The V8 Owners Forum -

Hi all
Been at a show today and have been asked by a chap with a completely standard 3.5 about the best rod and spring set up for the Webber 500
Its sat in a super straight MG and I said that I would post on here and see if someone can give me the best option for him.
I'm sure this has been well covered before but too lazy to scroll through dozens of pages.
Someone help out a lazy Gelmonkey?
Please.

Thank you in advance.

cheers
P

Paul, An 86 jet in the primaries with a 67-55 rod setup would be a good starting point. 80 or 83 jets in the secondaries and test the car on WOT to see which is quickest over a measured distance would show which jets are most suited to the engine.

The springs are more of a fine tuning thing. keep stock orange ones or try a pair of the silver ones. I do have some silver ones if he would like to buy a pair.

I'm running 86 jets with 67-55 rods in my 4L stage 1 engine and to be honest, it's a little on the rich side. I have to admit that until Friday, there were 95s in the secondaries, and changing them to 83s has made a huge difference in driveability.

I have ordered some 68-57 rods as it is a little rich on cruise (13-13.5) and still rich on power, (10 - 10.5). So we'll see when they get here.

I am also setting up a cold air system (the induction roar is too much) so I believe that may richen it up even more.

I tried the ones RPI advised and the car just wouldn't drive at all, too lean by far.

The smaller engines seem to need the carb setup with richer settings in order for the carb to deliver the right ratio of fuel and air, I guess this could be because the smaller engine does not pull as much vacuum as the bigger lumps. In my experiance the air fuel ratio for all RV8 lumps when running an Eddy carb needs to be 14.5-15:1 on cruise, any leaner and the throttle reponse goes bad. For the above reasons you may also find that the secondaries still need to be quite large compared to the ones required for a 4.6 lump, the AFR figure required for WOT would be 12.8-13:1.

Oh one other thing, I've seen right old cockups with regards to the air filter lid being way too close to the top of the carb, the engine will never run right with the lid too close, mine is around 75mm from memory.

Hi guys
Thank you all so much for the responses.
At least now I can give this chap the info and try to get him sorted.
Pete I totally agree about the filter being too close to the top of the carb and his looks really close but I don't think he has that much clearance under his bonnet so he may be a little stuffed on that one.

Paul I think I have some silver springs here and also so some 6755 rods so can get him equipped I think from here but I will call you if not.

The poor chap has been totally ripped off by someone down in Cornwall who charged him £800 to supply and fit the carb and a Offy 360 fanimould.

Thanks again guys you are stars

cheers
P

gelmonkey wrote:The poor chap has been totally ripped off by someone down in Cornwall who charged him £800 to supply and fit the carb and a Offy 360 fanimould.

My carb and mani was bought from RPI (by the previous owner of the car) and cost nearly that 5 years ago. I take it that is rather pricey then?

Richard

"My carb and mani was bought from RPI (by the previous owner of the car) and cost nearly that 5 years ago. I take it that is rather pricey then? "

Hi
Ah those magic initials R P I . . . for RPI not particulally expensive, however. . . . for what was bought yes pretty pricey
He didn't happen to know Mr Lund did he ?
best regards
Mike

kiwicar wrote:"My carb and mani was bought from RPI (by the previous owner of the car) and cost nearly that 5 years ago. I take it that is rather pricey then? "

Hi
Ah those magic initials R P I . . . for RPI not particulally expensive, however. . . . for what was bought yes pretty pricey
He didn't happen to know Mr Lund did he ?
best regards
Mike

I am beginning to understand

Saying no more

Richard