stevehg said:

Hi Chris

I just bought Mark's spare FZD. Looking at the pics I assume that I'm going to have to swap around the throttle linkage to get it to work on the 500. In the first page of this thread, you say this is possible, but not all of the parts are available - is it just a case of replicating the linkage on the other side? So for example making the reverse of what's on the rear and fitting it to the front?

Thanks

Steve

Click to expand...

Hi Steve,

The throttle lever should be on the correct side for mounting in our cars.

The part illustrated in the above photo is the choke 'lever'. This is the bit - particularly the butterfly shaft - that is mirror imaged and also the bit that is unavailable (unless Andrew has found some). If you don't need a choke, you don't have a problem.

I think that is part of the issue with a lot of these carbies - the choke was never used and most likely disconnected resulting in the interconnecting levers and rods being lost over time. Also from what I've read, these carbies were often fitted in pairs (on Minis etc.) and would have had different means of linking and activating the chokes. Hence the confusion now, where you separate what would possibly have been a mirrored pair of carbies and sell them individually.

If you are looking for one of these carbies to fit our engines, try to find one that has all of the interconnecting parts on the rear side - the side without the writing on it. Either that or we need to start making the bits for ourselves.

Chris

Thanks for the quick reply Chris. Sorry I should have added pic of the other side too...



So, if not using the choke, could you please tell me what parts do I need to source/make to fit to this side?

Thanks

Steve

Steve -a manifold, thermal spacer connector rod and gaskets are the external parts required.
I don't have my carb to hand as its with the engine builder - when I have it back I will photograph it and communicate my findings.
PM your email address and I will send you my photos of a number of FZD's from a second hand source that i have for info purposes.

AndrewHarvey said:

Steve -a manifold, thermal spacer connector rod and gaskets are the external parts required.
I don't have my carb to hand as its with the engine builder - when I have it back I will photograph it and communicate my findings.
PM your email address and I will send you my photos of a number of FZD's from a second hand source that i have for info purposes.

Click to expand...

Thanks Andrew, email sent. Ok that's clear, I just wanted to make sure I wasn't missing anything. When I place my next parts order, I'll get the manifold and gaskets. I already have a thermal spacer.

cheers, Steve

a thermal spacer for an FZD?
it sits between the manifold and carb and is special to the carb type ......I think

AndrewHarvey said:

a thermal spacer for an FZD?
it sits between the manifold and carb and is special to the carb type ......I think

Click to expand...

I had assumed that as the spacer sits between the head and the carb specific manifold that it would be a standard shape replicating the pattern of the head for the carb manifold to mount on.

cheers, Steve

Hi Steve,

All you need is a suitable throttle lever and any decent carby service place will have a wide selection. The choice of ball fitting or hole for the throttle linkage doesn't matter as once again suitable parts are readily available for either. Something like the third photo might work well.

I've attached a couple of photos of mine to give you an idea of dimensions and the angle of the slotted key. If not using the choke, you only need the bit between the vertical lines and depending on your linkage, the double 90 degree bend may not be necessary either.

The thermal spacer goes between the base of the carby and the manifold. They are available and I would think that they should be common to any 32mm single throat carby

Chris

Thanks Chris for explanation and pics, greatly appreciated.

cheers, Steve

Put 215 miles on the Fiat this past weekend. Great micro/mini car rally and show near Boston. The whole time, I had to feather the throttle on acceleration or it would just bog down. Part throttle cruising is also less than smooth. No adjustment on the pump mechanism made it better or worse, so I'm guessing that isn't my problem.

Emulsion tubes change the air/fuel mixture depending on throttle position, so maybe I should experiment there. I started out with 6747-3. I ordered a 6747-8 to match Chris' setup and it may have given me more top-end power but had no effect on the bogging down at part-throttle.

Looking at Chris' picture, the emulsion tube doesn't match what is shown on the Dellorto.co.uk site. My 6747-8 looks like their picture, with the four holes starting at the base of the thinner version tube. Chris' looks like the holes are more toward the end, and the diameter looks more like the fatter -1 or -10. Odd! Where the holes are will affect how they work in the throttle position. PITA to experiment with these, both from a cost position and having to pull it out of the car for every change.

Looking for more examples! Anyone else know of a FZD on a 500 or 650 engine? Or anyone know a Dell'orto tuning expert - I would gladly pay them for a bit of advice!

Hi Marcus,

The emulsion tube in the photo is a 6747-3 and is the one in my spare carby cover. The one that I'm running is a 6747-8.

I'm sorry for any confusion - the rebuild thread photos were meant to illustrate where everything went and were never meant for actual identification of exchangeable components.

Chris

No worries! I'm just trying to learn what I've got and what I need. Not much tuning info out there. I have a 6747-3, but mine has six holes in it?

Found some 'rule of thumb' for another type of Dellorto:
4 x Main Venturi Size for the Main Jet. 28mm x 4 = 112. I'm at 135 now.
Add 50 to that for the Air Correction Jet. 112 + 50 = 162. I'm at 190 now.
No idea what I have for idle jet, or how to size that. Time to pull it out again.

Mark

The picture on the website only shows one side of the emulsion tubes. The holes on the opposite side will be offset by half the distance between the holes and there may be either one or two more or less of them.

I'll post a picture of what I mean tonight.

I guess the only real answer to the problem is to get the car onto a dyno, though physical access is always going to be an issue. Either that or swap the FZD for an SU where you don't have to worry about jets and tubes and stuff ...

Chris

Ugh. I'm in the middle of fighting (now rebuilding) the dual-SU carbs on my '70 Datsun Roadster! At least there is a ton of information on them.

The two sides of a 6747-8 FZD emulsion tube.

Chris

Well, I found my issue and it wasn't jets or emulsion tubes. It was my clever air filter arrangement. I'm my own worst enemy. Just removing the U-Shaped tube and taking it for a test drive showed no issues with acceleration. I had read recently the intake tract length could allow for bouncing pulses and a short air horn/velocity stack is ideal.

So, now I'm looking for a velocity stack with the 3rd hole in it for the crankcase vent tube that allows for a small filter. Not much room in there. Does the Ram Flo mount right to the Dellorto?

marcus550 said:

Does the Ram Flo mount right to the Dellorto?

Click to expand...

Hi Mark

Assuming that your carb has the same inlet as the one you sent me, it has a 52mm OD. I happen to already have a 52mm ramflo here for my Solex carb. It doesn't fit straight on, but you could easily just splay out air filter neck, or alternatively you could shave 1/2mm off the inlet diameter.

It comes complete with three inlet pipes and blanks. The OD of these pipes is 13mm (1/2").

cheers, Steve

Hi Marcus,

I use a RamFlow filter (1st picture). It works well and sounds good.
I've also used a genuine DellOrto filter but didn't like the 90 degree angle on the inlet (2nd picture).
The velocity stack would be interesting (3rd picture) except that there is really no filter and I'd be a bit concerned about dust and dirt getting into the carby.

Glad you got the problem sorted.

BTW, on my engine I've diverted the crankcase ventilation directly onto the road ...

Chris

this is what I will be running on mine.....
http://www.ebay.co.uk/itm/252031695086?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Re: Float adjustment and tuning settings

Bambino said:

I'd been looking for this diagram for a while and finally found it - it's the float adjustment.

The float is adjusted by carefully bending the two small flanges that hold the fuel inlet needle valve. The distance (5-6mm) is measured with the gasket in situ.

Hold the fuel cover vertically so that the float just closes the needle valve and measure the distance between the top of the float and the gasket. Once adjusted sometime in the past, most floats do not need readjusting unless they have been abused somehow. New floats should ready to use and need no adjustment.

*
*
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I've asked around over the time that I've been running this carby and discovered that there is virtually nothing written about the FZDs. If I find any more information that may be of help, I'll post it.

Happy driving,
Chris

Click to expand...

Hi Everyone, this is my first post.

Can someone explain how to adjust the float level? On every other carb I've adjusted there's a metal tab that you bend so that it pushes the needle valve closed at a specific angle. On the FZD, there's no tab to bend to set the angle at which the needle valve closes. I'm confused.

-Lalo

marcus550 said:

Well, I found my issue and it wasn't jets or emulsion tubes. It was my clever air filter arrangement. I'm my own worst enemy. Just removing the U-Shaped tube and taking it for a test drive showed no issues with acceleration. I had read recently the intake tract length could allow for bouncing pulses and a short air horn/velocity stack is ideal.

So, now I'm looking for a velocity stack with the 3rd hole in it for the crankcase vent tube that allows for a small filter. Not much room in there. Does the Ram Flo mount right to the Dellorto?

Click to expand...

I've been wondering what that third hole was for! Can anyone confirm that it is for a crankcase vent tube?