to run the old dependable Ford EEC-IV on my 5.0 Liter with the aid of the "TWEECER RT" to change/trick some of the program tables. There is a new "Plug-And-Play" system out there and my understanding is the system learns after a few runs (cruise and hard). Beware althouh, a good after-market E.F.I. systems (engine management) is not cheap but it sure is "rewarding" to the one that demands the best behavior out of his "Prize Car" Once you've tried E.F.I. it's hard to go back with carburation.

The way the economy is, I wonder how I'll ever be able to finish my own car since it was being built with side work money (LOL).

Thanks so much to everybody for your invaluable input. I totally understand how in the end it comes down to a personal choice based on something somebody said that makes a personal connection....if you know what I mean. I really appreciate all the information and opinions that are being offered up here. I still have lots of time so no decision yet.
Cheers!

Hey Harv long time no talk. I had a new Holley and the first year or so and was great, after rejeting and installing new vacume springs, but the years after were never the same!! I went out and bought a new Eldebrook and it has never been better. Way less playing around do all the fine tuning crap.

Hey Harv long time no talk. I had a new Holley and the first year or so and was great, after rejeting and installing new vacume springs, but the years after were never the same!! I went out and bought a new Eldebrook and it has never been better. Way less playing around do all the fine tuning crap.