Setting Up Weber 45's

[Guest etimolod]

Hey

 

I was wondering if any one could help me? i've having trouble setting up my weber 45 carbs on my Mi16 engine and i don't have much experience with these carbs.

 

To paint a quick picture of what i have (will add photo later), these are weber 45's 152 bought second hand from another mi16 engine. I've just serviced and cleaned them with a service kit from weber. I'm running them using the mi16 engine management system and openning the TPS to max position. I've got an in line fuel pressure gauge, setting the fuel pressure to 3.5psi.

 

The first good point is that the engine starts and the engine runs. But the engine runs like a dog (sounding like it's only running on a couple of cylinders) and spiting back through the carbs. This should mean the mixture screw needs adjusting to make the mixture richer, correct?

 

I've followed a couple of guides on the Internet, saying to wind in the mixture screw to it hits the stop and then start to winding it out again 1/4 of a turn until the engine runs better. This seems to have no affect to my engine but to increase the revs (still sounding like a tractor and spitting back through the carbs). Can anyone help? Does anyone know the rough jet sizes these carbs should have for the mi16 engine?

 

Should i do one carb or one barrel at a time? I've read somewhere that you should take the HT leads off two of the cylinders and tune one carb at a time. Is this a good way of doing it?

 

Any help is much appreciated!

[sideways danny 0]

as you're in Bristol, the best thing you'll do to setup webers properly is call mech motorsport in Cheltenham and have a full setup done on the rollers

[mfield 20]

I would wind them all down untill they are very lightly nipped and then turn them all 2 1/2 turns out, I wouldn't worry to much about the jets at the mo because it's running on idle not mains. After all the mixture srews are the same I'd check the balance with a synchrometer or by taking the progression hole caps off to see where the butterflys are sat in relation to each carb.

[skinner2k3 3]

Deffinately sounds balance related to me. Do you have access to a syncronometer?

 

Just had mine on the RR in Castle Combe, they did a great job not far from you either.

Edited June 10, 2010 by skinner2k3

[MrG 3]

get them set up properly on an RR, money well spent IMO.

[mfield 20]

get them set up properly on an RR, money well spent IMO.

 

That's very true but you don't need to do that just to get them running ? surely if they came off a mi16 is a similar state of tune the jetting will be close enough before fine tunning on a rr.

[woodsy 0]

I bought a carb synrometer from tweeks only cheap for doing my mi16 ones and its dead easy to balance them with it.As said screw mixture in then back out around 2 turns and then balance them as sounds like they are way out of balance.Mine used to sound like a subaru when they where out

[MrG 3]

That's very true but you don't need to do that just to get them running ? surely if they came off a mi16 is a similar state of tune the jetting will be close enough before fine tunning on a rr.

 

very true they should be.

[Guest etimolod]

Cheers for advice. I never saw the carbs on the other car so i’m not 100% sure that they have the right jets.

 

I've got a gunson carb balancer which should do the trick on balancing them. Does everyone’s carbs run badly when the engine is cold?

 

Hopeful i can get the car running enough to drive it somewhere with a RR

[MrG 3]

mine has trouble in the first few minutes but once some heat is in they're fine.

[woodsy 0]

Mine runs fine from cold except tickover is low until its warmed up thats all.When setup properly theyre great.

[matyasg 0]

Mine runs fine from cold except tickover is low until its warmed up thats all.When setup properly theyre great.

Exactly the same with my setup. Even in -15 celsius.

[Guest etimolod]

I've sorted the carbs out and the car is running great (well, at the moment).

 

I solved the problems by starting again! I removed the carbs/inlet manifold, re-cleaned and took my time re-assembling everything, checking that it was done up correctly and no air leaks.

 

I found that i had done up one of the linkage bolts to much which caused the throttle plate to stick open very slightly. I also found that the float levels were very slightly different. Once these issues were fixed then i managed to set up the idle mixture after a little trial and error.

 

Just need to take it to a rolling road now to get it setup precisely. Cheers for the help, i’ll try and add some pictures soon.

 

Regards