The V8 Owners Forum -

Hi!
I've got a 4.8L engine built by V8Developments which I use in my Westfield on trackdays. Currently it is fitted with an Weber/Edelbrock 600cfm carb, which does not work very well on track, as the engine misfires in corners and under hard braking. I've been told that a Holley with center hung floats should work a lot better.
I have found one 0-4776 which I think would do the job.
However I am also considering upgrading to a bike carb setup from Bogg Brothers. Do any of you know/have experience with what would work best on track?

A bike carb setup would cost me a bit more than the Holley but hopefully it would make the car run a bit better as well(the engine runs a Kent M 248 camshaft which is somewhat "hot", resulting in slightly lumpy idle).

Upgrading to ITB's and injection would be the prefered/optimal solution
but does involve quite a bit of cost, given that the car is setup for carbs at the moment.

I know people who use an Edelbrock carbs in track day cars without any problems.

Firstly I would check that the float heights are set up correctly, and then ensure that you are getting the correct 5.5 psi fuel pressure to the carb.

The Edelbrock carb should work fine on track but it may be posssible that the 600 is a little large for your engine and the 500 spec may work better.

I'm not sure but it may be possible to change the 600's primary venturi's for 500 ones which would save the cost of a whole new carb, an e-mail to Edelbrock should get you an answer.

Kevin.

Hi!
Would a slightly oversized carb cause these kind of problems?
I've been in touch with Edelbrock and they adviced me to block the "balancing" channel inside the carb to avoid having all the fuel going to one side of the carb, which I have done.
I have also have the extra "off road" springs fitted just to check.
The float heights and fuel pressure have just been checked and should be ok, but after all this the engine still misfires/stops on the track Thats, why I am looking for alternatives

Tor

CastleMGBV8 wrote:I know people who use an Edelbrock carbs in track day cars without any problems.

Firstly I would check that the float heights are set up correctly, and then ensure that you are getting the correct 5.5 psi fuel pressure to the carb.

The Edelbrock carb should work fine on track but it may be posssible that the 600 is a little large for your engine and the 500 spec may work better.

I'm not sure but it may be possible to change the 600's primary venturi's for 500 ones which would save the cost of a whole new carb, an e-mail to Edelbrock should get you an answer.

Kevin.

I'd say 600 was too big tbh. Not had any experience of bigger rovers or track cars but I have heard of people saying on here that 500 edelbrock is fine for all rovers except for completely insane engines.

I'm probably wrong though.

Tor,

All I can say is that the carb should not be giving those problems if properly set up and calibrated.

What rods, jets and step up springs have you got, for example say you had the wrong step up springs and this was allowing the carb to go rich on a light or trailing throttle such as when entering a corner this could cause the symptoms you are describing.

You haven't by any chance removed the flap over the primary chokes have you?

Kevin.

Hi Tor,

I run a 600 cfm on my 4.6 & even with heavy braking into a corner & then powering out sideways it runs smoothly. I would check out Kevins suggestions before you discard this carb.

Ged.

ged wrote:Hi Tor,

I run a 600 cfm on my 4.6 & even with heavy braking into a corner & then powering out sideways it runs smoothly. I would check out Kevins suggestions before you discard this carb.

Ged.

lol. I was thinking about building a five litre and was wondering about whether to keep my 500 get a 600 and from what I saw on here the 500 and 600 are the same but with different venturis so it should be fairly cheap to convert the carb to 500 if needed but as you say, if yours runs fine I'm probably mistaken.

You have probably thought about this, but is the carb level?

Hi Tor,

Yes the carb is level.

Ged.

Ok. I've been told that the problem with the edelbrock carb for track use is that the float's are not centerhinged.
The car is not with me at the moment, but I have asked my father to pick the carb apart to check the setup we are running(it's been a little while since we played around witht rods,jets and springs). So I'll let you know the setup as soon as the carb has been opened.

One thing though, I have had no other problem with the carburation of the engine. It goes like stink in a straight line, and does not stop when I let go of the throttle pedal or brake moderately.

I have not removed the flap over the primary chokes or any other part from the carb

Cheers

Tor

CastleMGBV8 wrote:Tor,

All I can say is that the carb should not be giving those problems if properly set up and calibrated.

What rods, jets and step up springs have you got, for example say you had the wrong step up springs and this was allowing the carb to go rich on a light or trailing throttle such as when entering a corner this could cause the symptoms you are describing.

You haven't by any chance removed the flap over the primary chokes have you?

Kevin.

Sounds like it is possible to make it work then:)Do you use sticky tires?

Tor

ged wrote:Hi Tor,

I run a 600 cfm on my 4.6 & even with heavy braking into a corner & then powering out sideways it runs smoothly. I would check out Kevins suggestions before you discard this carb.

Ged.

Tor,

I think from what you said that rechecking the float height is where to be looking first.

Remove the air cleaner stud before taking off the top or you can damage the gasket.

Kevin.

I'll have a look at the float height this weekend
Here is the setup as far as my father could identify this afternoon
Secondary jets ,089
Metering jets , 095
Rods ,065 * ,047
Springs was not possible to identify from their colour

Cheers

Tor

CastleMGBV8 wrote:Tor,

I think from what you said that rechecking the float height is where to be looking first.

Remove the air cleaner stud before taking off the top or you can damage the gasket.

Kevin.

I had this exact same problem which is very frustrating and only happens on track when accelerating out of corners.
I was all ready to go down the injection route and then I found a Cure.

First of all remove the carb top and make another fuel inlet by drilling and tapping the opposite end. Tee the fuel pipe and have a double fuel entry to the carb.
Then Fit a High flow needle valve kit without filters.

This has transformed the car on track and I cant believe I suffered the problem for 7 years.

I dont think the double entry alone is enough but might be if you remove the small filters from the standard needle valves. High flow valves are cheap and available from the states.
This worked for me anyway.

I have tried the 600 carb on my 4.6, it made slightly less peak power but throttle response is MUCH better with the 500.

Im very pleased with my carburation and the only performance mods planned now are Merlin heads and maybe slightly larger dia exhaust.

Another mod worth considering is as I never needed to use the choke I removed the flap and spindle and also ground away the raised section that the flap sat on to ease flow into the carb.
Cheers
Mark

Cant remember the exact part number but these look the same
http://performanceparts.com/part.php?partID=53405

Mark

Great bit of info there, I have exactly the same problem since running on slicks with my car. Shall carry out the mods shortly!