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[ V8 Engine Fitting Information ] [ Rover 3.5, 3.9, 4.2 to 4.6 Conversion ] [ LPG Conversion details ] [ Fuel Injection Section ]
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A&R Dual Timing Modual & A&R Power Amp 'uses and explanations' FAQ section

A & R Amp.

The A&R power amp Upgrade and 'Tech. Support' pages.

Which Ignition upgrade is most suitable.
A&R amp frequently asked Questions & further Information
Some LPG Frequently asked Questions
Rover V8 Distributor Variants - Wiring Details.
A&R Amp. And Mallory Duel point.
Update on early A & R Amp Specification?.
Customer Comments
I have a Discovery with the A&R Amp. I am now experiencing a missfire what can it be?

RPi's Unique A&R Ignition amplifier.

Breaking new ground in appropriating V8 Ignition systems for Stand along upgrade or LPG use and improving significantly in Spark output. With so much to gain, it makes you wonder why most others don't even consider it, but then most specialize in LPG for all, not just V8s

Information about the A&R amp

Check out this build quality & features list.

.A & R Amp.

Internal View or the Dual Timing A&R Amplifier.

The A & R Power amp.
Unique to us and hand built by us, this unit offers superb spark enhancement.

Simple fitting for easy DIY installation.

Has the ability to run dual timing for LPG or as just a standard ignition amplifier.

And if that's not enough it also turns single and dual point distributors into fully functional electronic units.
Free return to base lifetime warranty.

A & R Amp. And Mallory Duel point.

Our A&R Unit is now fully compatible with the Mallory Duel point distributor so now you can have the 8-10 degrees extra dwell from dual point switching, giving optimum coil charge duration plus the reliability of the electronic upgrade, giving zero points wear (the points become low voltage switches) & optimized Spark output, Due 40% extra dwell.

The Mallory dual point is one of the best ignition options for all non-Efi engine applications. Indeed, short of mappable ignition, we believe with the addition of our A&R unit the Mallory Dual point is second to none.

More on Ignition issues & Mallory 'Click'

Update & Advice on early A & R Amp Specification.

Never underestimate the quality of Std, O/E, or High street spec. ignition.

A typical email. Thank you for helping me sort out my misfire problem with the amplifier. You may recall when we spoke that I said that the misfire was when on LPG when the engine was cold. You recommended fitting Magnacore leads as well, but as I had new Lucas leads fitted I said that I would try them out with the amplifier first. The result is the engine is sweet as a nut when cold and a definite improvement in power and fuel consumption.

I am very pleased with it and will be recommending other gas users I speak to. Yours sincerely Peter Munday

Misfire at high rpm or high engine load areas.

Although there are now over 1,000 of these A&R units supplied, a recent glitch has been encountered with only a few later date Rover V8 models (94 - 97) and only those fitted with engine immobilizers as std.

The problem seems to manifest itself as a very small misfire or, when severe, as though it has a rev limiter, set to about 4500 or 5000 rpm.

Having encountered this problem only 3 times In all cases it has been replaced with other non-original amps and the same has occurred, Also the A&Rs have all been re-tested on other vehicles to find, in every case, that the unit is functioning perfectly and no misfire is present.

The conclusion; having spent many, many hours swapping out units to test in various V8s, it is most likely a problem with the car's own original engine immobilizer system especially as this is the only thing that all these cars have in common.

The only solution in this case is to take off the A&R or any other dual timing device and fix the problem before any of these type upgrades can be used on your vehicle if you encounter the same.

Starting Problems or unit failure on start up.

In cases of starting problems, check the following section.

A design modification was later introduced to increase the sensitivity of the distributor trigger input at very low starter cranking speeds; units will already have the modification incorporated if either:

a) Serial no. on bottom of case is 1026 or higher.

b) There are 2 small 'dimples' in the case bottom near the end where the power/coil cables enter. If either (a) or (b) is true then this modification is not required.

Units before serial no. 1026 (or with no serial number) and which also do not have the 2 dimples in the bottom may well suffer loss of spark at very low cranking speeds, such as may be experienced on very cold mornings with a somewhat less than perfect battery. Modification (carry out yourself [we supply parts] or send unit back to us).

FAQ - section

The Dual Timing system sounds good but I don't know whether I need it or the dual point, or both?

Chris, I have a V8 Discovery G Reg converted to LPG. It has Carburettors. None of the Ignition system has been touched , and I was getting problems so I've changed the spark plugs, leads (all with standard for V8) and got some improvements. Reading up on your site it seemed to explain better what's wrong. What parts do you recommend that will fit my vehicle and will improve performance for the LPG?
The Dual Timing system sounds good, but or don't know whether I need it or the dual point thing? Also a Range Rover F Reg EFi LPG Converted, what parts do you recommend.


Assuming all is OK with your LPG system (at least), you will first maybe want to consider using your existing distributor with our A&R dual timing amp (Click)

however as most O/E distributors are far from being in good order mechanically (with regard to both vacuum and mechanical advance ability & correct function), & with shaft and gear wear also commonplace, this for sure will cause severe timing scatter.

The following Distributor checks are essential (Click) and need to be done thoroughly. Even this is not conclusive as we have had some O/E distributors as new as 1996 with new O/E amps fitted that still gave big performance losses with no signs of a problem mechanically or showing up on our tuning equipment.
Caps Leads 'Magnecor' (Click) and Rotor are also very important, and again, even new std equipment has given us problems so we default if possible to using only the best available and certainly avoid High street level equipment regardless of the 'miracle' claims and low prices.
Better still, swap it for the Mallory Duel point (Click) 'new distributor' and instantly gain from the additional Dwell and subsequent spark voltage increase, And better still, add our dual timing amp to it, and change it to a very high performance electronic system with the advantages of both, and the points will then become low voltage switches and last a lifetime.
Also this way, if you ever have any problems with the Electronic A&R unit, we repair it for free and you can still revert to the original points for continued use and get you home magic!

Other alternatives include: to use a brand new original equipment distributor or a Mallory Unalite, both are very good options but offer less or cost much more. I think the above would be appropriate for all V8s on LPG, and the single timing option A&R is perfect for non-LPG V8s.

The following feedback and information has kindly been supplied/inspired by Roy Allen.

Hi Chris, Many thanks for you help recently. Regarding my LPG blow-back problems. The Magnecor leads did a wonderful job!
The A+R Amp is fitted but not connected at present. On carrying out the ignition system checks you recommend, I found that the Centrifugal Advance was very stiff and did not "snap back smartly". The Vacuum Advance also did not work at all (so much for Main Dealer servicing).

I am ready to connect up the A+R Amplifier unit. Please could you answer a few questions for me.

1) The accompanying fitting instructions describe how to change various settings within the A+R unit. Am I correct in assuming that these have already been done for my requirements and I do not need to change anything?The motor is a 1993 Discovery V8i 3.5 Litre with Catalysts removed (Stainless Steel Sports Exhaust system fitted) and a Bedini LPG conversion.
Yes the A&R amp is pre-set and this is normally correct for all road applications

2) Can I get the Ignition switched 12V +ve supply for the A+R from the +ve terminal of the new ignition coil? Or could you recommend a better connection point?
I may need to confirm this, but I believe this is the correct point to take it from,

3) Setting the timing with the engine running at idle on LPG and the Vacuum Advance disconnected (and plugged) do I just move the distributor until I get 18 degrees BTDC advance?
Yes !

If this is correct when I switch back to petrol at Idle the advance should be 8 degrees BTDC?

In theory yes,but realistically the delay does not step in until about 1500rpm on petrol (at this point timing has become less erratic than at lower revs) you can tell it's happening because the red LED will illuminate, so under this timing will be the same for both LPG and petrol. You will find the petrol will be happy with this extra advance initially and should give a better idle. Also you can tell if you overdoing it because there will be a hesitation on LPG at around 1500rpm, if so, then 18deg may be too much, in which case take out 2 more degrees of timing mechanically and it should disappear, similarly you should also be able to try more advance than 18 deg (some run best as far as 22deg,) so as you can see there is sometimes more to be had with a little bit of trial and error testing.

You are also assuming the A&R amp is set to take out 10deg, I think in most cases the pre-set in these units is set to about 8 degrees of retard. Bearing this in mind try your first installation at 16 deg rather than 18deg as stated.

I would like to add that it is not that fussy, the above information is to help/assist in getting the very best from this unit.

I drive in remote areas, where the module for the standard Lucas electronic distributor is unobtainable. I want redundancy.

Can I wire the RPI A&R amplifier in such a way that I can get home on either the Lucas system or the RPI system?

Yes! The A & R amplifier can be triggered from the Lucas BLMD8 module, so that can be left in place. It's done by using the RPI amp in "points" mode (per included instructions), with the red trigger wire connected to the Lucas BLMD8 module coil output wire.

With this configuration you have all you need in place in the vehicle to cope with an electronic ignition breakdown, as long as you pack the things you need to move connections. Including RPI's instructions and the supplied probes to fit the distributor. If the Lucas unit should fail then you can remove it and connect the RPI unit directly to the distributor reluctance module, exactly as per the instructions supplied with the RPI A & R amplifier.

On the other hand should the A & R amplifier fail then by reconnecting the Lucas output wire to the coil you can run using the standard ignition. Interestingly with this setup if you care to you will be able to compare the way the engine runs between standard and with the RPI unit. The RPI unit is designed to put more energy into the coil, so producing more heat.

You will find the engine runs better with the RPI unit under conditions where the standard Lucas module produces a marginally adequate spark.

I have a high compression engine, how do I set timing for high octane premium unleaded petrol?

The short answer is to get a reputable tuning shop to do it for you. However a couple of words of caution are needed here. First of all many shops are unaware that the ignition timing marks on Rovers are not reliably accurate, and that they must be checked by turning the engine to top dead center with number one plug removed. A pencil in the hole will reveal top dead center accurately.
Secondly many organizations fail to get Rover electronic fuel injection set correctly, and merely set up for the right emission parameters at idle RPM and at say 2000 RPM with no load. You may well get your vehicle back from "shonky-tune" running over-lean or over-rich at high power.
You do need to use a genuine expert with Rover EFI, or you need to learn about the systems
A mixture that's too lean will increase the chance of detonation damage. OK so let's assume you are getting into this yourself. First of all ensure that you have pure high octane fuel in the tank by consecutively using at least four tanks of good brand premium fuel purchased from a reputable site with good turnover.
Second ensure that your distributor, plugs and plug leads are in top shape. In particular the vacuum and centrifugal advance mechanisms need to be perfect (sticking is common), there must be no air leaks. Now ensure the engine is running at 600 RPM or less (to inhibit centrifugal advance), with the vacuum advance hose removed or preferably plugged. Using a stroboscope set the timing for 6 degrees before top dead center. It's helpful to use correction fluid or white paint to mark both top dead center AND 6 degrees before (clockwise of) top dead center. 6 degrees is a good base setting, but may be too much advance for your engine. They do vary.
Reconnect the vacuum advance, and move on to road testing. If you have a carburettor system featuring a timed port (such as the superb four barrel Weber 500 cfm carburettor) then use the timed vacuum port (left side one on the Weber if standing in front). If your engine has electronic fuel injection you may find it helpful to include a vacuum delay unit which is cheap and takes only a minute to fit. Timed ports and delay units help ensure vacuum advance only happens when it is beneficial.
If you experience any pinging on the road then you will need to retard the ignition a bit. As timing is so critical retard the ignition by a tiny amount at a time, say one degree or as little as you can turn the distributor clockwise. Then repeat your road test, and retard again if you get pinging. As detonation is so destructive make sure that there is none at high power. Test full throttle uphill from low speed, preferably with the vehicle fully loaded. The idea is to eliminate pinging from all driving conditions, so anytime you experience pinging go ahead and retard the ignition one more degree.

Remember that too much advance will very likely ruin the internals of your engine, and if in any doubt get expert help. A modest amount of under-advance will not be destructive, but may make your engine 'fluff' when you accelerate away from low speed. If you are are needing to retard the ignition several times to eliminate pinging then consider whether top dead center was correctly established in the first place. Repeat the pencil test above.

Some LPG Frequently Asked Questions regarding ignition systems and upgrades.

What are the most important factors I should consider.?.
the most important issues. are with the actual condition and specification of your engine to run LPG efficiently.
If you first consult our "V8 Engines in general page" you can give yourself a good idea of what your engine condition is likely to be. There is little point in fitting LPG if your engine has a worn camshaft or leaking head gaskets.

LPG is a higher octane, what benefit can this have?
It is a know fact that LPG is up to 112 octane and petrol has continued to decrease in quality over the years and is now only 92 - 95 octane at best, This has caused manufactures to not only keep lowering engine compressions but to install ignition systems with less and less ignition advance. (early V8's 20 deg. and later ones only 12 deg.) Although we do not expect that adjusting you compression is a worthwhile upgrade, improving ignition spark quality and adding increased timing advance certainly is.

What can be done with ignition system quality and function (Carb Models only)
The best ignition system by far all Carb engines is The Mallory Dual Point, this will give the slower burning LPG 8 degrees more ignition advance and almost double the spark intensity off standard electron units, (higher octane requires better spark intensity to burn quicker) it will also (and perhaps most importantly) not be suffering from the normal mechanical wear that will be present in the advance system (Vacuum and mechanical) and shaft of a standard older distributor. (Mallory can be found here) Luminition on an Older distributor is a very poor compromise this added attention to your conversion will make the efficiency loss of LPG almost nil, For the Rover V8 with Carbs.

What about igniton Leads.
We have found the issue of "Backfire" on LPG conversions is nearly always caused by poor quality or older Plug leads, and often even new std quality ones will be problematic.
If not convinced you should try replacing going through a Hot car wash, and see how well it drives when it comes out. The huge rise in damp/humidity is sure to show up the worst in any lpg engine, with regards it plug wires.& igntion system. In all cases we would use spiral wound magnecore leads only.

Not only this but LPG being up to 112 octane not only wants a unique set of igntion timings, as explained above but it also needs a much bigger spark to get it going. Their leis the issue of not only replacing your Plug wires, but replacing them with a product that allows far superior igntion spark.

See the info on Magnecor leads, (click here )

I have a 1995 Discovery and have fitted your A&R Amplifier. I am now experiencing a constant missfire what can it be?
Assuming that you have a Lucas Cap and Rotor, with Magnecor plug leads then we would next bypass the Alarm Spider. From about 1994 onwards Land Rover used an alarm spider which had the ability to alter the ignition timing. A common problem with the Series I Discovery is for this Alarm Spider (called so because its a small black box with black wires comming from it like the legs of a spider) is for the unit to fail and for it to give a weak or interupted feed to your coil. On fitting our A&R amplifer which gives 100% spark output we rely upon a high quality supply to both the amplifier and also the coil. If you are having this fault once fitting the amplifier or even if you have a missfire before fitting our amplifier you should bypass the alarm spider. This is done by the following process.

The alarm box can be found behind the radio, so you will need to remove the radio and possibly some of the dash board covers. You will see a small black box with a multi plug with 10 wires going in to it. Unplug this box and then on the muti plug that is left going to the main wiring harness make the following connections.

Pin 2 to Pin 3 -> Fuel current cut off
Pin 4 to Pin 8 -> Coil power supply
Pin 6 to Pin 10 -> Starter Motor

For the very Technicaly minded the A&R amp can be used for other purposes.

The following feedback and information has kindly been supplied/inspired by Martin Geliot.

I have a high compression engine, which runs best on high octane premium unleaded fuel. I don't use LPG. Can I use the RPI A & R amplifier model intended for LPG vehicles to get a system that can be switched to safely run on ordinary unleaded petrol for when I can't get the good stuff?

Yes! Here's how. Set up the ignition timing for your high octane premium unleaded fuel. It is critical that this timing is correct, and must not produce pinging (detonation) on the highest octane fuel you use. Open the RPI A & R amplifier and adjust the retard potentiometer. It comes from RPI preset at mid-way (nominally 8 degrees of retard) which is a good setting for retarding from LPG to petrol.

This much retard will probably cause a flat spot if you have set your distributor timing for premium unleaded petrol instead of LPG. The amount of retard needed to change from premium unleaded petrol to ordinary unleaded petrol is a less, so turn the potentiometer clockwise a bit. Around three divisions of retard on the potentiometer gives about 5 degrees of retard, and is a good initial setting to try.
Purchase a switch for mounting on your dash somewhere. Ideally this should be one with an indicator lamp. If it's a single pole single throw switch (SPST) with a lamp it should have three connections. Connect the lamp terminal to +12V, ignition switched. Connect the middle switch terminal (other side of the lamp) to the blue wire coming from the RPI A&R amplifier. Finally connect the other switch terminal to chassis ground.
The lamp will light when the retard (ordinary unleaded, switch closed) setting is in use, and if the lamp should blow someday the system will safely default to the retarded setting. Position the switch so that the indicator lamp is not annoying at night.

You can test the installation as follows. Switch for unleaded petrol. The indicator lamp should illuminate, and under the bonnet you will see the red LED on the RPI A & R amplifier light when you rev the engine. Now switch for premium unleaded petrol. Neither the indicator lamp nor the RPI LED will light.
The retard mode will also be useful for when you are driving under extreme conditions that might cause damaging detonation, for instance when driving up sand dunes or when towing. Otherwise you can switch the retard feature out and safely take full advantage of superior petrol, so getting improved power, drivability and economy.

With this configuration you get the benefit of a hotter spark from the A & R amplifier, and as well get the very best from the superior fuels on the market. Why use high octane petrol, it is more expensive and is sometimes unobtainable?

Customer comments section

Customer comments has now moved to its own section (click)

This FAQ Section is solely for information exchange only, and RPi and its contributors accept no lability for any issues arising from following our printed advice, or subsequent costs that may arise from the same.
For our part we do our best to check all information provided and printed is correct to the best of our knowledge. And as V8 specialists for 15 years we don't get it wrong often.

links to other FAQ pages
[ V8 Engine Fitting Information ] [ Rover 3.5, 3.9, 4.2 to 4.6 Conversion ] [ LPG Conversion details ] [ Fuel Injection Section ]
[ Weber 500 & SU Carbs ] [ Mallory Ignition Systems ] [ General Engine Problems ] [ General Information ]

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Prices & stock are subject to change without notice. Information and advice, as always, is free.

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