10 replies to this topic

[Almond-1]

Ok here we go. I am running a pair of split 40 DCOEs. They have been set up on a dyno. But I have an annoying bog down through the progression phase.

once past 3000 RPM it's ok (This was there whilst on the dyno).

I'm just wondering if this is due to the 310 degree cam. The engine will idle all day at approx 1000 rpm on the current 50F2 jets & plug colour is good.

I have tried richer & leaner jets but to no avail, different pump jets, leaner & richer, different emulsion tubes.

 

Now run out of ideas!

 

36mm chokes, F14 emulsion tubes, 160 main, 175 Air, 50bleed back, 4.5 Aux & 45 pump jets.

 

 

[Dusky]

we have the same setup 1330 split weber ( its a dcoe 45 though) Ill see what jets we have tomorrow. What did they see @ dyno? any mixture problems @ that rpm? Could maybe be faulting ignition or so..?
Cheers

[KernowCooper]

Look at the manufacture of the cam and see where they say the powerband is

[Almond-1]

I'll dig out the readings, but I know it was over 115bhp at 7500.
Kent cam & power band 4-8.5k. Possible, funny it's ok at 3500rpm though.

[KernowCooper]

Maybe coming on the cam at 3500rpm and lower its strugling

[Almond-1]

Could be, as everything is lightened & pulls ok when floored, just really annoying. All weber info states no problems at low revs even with race cams though.

[KernowCooper]

Its the cam manufacturer not weber who should make that statement though, If they say 4000rpm - whats the car used for ?

[Dusky]

68F5 STARTERJET

55F8 IDLEJET

Mainjet aircorrector (5)200

Mainjet : 130

F2 emulision tube mainjet 

 

Thats what I have in my word doc from a week or 2 ago when I dismanteled the carb

 

this is used on a 1330 with 310° camshaft , cooper S head and split 45 DCOE webers

 

cheers

Edited by Dusky, 13 June 2014 - 03:17 PM.

[Cooperman]

I don't know about split Webers with a 310 degree cam, but I built a rally 1071 'S' engine with a 649 cam and twin H4's and it would not run under any sort of throttle below 3300 rpm. Below that it threw neat fuel back out of the carb intakes.

I guess your set-up will be worse because the cam is 310 degrees which is more than a 649.

Just keep it 'on the cam' all the time and it'll be no issue. With the 1071 I kept it above around 4500 all the time on stages and on road sections it was always run at 3500 to 6000 rpm. The gearing needs to be low with a SC CR gear set. Maybe a 4.1:1 FDR would be right.

[Almond-1]

Cheers Guys, Still playing. Dusky, interesting the difference in main to air corrector. I tried F2 emulsion tubes, 130 mains & 170 air correctors as a on off a little better but basically the same. did you have any trouble under 4000rpm?.

[Dusky]

Cheers Guys, Still playing. Dusky, interesting the difference in main to air corrector. I tried F2 emulsion tubes, 130 mains & 170 air correctors as a on off a little better but basically the same. did you have any trouble under 4000rpm?.

Didn't really have problems under 4 K , driven it around very slowly at about 2.0-2.5K and it went quite well to be honest, but it really starts at 3-4K. But it isn't undrivable at all. A really experienced driver could take it in the town ( not for everyday though).

But that will be bottom limit I think...

Powercurve in excel file. It has improved a bit with these jets and some minor mods, but you get the idea.

 

Bhp is in blue, torque in red

Attached Files

•  mini Rollingroad theminiforum.xls   43K   10 downloads

Edited by Dusky, 16 June 2014 - 07:09 PM.