Fuel Regulator Question

[Simon H]

Sorry for what may be a silly question but I need to check that I have set my fuel pressure regulator correctly. The Weber carb I have on my car requires a fuel pressuree of 5.5 psi (6 psi maximum). When I installed it I used the gauge supplied with the filter king regulator. I adjusted the pressure when the engine was on, running at idle. Is that correct? or should this be set when the engine is off?. Does the engine have to be hot or would this make no difference. Any advice on the correct proceedure would be most appreciated.

Regards

SImon

[Jim c]

Simon I have set them hot and cold it doesnt seem to make that much difference.
Set it with the engine running.

Jim

[Simon H]

Thanks Jim

I am going to have another go this evening and check I have set the pressure right. I don't know just how accurate these filter king pressure gauges are but they can't be that far out. My car is misfiring a bit and I think the pressure is somewhat low, making it run rather lean. Hopefully adjusting the regulator will sort it out.

Regards

Simon

[David Briggs]

What type of fuel pumps are you using? Webers like lower fuel pressure(3 lbs) but high volume. Are your carbs new? Jetted correctly? Float level correct?
If you have a miss it may be electrical and not carb related.

[Simon H]

Hi David

My car is using a Facet Red Top fuel pump and a Weber (or Edelbrock) 500 carb. The pump has a reasonably high capcity and can supply more than the 5.5 - 6 psi pressure required. I checked it last night and it still seems to be pushing out the correct amount. The carb was bought new and jetted / set up by the company I got it from. My next step will now have to be checking the internals for a blockage and the float level setting as you have suggested.

I have got new spark plugs, ignition coil, HT leads, rotor arm etc.etc. but there may still be an electrical issue I have missed I suppose. I will check the carb set up out and see what happens. If this does not work it must be an electrical problem causing this intermittent misfire.

Regards

Simon

[Russ Noble]

Simon,

I doubt that it's the carb itself. My experience with these 500 Edelbrocks is that if they are getting insufficient fuel, usually at WOT, then they just lose power and die with no misfire. Certainly these carbs seem to tolerate less than ideal jetting without too much complaint. Unless the carb has been tampered with I don't think that will be causing the misfire.

Did you ever get it running properly after your heat soak problems? Or have we got an ongoing saga here?

Under what circumstances do you get the misfire? And what sort of misfire is it?

Cheers

[Jim c]

[quote=Simon H]Hi David

The carb was bought new and jetted / set up by the company I got it from.

Simon

Question 1
have you just fitted this carby.
If so go to question 2

Question 2
was the miss there before you fitted the carby.

The carby has been on the engine for some time and the miss just developed.

Does it miss at idle or just under load.
Does it miss at idle but seems to get better as the revs go up.
Or does it just loose one cylinder now and then.
Or do you think it is loosing more than one cylinder.

Give some more info it may help.

Jim

[Trevor Booth]

Simon,
Dont take your gaige for granted that it is accurate.
Connect a long piece of clear plastic tubing to the pump and then hook it up to the ceiling or something else to hold it near vertical. the open end of the tube will need to be about 10 feet above the pump, turn the pump on and measure the height of the fuel level(in the tube). the height in feet x 0.434=psi You can mount the tube on a piece of wood with graduations marked it is easier

[Simon H]

Thanks for the responses guys,

Russ, you are quite right about the about the slight lack of power on WOT. My car is also showing signs of this so it would point to a lack of fuel getting through. I purchased a thermal barrier for the carb and this has indeed cured the problem of heat transfer from the manifold to the carb. I found it odd that on the Edelbrock packaging it stated that the thermal gasket was "not for road use!". Why I don't know, it sorted out the problem though.
The misfire is intermittent and seems to be more evident when the engine is cold, and put under load. However, then it can also happen when it is warm and just going along at cruising speed. Weird, and I have tried to check all of the usual causes.

Jim,

The carb was new and fitted a few months back. The misfire has always been there but has got worse in the last few weeks. It does get worse when the car is under load and in the lower rev range. If you put your foot hard down it does seem to power through it.

Trevor,

I think you may be right about the pressure gauge not being spot on. I have just had a go with another one and the reading is different again.

I have reset the pressure once more and installed another rotor arm on the distributor. The last one was not a genuine Land Rover part and I know the copies can sometimes be troublesome. I am just going to go outside and take her for a test drive. (I really should be working, but thats the advantage of being self employed!!)

Thanks for the help once again guys and I will let you know if this makes any difference.

Regards

Simon

[Ian Anderson]

I read somewhere that you should route the spark wires for 3&5 apart as running them next to each other can cause crossfiring on the Rover engine

So if you are running the 4 wire separators run No 7 between the other 2


Ian

[Ian Anderson]

The Landrover also has 2 distributor caps and Rotors - look similar but have a slight height difference. The Rotors will work for a short time then cause misfiring - need to get original matched set - even need to query the parts bloke and he he does not know the 2 sizes find another outlet!

Ian

[Simon H]

Well, just got back from going for a spin and.....NO MISFIRE!!!. The re-adjustment I did on the regulator or the rotor arm must have done it. I am keeping my fingers crossed but I really need to do a few more miles to be sure.

The pressure was at down at 4 psi when I checked it this afternoon so it was a fair bit out. I also adjusted the Weber a little bit richer. I have to say being a single carb it is quite easy to adjust the air/fuel mixture. I hate working on carbs!. I don't know how you guys get on with four of them to set up, it must be a nightmare. I think the worst car I have for that was a Dax Cobra with a Jag V12 and six carbs (see below!). It was way out of my league to set up. I did not have that one very long as it ran awfully.

I hope that my journey home tonight will be missfire free. That would give me plenty of smiles per gallon!

Simon

[Simon H]

Cheers Ian

That I did not know about. I will go and check to make sure the HT leads are spaced correctly. I was going get the rotor arm from our local Land Rover dealer on the Isle of Wight, but they don't keep rotor arms in stock!!!, can you believe it!. In the end I got one from a TVR dealer who had an orginal Lucus part in stock for my Chimera engine.

BTW, hows is the Dax going? Have you rectified the gearbox and driveshaft issues you had?. I know that I had to do some serious leak plugging on my Renualt 21 gearbox and driveshaf adapters!. No leaks now though so it was worth it.

Simon

[Ian Anderson]

Simon
I got the gearbox oil leak fixed - it was the electronic speed sensor was bunged and not properly plugged - leaked out dripped on drive shaft and the rotation puts oil everywhere. - So simple yet so long to find the problem.

Tomorrow the car goes into another EFI workshop to see if they can read the chips in my chipped ECU and get the basics in shape before letting the ECU do it's job. Real pain as I finally found a crowd that did have the EFi / ECU tools but when plugged in they could not read the ECU chips -back to square one.

If it don't work in the next couple of days I'm going for the Webber500 carb set up - at least that can be "fixed" by most garages!

It could be worth your while visiting V8 Owners Forum as they have loads of Rover V8 Gurus there - search function also works fairly well

cheers
ian

[Simon H]

Hi Ian

Glad to hear you managed to get your leak problem rectified. I have had some limited experience with ECU chips when I had my Nissan 300zx done years ago. I had a Uni-Chip installed and it did take a considerable amount of time setting up correctly on a rolling road. If you don't get any joy sorting your ECU out it may be worth contacting some of the TVR specialists like ACT performance of TVR Power. I know some of them deal with ECU mapping for Rover V8 engined Chimeras, Griffs etc. May be able to help you or advise on the best way forward. If you find that you need a new ECU also try Bellhill Garage who I bought my engine from. They break TVR's for spares and I am sure they would have various ECU's for sale.

When I bought my 4.5 Chimera engine from them I did have all the ECU, Injection set up and wiring. I was debating the pro's and cons of Injection versus a carb set up. In the end I went for a Weber 500 from RPI Engineering. If you speak to Chris there he would be able to advise and anwer any questions you may have. The kit I bought came with everything you need to change over from your existing set up. I had it all installed within a couple of hours and it started first turn of the key.

If you are going to go this route make sure you get an inch thick thermal gasket. This will save you from having boiling fuel in the carb as I did!. You will find there is two inlet manifolds to chose from. The JWR offenhauser manifold (that is lower in height) or an Edelbrock performance manifold. The Edelbrock is supposed to give slightly increased performance but RPI said they have never noticed any difference. I went for the JWR as height space is a bit resticted in the back of our cars!

During a moment of half witted incompetance I also managed to fit the carb the round way round (a common mistake according to RPI). The engine still ran but for anyone who is going to fit one the Edelbrock sticker on the carb should face the distributor. I really should read instruction more carefully!!. If I can be of any help Ian please let me know.

Regards

Simon

BTW. The pictures show my carb the wrong way round!!!!I kept them to remind myself that i'm not so perfect!

[Russ Noble]

OK. I'll ask the dumbarse question! What is wrong with fitting the carb back to front?

Where the floats are symmetrically positioned in relation to the middle of the carb, I wouldn't have thought that would make any significant difference?

Obviously with a single or twin choke carb the float chamber is usually to the front and this provides a degree of mixture enrichment under acceleration or uphill and leans out in the reverse situation.

As a matter of interest I had planned on mounting my BG 825 RS Race Demon back to front just to simplify the throttle linkage.

Anyone got any good reasons why I shouldn't? Jac Mac?

Cheers

[Jac Mac]

Originally Posted by Russ Noble

OK. I'll ask the dumbarse question! What is wrong with fitting the carb back to front?

Where the floats are symmetrically positioned in relation to the middle of the carb, I wouldn't have thought that would make any significant difference?

Obviously with a single or twin choke carb the float chamber is usually to the front and this provides a degree of mixture enrichment under acceleration or uphill and leans out in the reverse situation.

As a matter of interest I had planned on mounting my BG 825 RS Race Demon back to front just to simplify the throttle linkage.

Anyone got any good reasons why I shouldn't? Jac Mac?

Cheers

Hey Russ, are you ready for this!! In your application with the manifold you intend to use it will be OK--- provided you fit the the rear float bowl assy to the other end and vice versa along with jet extensions if fitted. This is due to the front rear bowls being configured to different fuel levels.
In the edelbrock carb above I think it will have larger secondary bores which could foul on the manifold @full throttle. Also as the floats are hinged at the rear (from memory) & would now be changed to front hinge in this application ,fuel level characteristics may be a problem. Like most things in life you wont know if you dont try.

Jac Mac

[Russ Noble]

Thanks Jac Mac, you're a mine of information!

Cheers