TheSamba.com :: View topic - PIct 3 venturi removal and diameter suggestions.

Wed Aug 14, 2013 6:54 pm

I want to have my venturi opened up and detailed instructions or any pointers would be very appreciated on removing it. The throttle shaft has to come out and a plug as far as I know. Specifically, where is the plug and how should it be removed? How much force holds in the venturi? Is there anything that is out of the ordinary or common with a like repair?

Also it was recommended to me to go with a 28mm. I'm building a 1776 with 40 x 35 valves and most likely a CB 2228. Will a 28mm work with this combo?

Thanks in advance!

Wed Aug 14, 2013 7:11 pm

Yep, the throttle shaft needs to come out and plug removed. I sent mine to Blackline Racing to be be opened up to 28mm.

I'm not quite done yet - but real close. See the following thread.

http://www.thesamba.com/vw/forum/viewtopic.php?t=511245&start=20

On your build - why are you using a mild cam with big valves?

- Andrew in Austin, TX -

Thu Aug 15, 2013 7:45 am

Thanks for the reply on the message I sent you as well! Do I drill the plug out ,press or pull it out?

Reasons for a miild cam.
-Peak Rmp engine builds are not good for a reliable daily driver. A car with a broad torque peak will usually beat a peak hp car unless you abuse the peak hp car. Broad torque cars don't need a lot of gears and don't have to be shifted as much while casually driving.
- I don't plan on hitting rpms over 4800 and the lower end is going to be stock.
- I want decent length cam rams so the valve train does not get chewed up on a non race car. A cheap Chinese stock replacement cam will last for over a hundred thousand miles but a expensive mild cam last sometimes less than 20k. Why make your odds. worse if you don't want it or don't need it.
- The only reason I want a carb at all is to drive the car before I have a fuel injection system ready for it. Two carbs would be a step in the wrong direction.
-I might use a dtronic system on the engine for a while. They won't work with an aggressive cam.

Reasons for the big valves.
-I need replacement heads and I want them to have a higher resale value and greater market appeal.

- You can get better breathing ability with the bigger valves without using a cam which idles rough and chews up the valve train. If you use bigger/short header primaries the engines rpm range with go up with the bigger valves but there will be some loss at lower rpms.

Thanks for the link to the thread! :D

Thu Aug 15, 2013 8:43 am

You would be best to put heads with stock size valves on this motor, with a little bit of porting work if you like. Buying big valve heads for the resale value later is a poor reason for putting them on this combo; it will seem to drive alright, but torque readings in the lower part of the rpm range will be down and mileage will suffer. Stock valve sizes will suit the combo much better, giving more power throughout the rpm range intended and will be more fun to drive on the street.

As usual, just my 2 1/2 cents (I'm Canadian, eh). Al

PS- I just looked at CB's cam list, and the 2228 is ground on 112' lobe centers, where most cams for naturally aspirated VW motors are ground on 106-108' lobe centers. 112' lobe centers are frequently used on turbocharged motors; I would speak with someone knowledgable (Pat Downs at CB?) before using that cam. Al

Sun Aug 18, 2013 8:19 pm

I just removed the venturi and wanted to post how I did it to.

1-Remove the air horn or whatever vw people call the top of the carb that covers the fuel bowl.

2-Remove the throttle shaft. Hit the shaft with a little heat if reasonable force does not loosen the plate screws. Remove plate first and then take off one or both nuts on throttle shaft and slide it out.

3-Remove plug that keeps venturi from sliding down. I used a piece of a wood broom handle that was about 4 inches long and placed that inside the venturi. I then placed a very small piece of wood on the plug/pin its self and used a screwdriver in between the two pieces of wood to pry the plug/pin out. Wrapping the screwdriver blade end with electrical tape or nothing at all would work too. It came out easy and actually flew across the room.

4-Remove venturi. I used a wooden dowel ;like the broom handle, and used that as a punch/drift on the venturi. The venturi does not have a lot of surface so angle the dowel pin on an angle so your putting force to the side as well as down. I heated mine up but I think it was stuck because of carbon. I had to give it a few solid taps with a medium ball peen hammer.

Here is a picture of the plug/pin removed. [img]http://www.thesamba.com/vw/forum/album_page.php?pic_id=1100506[/img]

Mon Aug 19, 2013 5:09 am

Well done. The wooden dowel doesn't leave marks.

- Andrew in Austin, TX -