Backfiring & lack of revs

machman767

Active Member
#1
Hi, all, I was hoping to spend the day trying to get MVD307P running some bit like, problem I'm having is she doesn't want to rev beyond 2000 - 2500 without backfiring and cutting out. When it last ran reasonably well I managed to get the timing bob on, any suggestions? And, if there is any one around the Lostock Hall area with knowledge and time to spare I can supply tea and biscuits!
Cheers,

Mick
 

Quagmire

Active Member
#2
Hi Mick,

Does the car idle ok and rev below 2000rpm at all?

If it idles ok and revs at lower speed it could be a fuel starvation problem when the demand is higher. If this is the case check all your filters are clear and your pump is doing its job ok.

If it doesn't idle well and generally won't rev but you know the timing is correct you may have a lump of crud in one of the carbs. To check this pull the ht leads with the engine running (wear suitable rubber gloves so you don't get zapped) and see which ones make no difference when removed. If it is crud in a carb then you will find four pots are doing next to nothing. Which pots these are will tell you which carb is the problem.
 

machman767

Active Member
#3
Had the pleasure of Mark Powell from the P6 club calling by this afternoon, gave me some useful advice, apart from his initial comment (scrap it!!) I'll be looking for some carb kits and possibly a new distributor. AND we got it running, the worlds first Rover V4/5!
Thanks also, Quagmire, you'd also mentioned the carbs, the evidence is irrefutable!

Mick
 

quattro

Administrator
Staff member
#6
Have you had a good look at the distributor? Check to see if the bearings are suspect by wiggling the rotor arm about. The shaft its turning on shouldn't have any play in it. Also check the advance retard is working, by taking the vacuum hose out of the rubber elbow in the manifold and sucking on it. The plate inside the distributor should move smoothly when you do this.

As an aside (Whatever that means :confused: ) my wife bought a Peugeot 108 the other day. When the salesman was giving us the usual BS I cocked an ear at the engine noise and proclaimed that it was only firing on three cylinders. That shut him up :)
 

machman767

Active Member
#7
Hi, quattro, just had a look at the dizzy, no play in the shaft. Now, I've got to admit, I read the second part with a little scepticism given the date, wondering if I was going to be the victim of an elaborate prank! So, in the spirit of endevour I've had a go (;)) and I think I emptied the garage of air before the plate moved, nearly did meself a mischief! So, it does move but takes some effort, whats my next move? I couldnt try and start it as my wife has parked her new C1, which is white, in front of the garage, might be able to have a go tomorrow.
Cheers,
Mick
 

clive P62

Active Member
#9
Hi mick
This is a simple thing to check.
Do both dashpot pistons move up/down,ie not seized?
Easy to remove these and check/clean.
Only reason for asking is that i went to the feb ice breaker show and a chap turned up with his 3500s only running on 4 cylinders/not revving up.
Had a quick look at and found one of those pistons jammed,a bit of a clean and car ran ok.
Clive.
 

machman767

Active Member
#10
Hi, Clive, dash pot pistons are free, no issue there. Following Marks visit I'm leaning towards it being a carb issue even though they've allegedly had new jets, needles, etc. Should I be concerned about the dizzy plate not moving easily?
And quattro, having clicked on what you said not to, yes elaborate prank!
Cheers, all.
 

SydneyRoverP6B

Well-Known Member
Staff member
#11
Hi Mick,

The vacuum advance not working will not result in the symptoms that your engine is displaying, but a seized distributor plate certainly will.

The plate must move. One way to check, take the vacuum advance off and then see if the plate is free to move.

Ron.
 

clive P62

Active Member
#12
The dizzy base plate only moves when operated by vac unit/many cars out there have non working units.
A non working unit does not cause your very bad running that said base plate comes out very easy then you can check advance bob weights to see if they move outwards if twisting rotor arm then should spring back once released.
Are you still running standard points/condenser? if so are points correctly set with dwell meter.
A faulty condenser can also cause back firing.
Clive
 

machman767

Active Member
#13
Thanks, Clive, electronic ignition was fitted whilst the garage had it, along with a new coil. I'll try and get a picture up as there seems to be a stray wire near to the coil but not connected.
Ron, the base plate does move but it took some effort, had spots before me eyes! When it's running it seems incredibly rich so I think I need to concentrate on the carbs. Really grateful for everyone's suggestions, this thing will not win!
Mick
 

unstable load

Well-Known Member
#14
Following Marks visit I'm leaning towards it being a carb issue even though they've allegedly had new jets, needles, etc. Should I be concerned about the dizzy plate not moving easily?
That the carbs have had new jets etc simply means they have been fitted, in my opinion. Post fitting they need to be set up correctly.
You are right in starting with the carbs, but the distributor plate is also going to need investigating as to why it doesn't move without
rendering you faint.
 
#15
Hi, guys, quick update, carbs are now off ready for me to strip them down and rebuild with new bits from Burlens. With a bit of luck we should make some progress, although I'm thinking I might invest in a new dizzy from Powerspark even though a kit was fitted to the existing one. If this doesn't work I'm thinking of calling in a mobile expert, anyone dealt with a guy called George Reid, based in Sabden?

Mick
 

machman767

Active Member
#16
Evening, all, carbs rebuilt last weekend but still she wont start at all, but its SO close! Mark the (P6) horse whisperer came and still no joy so next step is get mobile tuner in. One downside, seems to have developed a petrol leak, not had chance to look properly but seems to be dripping from back of engine :( could be an overflow from the carbs? It will not beat me.....
Mick
 
#17
Have you checkt how much power the ignition is getting? I hade some missfiring and a unwillingness to rev and after a lot!!! A LOT!!! of searching i found that the cable from the ignition lock only feed the coil whit 4-5 volts
which was enough to get a weak spark but not enough to get the engine to run properly.

/Stefan
 
#20
Hi, Stefan, afraid not, my wife wasn't too well over the weekend so didn't get round to it, hopefully will this weekend. Leak seems to be a mixture of oil and petrol so need to look more closely at that, it can't be good though!

Mick
 
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