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What's Best Carb Set Up For Pinto


squashy76

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exactly DanE why pay over the odds for webbers when bike carbs are just as good the sound the power easy to set up and of course the price no need for the anderson shelter you are right bike carbs are far better :rofl: :rofl: :rofl:

Edited by tractor
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Guest lotusPaul

Isn't it strange that the 'which carbs' issue constantly creeps in.

A long time ago there was a manifold developed to use bike carbs on a rover 3.5

Not sure what carbs were used but I think,big think, they were around 36 or 38mm. I can't remember who the maker was or the spec exactley but I recall the power and torque delivery was far better than his mates car. Which was a 4ltr TVR.

Esentialy the two went to a RWYB at Santa Pod and the 3.5 won every time.

 

As far as the original post is concerned id go for the 32/36.

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exactly DanE why pay over the odds for webbers when bike carbs are just as good the sound the power easy to set up and of course the price no need for the anderson shelter you are right bike carbs are far better :rofl: :rofl: :rofl:

having had both I. M afraid it's the webers that are best in my opinion...that said I. M ditching carbs and going steamer powered Edited by DanE
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This is why I like kit cars over other patrol head hobbies, we tend to be different, personal preference, likes and dislikes. Unlike restoring a classic car which is normally rebuilt to manufacturer standards with off the shelf parts or fancy sport cars which only have limited manufactured parts by very few specialists.

You build it how you like it!

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I might be mistaken but bike carbs have variable Venturi. The diaphragm opens them more under higher vacuum. Prob the reason for better fuel economy over big fixed Venturi web bets. Secondly if you add up the hole sizes of the bike carbs vs the 32/36 and it is bigger or equal then the same amount of air must surely flow.

 

Of course the above assumes that the diaphragm opens at the correct pressures for a car engine.

 

These are just my musings and limited understanding so happy to be corrected

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  • 3 weeks later...

I would go FI too

 

it is nothing to do with RPM.

 

 

one cylinder of a two litre engine, is 250 cc per cylinder.

 

air flow dynamics accepted. each cylinder would draw in approx 250cc of air at each induction stroke, the carb must mix this air with fuel so that is meets the correct fuel air ratio.

 

a bike carb, designed for a 1 litre engine, will expect 125cc of air for each induction stroke.

 

correct fuel air ratio?

WRONG

 

2000 divided x 4 = 500cc

 

Bike carbs have a variable Venturi similar to SU carbs and they work on Minis and big Jags alike.

 

The port size of bike carbs is similar to Webers so you can find a diameter to suit, that said the variable Venturi does a lot of the work for you.

Then it's the needle/main jet/vacuum combination.

 

They work and they work well for less money than Webers

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My maths may be out, prob late, prob to much beer, but the challenge of my previous post till stands.

 

I can't cite any learned paper in relation to the use of bike carbs on a pinto engine but I can say that the use of bike carbs on a pinto engine was recommended to me by Richard Hall at GBS, who, at that time had them fitted to the then zero demonstrator.

 

In fact, having accepted that advice, GBS sold me the conversion kit consisting of bike carbs and inlet manifold to suit a 2.0l pinto head, surely they would not have done so, or even offered the kit for sale, if they knew it was not fit for purpose.

 

I later identified the carbs as being from a Kawasaki zx6r a 600 cc motorcycle (150cc per cylinder).

 

My car with bike carbs fitted was assessed and prepared for IVA by Simon Firth at GBS who took it for the test.

 

I received detailed feedback on all aspects of the car and the remedial work required for the IVA but nothing was said about Bike Carbs being unsuitable for a 2l car engine.

 

Since I was paying for a preparation service for IVA which includes an emissions test, I would have expected to have been told that bike carbs were no better than a fuel tap (if that is true).

 

I don't know Richard's and Simon's qualifications but I was prepared to accept their advice based upon their apparent experience and relied upon the technical knowledge of GBS to ensure the engine in my car passed the requirements of the IVA.

 

In any event my experience with bike carbs was good, I found them easy to maintain in balance once I was shown how to do it at the rolling road session, they gave good performance and reasonably good fuel economy.

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I would go FI too

 

it is nothing to do with RPM.

 

one cylinder of a two litre engine, is 250 cc per cylinder.

 

air flow dynamics accepted. each cylinder would draw in approx 250cc of air at each induction stroke, the carb must mix this air with fuel so that is meets the correct fuel air ratio.

 

a bike carb, designed for a 1 litre engine, will expect 125cc of air for each induction stroke.

 

correct fuel air ratio?

 

I disagree and I think it has everything to do with RPM;

 

One cylinder of a 2ltr car engine = 0.5ltr capacity per cylinder per stroke.

Once cylinder of a 1ltr bike engine = 0.25ltr capacity per cylinder per stroke.

 

The cylinder draws air every other revolution.

 

At 6000 RPM (typical car engine red line), one cylinder on the 2ltr engine would be drawing 1500 ltrs of air per minute through the carb barrel.

 

At 13000 RPM (red line figure of a cbr1000), one cylinder on the 1ltr engine would be drawing 1625 ltrs of air per minute through the carb barrel.

 

So by my understanding, bike carbs are able to handle the mass air flow rate that a car would put them under.

 

Fuelling on the other hand - for every intake stroke, whilst the bike carb can provide enough air as calc'd above, the car engine would also need more fuel due to it's larger cylinder capacity (for every suck, it can get all the air it needs but not enough fuel), which to me explains the reason why the jets on bike carb need adjusting / enlarging to suit a car applications.

 

Lets face it, if people didn't get acceptable results from bike carbs, they would be as common on car engines as they are currently.

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The topic started with a simple question, the choice was not given, but quickly came down, from memory, I am not bothering to read it all again, to bike carbs, car designed carbs and FI. FI was dismissed, through cost I believe, so we are left with the current discussion.

 

I really am not that concerned with what people fit, I, like a lot of other contributers, simply offer my opinion. If we are comparing bike carbs for a one litre engine on the side of a two litre engine, and cards designed for a two litre engine ? That does not mean they won't work, they do, but in a fashion, and not efficiently.

 

Who cares, they work!, True but we are comparing which is the better.

 

Bike carbs are constant depression, like the old SU, if were discussing those, they would win hands down, you prob have them on you V8 Steamer, if you still have it, run the engine and watch the sliders, the movement is pergressive, and smooth, because the air flow is constant, even at full throttle the sliders do not top out. Now have a look at bike cards on a 2 litre, the sliders pulse, because the air being drawn through only happens on induction, why the high rpm argument is a myth, At anything over half throttle they are jammed full top, especially if they are designed for 600's, you can tinker with the jetting, but with the slide at full top, thats just a bigger main jet, possibly lift the needle, but very few tuner's play with the air compensator, because the slides are jammed to the top even at cruising so air compensator does not come into play.

 

Best reason for use they are cheap and give the power we all desire.

 

IVA, now there's a test, yes you can get them through, on an old engine the standard is achievable even with opened mains as the adjuster has effect over a greater range of throttle. Current emmision are possible, solder up the main, lower the float level, drop the needle, and in bad cases bleed air into the manifold, you can get them through.

 

As for the advise from GBS? They sold you the cards and a manifold, think one was the owner, the other an employee, qualifications? perhaps one of them would be prepared to give the technical evidence for my challange. :-)

 

OK, I joke, pretty sure Ozz knows me anyway, regards to all the kit world.

Edited by knights_templar
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