Heat Shield - Carb Springs

[wfl_colorado]

I have a 73 and am converting over to 72 SU's. I got the flat tops off the car, but noticed that there are not holes in the heat shield to connect the springs from the carbs. do I need a new heat shield or can I simple add some holes to my existing shields? How critical are the locations?

Tx,

Bill

[jackboxxx]

I have a 73 and am converting over to 72 SU's. I got the flat tops off the car, but noticed that there are not holes in the heat shield to connect the springs from the carbs. do I need a new heat shield or can I simple add some holes to my existing shields? How critical are the locations?

Tx,

Bill

well the locations are a specific distance from the carb linkage, as to create a certain amount of pullback . if you go too short on distance for example,

when you let off the gas your carbs may not completely close to idle.

if you go too long, youll have a "hard gas pedal" feel...meaning you have to push too hard to give the car gas...which can make it difficult to drive.

[jmortensen]

Measure the distance now, drill holes at a similar distance after. Easy enough.

[krispy_kgc10]

When i wrapped my header, i removed the heat shield and bent a piece of 1/8 inch stainless rod to connect the springs too. i just made sure the butterflies closed all the way, its not that critical of a length..

[=Enigma=]

The PO of my 73 had the conversion to SUs done and the springs are simply attached to the heat shield in a crease or gap in the shield. As krispy said, I don't think it's that big a deal. Drill some holes if you want.

[wfl_colorado]

Yea, I took a look at it and there is a seem between the heat shield and the piece that directs hot air back to the air cleaner. As you said, it appears I can attach them at that seem and I don't think they will move around.

[Bruce Palmer]

A small point but I would make a wire loop affair to hook into the sharp edged hole in the heat sheild. The sharp edged hole in the heat sheild will then over time saw thru the wire loop instead of your spring. Cheap and easy to form another wire loop.

[wfl_colorado]

I had a few more questions. What about the water lines into and out of the flattops. Can I simply route a water line around them or can I just plug the holes somehow?

I haven't tackled all the vacuum lines, etc yet...

Tx,

Bill

[240ZX]

Yes, you can eliminate the water lines that run through the carb bodies! However, by doing so it will likely take a bit longer to warm up when its cold out. Many folks do eliminate those lines.

[wfl_colorado]

Since the roundtops don't use the water lines, I am wondering if I route a line from the back connection to the front connection or just simply somehow plug the 2 holes?

Bill

[krispy_kgc10]

You can just plug the two holes, i believe they are regular NPT national pipe thread, nothing causes a force in the line that would require it to recirculate.

[kenz240z]

Bill, the '72 round top carbs have a water passage and will work with the '73 intake manifold. So, you should be able to leave the coolant lines connected to the intake. It will provide a quicker warm up in cold weather.

Here are a few pics showing the differences between the '72 and earlier round top carbs. In the photo with the two carbs side by side, the one on the right is a '72 carb with a water passage at the bottom of the manifold side. The one on the left is off a '71 and does not have the water passage.

The second photo shows the top of the '72 carb, it is also referred to as a 3 screw carb. Look close and you'll notice that there are three screws that mount the dome to the carb body. The last photo shows the top of the '71 carb, also referred to as a 4 screw carb. You'll see four screws that mount the dome to the body.

If it turns out that you have the earlier round top carbs then you will need to disconnect the coolant lines to the intake and block them off on the engine side, or replace the intake with a '71 or earlier intake.

When I bought my '73 it was setup with '72 round tops and the '73 intake. Keep us posted with your progress!