4 barrel weber /edelbrock on 400 rover v8 & cats in a chim

[garagebench]

HI ,
I am seriously thinking of putting a weber/edelbrock 500cfm carb on a edelbrock performer inlet manifold on my 94 chim 400 with cat ,
Now i know some people will say you wont get through emissions ,

But has anyone actually tried it ?

Surely if it is set up right it will get through,
i just want to make it a simple car and do away with the ecu etc etc
i know i might be a bit down on power but not by much if at all

Anyone tried it and it did'nt work ?

[Chimjunkie]

The big advantage of EFI is the smoothness of the engine throughout the rev range. Dont hear of many TVR V8's being converted back. This is a step backwards IMO.

[GreenV8S]

I think the cat will only work properly if you keep it very close to lambda 1. Since it's most unlikely your carbs will achieve that, I don't think you can reply on the cat getting you through any emissions tests. Cat plus carbs has been done in the past, but I believe only by running the carbs in closed loop with an electronically controlled valve applying vacuum to the float chamber to fine-tune the mixture.

[garagebench]

Hi ,
yes thanks ,
But i know all this
has ANYONE
ACTUALLY DONE IT ?
at the end of the day its just a rover v8 with one carb
if i ditch the cats and set it up for the mot emissions
can anyone see any other problems
i know it wont be as smooth ,but i actually prefer it
just think it will be more reliable and simpler for less expense
also looks a lot better under the bonnet
thanks

[Chimjunkie]

Since you are new on here you may not be familiar with the search facility. A similar question was asked recently. See the link below:

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[pwd95]

A few of the Wedge boys have done it sucsessfully. Would have thought you'd need to take the cats out though. Emissions would be your only barrier, but if you had a set of MOT jets to install for that day to give you your emissions then I can't see a problem. Fit & forget IMHO. No more dodgy sensors, readings etc. Saw an MGB lapping Castle Coombe this year & last year at the 'Action Days' with a stage 3 4.6 on a Webber 500. It was lapping Combe in 1:19. Spoke to the owner about it & he was showing me the ins & outs. Very simple if your ok with the spanners. Go for it.

[Tvr Power]

garagebench said:

HI ,
I am seriously thinking of putting a weber/edelbrock 500cfm carb on a edelbrock performer inlet manifold on my 94 chim 400 with cat ,
Now i know some people will say you wont get through emissions ,

But has anyone actually tried it ?

Surely if it is set up right it will get through,
i just want to make it a simple car and do away with the ecu etc etc
i know i might be a bit down on power but not by much if at all

Anyone tried it and it did'nt work ?

Edelbrock will work perfect easy to tune and will make more power than than injection


Dom

[djc100]

I run a 4.0 RV8 in an M with a 4 barrel Edelbrock 500. With a Piper 285 cam and worked heads, tickover is lumpy (probably same for carb or injection) but no other flat spots.

It's a May 1975 reg. so no cats and emmissions are not a problem (visible smoke test!). However the car has lamba ports in the manifolds (for tuning only) and after setting up on a rolling road they said it would have passed 'normal' emmissions test.

As previous posts suggest, it seems more sensitive to timing rather than carb settings.

David

[heightswitch]

garagebench said:

Hi ,
yes thanks ,
But i know all this
has ANYONE
ACTUALLY DONE IT ?
at the end of the day its just a rover v8 with one carb
if i ditch the cats and set it up for the mot emissions
can anyone see any other problems
i know it wont be as smooth ,but i actually prefer it
just think it will be more reliable and simpler for less expense
also looks a lot better under the bonnet
thanks

Take the electronic ignition away and convert it to points and condensor as well??.

Drain and re-fill the sump with older mineral oil and while your at it replace the rubber seals on the rear crank beearing with the old rope type seal.

[dbv8]

Whats a 2nd hand Webber 500 and offy manifold etc worth these days?
Ive got a full set up sat on top of my 4 ltr in my SD1.

Got to admit it ran really well, with good power and mpg.
It was a massive improvement over the SUs and got rid of all the niggling faults i had when i ran the Vitesse injection. Simple but effective and tou can fit a nice nitrous plate under it very easliy. I have that too

[V8s ONLY]

Ive got this setup on a 4.6 RV8 in a Land Rover and im not that impressed.The injection systems Ive run on two Range Rovers was much smoother and much more economical and Ill bet much better on emmisions.

[GV]

garagebench said:

HI ,
I am seriously thinking of putting a weber/edelbrock 500cfm carb on a edelbrock performer inlet manifold on my 94 chim 400 with cat ,
Now i know some people will say you wont get through emissions ,

But has anyone actually tried it ?

Surely if it is set up right it will get through,
i just want to make it a simple car and do away with the ecu etc etc
i know i might be a bit down on power but not by much if at all

Anyone tried it and it did'nt work ?



I did it to my Wedge last year and have been driving it successfully ever since. It sailed throught the emissions test on the MOT. My car is a 3.5. As far as I'm concerned its probably the best mod going.

What I can tell you is that there is no loss of power although I upgraded my ignition to a mallory Unilite with a Hyfire 6AL Ignition Amplifier thrown in for good measure which made a significant improvement all round.

My reasons for doing it were the same as yours - in fact if I decide to jump to a Griff 5 ltr I would do the the same if the car needed some engine work.

The overall conversion will take a few hours - the hardest part for me was identfying which pieces of wiring were needed after the injection loom was taken out as it appeared on my car at least - some of the other electrics were connected to it.

Drop me a line and I will talk you through what you will need to do. There's a few people selling the carbs and manifolds so shop around for the best prices. I would even consider buying from the USA as their stuff sells much cheaper although you may have to pay the import duty and wait a while to get the stuff through customs..

The beauty of the mod is that you can fine tune the car so easily with slightly better MPG depending on what manifold you are using. I opted for the Offenhauser because it sat lower in the engine bay. The other thing you should notice is that your engine will run cooler as you will have no plenum storing all the heat plus the water will circulate quicker through the engine once the plumbing is reconfigured...

[B Oeuf]

We did it on our Griff 5.0. V8 Developments did the conversion as a last ditch attempt to cure the kangarooing.
The benefits were, smoother running, no kangarooing, better acceleration esp when the second choke opened up, less to go wrong (no AFM, ECU, Lambdas, loom etc)
On the negative side, we had to change the jets to get it through an emmissions test and I found it tricky to start although Mrs Egg didn't.
On the whole I found the mod suited the raw character of the car

[blitzracing]

The ECU cycles the mixture through a rich lean cycle to make the catalysts work. Basically it starves the catalyst of oxygen in the exhaust gas on part of the rich cycle so the catalyst rips a oxygen molicule from one of the oxide gasses, and makes them less nasty, and then on the lean part, it allows enough oxygen to allow any unburn fuel (the HC'S) to ignite in the catalyst and turn into water/ C02 etc. There are three pollutants that get reduced this way, hence a three way catalyst. Its not simply a case of running lambda 1 to get the catalyst to work, so in real terms its very difficult to get a carb to cycle like this, and there are very few (if any)production cars that have done this sucessfuly. You certainly wont do it with a stock Weber or Edelbrock.

Mark

[garagebench]

HI again ,
I have deciced to dump the cats,
Fit the carb and have a set of jets for mot as advised
And have it all set up on a rolling road
and have a simple car with less to go wrong
SEE YOU ON THE DRAGSTRIP!

thanks to all the positive posters

[Chimjunkie]

garagebench said:

HI again ,
I have deciced to dump the cats,
Fit the carb and have a set of jets for mot as advised
And have it all set up on a rolling road
and have a simple car with less to go wrong
SEE YOU ON THE DRAGSTRIP!

Good luck. Keep us posted on the outcome.

garagebench said:

thanks to all the positive posters

The forum would be a boring place without controversy and argument

[v8 racing]

garagebench said:

HI again ,
I have deciced to dump the cats,
Fit the carb and have a set of jets for mot as advised
And have it all set up on a rolling road
and have a simple car with less to go wrong
SEE YOU ON THE DRAGSTRIP!

thanks to all the positive posters

Dump the main cat and it never going to go through an mot regardless what jets you use or who sets it up, i would definetly leave the main cat in, or at least save it for mot time, the only other thing i will say is DEFINETLY invest in a thermol insulator between carb and manifold, the temps under a tiv bonnet are very high and can bring fuel evaraparation problems on start up when warm, I am still a massive fan of the old fasioned carbs and when set up correctly they will still produce the same peak torque and peak horsepower of injection, what you will loose however is fuel consumption.

[eliot]

The other issue with those carbs is they tend to slosh their fuel down the inlets when cornering or braking hard.
And if you did keep your cat a rich mixture poisons the cat. A weber out of the box is configured "rich as a pig" and you can get it down to "eye wateringly rich" with some tuning as for what edelbrock would consider "lean as a pencil" and what EFI's would call lambda - so good luck.

If you are only doing WOT runs down the drag strip - it doesn't really matter A carb or EFI will do an almost identical job.

I fitted a narrowband to a carb which was a real eye opener on how poorly they control the mixture for idle/part throttle. Suffice to say I've got an Edelbrock 600 and full jet kit sat in the loft doing nothing.

[garagebench]

elliot you bought the wrong size carb!

[eliot]

garagebench said:

elliot you bought the wrong size carb!

600 was on the 5.7 chebby - not a weedy rova.