Am I Over Carbed?, Dual Weber 40 IDFs on 1.7 Options

[7TPorsh]

I have been trying to drive my car comfortably but I am running across issues. Mainly after the car warms up it starts acting weird.

Coming to a stop and revs dropping. it just dies. Then I have to wait a minute or two to get started again. Then it runs a little rough, pops, backfires.

Just did the valves, points, timing but runs like crap when hot.

The engine is a 1.7 block with 1.7 heads and dual 40s. I don;t know if there was any work done internally but the block is a 71 and car is a 70.

It has been suggested that I am way overcarbed and running rich. i have no plans of building out this motor to match the carburation.

Am I better off selling off this dual weber set and putting on a single Weber 32/36?

I have my eye on this: http://www.ebay.com/itm/310953732343?ssPag...984.m1423.l2649

I am thinking the weber and hex setup should be worth around $450?

What say you?

[rhodyguy]

look down one of the venturis and see if a number is on the top. a 28, 32, 36? using just one of the idle speed adj screws, increase the idle a bit. what happens? more investigation and info is somewhat important. take pictures of what you have and post them. linkage, fuel pump, etc. if you think you're rich take a look at the plugs. that single carb ebay package prob isn't going to be the solution to your issues.

[Alapone]

I have been trying to drive my car comfortably but I am running across issues. Mainly after the car warms up it starts acting weird.

Coming to a stop and revs dropping. it just dies. Then I have to wait a minute or two to get started again. Then it runs a little rough, pops, backfires.

Just did the valves, points, timing but runs like crap when hot.

The engine is a 1.7 block with 1.7 heads and dual 40s. I don;t know if there was any work done internally but the block is a 71 and car is a 70.

It has been suggested that I am way overcarbed and running rich. i have no plans of building out this motor to match the carburation.

Am I better off selling off this dual weber set and putting on a single Weber 32/36?

I have my eye on this: http://www.ebay.com/itm/310953732343?ssPag...984.m1423.l2649

I am thinking the weber and hex setup should be worth around $450?

What say you?

For dual 40s with hex (and linkage?) you are probably right on with your value from what I remember (3months ago). I have heard that a single carb setup on the type IV is a road you don't want to go down (so to speak). Many unhappy comments were read by me on this forum related to cornering and fuel starvation and assorted other not good stuff regarding single carb. Maybe get to the root of the cause with the current set up?>

[stugray]

The carb bodies should be fine.

What size venturis do you have?
You should be running the smallest you can find.

Someone on here makes them with their 3D printer.
If you could get a set to try out, you would know if that was your problem before spedning the cash on a complete set of permanent ones.

[7TPorsh]

I am a total novice when it comes to fuel delivery. It starves now on left corners and turns...dies out and I have to wait to start. Running a Carter rotary pump up front, steady 4psi.

I though the venturis were the carb bodies, thus the size being 40; and I thought the jets are what the variables parts are.

I am told these are 40 IDFs. Would the number on the inside be the venturi be body size? Have to take a closer look. Here is a pic I have handy.

[stugray]

you have to remove the air filters.
Then look down into the throats.
The venturis are where the bore begins to restrict the flow before reaching the butterflies.
There will be a number imprinted on the venturi that can typically be seen from there.

Google some Weber 40 IDF venturis for examples.

[rhodyguy]

for your reference. the venturis look like this. this one happens to be a 36. they are held into the carb bodies with a set screw.

[rhodyguy]

where does the pass side line from the bb terminate? just stuck thru the tin and spewing under the car?

[7TPorsh]

where does the pass side line from the bb terminate? just stuck thru the tin and spewing under the car?

The hose from the breather? It's down through the tin and plugged...no oil makes it down there. I am hoping at some point to vent the valve covers.

So on the venturi, I need to check later.

If these vary then I guess there are sizes up to 40? I can use?

What's the normal setup for a 1.7 or over-bored 1.7? I guess jet size is the next factor?

[Kansas 914]

where does the pass side line from the bb terminate? just stuck thru the tin and spewing under the car?

The hose from the breather? It's down through the tin and plugged...no oil makes it down there. I am hoping at some point to vent the valve covers.

So on the venturi, I need to check later.

If these vary then I guess there are sizes up to 40? I can use?

What's the normal setup for a 1.7 or over-bored 1.7? I guess jet size is the next factor?

1.7L heads have a tube just above the engine tin on each side for that hose from the breather puke can. Look at the left side in this picture of the intake just below the mounting nut. The passenger side would be towards the rear of the car.

[7TPorsh]

wow, I haven't noticed anything like that on my car. I sure do have to look close tonight.

[Rand]

Am I better off selling off this dual weber set and putting on a single Weber 32/36?

Hopefully you've heard feedback that says NEVER on that note. Never single carb a flat4.

[ThePaintedMan]

Not all 1.7s had head vents - it's only the early or later ones (I can't remember which).

[rhodyguy]

if you have those head tubes…one line from the pvc, center one on the box, and the sides to the tubes. the little filter on the box is not needed. there are usually little venting stand-offs on the lid and a piece of foam on the inside to help contain/control the vapors. oil builds up on the foam and becomes a part of regular maintenance. the plugged line is just going to fill up over time.

[Kansas 914]

Not all 1.7s had head vents - it's only the early or later ones (I can't remember which).

George,

Now that you mention it a friend called me the other day and said his 1.7 was puking oil. I asked him about the tubes in the head and he said he didn't see any.

[Kansas 914]

Not all 1.7s had head vents - it's only the early or later ones (I can't remember which).

George,

Now that you mention it a friend called me the other day and said his 1.7 was puking oil. I asked him about the tubes in the head and he said he didn't see any. I think his is a 1970 model.

[wndsnd]

I do not think you are over carbed at all. You just need the right venturies and jets.

I am running 44IDF's set up by Tangerine Racing on my 1.7 and it screams. Sometimes it bogs in transition but that is very rare. So I am sure you could get your 40's to run well with the expert guidance of the the knowledgeable ones here.

Once set up correctly, you will have a blast... (IMG:style_emoticons/default/driving.gif)

John

[Mblizzard]

I think you may need to check your float level settings.

[7TPorsh]

Ok I checked one of the throats...assuming all four are the same. Couldn't see down there but camera got it.

28...what next?

[stugray]

Next check all of the jets and write down the numbers while you do it.
Dont just blow through them. Inspect them FIRST then clear them.
Dont use any wire or anything to clear the passages.

The mains come out the top on the tall brass tubes.
Write down the numbers on the tall brass tubes as well.

The idle jets are on the outside of the carbs near the top and are kind of hard to get to.
Use a mirror and verify the o-rings stay in place on the carb body ( and that they are there in the first place). They are usually green.

Clear the idle jets, write down the number and screw them back in gently (do not over tighten).
Use the mirror to make sure they are all seated to the same depth.

Report back with the numbers and if clearing them all makes a difference.

Also while looking down the barrels, turn the throttle linkage and verify that you see a squirt down each barrel and that they are approximately the same. These are the acceleration pumps (the phallic shaped thing directly in front of the number in your pic above)

Finally after all that, you should check the float levels ( as mentioned above), but that requires you to take the linkage off and remove the tops of the carbs. I never do that unless I already have a spare set of carb-top gaskets.
There is a chance you will tear one especially if it is your first time.