An old mate said i didn't have to change jets if carb on smaller motor than intended??

Was talking to my mates father, whose been a mechanic in the industry for 20 yrs. I trust him, but it seems to good to be tru. However, even the 'theory' behind it works.

IF i have a carb (or two) and use them on a motor whose overall capacity is less than that of what the carb was originally off or intended to be on, does that mean i don't have to change the jets? i just change the idle speed and idle mixture screw?

He was saying that the negative pressure created by the displacement, being varied between the different engines would only draw out what it needs, as long as the jet is large enough to reach the engines maximum thirst.

Sorry if it seems like a dumb question, i'm very much an efi boy. Although the lack of wiring in these carb motors do make them a favourite 😂

well for starters fuel 20yrs ago had a mega different octaine rating to todays for excuse for motion lotion
so my money is on getting someone who knows what they are doing to sort it out for you
there are plenty of peeps about on here and around who can nut this out
aircooled stuff is a different animal so needs extra speccy care
efi pleeeeeezzzzzeeeee

Thanks for the reply h!
These carbs are from a 1990 model renault :P

I will have to find a tuner for sure though like you said, i want it running 'perfect'...

back yard bogan jobbies don't seem to flash for precision. It just seemed like a 'curious' point.

If you have 2 carbs of the same capacity motor the jets can be different

Depends on cam, heads, valves - a HEAP of things

You change jets if it runs rich or lean

Mixture screws can compensate a lot
Mains i guess you have a little room for margin

Whack it on and see what happens

Thanks mate. 👍

If worst comes to worst, I can just rock up to any vw workshop pretty much?
or is carb tuning a whole different ball park?

They are still solex carbs. Was told different jets aren't available, but what they do is solder them up and redrill them?

Check this guys supplies

http://stores.ebay.com/ALFA1750S-CARBURETORS-PARTS-STORE

If he doesnt have them then no one does

Go the the Aircooled.net and read the articles on jetting

Fairly easy once you get the jist

You really dont want to pay for some one to learn to jet your carbs.
As i said - they can all be different.
Change - tune - drive - tune - change - round and round we go

Main thing is to be able to walk away from the car if you havent got it right

Yes - you can solder up and drill/ream.
Ream is better as it isnt as sharp on the edges.
Not the best practice but been done for ages