Twin 45DCOE's Venturi sizes????

[vibrating_Cake]

Rightt...

 

my engines been running rich for a while, and ive just popped through the spares in my shed and have found some little things (extra jets etc)

 

but the thing that caught my eye were the venturies...

 

on my 2.0 zetec i have 32mm venturis in the twin 45's... and i cant remember the jets but they run rather rich all the time.

 

but in the shed, i have some 36mm venturis, and some richer jets.

 

the thing is. the cam in the engine "comes on" at about 3000rpm, which is where the engine starts to pull like a train atm, but the torque kinda trailes off after about 4500rpm. but the power still stays (it goes faster the higher the rpm but it feels to pull more at the lower rpm's)

 

i was just wondering, would the 36mm chokes suit the engine better, and produce a faster car overall, sacrificing a little bit of torque lower down?

 

 

bearing in mind its a 2.0 zetec ported n polished (god knows what stage) tubular manifold to a 2" exhaust, twin boxed right to the back bumper.

 

unknow what cam is in it but it comes in quite agressivly at 3000rpm, can tell the difference in sound and power.

 

 

how hard is it to change the venturi's and do you think it'd be worth it... would the 32mm venturi's be restricting a bit of power higher up in the rev range... and would the 36mm venturi's be a bit of an overkill

 

 

oh yeah, rev limiter is at 6750rpm

[Fiesta Steve]

32mm on a 2 litre !!! It's no wonder it moves at all !!!

 

I use 40mm chokes on my little crossflow and they are not big enough !!!

 

You NEED 36mm chokes to get the best out of your engine, the 'porting' that has been done is a waste of time with 32's as the chokes are strangling the engine.

 

They are the reason it pulls well low down, nice on a road car but useless on track as the revs will never be below 5k.

 

36mm chokes will unleash top end power without killing low down torque, they suit Crossflow's really well so should be excellent with 2 litres.

 

You can go up to 40mm but at this size you will lose 'drivability', and its time to switch to 48's.

[Fiesta Steve]

how hard is it to change the venturi's and do you think it'd be worth it... would the 32mm venturi's be restricting a bit of power higher up in the rev range... and would the 36mm venturi's be a bit of an overkill

 

Very easy to change the chokes, remove the trumpets and there are small bolts underneath that hold the chokes in.

 

Yes, 32mm chokes will be restricting power higher up the rev range.

 

No, 36mm would definatly not be overkill on a ported, cammed up 2 litre engine.

[vibrating_Cake]

i thought so!!!!!!!!!!

 

 

guess what im doing next week....

 

lol:D

 

so its just a case of whapping the carbies off the engine and pulling the trumpets out

 

TRUMPETS!!!! BRING ON THE TRUMPETS

 

 

sorry, got a bit excited there

 

 

then going on the underside of the carbies and removing the 2 bolts that are heald together by that metal sheet locking tab.

 

then just pull them out, is that all that holds them in???

 

and then just "push fit" the others and align the holes for that single bolt so the tip of the bolt goes into the hole and tighten em back up??

 

(how tight do these need to be?)

also, any ideas of the kinda jetting the engine should have with the bigger chokes, as i say my smaller chokes have jets in which are raather rich, nice coked up exhaust etc, any idea how to work out a ballpark figure of what i should be looking at?

[Fiesta Steve]

You can swap them without removing the carbs if you can get the trumpets off.

 

If I remember correctly it is only the bolts that hold them in, the aux vent sits in front and that will need pulling out first, again held in with a bolt underneath.

 

As for jetting its very difficult to guess, if you jettings wrong now then it could be closer with just a choke swap, I've gone up 2mm before without changing jetting and the fuelling was fine.

 

It needs to be set up on the rollers really m8

[vibrating_Cake]

yeah its goin for rollers in about 3 weeks anyways i just thought if i did that before we went out to get it rr'ded and got it near enough with the jetting, itll save on costs for them to change over the venturis which is a pain in the backside of a job seeing as though they are on the bottom of the carbies

 

and if they suit the engine better ill get better results than getting it rrded on 32mm venturis =)

[Fiesta Steve]

I'd just put the 36's in and take it as is, they'll sort it no problem if they know what they are doing.

 

Make sure you have no air leaks from your carbs as they won't be able to set it up accuratly if you have.

[escort21]

I just put 36mm chokes on my pinto after using 30s and rejetted it and it foooooking flys now

[vibrating_Cake]

ahhh ahh ahh ahh BUMP

 

 

(aka choooo)