9 replies to this topic

[S pack]

Hi, as I mentioned in previous post, we are running 3 SU carb's on 186 LJ Torana. WE have a big starting issue with the SU carb's. Does anyone have similar issues?

 

 I have an E Type with 3 2inch SU carb's and I have no problems starting it.

 

Chris

Most likely to do with the balance or tune. Do you have the chokes operating for cold start conditions?
 

Edited by S pack, 09 July 2021 - 12:18 PM.

[LJ RB30]

Try choke on one only. 

Not my idea but its been done with success.

[caterham2]

Chris, I have 3 x 2" Su on my 202. They were ex E type Jag, 3 chokes set up on them etc. Always takes a little bit of work to start if been sitting around a while, I think related to fuel bowls drying out because of proximity of exhaust headers below.

An electric fuel pump with a reg at 2.5psi will help. What size carbs are they? My carbs are having to use the fast idle screw s as well as the air bypass idle screws to get an idle due to the spec of motor and camshaft I am running. Don't know what experience you may have with SU carbs , but, don't use the throttle when cranking with choke on as SU carbs lose choke action when you do that. 

[hanra]

Twin SU’s on my little red cute car. Both carbs are choked. Hasn’t started for over 6 months. Pulled the choke out the other day. Wound over 3 cranks and fired on 3 cylinders. Then cleared up onto 4. Then sat on the fast idle for a bit then back to 600rpm no worries.

Awesome carbys.

Edited by hanra, 10 July 2021 - 02:22 PM.

[hanra]

Yeah I always found the float height to be a fairly critical thing.

[rodomo]

Try choke on one only. 

Not my idea but its been done with success.

I pull down the middle jet and stick a clothes peg on it till it fires, a few revs then take the peg out.

[caterham2]

Thanks for reply to SU carbs. 

   I have worked with SU carbs since about 1970, the E Type I have was my fathers, be bought it in 1970 and been in the family ever since. I also had a business in central QLD as Jaguar specialist, I have had a bit to do with SU carbs.

  Caterham, I would have thought the 2 inch SU was to big for 202 but obviously you have them sorted. They are much better for tuning and balancing as well.

 

 I just put air flow meter on each carby and my wife cranked engine [ not started ] and checked air flow. First carby was 3 kg/h, 2nd 3.5 kg/h and 3rd carb 3 kg/h. I lifted dash pot while cranking and there was no evidence of fuel in jet. I'm wondering if float level is to low. Will look into it.

 

Chris

Chris, the car as I received it had a set of 1.75 SU carbs on it. The previous owner had touted the car around to a variety of brain surgeons spending lots of money on "tuning". When I bought the car I consulted Ian Tate who had built the motor  for this previous owner, and he told me what he had told him, that this particular combo needed bigger carbs. Ian just happened to have a set under the bench with a suitable manifold which he gave me to try. Frank Lowndes set up the tune/ needles etc after I had kitted the carbs to freshen them up, I still have them on the car 17 years later and never have to touch them tune wise. They work superbly on this motor which has one of Clive Cams " secret squirrel" cams in it plus Ians magic touch, which is a bit of a dog around town, but gets going rather nicely when you run it in a competition event etc. The car was in an earlier life a Group C race car and has been kept pretty  much in that spec ever since.