AMAL 289 questions

[R]

By the way, in consideration of the difficulty in synchronising eight of these wee monsters I have been reminded that in 1938 the approved method was to remove the exhaust manifolds and, in a darkened workshop, tune to the colour of the flame exiting the exhaust ports. Nice bright blue is good. Some Aston Martins had small plugs screwed into the top of each exhaust pipe, close to the cylinder head, which would be removed to allow viewing of the flame shooting past. These days we have Gunson Colortune plugs. Since I already have a kit I asked Gunson to supply just seven plugs to save me having to buy complete kits. They declined, so I made my own 18 mm. see-through plugs to assist the tuning.

I have a feeling that chasing eight of these is going to drive you nuts  !
Over to you ...

[33d6]

Having now seen the application can I ask a few questions? Do the carbs have identical part numbers stamped on the mounting flange? Having identical carbs is not as simple as it looks.

There is little point having this discussion if we don't know exactly what you have.

To me your carbs look like post war 289's not prewar. It does make a difference.

If there are different numbers stamped on the mounting flange can you please list the numbers.

Cheers,

[R]

I pondered that too.
If the heads were done postwar ?. then the carbs would have been too. ?

Also, the carbs don't have the 4 airholes that mark prewar carbs ?
Maybe they do have the airholes, I can see one there ??

[chris mac]

Is this pin hole threaded ?  I can only think this may be an air injection to improve MPG

[R]

This is the little hole in question ? (arrowed)
(Pardon the baby beat up 274.)



I can recall investigating what this was for, but don't recall the conclusions !

There are quite a maze of passages in Amals, its black magic that they contrived to get it all to work ... !

[john.k]

Behind that is a through hole in the jet block that is listed as small primary air/fuel drain to prevent the engine filling with petrol when parked and the tap left on......Obviously this only works as a drain when the carb is conventionally mounted .......and furthermore ,this feature is absent on the prewar carbs .....which are somewhat different in the jet block as well ......This is because the  jet block  air comes in through four holes in the carb body ,and corresponding holes in the jet block ......this air is unfiltered ,and the system was changed in WW2 ,when engines were wearing out in 3000 miles in the choking dust of the Libyan desert.................Consequently ,I suspect this is the reason post war 2 prefix carbs wont work in odd positions............More to follow.

[john.k]

Yes ,agreed ,the carbs on the fabricated manifold are postwar......prewar carbs quite clearly have four large holes .two in either side ......postwar 2 series(289) have only the front internal intake .........The other pic with the Holley also has a 4/71 blower mounted beneath the carb.......now while the 4/71 came out in 1937,the blowers were so expensive as a part  that no one in England would have used one........However ,now they are worth diddly,as the GMs are just scrap (except to a few one percenters who think everyone likes noise).......I have several 4/71 blowers I saved off compressors when the sandblasters sold out.....also one off a 6v71............The favoured one is of course the straight 6 blower off a late 6/71.,next the blower from an 8v71.

[Amal289]

I'm glad I came on here - thanks for your interest, chaps.

All the carbs are stamped 289/014. None have air holes in the base. According to information on Hitchcocks website
https://tinyurl.com/y36zdlns
"... the standard design where the primary air to the main jet and the pilot jet system comes in jointly through the main air intake, see figure 3, sheet 3 . The type numbers are 274, 275, 276 and 289. An alternative design is made where the primary air to the main jet comes in through four visible ports around the base of the mixing chamber, and where also the air supply to the pilot jet system is separate. The type numbers of these carburetters are 74, 75, 76 and 89."
There is no mention of dates.

I noted earlier that the pin hole feeds through the jet block into the volume surrounding the needle jet - see photos below.

I also noted earlier that the original heads and carbs had disappeared from the car in the 1950s. Eventually a replacement pair of the two piece copper/aluminium heads was found in deepest Utah and very shortly afterwards a serendipitous meeting with the man who had just rebuilt Sydney Allard's Steyr-engined hill climb special led to the acquisition of the AMAL 289s from that engine, which had been replaced by GP Dell'Ortos.

Thanks to John.K for the description of the pin hole with "Behind that is a through hole in the jet block that is listed as small primary air/fuel drain to prevent the engine filling with petrol when parked and the tap left on." Please will you point me to the source of that - where is it listed, please?

I am coming to the conclusion that the fuel level should be set just below the centre line of the main jet. My fuel reservoir box (baffled) will be mounted on adjustable height pillars, and, being sealed and effectively fixed to the carburetters, will maintain the fuel level under all conditions of acceleration, braking and cornering. Well, that's the plan, anyway!

[mini-me]

why don't you discuss this problem with Burlen who make these carbs and who will provide you with all the info you need plus a set of matched carbs?

[Amal289]

why don't you discuss this problem with Burlen who make these carbs and who will provide you with all the info you need plus a set of matched carbs?

Thank you for your suggestion.
I have asked Burlen for information and await a response.
I have a matched set of carburetters.
Meanwhile, a number of folk on here seem to be interested in my project and are being helpful, for which I am grateful.

[Amal289]

Bang on cue comes the word from Phil Beresford at Burlen:
"It (the pin hole) is an overflow outlet to prevent fuel entering the engine in large quantities if the float chamber overflows."

[mini-me]

Where in Beckenham was the thing built? I used to live there when it was posh.

[Amal289]

Where in Beckenham was the thing built? I used to live there when it was posh.

After WW1 the Batten family business branched out from patterned linoleum machine design and build into motor car sales and then into special building. They were located in the old premises of Thomas Tilling, jobmaster and omnibus operator, at 181 High Street in Beckenham (now a supermarket).

[mini-me]

a country village then, it was in kent, now just another  suburban craphole.

[john.k]

I also note the aim of using a single carb per cylinder is air resonance in the intake ,and the overall length of the intake would need to be 15-20 inches long .......this is easily seen in the elaborate intakes of high performance US V8s of the 70s.