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Author: Subject: Cheapest side draft carb solution?
jps

posted on 14/5/20 at 02:39 PM Reply With Quote
Cheapest side draft carb solution?

I have a 1.6 Pinto, complete with downdraft carb from the donor Sierra. But i'd rather not have a hole in the top of my bonnet, so have been looking at side draft carb options.

A pair of twin Webers seems to be extremely pricey - I've seen people wanting c. £500 for a set. But I guess would largely bolt straight on, and work from the existing fuel pump/ignition system, etc?

I do have a set of bike carbs that I got with my build- but am not clear on how much additional kit (other than the manifold) I would then need to buy to get my engine running with them? Would I need to change the ignition system (it currently has vaccum advance on a distributor), would I need both high and low pressure fuel pumps (and not use the Pinto mechanical pump), would i need to have a fuel swirl pot in the engine bay, could I still tap the crankcase breather into the inlet manifold - or would I need an oil catch tank too?

Any advice appreciated!

[Edited on 14/5/20 by jps]

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SJ

posted on 14/5/20 at 03:48 PM Reply With Quote
On the induction front you just need a manifold of some description and a bike fuel pump.

If you need a vac takeoff for the dizzy you will need to ensure you get a manifold that has this.

Bike carbs are way easier to set up than what will probably be an old set of Webbers.

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theconrodkid

posted on 14/5/20 at 04:17 PM Reply With Quote
webbers like to drink like a fish and need constant tinkering, the sun goes behind a cloud and they go out of tune.
better to use bike carbs or bike injection, there is plenty info on the interweb about the conversion





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Slater

posted on 14/5/20 at 04:46 PM Reply With Quote
Can I suggest you contact Bogg Bros, tell them what engine you have and send them your old bike carbs, they will make manifold, supply gasket, air-filter, back plate, fuel pump, etc and set up your carbs to suit the engine. I did this and still have same carbs on my 1.8 zetec engine after 12 yrs and not even had to touch them since fitting. I am running Megajolt for the timing advance. Probs cheaper to do this all yourself mind.





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steve m

posted on 14/5/20 at 05:16 PM Reply With Quote
"webbers like to drink like a fish and need constant tinkering, the sun goes behind a cloud and they go out of tune. "

I totally agree with Conrod, webbers are for race engines and be tuned on a daily/weekly basis,
Mine that were given to me, had to be balanced and tuned every time before I drove the car, and did about 15 mpg
a nightmare with a 6 gallon tank!

I sold them on ebay, genuine matched 1960's twin 40's, I got over a grand for them,

On crossflows they did a Siamese manifold, so you could have just one twin 40 feeding all four cylinders, that could be an option,

or just build a bulge, like I had on my car, its easy, with a mud mould and some fiberglass
pics in my archive

steve





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snapper

posted on 14/5/20 at 05:35 PM Reply With Quote
I am close to you but shielding that said I have some experience with both Pintos and bike carbs and currently have a set that I considered to small for a 2.0L which may be just right for a 1.6





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gremlin1234

posted on 14/5/20 at 05:36 PM Reply With Quote
as I remember...
webbers are great when they are spot on, but thats like never,
su are really good when they are spot on, but when they are just close they are still good

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snapper

posted on 14/5/20 at 05:46 PM Reply With Quote
You can fit bike carbs and keep the distributor but may need a low profile distributor cap.
You will probably need a catch tank.
Bike carbs only need 1.5psi so the manual pump may overload the bike carb float valves, you can use 1 low pressure pump from the tank and a fuel pressure regulator, swirl pot is advised if you don’t have a tank with a sump and that would require 2 pumps.
Manifold can be tapped for vac takeoff
Bike carbs need a specific manifold made for them as they have different spacing





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snapper

posted on 14/5/20 at 05:48 PM Reply With Quote
Bike carbs are variable venturi so better in most cases as the engine draws the slides up on demand





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snapper

posted on 14/5/20 at 06:00 PM Reply With Quote
When you get a chance tell me more about the bike carbs and I can compare with mine on a 2.0L
You biggest step to more power is to fit a 2.0L





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perksy

posted on 14/5/20 at 07:35 PM Reply With Quote
I'd agree that Bike carb's provide the most cost efficient route and when correctly set-up they work and stay in tune very well


Just for some balance though (excuse the pun) Correctly rebuilt and set-up Webers can be made to work very well (and stay in tune)
My old 2 litre Zetec on twin 45 DCOE's and Weber Alpha ignition would pull from 25mph in 5th
(Admittedly they did have the five progression hole modification)

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mcerd1

posted on 14/5/20 at 07:56 PM Reply With Quote
As above assuming you don't want to spend the £££ one EFI then Bike carb's are what you want

ZX6R / R6 ones (or similar) should be plenty big enough for any 1.6 pinto

quote:
Originally posted by jps
I do have a set of bike carbs that I got with my build- but am not clear on how much additional kit (other than the manifold) I would then need to buy to get my engine running with them?

FASTdan on this site sells full kits, just the manifolds or even just the flanges to weld your own manifolds + all the bits and bobs you'd ever need:
ebay linky

or here: https://danstengineering.co.uk/Manifolds-and-Plates/Bike-Carburetor-Inlet-Manifolds/Bike-Carb-inlet-manifolds-Ford/Ford-Pinto-Inlet-Manifold-for-R6-Ca rburettors

quote:
Originally posted by jpsWould I need to change the ignition system (it currently has vaccum advance on a distributor)

In a word - No

but you'd need to take a vac. runner from each of the 4 inlets and connect them together in small chamber and then connect that to the dizzy (google for vacuum manifolds if you want ready made ones, often quite cheap) - this would also be needed to run the vac. advance on the webbers

quote:
Originally posted by jps
would I need both high and low pressure fuel pumps (and not use the Pinto mechanical pump)

Ditch the mechanical pump (the EFI engines just blank them off with a plate)

You can use an decent low pressure carb type pump with a reg, but bike carbs are reckoned to run best with a bike pump - these are self regulating and perfectly suited to the carb's needs (should be all you need if you can get a good gravity feed to the pump) - plenty of second hand cheap options too

I like the old ZX6R / ZX9R style ones that come on a handy bracket with a fuel filter: (obviously you'd change the filter)
https://www.ebay.co.uk/itm/KAWASAKI-ZX6R-ZX6-ZX-600-R-F3-1995-1996-1997-Fuel-Petrol-Gas-Pump/202740397567?hash=item2f3444f5ff%3Ag%3AR9IAAOSwJWddNt98&a mp;LH_ItemCondition=4

quote:
Originally posted by jps
would i need to have a fuel swirl pot in the engine bay

No

quote:
Originally posted by jps
could I still tap the crankcase breather into the inlet manifold - or would I need an oil catch tank too?

No, but a catch tank doesn't need to be anything fancy - best find / make one with 2 inlets (one for the cam cover) and make sure its big enough if your planning to take it on any tracks (most have a rule about the min. size of catch tanks - I think its normally 1l ? )

*

other than that the you'd need:
1- some kind of air filter / airbox - sausage filters (eg. from ITG) are always an easy option
2- possibly a new throttle cable
3- someone to tune them
All these would also be needed for the webbers or EFI though


I hope none of that puts you off in any way - there are cheap ways of doing nearly everything (especially if you can weld alloy) - getting them tuned properly is probably the old bit you can't do much about on costs (and even that shouldn't be too bad)



[Edited on 14/5/2020 by mcerd1]

[Edited on 14/5/2020 by mcerd1]

[Edited on 14/5/2020 by mcerd1]





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SJ

posted on 14/5/20 at 09:04 PM Reply With Quote
No need for a catch tank. Just tap the crankcase breather into the air filter back plate.

Also, with a wideband O2 set up you can easily tune bike carbs at home if you want.

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jps

posted on 15/5/20 at 07:59 AM Reply With Quote
Thanks everyone for the responses, much appreciated. In the first instance i'm going to get the car running with the downdraft carb, but from there I am reassured it's very doable, and not too expensive, to use the bike carbs.
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David Jenkins

posted on 15/5/20 at 08:48 AM Reply With Quote
Don't underestimate the amount of work involved in fitting bike carbs! I did...

My linky (extract from my website)

Mind you, I did everything, including making the manifold (apart from the welding, which was done by Mr 907). If you buy a manifold then the workload goes down a huge amount. Still not trivial though...





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mcerd1

posted on 15/5/20 at 08:59 AM Reply With Quote
quote:
Originally posted by David Jenkins
Don't underestimate the amount of work involved in fitting bike carbs! I did...

My linky (extract from my website)

Mind you, I did everything, including making the manifold (apart from the welding, which was done by Mr 907). If you buy a manifold then the workload goes down a huge amount. Still not trivial though...

^^ You went with re-spacing the carb's too though - nicer end result but probably even more work overall





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David Jenkins

posted on 15/5/20 at 09:19 AM Reply With Quote
Absolutely right! I think that I confessed my fussiness at the end of the web pages...

However, if you're making your own manifold then it's easier to respace the carbs IMHO - the shapes of the pipes in the bought manifolds are downright scary!


[Edited on 15/5/20 by David Jenkins]





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jps

posted on 15/5/20 at 09:45 AM Reply With Quote
quote:
Originally posted by David Jenkins
Don't underestimate the amount of work involved in fitting bike carbs! I did...

My linky (extract from my website)

Mind you, I did everything, including making the manifold (apart from the welding, which was done by Mr 907). If you buy a manifold then the workload goes down a huge amount. Still not trivial though...


Thanks David - I had looked at your site, and having considered I was going to buy the manifold (Bogg Bros or similar) and not respace the carbs, it did seem it might simplify somewhat.

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rusty nuts

posted on 15/5/20 at 11:42 AM Reply With Quote
I made my own inlet for my Xflow when I converted to injection by using an ally plate (12mm?) onto which I laid a gasket then marked the plate using a scriber , drill a hole where each port was and then cut roughly to shape using a wood working coping saw and plenty of cutting fluid.Way quicker than chain drilling, filing etc. It took about an hr to roughly cut to shape , the inlet runners I turned up from a piece of ally bar before getting it welded, again using a head to minimise distortion. When unbolted from the head there washers some distortion so I placed wooden blocks between the head and manifold and tightened the retaining bolts to “pull” the manifold nearer straight then a very light lapping using a sheet of emery and a surface plate. Final job was to match the ports with the head. Total cost was around £20? for the complete manifold
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SJ

posted on 15/5/20 at 11:59 AM Reply With Quote
quote:

However, if you're making your own manifold then it's easier to respace the carbs IMHO - the shapes of the pipes in the bought manifolds are downright scary



If you re-space you can just use the manifolds Mr Kawasaki designed for the job. Costs about £20 2nd hand

Description
Description


[Edited on 15/5/20 by SJ]

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David Jenkins

posted on 15/5/20 at 12:42 PM Reply With Quote
quote:
Originally posted by jps

Thanks David - I had looked at your site, and having considered I was going to buy the manifold (Bogg Bros or similar) and not respace the carbs, it did seem it might simplify somewhat.


One reason I didn't buy a manifold is that they put the carbs quite a way from the cylinder head - you have to put all that twisted pipe somewhere - and I wanted to get everything under the bonnet, without cut-outs for the filter. My manifold has very short stubs (this is probably bad for the fuel-air flow, but what the hey...)





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SJ

posted on 15/5/20 at 06:13 PM Reply With Quote
I think longer inlets give more torque theoretically. 7s are very light so torque usually isn't lacking. My manifold is very short and seems to work ok.
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SJ

posted on 15/5/20 at 06:17 PM Reply With Quote
I think longer inlets give more torque theoretically. 7s are very light so torque usually isn't lacking. My manifold is very short and seems to work ok.
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alfas

posted on 2/6/20 at 07:28 PM Reply With Quote
a pair of decent 40ies dellortos will cost you 160-180pound....you should buy some with 28 venturis for your 1600 engine...than you need a manifold with gasketset for twin 40ies (all have the same stud pattern: dellortos dhla, solex addh and weber dcoe), throttle linkage and air filters.

depending on the length of the manifold you will finally end with a hole in the bonnet as well, not on top, but on the side.

from the technical (tuning) point of view, a 1600 pinto does not profit at all from sidedraugts.

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