rover P6 3500s exhaust / induction?

[paolow]

Can anyone help? ive binned my snazzy turbo and gone retro with an old rover. its lovely inside and out but dismally slow and not quite got the noise im after. What id like to do (sacrelige i hear you cry) is to cut out either the mid or back box to give a bit more growl and replace with a straight through piece of pipe. The question then - do i cut out the mid box or the back box? any ideas? the mid seems to be a resonator and the back a muffler. i dont want it too loud - just a bit growlier?
Also my twin SUs are probably not helping with oomph matters - im looking to swap them for a quad barrel holley 390 on a suitable manifold. will this reap rewards or is it not worth it really if im not doing any further mods? anyone able to help?
TIA!

[Huntsman]

paolow said:

Can anyone help? ive binned my snazzy turbo and gone retro with an old rover. its lovely inside and out but dismally slow and not quite got the noise im after. What id like to do (sacrelige i hear you cry) is to cut out either the mid or back box to give a bit more growl and replace with a straight through piece of pipe. The question then - do i cut out the mid box or the back box? any ideas? the mid seems to be a resonator and the back a muffler. i dont want it too loud - just a bit growlier?
Also my twin SUs are probably not helping with oomph matters - im looking to swap them for a quad barrel holley 390 on a suitable manifold. will this reap rewards or is it not worth it really if im not doing any further mods? anyone able to help?
TIA!

Leave the car as it is, change your mindset to gentlemanly wafting about.

[Sporting Bear]

Assuming this is not a wind-up:

Whilst not ultra fast by modern standards it should feel reasonable quick if it doesn't get it fully properly serviced (that's not just an oil change)

Exhaust noise is up to you

Sounds like you want a different car but I know there are some quick P6s about

If you've not already got one, an early auto or a manual 3500S would feel quicker

This is a wind-up isn't it

[paolow]

Wind up? im afraid not
the whole thing with the induction side is that its often somewhat unhappy with moving anywhere with any speed and itll sometimes drop 4 cylinders for a period of time before 'coming alive' again. I thought if i was going to change the carbs - i may as well go down the upgrade route no?
And the exhaust? well - v8s sound so lovely i just wanted to hear it a bit more!
I feel that there is more performance to be found in the car - it presently moves about as quick as a 1 litre H reg fiesta so something is clearly amiss and possibly a problem with timing / carburation. Im going to get it looked at but wanted to wait until i had advice on carbs as obviously its pointless tuning the ones ive got if theyre to be swapped.

[Nick_F]

Get it going properly and then decide what your priorities are for making it more entertaining to drive.

[Sporting Bear]

paolow said:

Wind up? im afraid not
. . . sometimes drop 4 cylinders for a period of time before 'coming alive' again.

I had this with a Rover V8 engined car with Holley carb and Offy manifold first professional "expert" couldn't find the problem after a week but the second (real) professional expert found the cause of the problem after 45 mins it was a vacuum pipe connect which should have been blanked off

It'll probably have absolutely nothing to do with your problem but always worth doing - for £40 you can get new dissy cap, rotor arm and leads, you'll be suprised what trouble these items can cause together or between them

paolow said:

so something is clearly amiss and possibly a problem with timing / carburation. Im going to get it looked at but wanted to wait until i had advice on carbs as obviously its pointless tuning the ones ive got if theyre to be swapped.

Sounds like you're thinkimg about crossing a bridge you may not even arrive at - fully service the car replace all service items even long term one like dissy cap ect. (P6B loves regular oil & filter changes and regular air filter changes) and clean and set carbs (clean oil in carb dampers) and then set timing ect. before think of changing carbs

Edited by Sporting Bear on Tuesday 18th September 11:43

[paolow]

ok - you guys have talked me round! im having a tune on monday and will go from there.
I think fundamentally its the lack of performance thats been bugging me so if that can be addressed ill be happy
Its very slow and very thirsty - fingers crossed for a fix!

[Sporting Bear]

paolow said:

ok - you guys have talked me round! im having a tune on monday and will go from there.

Paolo it'll be a wastse to have a tune up before you've given it a full service and checked/replaced leads ect., diagnostics Monday maybe

My 3500S (manual) returned (an indicated) 28 mpg on fast long dual carriageway runs but 17 mpg round town

Let us know how you get on, good luck

ETA: spelling as usual

Edited by Sporting Bear on Tuesday 18th September 14:32

[paolow]

Sporting Bear said:

paolow said:

ok - you guys have talked me round! im having a tune on monday and will go from there.

Paolo it'll be a wastse to have a tune up before you've given it a full service and checked/replaced leads ect., diagnostics Monday maybe

My 3500S (manual) returned (an indicated) 28 mpg on fast long dual carriageway runs but 17 mpg round town

Let us know how you get on, good luck

ETA: spelling as usual

Edited by Sporting Bear on Tuesday 18th September 14:32

i dream of MPG like that! i get an average of 16 on an 'urban cycle' and dont go above 2750 rpm in a bid for economy. this tune up will pay for itself hopefully!

[flat16]

Down under, they fitted the venerable P6 with 550 horses' worth of Repco-Brabham engine, you can see photos here: http://www.roverp6.info/Fotos/exWorksRacer/exWorks...

Whilst I'm not usually one for aftermarket styling, I absolutely love the look of the racing version with its skirts - it's the P6's delinquent cousin!

[Hooli]

as said above, service & tune it. they normally sound nice if a touch quiet & go well as stock.

[danhay]

I once test drove a P6 3500 that had 4 twin dellorto carbs. It made a very nice noise, and was indecently quick.

[Sporting Bear]

paolo

Did it go in Monday ?

Update us please

[paolow]

ok, its tuned up and running sweet. needed a new coil and a big adjustment to the throttle. it wasnt even opening 50% when foot was flat. Now its scarily fast! the difference is utterly phenomenal and im happy. well, apart fromt the sound which i still rekon is a bit muted, but its ok for now
one thing tho, the tickover has been adjusted down to 500 rpm and the oil warning light comes on when it gets this low. still shows about 15 psi but this is obviously an issue. going to readjust to 800 where it shows 30 psi unless theres a reason not to?

[Sporting Bear]

paolow said:

ok, its tuned up and running sweet. needed a new coil

Blow, so rare they go I'd forgotten to add to ignition parts

paolow said:

one thing tho, the tickover has been adjusted down to 500 rpm and the oil warning light comes on when it gets this low. still shows about 15 psi but this is obviously an issue. going to readjust to 800 where it shows 30 psi unless theres a reason not to?

tick over was probably set when engine was quite hot, 500 sounds far too low and 800 sounds a bit high, check in manual and remember your rev counter and oil pressure gauges could be slightly inaccurate

The oil pressure on Rover V8 engines are lower than other engines, TVR for their Rover V8 engines used to say not to worry unless the pressure dropped below 10psi on tickover !

Don't forget the engine loves frequent oil & filter and air filters changes

Don't worry about mutted exhaust it's part of the car, if you must have a bit more noise start with K&N air filters - lovely induction noise

[215cu]

Sporting Bear said:

paolow said:

ok, its tuned up and running sweet. needed a new coil

Blow, so rare they go I'd forgotten to add to ignition parts

paolow said:

one thing tho, the tickover has been adjusted down to 500 rpm and the oil warning light comes on when it gets this low. still shows about 15 psi but this is obviously an issue. going to readjust to 800 where it shows 30 psi unless theres a reason not to?

tick over was probably set when engine was quite hot, 500 sounds far too low and 800 sounds a bit high, check in manual and remember your rev counter and oil pressure gauges could be slightly inaccurate

The oil pressure on Rover V8 engines are lower than other engines, TVR for their Rover V8 engines used to say not to worry unless the pressure dropped below 10psi on tickover !

Don't forget the engine loves frequent oil & filter and air filters changes

Don't worry about mutted exhaust it's part of the car, if you must have a bit more noise start with K&N air filters - lovely induction noise

Firstly, congrats on getting one of the classic cars Daddies. Welcome to P6 ownership.

Sounds like the throttle cable had slipped in situ, very common

Here's some hints and tips to get more out for very little I can say these are all tried and tested and they work! The great thing with this engines is there's no computer to stifle any 'improvements'.

Also, I know the workshop manual for idle for P6 V8 is between 600 to 800 rpm. As for a 3500S, this will be 9.5:1 compression version down on power to the Mk1 V8s but they compensated for a lack of power through compression for a freer breathing exhaust.

One poster here said 'get it working proper first before tweaks'

Absolutely. Regular oil changes with Valvoline 20W/50 Racing and new filters is recommended. The filter change needs careful thought it is possible to vacuum lock the oil pump unless you do it right.

Here's the list.

Dashpots on the carbs. These SUs can ingest the carb dashpot oil under heavy acceleration. Keep these topped up, I use my auto gearbox oil but a light oil is perfectly acceptable, 20W/50 is too heavy. This makes a hell of difference in getting the right fuel/air mixture.

Crankcase breather filter, this sits behind and under the airbox and is well hidden. If this gunges up, it will affect engine performance dramatically. Easy to source, cheap (£3) and simple to fit.

HT Leads, get a good set of silicon free leads, not the cheapest set. Disconnect the old set one at a time and replace with new. V8s need a good spark.

Spark plugs, go for a very good Champion set and get the right spark distance set, plenty of WD40 as it's an ally head and off you go.

Rotor arm and dizzy cap, Rover V8 eat points for breakfast, at the least they carbonise quickly, 1000 grade wet and dry on these and plenty of Wd40 offers a temporary alternative but a new set (£20) is very easy to fit and really makes a difference. Also look at replacing the condenser, these don't last forever either, £5.

Fuel filter. Notoriously difficult to source an original now, go for a generic filter and spending a bit more, one with a rinsable filter core (£15). A blocked filter is a total nightmare as it falsely points to a lot of symptoms that suggest more expensive maladies.

Fuel pump. The original is driven by an actuator from a timing chain cam and these are prone to develop faults as the rubber diaphragms age. A repair kit is about £40 and an exchange pump about £80. I took an exchange, simple to fit, again, one hell of a difference. Alternatively, look to site a facet electric pump to push fuel from the tank, about £80 and less prone to wear and failure. Also they help with the V8 curse of fuel vapourisation.

Air Filter, easily available and very simple to fit and again, big difference if these are blocked in any way (£12 for two).

Coil. These are prone to suffer old age (aren't we all), very easy to source (£20), very easy to fit, you will need a straight replacement or expect to fit a ballast resistor.

Timing is everything. Modern fuel is rubbish. Series 2 V8 were set up for 4* Leaded (about 98RON) so ordinary UL won't cut it. Get the timing reset depending on your poison. Most P6 V8 owners swear by V-Power + Valvemaster additive/octane booster.

As for more expensive mods.

Lumenition ignition, replaces the friction parts of the dizzy and completely hidden inside the dizzy cap. About £100 for the right one. Guaranteed spark, easier ignition especially from cold.

Facet electric fuel pump.

Mallory dual point distributor, far more effective, delivers a great spark. (£150)

Replace the viscous fan, the cooling fan is driven mechanically and can sap power from the engine (I'm told as much as 10bhp). Remove the fan and belt (very easy) and fit an electric Kenlowe (£120), either permanately engaged or on a thermostat. I've heard two Ford Fiesta fans (one for redundancy) are a great fit cable-tied to the rad and set on a relay do a great job for the cost-conscious.

Reconditioned Carbs. About £400 for the two but can make one hell of a difference to economy and power. Half the price of an upgrade if you want to keep SU originality.

Once all that is done then consider a Holley/Weber Carb setup and Edelbrock manifold. If you want to up the power, the gearboxes will require an upgrade too, most fit a strengthened Sherpa/SD1 LT77 or go for a PG1.

Edited by 215cu on Thursday 27th September 17:37

[Sporting Bear]

to all above from 215cu

Only thing I'm not sure about (and I was wrong about tickover remember) unless I've read it wrong - I don't think you use WD40 anywhere inside dissy cap (apologises if I misread or I am wrong)

I would also suggest for the carb dashpots the use of SU damper oil for all year round use, one small bottle even it you share it with friends will last you years (don't overfill)

You can pick up MANN replacement air and fuel filters so very cheap that you can afford to change them twice as often

I'm a big fan of electronic ignition (Lumenition and others)

I also favour electric fans and fuel pumps but try to wire them in with new individual and fused supplies - the only breakdown I had with my daily drive 3500S was a blown fuse that was shared between fan and fuel pump (which was fitted in engine bay and worked very well)

I've used Tesco 99 petrol in three daily classics now and can recommend it, smooth running, cheaper and more readily available for me at least (Valvemaster also required for unleaded heads)

As said before the best tune-up for a lot of cars is a thorough service and you'd be surprised what a difference cleaning and lubing some components can make

Once fully serviced enjoy your P6 for six months of regular and sometimes hard driving before doing anything else

ETA: spelling as usual

Edited by Sporting Bear on Thursday 27th September 21:09

[215cu]

Sporting Bear said:

to all above from 215cu

Once fully serviced enjoy your P6 for six months of regular and sometimes hard driving before doing anything else

I'll second that, unless you have a big folder of all reciepts and repairs. Get a very good idea of what the car is like by driving it. Including some hard driving, they will happily sit at 2000rpm going fast, boot it a bit harder still, those V8 love some revs.

[paolow]

215cu said:

Sporting Bear said:

paolow said:

ok, its tuned up and running sweet. needed a new coil

Blow, so rare they go I'd forgotten to add to ignition parts

paolow said:

one thing tho, the tickover has been adjusted down to 500 rpm and the oil warning light comes on when it gets this low. still shows about 15 psi but this is obviously an issue. going to readjust to 800 where it shows 30 psi unless theres a reason not to?

tick over was probably set when engine was quite hot, 500 sounds far too low and 800 sounds a bit high, check in manual and remember your rev counter and oil pressure gauges could be slightly inaccurate

The oil pressure on Rover V8 engines are lower than other engines, TVR for their Rover V8 engines used to say not to worry unless the pressure dropped below 10psi on tickover !

Don't forget the engine loves frequent oil & filter and air filters changes

Don't worry about mutted exhaust it's part of the car, if you must have a bit more noise start with K&N air filters - lovely induction noise

Loads and loads of interesting and relevant stuff!

Thank you indeed for the above post - really really useful and covers just about every aspect! im a little busy to asnwer to it all but im going to get new filters (all kinds) and see where we are then with how happy it is. currently im trying to get a stereo into it (well - a mono) which should hopefully make boring drives more enjoyable. will keep people posted

Thanks again

Edited by paolow on Thursday 4th October 19:51

[Sporting Bear]

paolow said:

currently im trying to get a stereo into it (well - a mono) which should hopefully make boring drives more enjoyable.

you can actually hear a period radio quite well in a P6 (with standard exhaust anyway)
Classic Gold music on a peroid radio with a single speaker and AM whistle and fades very authentic
I had this set up in my P6 and it was perfectly adequate just needs retuning slightly on very long journeys

paolow said:

will keep people posted