Weber Downdraft 38/38

[tylerrice]

Hi I'm looking at a Weber Downdraft 38/38 for a 4K Corolla Engine... How will it run on that?

 

Thanks for the info and help guys. this forum and the people on it have been excellent...

Edited November 6, 2009 by tylerrice

[Felix]

Hi I'm looking at a Webber Downdraft 38/38 for a 4K Corolla Engine... How will it run on that?

 

Like shit.

[tylerrice]

elaborate please, i read that for a stock engine its good and for a engine that is getting modified small bits at a time its perfect.

 

and i will be running stock for a bit then adding as i go...

[Felix]

Don't know where you read that. That carb would suit a worked 2L motor nicely. A stock 4k is only 1.3L, and until you add extractors, exhaust and a cam you are wasting your time fitting a larger carb.

 

Do yourself a favour. Google "engine cfm calculator". Find a calculator, enter in your engine specs and find out the CFM requirements for a stock 1300cc 4k revving to 6500 rpm.

 

Then go and google "weber 38/38 dgas cfm".

 

When you've done that come back and report on how many cfm a stock 4k needs, and how many cfm a weber 38/38 dgas can deliver.

[never]

Like shit.

what he means is that it's too big and therefore will go like shot. Do a search of the FAQ or forum for suitable carbs

[tylerrice]

weber 38/38 dgas: 300 cfm

Stock 4k Engine: 207 cfm

 

Thats what i found but caus i have no idea could be very wrong...

[Felix]

weber 38/38 dgas: 300 cfm

Stock 4k Engine: 207 cfm

 

Thats what i found but caus i have no idea could be very wrong...

 

 

I actually got 124 CFM for the stock 4k at 83% volumetric efficiency.

 

Right on for the carb.

 

Ok, I'll make you think again (well not to hard, it is an easy question). Do you think having a carb that is over twice the CFM capacity of the motors requirement is a good thing?

[tylerrice]

not a good thing at all, what if you get it jetted down? is that the right thing? sorry guys i know I must be so annoying but I'm reading and slowly learning these things..

 

Relises jetting it down wont fix anything... what could?

Edited November 6, 2009 by tylerrice

[Toy-Yoda[RL]]

To put it bluntly, a smaller carby......

 

A 32/36 is about as big as you'd want to go on a 4K......

 

A 32/32 is considered by many as ideal.

 

As I understand it, it has something to do with air velocity and fuel vaporization, but I'm unsure of specifics.

 

In short, the 38/38 will make the engine run like a dog, and there are many more viable options available to you.

 

*edit* Regardless of the carby you choose, you will likely need to re-jet it to suit the motor if it hasn't been already.

 

Google will provide the bulk of the answers to anything mechanical, all you need is a little patience...... Kgo.

Edited November 6, 2009 by Toy-Yoda

[tylerrice]

thanks for the help guys, So Ideal Carby's to get are: Weber 32/32, Weber 32/36 re-jetted down, Twin SU HS4's, Twin Asia (corolla) sidedraught. Could someone please lead me to what would be the best Carby to go for... Thanks everyone for your help.

Edited November 8, 2009 by tylerrice

[philbey]

Twin SU's will need engine work to get the gains out of them, I think you'll have trouble with them on a stock motor. Best you run with a Cam and some extractors at least.

[tylerrice]

ok cool and what about the others?

[Raven]

a twin down-draught 3K-B setup would be suitable. Wouldnt be ideal but would work with a few small mods down the track.

 

I've got a set on my 5K.

[tylerrice]

so thats the stock asian things?

[Taz_Rx]

correct