2" SU carburettors

ChrisJC · Post by **ChrisJC** » Mon Oct 06, 2008 11:42 am

I've just acquired a pair of 2" SU's from a Daimler 6 cylinder (mid 70's)

Has anybody ever set up a pair of these on a 4.6 RV8?, if so, what needles are required?

(long shot I know!!)

Thanks,

Chris.

CastleMGBV8 · Post by **CastleMGBV8** » Mon Oct 06, 2008 3:24 pm

Chris,

I do know that it's been done and suggest you sign up to the MG Experience web site and do a search in the archives for MGBGTV8. and look under 2" SU's

There is a good section in the Des Hamill book and Speedpro also do a specific book on How to build and power tune SU carburetors.

Yuo will need to modify the inlet manifold to get any benefit from the bigger carbs which will mean removing the two air straiteners? and boring out to match the carbs.

The 4.6 even in standard form is going to be strangled by a pair of HIF6 1 3/4" carbs so you are really looking to regain lost power

Just checked and hardcastles book recommends AAB needles for the HD8 2" SU on the Rover V8

Kevin.

ChrisJC · Post by **ChrisJC** » Mon Oct 06, 2008 3:50 pm

Excellent - thanks. I have some of those books already!, I will have a good look through them and maybe buy the tuning SU's book.

Chris.

landrovernuts · Post by **landrovernuts** » Mon Oct 06, 2008 4:37 pm

I have done this on a standard but ported SU manifold. When the engine was up to temperature this set up worked very well and had good economy for a v8! I regularly got 19 MPG out of my Landrover, however being high geared helps.
You dont say what type of carbs you have, but you need HS8 type and not HD8 type as these will not work at the angles the carbs sit at on the standard manifold.
The needles I ran were BCG and while not perfect seemed the best I could get without modification. Make sure you fit a good fuel pump with a pressure regulator and a fuel return line.
The downside to this conversion was there was no choke and while in reality it always started without, it ran abit lumpy until it was warmed up as expected. Another downside was that the carb bottoms sat very close to the rocker cover tops, so much so that the rubber type rocker gaskets wouldn't fit. If I was to do this coversion again I would put bigger insulating blocks between the carbs and the inlet manifold as temperature caused a couple of headaches, but this would sort out the rocker cover clearance aswell but also may cause bonnet clearance issues. The only problem then would be getting a choke mechanism sorted which while fiddily is not out of the question.
I have to say the only reason I removed it was fuel injection. I am sure I can dig some photos out if you want.

Toby

ChrisJC · Post by **ChrisJC** » Tue Oct 07, 2008 7:36 am

I am sure I have the HS8's - the float bowl can be rotated such that it is horizontal (which I have done).

The lack of a choke did have me a bit worried. The Daimler had a solenoid which raised the tickover, so I could do something similar if it becomes an issue.

Interesting point about fouling the rocker covers, I'll have to watch out for that one. Presumably they foul on the float chamber as the carb body is higher than the HIF type that fit OK.

Thanks,

Chris.

landrovernuts · Post by **landrovernuts** » Tue Oct 07, 2008 11:17 am

Sounds like you do have the HS8 carbs as the HD8 are connected to the float chambers with a solid link.

The float chambers are close to the rocker covers, but not as close as the jets are. I would put 2 insulator blocks in as the temperature created some coughing when really hot which didn't seem to bother the HIF 44 carbs. Yes you are right you can rotate the float chambers to get the right angle when fitted on a v8 inlet manifold (all the bits you need are available at Burnlen or what ever they are called now) One of the chaps at burnlen was very interested in this conversion and I think were looking into developing this into a conversion, but he never phoned me back. I did also have a fast idle connected to mine, however for cold start you really need to lower the jets fractionally aswell to richen the mixture which should be to hard to do.

I would only consider this if the inlet manifold has been taken out to 2" at the carb mountings and that the manifold has been ported, otherwise I would stick with HIF 44's. I would consider this to be a much better option than a weber 500 or a holly (think that may cause a few riots in the ranks!)

ChrisJC · Post by **ChrisJC** » Tue Oct 07, 2008 12:13 pm

I have heard about either Webbers or Hollys causing a fire in a 4x4 application..... SU's will hopefully be better.

And yes I do plan to port the inlet manifold where it mates to the carbs as there's quite a step otherwise (well, 1/8th inch!)

Chris.