Setting up a Webber 500

[Sidecarbod]

Hi Everybody,

I have recently purchased a pilgrim MkIII with a tuned RV8 3.5 installed and I am slightly concerned that the carb has just been bolted on and not specifically setup for the engine. Mods to the engine include V8 Development heads with big valves, a typhoon hurricane cam and an Edlebrock performer manifold. (I was told that it should be knocking out 250BHP but I doubt it).
My question is does anybody know someone with a rolling road near Camberley who will tune the carb if required. (Surrey Rolling Roads are happy to put the car on the dyno but won’t actually do any work on the carb and after reading the on-line manual I can see why!). The engine does seem to run OK after I messed about with the pilot screws, 2 ¼ turns out, but I hoping to find another 30 BHP from somewhere!.

Any help would be most appreciated.

[tony]

Hi and wellcome.

Do you know what sort of carb you are running, is it Edlebrock or Holley etc. You can get tuning kits for the Edlebrock with an assortment of jets, needles and springs etc.This may a good place to start.

Also what sort of RV8 is it, is it from a Rover SD1 , P60, range rover etc. as this will make a difference to expected output.

The SD1 motor is good for around 150bhp brand new so a cam and intake mod with big valve heads would see around 200bhp 210 at best, I doubt your making anwhere near 250bhp at the mo. unfortunately .

220 -230 from a 3.5 would be about the max in my opinion and you`ll probably be stressing the engine quite a bit at that.

How much bhp are you looking for, it may be best to consider an upgrade to 3.9 or 4.0 block,you`ll get a lot more torque and your heads should fit ok.

Sorry can`t be anymore help.

[Sidecarbod]

Hi Tony,

Thanks for the reply, the carb is an Edlebrock (webber 500), as to what the actual V8 is I don't know!! I'll get the engine numbers of it and try to find out.
(I think a chap called Mark Adams built it, it runs 9.75:1 compression).
The motor does have a nitrided crank and I don't rev it over 6K so hopefully it won't go BANG!
As to "how much BHP are you looking for".....I'm not sure, I just don't quite get the "grin factor" when I floor it at the moment.
Rather than swap the engine out I may keep the car for a year then sell it to build one with a 5.7 lump in it. (Although I've been told that there not much quicker due to the weight....I'll probably start a argument now!).

[wilf]

Sidecarbod - if you are not experiencing any of the typical signs of carbs needing re-setting (flat spots, hesitancy, blue/black smoke, wrong sparkplug colour, excessive consumption, etc.) then the carb is unlikely to be far out.
Whether it is "spot on" for max power (just on the rich side of stochiometric) does need a rolling road/exhaust gas analysis to check.

[tony]

Originally Posted by Sidecarbod

Hi Tony,

Rather than swap the engine out I may keep the car for a year then sell it to build one with a 5.7 lump in it. (Although I've been told that there not much quicker due to the weight....I'll probably start a argument now!).

Plenty of arguments on this forum .

I`ve built 2 AK`s, the first had an RV8 with a very similar spec to yours and although it was quick, it wasn`t fast by Cobra standards and you had to work the engine to get the best out of it.
I`ve just got my new one on the raod with Chevy 350 approx 400bhp and the difference is unbeleivable (and I`m only running the engine in at the mo` 3000rpm limit) . The torque from the 5.7 makes a huge difference and if you want the grin factor then keeping yours for a year and then building around a 5.7 engine may be your best bet.

What I would say is that driving the Cob with a Rv8 and then moving up to the Chevy gave me a good learning curve , you do have to treat these cars with respect or you can easily end up in serious trouble.

Tony.

[maxGD059]

SCB -can I use that for short (?).

I suspect your 3.5 will be overfuelled by a stock webber 500. I used to have a V8D 4.1 vitesse with the same carby & it needed tuning down a bit with weaker rods. However, don't be put off by the manual that comes with the carb. You can get a tuning kit for about 50 quid & it's easy/fun to do as the rods/jets are changed in minutes. Infact I think I have one somewhere in the garage......not quite sure where though.

However for the ultimate set-up, you need to go on a rolling road.

[Sidecarbod]

Guys....what can I say, thanks for all the advice!

The carb is not miles out as the plugs look OK and it only puffs a bit off black smoke as you floor it which I guess is the accelerator pump dumping neat fuel into the inlet.
You are right in that it goes OK once the revs are up, it just hasn't got the the low down grunt I was expecting. (maybe the cam is a bit top end-ish). I haven't actually got a manual for the carb, I've just read some stuff on the web about it.
If you find the tuning kit in your garage and it comes with some sort of manual maybe we can do a deal on it?

One idea I had which is probably nonsense is that I thoght that the 3.5 might not pull enough vacuum to open the secondaries fully (the pedal opens one both sets of butterflies but there is a vacuum controlled set above the secondaries....I was going to lock wire them open! what do you recon?).

I recon I'll put it on Surrey Rolling Road's dyno just to see whats what.
What do you recon its OK to rev the V8 to, sovereign cars sort of said 5k but they say that about the larger yank lumps.

As to SCB....I guess thats OK, as to "end up in serious trouble"...I used to race a formula one sidecar outfit...serious trouble was par-for-the course!!

Anyway thanks again!

I guess SCB for short is OK by me! As

[wilf]

SCB (that is going to stick now, isn't it?)

DONT wire open the secondaries. It won't run properly if you do. The "vac operated " set of butterflies above the mechanically opened ones automatically compensate the carb for the amount of air the engine wants, in effect.

Whilst the carb may be a bit "big" for a 3.5 RV8, it won't overfuel if it is set up right, but if you experience major bogging down when you floor it, the size of the carb could be the issue. It is a commonly - sold carb for Rover V8s, so can't be too far out.

What you want to see is 1.5" wg vacuum in the inlet manifold at WOT and high revs - any more and the carb is too small, any less, too big. The 1.5" wg is the vacuum needed for the carb to see a proper signal and meter fuel accordingly. If you wanted to, run a line to the "always on" vacuum port on the carb and back to a vac guage in the cockpit, and see what you get.

I suspect you will be moving up to a US V8 engined Cobra before too long. You may want to think twice about re-engining the Sumo - can be and has been done, but maybe not a 100% solution.

[Sidecarbod]

Hi Wilf,

I suspected wiring the secondaries open was a silly idea!

I've got a vacuum gauge so I'll definatley see what the vacuum is at WOT. (I'll get the missus to read the gauge, it 'll get her eyes of the road which might stop her moaning!).
I don't think I'll re-engine the sumo, these V8 lumps look far too heavy, I'm used to a Yamaha R1 bike engine....you can carry it around the garage!

One last thing, the engine number is 38A00305, do you know how I can find out what flavour of V8 it is?

Cheers, SCB!

[colinb]

well it seems i have only been a mamber 5 mins and all i do is ask questions but it is fun , well you have answered a question for me already because my 5.7 has the webber carb and i guess it is the 500, my sumo apparantly started life as a 3.5 and was changed last year so i wonder if the carb was changed over, in fact i have power loss at the top end and the beat seem to be more of a clap than a bang when you are pulling up the rev band although lower touque is fine. I have been confused with the fact webber is also a Elderbrock i thought they were different companies and carbs, they say the webber is easier to stay tuned as it relies on jets and emulsifing tubes rather than plungers and springs, anyway i havent really helped you but might make you feel better as there are two of us with a prob, i wonder if that box of tunning bits for the carb are about locally.
Colinb