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#301531 - 03/05/10 2:37 pm 4 Amal Concentrics on 4-cyl Car engine?  
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ian928 Offline
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Norway
I am not sure if this is the correct forum to ask about this, but I am wondering about putting 4 AMAL Carburettors on my 1965 Triumph Spitfire with 1300ccm engine.

My initial plan has been to use 4 keihin carburettors on my engine with bigger cam and lower compression as this swap has proved to be successful by others. But, after we bought a new carburettor for my Girlfriends BSA Victor, I started wondering about using four of these. The main reason to do it would be the period looks.

One problem I can see is that these carburettors don't have a choke mechanism, and I would like not to have to open the front each time I start the engine cold. This could of course be solved with a mechanism that push on all plungers when I pull the choke.

The real question is: Are this a good idea, or should I just go for the modern carburettors? I know the Amals don't last very long, but this is purely a hobby car, so that doesen't concern me much. How about different size jets and needles, are this available to make the carburettors run right for any application?

#301534 - 03/05/10 3:07 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: ian928]  
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Alex Offline
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Seattle
Find yourself some DCOE webers or some DHLA dells. Most motorcycle carbs don't have any acceleration enrichment, which cars seem to like and I just can't imagine what a PITA trying to couple all those slides to a pedal and the tickler thing would be.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
#301548 - 03/05/10 4:34 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: Alex]  
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hh Offline
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British Columbia
I second the recommendation for the Weber. A single DCOE45 would work nicely. I used to run one on a 1380 Mini and there's nothing that sounds like a Weber with the throttle WFO. David Vizard mentions the use of Amals on Minis in one of his books with an 8-port head, but he didn't elaborate much. I think it would be much more trouble than it's worth. The beauty of the Weber is two throats linked together and a very effective enrichment system. Tunability is also excellent with a wide range of adjustments throughout the throttle position range.


"Beer is proof that God loves us and wants us to be happy" - Benjamin Franklin
#301563 - 03/05/10 5:55 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: ian928]  
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Stuart Online content
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Scotland
Hi,

Originally Posted By: ian928
4 Amal Carburettors on my 1965 Triumph Spitfire

Don't know about the Spitfire but four Concentrics on a crossflow head was definitely a (expensive) 1960's and 1970's tuning mod. for Minis. If the Spit uses the BMC 'A'-series engine, it obviously won't be impossible, but you'd have ask yourself whether the work and expense are worth the hassle, particularly when you might have continuing hassle with things like no choke (unless you use Mk.2 Concentrics?), keeping four Concentrics balanced, etc., etc.

A better site to continue your enquiries is probably somewhere like the Mini Register. Btw, if the Spit does use the 'A'-series engine, take a look at the modification that uses the head and fuel injection system from a K100 BMW. Might be easier to live with than four Amals? wink

Hth.

Regards,

#301588 - 03/05/10 8:31 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: Stuart]  
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ceefer Offline
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The Spitfire engine is completely different from the BMC Mini motor, coming from a rival firm. It was derived from the earlier Standard 8 engine which came out in the early 50s.

A friend of mine had the six cylinder version in his GT6 and became fed up with constantly trying to keep the carbs in tune, so fitted the injection system from the Triumph 2500 PI. It went like a scalded cat and it was all in keeping for the age. Perhaps something similar could be grafted onto the Spitfire?

Regards,

James


James Alford
Copper Water Features and Garden Ornaments
www.craftedcopper.co.uk
#301602 - 03/05/10 9:27 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: ceefer]  
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ian928 Offline
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Norway
Thank you guys! Yes as james said, this engine is not related to the BMC unit.

I did not think about acceleration enrichment! I wonder why this is a bigger problem on cars than on bikes?

The enrichment problem will probably be the same with the Keihins, although I have heard they work beautifully?

It is to bad there are no smaller SU's, I love those carburettors and would like to have 4 of those instead of 2.

Here is a picture of a Spitfire engine with Keihins:
http://www.triumphspitfire.com/images/engine/rickengine.jpg

And yes, you can make the PI work on a Spitfire, this guy say in his webpage that he has "some drawings and the calibration curve". He also uses the same camshaft so in fact I could do the same as him:
http://www.lucasinjection.com/4_cylinder_triumph_spitfire.htm

#301623 - 03/05/10 11:37 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: ian928]  
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MarksterTT Offline
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ian928, I like the above recommendations of Webers etc., would stay far away from 4 amals for reasons stated; linkage,choke and especially lack of accelerator pump not to mention wear problems. The rack of 4 CR Keihins or Fcr Keihins(which have accel. pump) look good, could adjust intake length to optimize, come already racked together for easy linkage setup, however, are a bit pricey. If you like SU type carb and want to experiment, you can pick up CV type motorcycle carbs with accel. pumps off eBay by the truck load, removed from Harleys etc. Most of the Jap bike CVs don't have accel pumps but Mikuni and Keihin are available in all sizes for cheap. Once set up, dual CVs with split manifolds, accel. pumps, good air cleaners would probably work great and yield good performance and mileage and did I say they are cheap on eBay, a lot of Harley's are removed from brand new. I believe CVs of about 2mm larger throat size then non CVs should be considered due to restriction of throttle butterfly valve in CV carbs...good luck there...mark

#301934 - 03/07/10 10:32 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: MarksterTT]  
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GrandPaul Online content
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Forget that whole idea.

Get a targetmaster Chevy 350 and drop in with a Holley 600.


GrandPaul (does not use emoticons)
Author of the book "Old Bikes"
Too many bikes to list, mostly Triumph & Norton, some BSA & European
"The Iron in your blood should be Vintage"
#301968 - 03/08/10 2:08 am Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: GrandPaul]  
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dave - NV Online content
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This discussion brings to mind a carb setup I saw years ago. They had mounted 6 Monoblocks on a destroked 90 ci Ford Falcon 6 cyclinder engine in a Midget runnin on the paved 1/4 Mile in Denver. Another attempt to beat the high cost of racing with a Offy engine. I remember it had a great shriek coming off the corners but no wins..

Someone mentioned DCOE45 Webers ... I have a pair on my partially dismantled '69 2002 BMW that's languishing in rental storage. Yuppers, WFO with those babies honking is uuhh fun.


dave - NV
#301979 - 03/08/10 3:30 am Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: dave - NV]  
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DMadigan Online content
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You do not need accelerator pumps on CV carbs because the rise of the slide is vacuum controlled, not operator. Take any AMAL carb'ed engine and whack the throttle open from idle - it will die due to fuel starvation. The slide type Keihins in your picture will do the same.
Depending upon what size you are after, they can be picked up fairly cheap. I got two sets of 30mm dual CVKs for $50 and $78.
If you are determined to use Amals, look at the gantry on the triples, just add another carb. Feed the fuel to one end of the fuel rail and return the other side to the tank (or input of the pump).

#302516 - 03/11/10 4:34 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: DMadigan]  
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ian928 Offline
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Norway
I really like the idea of the Keihin CV's, they are almost like small SU's! I did a search on the net that they have accelerator pumps though, wonder why they don't have the damping function for enrichment like SU's or Strombergs?

DMadigan, you mention CVK's it looks like the Kawasaki ZZR600 have 4 36mm Keihin CVK's this looks like a promising setup!

And regarding engine swaps, yes I have thought about it, I even have a Triumph GT6 engine (6-cylinder) in my worhshop that I planned to use. But this is a Spitfire Mk1 and they are getting rare. Plus a heavy engine upsets the balance of the car and the drivetrain can't handle much torque. I have another Spitfire, maybe I will get wilder with that one.

#302560 - 03/11/10 8:51 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: ian928]  
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Alex Offline
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I would say resist the temptation to put more cylinders in there. Particularly the total redneckification suggested by grandpaul. But no matter what you use to power your Mk1, be very careful in the corners. Two words: Camber Tuck!


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
#302572 - 03/11/10 9:39 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: Alex]  
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ceefer Offline
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England
Originally Posted By: Alex
be very careful in the corners. Two words: Camber Tuck!


My Mk 1 Vitesse 2000 used to have the same rear suspension as the early Spitfire and its handling was truly evil. It was fine in a straight line, but corners were a worry. I cured it by fitting the rear spring from a later MKIV Spitfire. It had a pivot in the middle: this lowered the back of the car, reversed the camber and completly transformed the handling.

If you upgrade the power of your Spitfire, this might be worth considering, assuming that you have not already considered it.

Regards,

James.


James Alford
Copper Water Features and Garden Ornaments
www.craftedcopper.co.uk
#302691 - 03/12/10 3:40 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: ceefer]  
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ian928 Offline
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Norway
Thank you for your concern! I have driven a Spitfire Mk2 for 10years, and I know about Camber Tuck yes! I almost overdid it once by driving much to fast into a long fast turn. I felt the rear outer wheel wanting to tuck under, and had to keep on accelerating to bring the rear end down through the whole of the turn. I just made it, but had to pull over and take a rest afterwards...

I could have fitted a MkIV spring, but this makes the car understeer and I don't like that. The idea of the pivoting spring is that when the car tilts in a turn, the front outer spring stops the tilting, and not the rear (it just pivots), thus there is not much force eceeded on the rear wheel and it will not tuck under as easily.

I have fitted very stiff front springs at the front, this makes the car turn flatter and stops tuck-under, plus at the rear a "lowering block" between the transverse leaf spring and the differential. The lowering block lowers the car, changes the camber and the angle of the driveshaft so that cornering pushes the rear end down instead of up. You still have to be very careful not to move to much weight forward during a turn or you will be doing a 180 turn faster than you like!

When you fitted the Spitfire MkIV spring to your heavier Vitesse you also lowered the rear end of the car, getting even safer handling.

#302894 - 03/13/10 5:40 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: DMadigan]  
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tomterrific Offline
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Columbus, Ohio, 1978 T140E
My friend bought a cheap Spitfire from a junk yard for $200. He sold the engine and transmission and dropped in a V6 and 4 speed from a 74 Capri. The first time I drove it Steve cautioned me not to floor it in first. It's a loud fast car! I coined the name Belchfire! :^)

of course I forgot my point. The Spitfire weighed 50 pounds less with the new engine and trans.

Tom Graham

Last edited by tomterrific; 03/15/10 7:26 pm.
#307263 - 04/09/10 2:57 am Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: DMadigan]  
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norton bob Offline
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for a period look a couple of Sromberg CD 125/150 carbs on an Alexander Manifold work ok,hard to find tho!

#307284 - 04/09/10 8:44 am Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: ian928]  
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Pete R - R.I.P. Offline
In Remembrance
Pete R - R.I.P.  Offline
In Remembrance

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Vic. Australia
Its pretty hard to beat Webers (DCOE)and they're user-friendly and well made.I even run one on a Triumph Bonneville.It helps if you know that emulsion tubes are related to cylinder size,I use F11.Pilot jet area is proportional to cylinder size and idle speed.
The next best thing is C.V. carbs.
In either case the biggest butterflies necessary would be equal to the head of your intake valve,but 40mm Webers will do the job.Effective throat/choke/venturi diameter can be up to 80% of butterfly diameter.

#307623 - 04/11/10 6:29 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: Pete R - R.I.P.]  
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MarksterTT Offline
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PeteR, any chance you could post a pix of that Weber equipped Bonnie? Mark

#307647 - 04/11/10 8:45 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: MarksterTT]  
Joined: Jul 2009
Posts: 3,549
Pete R - R.I.P. Offline
In Remembrance
Pete R - R.I.P.  Offline
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Vic. Australia
There's a fair chance,if I become more computer-literate or get some assistance.Need to move some other small projects to even get it out of the shed at the moment.
Please don't think this all fits in a standard frame,but it fits in a Rickman frame.
I'll try to arrange some pictures.

#307651 - 04/11/10 9:21 pm Re: 4 Amal Concentrics on 4-cyl Car engine? [Re: Pete R - R.I.P.]  
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MarksterTT Offline
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San Francisco Bay Area
That's fair Pete, I'm afraid I'm in the same boat computer wise, my wife says if it was a motorcycle I'd have it mastered by now. She actually got me on the computer years ago when muttering this short phrase "Hey, have you seen all the motorcycle parts on eBay?" Say what? says I. Mark



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