mpk490p

Hi
i have a street ported 13b 4 port with a weber 45 sidedraft carb, the car made 150RWHP on the dino but it feels like it has more, question is do i look at the jetting on the weber i have or go 48IDA?
if i do stick with the 45 A) how do i check what jets i have and B) what would people recormend changing to

thanks all

Mark

trochoid

iTrader: (6)

Go with the 48.

mpk490p

Thats what im thinking to be honest (wish i had gone that way to start with!) do i need to go premix with the 48 as i still have the omp with the 45

Thanks
Mark

trochoid

iTrader: (6)

Depends on whether you make the rod to fit the 48 or not, your choice. Premix, in the long run gives better internal lubrication than the barbs on the intake.

680RWHP12A

13B needs at lest a 48 mm carb .. you can still premix too, but as trochoid stated premix is da best

killjoy7

iTrader: (6)

I have a 4 port, streetported 13B with a 48 IDA and It dynoed (with a high RPM missfire due to bad plug wires) at 168rwhp

go IDA

mpk490p

i have some details on the jets in my 45 at the mo, need to check the chokes but will update this when i do
60F9 Idle jet
165 air
F11 Emulsion
180 main

i want to try and re jet before going 48ida there is a lot of recormendations on the jetting for a 48ida can i use this set up in a 45DCOE?

thanks
Mark

680RWHP12A

try 200 air jets 200 fuel jets with a 40mm venturi

but, you really need a 48-51 ida to get the power out of your motor

mpk490p

thanks, i will get a 48 on there soon but jets are fairly inexpensive so it carn't hurt untill it arrives!
im no weber guru but i always though you should have a smaller air than fuel?

Mark

Kill No Cone

iTrader: (6)

Ok, if you have a 40 mm venturis in both the side draft and the IDA, won't they flow pretty much the same amount of air. Then you tune with the fuel jets?

mpk490p

this is kinda my point, ive read on Mazspeed's website that the following settings are the best for my engine with a 48IDA

Venturi 38mm

Main fuel jet #190

Air Jet #160

Emulsion Tube #F-11

these same jets and chokes can be put into a 45 so whats the difference? i dont know a great deal about these carbs but the only difference i can see is the intake manifold

Mark

Siraniko

iTrader: (13)

nope

680RWHP12A

+1
in an IDA i wouldnt use smaller than a 42mm venturi if you wanna make good power

Kill No Cone

iTrader: (6)

Wacky and 680 please tell us more.
Ok, so you would use larger venturis
But, if you used the same size venturis is there something that make the IDA so much stronger than a side draft?

Kill No Cone

iTrader: (6)

C'mon Wacky, share some secrets with us.

brandon davis

iTrader: (3)

Yes please. 680 and wacky!!!

mpk490p

pulled the chokes out and there were no markings but messured them and they are 40's
would i really see a big benifit from spending $750 on a 48 and manifold?

Mark

Siraniko

iTrader: (13)

Simple answer to a simple question. the specs he posted from mazspeed.coom are for track cars and doesnt apply to street cars. Less than 42" venturies will give you lots of low end but once you're on a open road (especially on a freeway), you are limited on how fast you want to go. Its like having a rev limiter. Try them specs against my cars and you will loose, I **** you not.

An IDA is an all-around type of carb. It will work on stock, streetport, bridge and p-port. Well for bridge and p-port, it needs to be modified to a 51. So what is the bottom line?

1. You only have to spend $$$ once.
2. Parts are easy to get (VW partshouses and such).
3. Easy to tune and has less parts than any other carb.
4. 51 IDA for BP and PP. My last conversion cost me less $200 to machine a 48 to a 51.

mpk490p

thats cool and i understand the 48 is a better all round carb, but will the same jetting and chokes produce the same results in a 48ida and a 45DCOE?

Thanks
Mark

680RWHP12A

nope

a 45mm carb has smaller throttle plates than a 48mm, a 51 carb even bigger, all the way up to a $1,500 62mm jay cee enterprize IDA style carb..



even if you have all the save jets and ventries the 48mm will flow more than the 45

mpk490p

Thanks
going to try the 200air and fuel jets for now and get a weber 48ida on my shopping list for the future

Mark

Kill No Cone

iTrader: (6)

Ok, I just got the whole racing setup with a 38mm venturi. The venturi size is limited by the racing class to a 38m, venturi. I was trying to figure out why in the heck you would only go to a 38 on the track and much bigger on the street. It is all becoming clearer now.

Kill No Cone

iTrader: (6)

Ok, I have been looking around...which scca classes limit the venturi size?

Hyper4mance2k

iTrader: (40)

I've never seen one... I think he was refering to a car that spent most of it's time in the middle of the power band instead of at the top. 38 to 40 you won't notice that big of a difference, but from 38-42mm chokes is a huge difference. In my old 45dcoe on a stock port se block I gained 4whp fron just changing from a 38mm to a 40mm choke, but that gain was at 6450 rpm. From 3000-4200 rpm the 38mm choke made from 5-9 whp more than the 40mm choke, but in every sercrumstance the 40 was better above 4200 rpm all the way up to redline of 7k. with the 38mm choke the car made between 135whp@5900 and peaked at 136 @6350 and didn't drop below 135 until 6650. so the car made 135 hp for 750 rpm. You can clearly see that the choke was starving the engine. where with the 40 it hit 135 at 5750 an dpraked at 140 at 6450 and didn't drop below 135 until 6700.
It basicly looked like this:

DriveFast7

iTrader: (1)

Road racing. e/p. Gt-3 used to but I think it's wide open choke size for carb and a weight penalty for fuel injection.