Bike Carbs Again I Know!

[Guest Larson250]

I was talking to an ex ford mechanic about my intentions to run ZX6r Carbs on my pinto the other day.

I explained how I was going to make my manifold and mount them etc.

 

When he suddenly went off on one talking about the different lengths of tube used on 1 and 4 cylinders as apposed to 2 and 3.

 

This would affect the ability to tune due to fuel pulsing and the distance to travel. I have to say from that moment I could see his lips moving but all I could hear was Blah Blah Blah...

 

He then asked me how I was going to prevent carb icing due to not having a heated manifold.

 

I changed the subject and he left shortly after.

 

Any comments on above problems?

 

Dean

[Andi]

An additive called pro fst

http://www.opieoils.co.uk/p-809-silkolene-...ol-engines.aspx

should do the trick for carb freeze, but it shouldnt be a problem unless your using the car in nasty freezing fog type weather, even then I wouold have thought the heat under the hood should compensate once warmed up (as opposed to bikes)

[Longboarder]

The length from valve to butterfly and valve to mouth of intake are both important in determining what HP a cylinder makes and the revs it makes it at. The engine will be smoothest if all four cylinders and inlets are identical. However in the real world small differences don't matter much. Some manufacturers have to have different induction lengths for different cylinders just to fit under the bonnet and just live with it. Some bike installations deliberately two pairs of different length trumpets. The two pairs of cylinders then make their torque at slightly different revs, thus lower total torque but over a wider rev range.

Icing under a Hood bonnet must be very rare! If it happens it should not be difficult to feed a bit of warm air into the intake to prevent it.

 

Nigel

[agent_zed]

When he suddenly went off on one talking about the different lengths of tube used on 1 and 4 cylinders as apposed to 2 and 3.

 

I may be completely wrong (wouldnt be the first time) but my understanding is that a standard manifold for, say, a pinto with a standard carb does have different lengths to each of the cylinders because the carb is mounted centrally. The 2 outer cylinders therefore get less fuel slightly in the grand scheme of things. This is partly why you will get more power with a set of webers/bike carbs as the manifold is of equal length to each cylinder and therefore the same amount of fuel and therefore gain a bit of power on the 2 outer pistons (although you will also get better fuel/air overall).

 

as i doubt you will be welding the bike carbs to a standard type manifold this shouldnt effect you and the mechanic is wrong

 

hopefully iam not talking rubbish

[Guest Larson250]

I may be completely wrong (wouldnt be the first time) but my understanding is that a standard manifold for, say, a pinto with a standard carb does have different lengths to each of the cylinders because the carb is mounted centrally. The 2 outer cylinders therefore get less fuel slightly in the grand scheme of things. This is partly why you will get more power with a set of webers/bike carbs as the manifold is of equal length to each cylinder and therefore the same amount of fuel and therefore gain a bit of power on the 2 outer pistons (although you will also get better fuel/air overall).

 

as i doubt you will be welding the bike carbs to a standard type manifold this shouldnt effect you and the mechanic is wrong

 

hopefully iam not talking rubbish

 

 

Thanks for the replies.

 

I am also of the opinion that the small difference in tube length would not cause any major problems.

 

As for the icing problem I don't have any vents in the bonnet yet as I have not got to that stage. I'm not sure whether I will need them or not. I think it will be a case of seeing what it does when it is eventually running.

 

Cheers for now,

 

Dean

[Guest cryoman]

Your bike carbs will NOT freeze up under the bonnet. Unless maybe you go for a long spin in siberia.

 

Nige