non-matching Weber 45 carbs

[bmwv8capri]

Just noticed the two dcoe 45's on my pinto-powered Westfield aren't a matching pair. They are jetted and choked identically however the one is stamped dcoe 45 152 and the other is a dcoe 45 152g. The difference seems to be that the 152 has three progression holes and the 152g has 4 progression holes. The 4 holes apparently gives a smoother progression from idle to main jets.

So wondering if the 2 I have ever work satisfactory enough to run smooth, get clean emissions and pass the IVA?

Or should i sell the 152 and get another matching 152g?

(posting this for a friend, not my Westfield unfortunately!)

[baggabones]

I it running okay at the moment?

[Bozwell]

the 152g was brought out for 16valve engines as they seemed more sensative to progression and needed the extra hole.

ideally the progressions needs to match for smoother running at light throttle.

[Rich]

I could be interested in one of the 45's if you decided to replace. I have a set of matched 40's but I'll assume they are too small for what you need?

[Copey]

To be honest it should be fine if they are both jetted and set up the same, guessing with twin 45s on a pinto its gonna have a fairly lairy cam so you won't notice the difference at low revs and at high revs the carbs will be fine

[Bozwell]

be fine flat out. drivability will be affected, maybe not enough to notice but it will be affected.

mismatching carbs isn't ideal and will be harder to set up leading to "weber carbs are (insert your own swear word)". also matched carbs may not have the correct progression holes anyway for the application thay are used on and will also be near impossible to set up.

iv'e tuned quite a few engines where iv'e modified progression holes or added some.

DCOE 9's i thought were the prefered carbs for old school Ford engines.

[usedabused]

Why not drill a fourth hole?

[Bozwell]

that will only work if the other three are matching between carbs and you get the fourth in the same place and the same size as the other.

you can't just randomly drill holes in the carbs without knowing what affect it has on the mixture. modifing the progression holes will mean an idle jet change. the idle jet has the main fuel feed in the bottom and an air bleed in the side. ie 50F8 and 50F6 has the same 0.5mm jet size but different size air bleeds which change the mixture at light throttle openings but hardly changes the mixture at idle. (the idle mixture screw also has a partial affect at light throttle openings so leaning with the screw will also partially lean progression)

the later carbs have an air bleed screw in the body which is NOT for balancing the idle. it is there to tune progression. it causes air to bypass the butterfly so as to lean the mixture at idle but will allow more fuel through progression at light throttle openings by allowing the mixture screw to be out further or run a larger jet.. it is another way to tune progression.

with the earlier carbs without an air bypass i have drilled a small hole in the centre of the butterfly to do the above. there is only a certain amount of tuning you can do with idle jets, the rest is with cunning modification of the carburettor

[bmwv8capri]

thanks Bozwell and others for the info, I know little about webers myself.
The car isn't IVA'd yet so there hasn't been much chance to test it out, although after some adjustment it runs well enough to get it down to the local rolling road