45 weber conversion & jetting?

[FORZALANCIA]

Hi there i just finished builing my new engine & i am not sure wat jetting to use on the 45 weber, firstly i was running her with 170 mains and 160 aircorrectors, 32 chokes, but she is running way to rich & blowing smoke & wen i hit 4,000 rpm a huge cloud of smoke comes out & its like she is hitting a rev limiter any ideas??? have jetted her down to 160 mains but still have that stutter at 4,000 rpm? with stats as follows:

-2L

-ported polished

-match ported

-combustion chambers ground out

-312 duration inlet cam with 10.5mm lift with special valve springs & 1608 exhaust cam

-copper headgasket

-standard 8.9:1 compression

-1.4L sc 14 supecharger running ratio 1:1.32 i get 6 psi at 3,500 rpm havent taken her much further

-45 sidedraft weber

-fully cermic race clutch to hold the power

Thanks,

Antony

[Tom McGaffigan]

On a supercharged engine you want more duration on the exhaust cam compared with the intake, you have it the other way around. What are all the jets in the carb? Idle jets, emulsion tubes, accelerator pump jets. Has the carb been rebuilt recently? Float level checked? Brass or plastic float? The specs are different for the plastic float height versus the brass ones. Fuel pump pressure should be 3- 4 PSI
Tom McGaffigan :twisted:

[Hamish]

Sounds to me like it's 'over' jetted - by that I mean remember fuel is getting 'pulled' into the blower and engine :arrow: so you need smaller chokes :? emulsion tubes etc etc.

I had a look at a DCOE's specs waiting to be fitted to a VX engine (not done the DCOE myself, did the DCNF conversion though :twisted: ) and they were pretty close to what GC suggests in his book as a starting point on a VX with DCOE/DHLA conversion:

Emulsion tubes - F16

Needle valve - 200 (GC book says 210)

Chokes - 30 (GC book says 32/33, 32's might be suited to your engine)

Main Jet - 150

Air corrector - 175 (GC book says 180)

So all in a lot more restrictive than what you've got on the carb at the moment :!: Give these settings a try and see how you get on, but I'd think about choking it down a tad first before playing with your jetting.
I'm not sure I agree with Tom about duration, running an (I admit a different spec) engine with more inlet duration with a 130TC cam and standard exhaust cam I did OK :arrow: don't understand that one Tom, could you explain what you mean/the reasoning for more exhaust duration over inlet :?: