Sorry Pete you posted that before me!!!
I suspect that manifold will not fit a Rootes head. The runners are not equally spaced. That manifold does look familiar but it's not "ours" I can assure you.
The downset is unusual too.
Anyone have an idea what engine that fits?

Regards Eddie

I bought the new carb, a second hand manifold, bored out the manifokd bridge, converted the carb linkage to a cable setup (my car had all the linkage rods removed before I got it), changed the 0.55 idle jet for a 0.6
Fired it up no problem and it drives much much better than the twin 40's setup, 10 times better. Smoother, just as powerfull. It doesn't quite have the nice sound of the 40's but it still sounds sporty.
But, there's allways a but; idle is still a little lumpy and the very first bit of acceloration is very slightly hesitant'
Could the lumpy idle be down it it being a Holbay engine, different profile cam to normal 1725's?
I changed the 0.55 idle jet to 0.6 as advised but I read elsewhere that 0.7 jet had be used with good results, what do you think Ed.
Verdict - very pleased, it's nice just to have a couple of screws to mess up. I've just aquired a plenum chamber for the yop of the carb, will be getting a remote K&N filter setup

Well done Mackem, that's good news. As for the lumpy idle, it could be down to a warmer camshaft which may mean settling for a slightly faster tickover. The idle jet may well be slightly too small at 0.60 for a full blown Holbay motor. As they only cost £3 or so I'd get a 0.65, and a 0.70 as well, and then try again. My engine has a Holbay short end ( ie. the block ) but a standard 1592 head. Mine is happy with the 0.60 but this could change because we have now aquired a Holbay head as well and it could be used to develop the new manifold, so we could offer either small ported ( Holbay ) or standard ported. We'll take it as it comes one step at a time.
I'd be interested in your fuel consumption figures now as well.
Maybe not 48 MPG with your set up but I'd bet it walks all over the DCOE's.

It all seems to confirm that we are getting consistent results with this superb carburettor. The hardware costs of fitting this along with a new manifold are practically half that of a twin DCOE set up as well. Add the fuel saving and all the other benefits and it becomes really hard to ignore the fact that DCOE's are ultimately only suitable for racing and track days.
For road use the 32/36 DGV is peerless.
Of course there are a few other tweaks up my sleeve for you now Mackem if you're up for them. Say the word.
Best Regards Eddie.

I'm open to any suggestions, I think next on my list is electronic ignition, I see then advertised on Ebay but they all seem to be for Lucas 25D4, mine has the 23D4. is the same unit used?
And get my overdrive working, relay is not working. I've found a temporary set up on SAOCA using two modern relays, going to give that a try

Try this ( I'm presuming that you're not using the water heating on the manifold ).
Wrap the exhaust manifold headers with heat wrap tape. This will stop heat being radiated onto the underside of the manifold thus keeping the mixture cooler. This will become even more important once you are using the cold air induction system.
Also the heat wrap will prevent the exhaust gases cooling so quickly which will keep the kinetic energy of the escaping gases high.
This exerts more pull on the overlap and helps draw more mixture in whilst the piston is starting to rise on the compression stroke.

Definitely use a Lucas Sports coil for a fatter spark and I use 3 Electrode spark plugs. I am not using electronic ignition because I am using Lucas 32 oz ( Mini Cooper ) 2 piece contact set. These are available from Holden Vintage. Genuine brown old stock points. They look like they are made from brown paxolin.

They seem to last forever because the contacts are made from platinum, the heel NEVER seems to wear. You NEVER get a pip or hole on these babies I assure you. If points were still made like this no one would have invented electronic ignition. In eight years the gap hasn't even thought of closing up. And the strong 32 oz spring prevents bounce. Use a genuine Lucas condenser and it all performs as well as any electronic ignition. But you do need a dizzy with the long pivot pin to use these points. The advantage with this set up is you can fix it if anything plays up.

Don't forget to use a decent set of HT leads.
No carbon trace rubbish only metal cored leads like MagnyCour or similar.
Good ones usually have silicon insulation.
The multi electrode plugs with all this perform mind blowing wonders. I swear by Champion.
Try it all one step at a time.
Best Regards Eddie.

Quote; But, there's allways a but; idle is still a little lumpy and the very first bit of acceloration is very slightly hesitant'
I would think the 23D4 will contribute to these symptoms too.
Pete

The 25D4 had Vacuum advance to cater for light throttle conditions, Where as on the 23D4 used mainly on "Hotter" engines it was omitted, relying solely on the centrifugal advance
Pete

Vacuum advance is mainly for clean running on the overrun. ie. it prevents backfires, during high manifold depression states. At idle, although there will be a degree of advance or so ( on a Holbay with hot cam remember ) this wll not be significant, in this case.
Since hot cams usually produce erratic idle due to fluctuating manifold vacuum, I don't suspect the distributor in this case.
Peter's car with the fast road cam exhibited exactly the same behaviour as Mackem is describing. In Peter's case he was using Arnoud's distributor which does have vacuum advance so I tend to feel this hesitation is due to the idle jet still being too "lean" on transition to the primary circuit.

These twin choke carbs rely on the idle jet at small throttle openings after idle and before primary transition so for faultless operation it must be correct. If other people say it needs to be 0.70 then I have no reason to doubt this may be so. In which case I would try that first before touching anything else. Don't forget either that you will need to adjust the Volume control once again, to get smooth running at idle, since the larger jet will upset the mixture on tickover.

If you do decide to fit electronic ignition I would investigate the Pertronix modules which should fit your 23D4.

Best Regards Eddie

Maybe jumping forward a bit here Eddie, but you touched on exhaust manifolds earlier. From reading DV's manual the exhaust set up plays an important part in tuning. Has any research been done on the optimum for the Alpine? I've been checking e bay out and there seems to be a few different ones fitted to the different Rootes models, variouse shapes and sizes. I know whichever one would need modding but obviously some would be better to start with than others.

The type of system fitted to the early cars 2 X 2 into 1 then 2 into 1 at a Y piece is very good at producing high velocity gas flow and a good "extraction" effect. The Series 4 GT's ( my car ) were fitted with a fairly compact cast iron manifold which largely aimed to quieten the engine rather than extract the last ounce of power out of it.
Consequently I fitted the performance stainless steel manifold sold by John Hayter of the Berkshire Sunbeam Alpine Centre ( now in Spalding ) as part of the Falcon S/S system.
This replicates the early Series car's exhaust manifold but in larger bore.
DV would approve of this layout as it equates to the LCB system on the A series and ticks all his boxes.
The results speak for themselves, even with the 28/36 this was a milestone in performance improvement for my car.

With the work looming over the winter ( NZ manifold ) I will take the opportunity to improve on this by wrapping the headers in heat bandage to insulate the pipes thermally. This will produce improved power on 2 fronts.

1. Reduce the amount of heat radiated and convected from the headers thus preventing the inlet manifold getting hot and diluting the fuel /air induction charge.
2. Maintaining a high velocity of gas in the headers ( cooler it gets the slower it goes ) and producing a stronger pull or extraction on the incoming charge.

The thing is that all these tweaks which are by themselves fairly innocuous, once they start adding up, the extra power is unmistakeable.

The Falcon SS performance manifold is a very good bit of kit, not cheap but good stuff rarely is these days.
Best Regards Eddie

Take a look at this set up. Since the supercharger has yet to be fitted it affords a very good view of the SS Exhaust manifold fitted to the Mog.

Only registered users can see links on this forum! Register or Login on forum!

This is the LCB system so beloved by DV ( Long Centre Branch )
Remember the centre pipe actually carries the flow from the two centre cylinders.
It is not too disimilar though to the Alpine one and will improve throughput enormously.

You'd try hard to better this sort of set up.

Best Regards Eddie

I take your point there and if your experience is with stainless steel which is already brittle then I agree the ceramic coating is a better engineered solution. On my car the performance manifold has very adequate ground clearance and maybe this has a bearing on how successful the heat wrap may be.

Time will tell methinks, but thanks for the input here. It may be needed later on. I take it you saw an increase in performance though ?
Best Regards Eddie

My headers were made of regular steel,however the rest of the system is 2"SS. I didn't notice any real increase in HP. The biggest 'bolt on' changes to horsepower were the removal of the mechanical fan and water pump replacing them with an electric thermal fan and electric water pump (only comes on when needed).