Technical Connecting 32/36 DFEV

[Slotman]

I purchased an extra fuel cap on ebay for penny's, and drilled a tiny .053 hole in it to try for fun as an additional vent...I'm with Mike about the lower pipe...if you don't use that for vacume advance for your distrubitor where are you getting it from? Does your carburator have more than one line out, and if so is it ported, or unported?

 

[bugsymike]

Basic flame trap in the crank case vent hose may just look like this.
When you got the carb new, did it have a blank pushed over that vacuum outet on carb, I have seen cars with them on for years.

 

[Slotman]

Mike I'm not sure if you meant smahaleys carb or mine, I have 2 identical 32/36 carbs and here's a couple of pics of the one currently not on the car...regarding the flame trap, is one of the 2 holes in the block, between the valve covers the connection to the flame trap?
funny story (for me anyway) about those 2 holes...when I went to view my spider that was for sale (having never seen a spider motor before) something looked funny, the seller had a spark plug screwed in to one of the holes so there was actually 5 spark plugs visable, the other had a rubber hose open to the air in the other hole...seller started the car, even though it ran o.k. it made a horrible knocking noise like a connecting rod was about to go thru the side of the block.

When asked about the noise seller said he didn't know what it was, and said a few people before me had walked away after hearing it...when I asked to see the ownership papers, seller went in the house to get it leaving the car running, when he went in the house my friend pinched the open hose closed and the funny noise stopped, and the motor ran perfectly...my friend let go of it just as seller came out of the house...seller then said he would accept half of the price he was asking ....needless to say I bought it, drove the car home a long distance, 50 miles at 70 miles per hour on the freeway and when we got to my friends house, he tossed me a wine cork, and with out words I stuffed it in the open hose and drove the car like that for a year! Not sure about the blank you mentioned

 

[smahaley]

I am still not sure about connecting that vacuum pipe to carbon filter, has anyone got any diagrams?
Re the return to the tank and blanking it off.
If Fuel tank isn't vented through a breather of a vented cap it can cause an issue. In the past when tank breather blocked either car will break down due to fuel starvation or I have actually seen a fuel tank collapse/implode until fuel cap removed. So you do need to know what your system is.
An advantage of a fuel return is it helps keep the fuel cooler if in warmer areas.
The crankcase ventilation pipe should have some form of flame trap, even if only a basic twisted wire gauze in the pipe.

I found this on a related FB group:

 

[Slotman]

If it helps you any, my carbon filter has 2 large hoses on the bottom, one hooks to a hard metal line, hard to see, but in center of pic, that appears to run back to the tank...the other is currently open..., on mine the small diameter hose at the top is currently open...only seeing 3 lines on my canister.

 

[bugsymike]

Mike I'm not sure if you meant smahaleys carb or mine, I have 2 identical 32/36 carbs and here's a couple of pics of the one currently not on the car...regarding the flame trap, is one of the 2 holes in the block, between the valve covers the connection to the flame trap?
funny story (for me anyway) about those 2 holes...when I went to view my spider that was for sale (having never seen a spider motor before) something looked funny, the seller had a spark plug screwed in to one of the holes so there was actually 5 spark plugs visable, the other had a rubber hose open to the air in the other hole...seller started the car, even though it ran o.k. it made a horrible knocking noise like a connecting rod was about to go thru the side of the block.

When asked about the noise seller said he didn't know what it was, and said a few people before me had walked away after hearing it...when I asked to see the ownership papers, seller went in the house to get it leaving the car running, when he went in the house my friend pinched the open hose closed and the funny noise stopped, and the motor ran perfectly...my friend let go of it just as seller came out of the house...seller then said he would accept half of the price he was asking ....needless to say I bought it, drove the car home a long distance, 50 miles at 70 miles per hour on the freeway and when we got to my friends house, he tossed me a wine cork, and with out words I stuffed it in the open hose and drove the car like that for a year! Not sure about the blank you mentioned

The new carb I was referring to is on the photo #1 of this post sat on the manifold, it is easy for me to get confused, but the query re fuel in and return was regarding that one. As you can see there is a brass blank opposite the fuel inlet pipe to the float chamber and on some carbs I have seen a return outlet in that drilling, I notice on the two photos you have posted yours doesn't have that option and the casting is all aluminium without the brass blanking plug, but does have the blank under that area which usually contains a gauze filter which we used to check during servicing on that type of carb along with in some cases the gauze filter in the top of the mechanical pump, although some where more inaccessible. . @smahaley was going to blow through to confirm I think at one point. I was concerned he was going to connect to the larger breather pipe further along at top of carb to try and use for fuel return which is obviously wrong.
I love the bit about the knock and getting the price reduction. I went to look at a Citroen some years ago from a dodgy car salesman, he said I couldn't road test due to a brake issue and sure enough the pedal went almost to the floor and there was a warning light on . I insisted if I was going to buy then I would road test first! As soon as I did I knew what the problem was and negotiated a suitable low price. At home I removed rear brake drums and soon saw all new parts inside, however the "mechanic" had fitted the left side self adjusters to the right hand side, the effect being the more you used the brake the further the travel would get, I swapped left to right, manually adjusted it and problem solved, the brake warning light was the wear indicators on the front brake so although not very low I replaced them, problem solved and ran the car for several years.

 

[bugsymike]

I found this on a related FB group:

That is just what I was thinking about for that system, the only bit that it doesn't show clearly is the pipe fitting on the carb for the return, it just shows it coming up towards the bottom of the fuel inlet pipe area. I am fairly convinced that a return outlet should be roughly opposite the fuel inlet at that part of the float chamber before the needle valve and that is to the left of what I think is the fuel filter under a bolt with probably a tapered head to seal the fuel although some had a gasket.

 

[bugsymike]

If it helps you any, my carbon filter has 2 large hoses on the bottom, one hooks to a hard metal line, hard to see, but in center of pic, that appears to run back to the tank...the other is currently open..., on mine the small diameter hose at the top is currently open...only seeing 3 lines on my canister.

Sorry I can't see enough to work out the flow system on that.
Maybe somewhere is a diagram?

 

[smahaley]

If it helps you any, my carbon filter has 2 large hoses on the bottom, one hooks to a hard metal line, hard to see, but in center of pic, that appears to run back to the tank...the other is currently open..., on mine the small diameter hose at the top is currently open...only seeing 3 lines on my canister.

Yes - my filter is cylindrical, with a small port on the top, a larger one on the side, and a larger one on the very bottom. As you said, the larger one on the bottom connects to a hard line that travels back to the gas tank - that is for letting the fuel vapors head back to the vapor separator that then lets the liquids fall back into the tank. This is my understanding at the moment )

I'm going to try running it (whenever I get to that point) with the top line going to the equally small vacuum port at the base of the carb, and the larger line on the side of the canister connected to the top port on the carb - presumably to handle vapors that would be collecting up there. We'll see what happens! But for now I have to finish wiring up an oil pressure sensor and gauge, and reconnect all the dash, and install the radiator and hoses...

 

[Slotman]

Where will your vacume advance for the distrubitor come from? Sounds like you are making great progress!

 

[smahaley]

Where will your vacume advance for the distrubitor come from? Sounds like you are making great progress!

I've got an old fashioned mechanical advance unit - no vacuum hose to it. TRYING to make progress, lol, between all the other life things going on...

 

[fiatseattle]

View attachment 488073
Thank you, @bugsymike, for your suggestions! I’ve marked up this version of the photo to be a bit more precise:
Red: there is a vertical sensor on the intake that I *think* could be plugged, as it just had tape on it when I got the car. Would like to know if that is correct..
Blue: I think this is fuel in from pump and after filter.
Green: this pipe has ridges on it to be really grippy. Given its position at top, perhaps it is the fuel in, and the lower (blue) smooth line is for overflow?
Yellow: there is a smaller diameter tube towards the base of the carb that could be a fitting to go to the charcoal canister? Or it could be a vacuum line as you pointed out, however my distributor is a simple mechanical advance and does not have a vacuum port on it.
Orange: hard to see but there is a blade connector for an elec choke. The original had a choke managed by water temp, I believe and has a solenoid with a blade connector. I wonder if I can use that wire that was for the solenoid on the new carb to connect the elec choke?

That’s what I’m noodling over and searching through the manuals etc … fun! Thanks for any further advice on the above - and I may just try blowing through the blue and green to see if there is clear evidence of “in” vs “ out”…

I have this exact carb installed on my '76.
Red is a vacuum switch for emissions, block it off or remove it and block off hole.
Blue is fuel IN from pump.
Green is fuel return.
Yellow is a vacuum line port for the distributor but since yours is mechanical it needs to be blocked.
Orange is the power for the electric choke - needs a 12v power supply, that circuit that you mentioned should do the trick, just check for voltage ya know.

 

[bugsymike]

I have this exact carb installed on my '76.
Red is a vacuum switch for emissions, block it off or remove it and block off hole.
Blue is fuel IN from pump.
Green is fuel return.
Yellow is a vacuum line port for the distributor but since yours is mechanical it needs to be blocked.
Orange is the power for the electric choke - needs a 12v power supply, that circuit that you mentioned should do the trick, just check for voltage ya know.

Not sure that I agree, suggest confirmation.
For example undo the one marked with a red circle on the actual carb, I think you will find that is a fuel gauze filter for the inlet and not a vacuum switch for emissions, unless you are talking about the black plastic unit with broken vacuum pipes on it to the left of the carb.
I agree blue is fuel in and yellow is vacuum for distributor advance if used or in OPs case blank off as only mechanical advance.
Also agree orange is the bimetal spring electrical terminal that controls the auto choke mechanism which as it heats up it pulls the choke flap back, so presumably it would need some form of temp control activation and not just a straight power supply otherwise as soon as it activated it would turn the choke off?
The green pipe I would like to take top off carb to confirm it is actually a fuel return and not some kind of breather as seems above the fuel level and also I have seen Weber carbs with a fuel return in the blank that is opposite the fuel inlet.
Perhaps @124BC1 can advise?

 

[smahaley]

I have this exact carb installed on my '76.
Red is a vacuum switch for emissions, block it off or remove it and block off hole.
Blue is fuel IN from pump.
Green is fuel return.
Yellow is a vacuum line port for the distributor but since yours is mechanical it needs to be blocked.
Orange is the power for the electric choke - needs a 12v power supply, that circuit that you mentioned should do the trick, just check for voltage ya know.

Thank you very much!

And this is where we are today, after 2 days of wrestling with the intake to attach a crankcase breather hose… found out it’s easier to *not* have a stud mounted in one of the two central attachment points for the intake to head.

I have not finalized the fuel line attachments - and think I’ll take the top off the carb to see if I can tell if that barbed pipe at the topmost position is a return or if it looks to be vapor collector of some sort (to attach to the charcoal canister as I have it now). Any advice on what to use to stub off the vacuum at the base of the carb? I also thought it might be attached to the top of the charcoal canister to help pull vapors in there…

 

[bugsymike]

Thank you very much!View attachment 489301
And this is where we are today, after 2 days of wrestling with the intake to attach a crankcase breather hose… found out it’s easier to *not* have a stud mounted in one of the two central attachment points for the intake to head.

I have not finalized the fuel line attachments - and think I’ll take the top off the carb to see if I can tell if that barbed pipe at the topmost position is a return or if it looks to be vapor collector of some sort (to attach to the charcoal canister as I have it now). Any advice on what to use to stub off the vacuum at the base of the carb? I also thought it might be attached to the top of the charcoal canister to help pull vapors in there…

I still wonder if that small vacuum outlet at the base of carb on right is connected to the broken plastic thing on the left of the carb?

 

[smahaley]

I still wonder if that small vacuum outlet at the base of carb on right is connected to the broken plastic thing on the left of the carb?

Yeah the broken sensor mounted on the plane of the intake between carb and motor was a sensor for the smog system - as I recall from looking that up. I have since plugged it. I’m 90% of the opinion that the small vacuum port at the carb foot is for vacuum advance on the distributor - as has been suggested.. and as I don’t need that, I think I might put a plug of some sort on it and then try to figure out what if anything connects to the top of the charcoal canister…

 

[124BC1]

I am still not sure about connecting that vacuum pipe to carbon filter, has anyone got any diagrams?
Re the return to the tank and blanking it off.
If Fuel tank isn't vented through a breather of a vented cap it can cause an issue. In the past when tank breather blocked either car will break down due to fuel starvation or I have actually seen a fuel tank collapse/implode until fuel cap removed. So you do need to know what your system is.
An advantage of a fuel return is it helps keep the fuel cooler if in warmer areas.
The crankcase ventilation pipe should have some form of flame trap, even if only a basic twisted wire gauze in the pipe.

Here's a diagram showing one version of the carbon canister, it doesn't seem to have any connection to the carb., just one line (item 9) from the top of the c/c to the inlet manifold (item10). It seems that the carbon filter is fitted primarily to deal with fuel vapor from the fuel tank, rather than venting the tank to the atmosphere?

I did see a carb diagram recently for the Weber 32 ADFA carb, fitted to later USA 124 Spider and Coupe models, where the item circled in green by @smahaley was described as the "bowl vapour vent" (presumably bowl means carb. float chamber) - but I don't know where this vent should be connected to, maybe the original air cleaner? Or possibly the carbon canister? It seems that a warm air feed (item 9 in diagram) from the exhaust manifold needs to be supplied to the carbon canister for it to function correctly?

I agree that the item circled in blue is the fuel inlet (supply) to the carb. and that the brass blanking plug on the carb. top (nearest to the engine) is most likely where the fuel return pipe to the fuel tank would be connected - if so, there should be a restrictor inside to limit fuel flow.