Outer Limits 4x4 Board

Fuel injected 4.4 leyland we believe might have a stactic/dynamic compression issue . Problem is we have a triple knock at 1500 rpm we can't tune out we have tried 25 % more fuel and less fuel and 12 degrees more /less timing all this does is move it up or down the rpm band by around 200 rpm . The engine has a compression ratio of 160 , the cam in it at the moment is a crow 37771 rev range 1400 -4200 max size for efi engine so crow states on their web site . Has anyone come across this problem before ? Who esle makes cams for rovers besides crow in australia ?

have you tried a differant fuel, optima or any other high octane unleaded.

John Davis in melbourne should be able to help, he builds some wicked rover V8s

glen

only thing i haven't tried is avgas .. What is john davis ph number ?

Could Glen be thinking of John Davis from Sydney?

John and his brother Bruce used to be partners in John Davis Motor Works, but have gone separate ways now.

John has Extreme Special Vehicles and concentrates on falcon hunting vehicles etc. active suspension and Bush Ranger conversions.

Bruce has Bruce Davis Performance Landys at Amaroo Park Annangrove. I suggest you give them a call (02) 9679 1978

Hey MadRangie , i use and highly recomend Dynotec cams 217/216 they are unreal , the price is on average $190 and sourced from Rovercraft 0893770080 in W.A

1st thing to wear on rover/leyland v8 is the timing chain, causing cam timing to retard and fluctuate and power loss. Cam and lifters also wear. When you replace the cam, fit a duplex roller timing chain and sprockets - far better than the stock rubish.

what are you using to check mixtures?
what sort of ignition system, is it direct fire, crank trigger, triggered computer controlled or dissy?
fuel type, fuel pressure, regulator type, manifold type ?
Have you had it apart and CC'd the heads so you know what the comp ratio really is, not just pressure measurement?
how much leak down does it have?
have you degreed the cam?
what sort of intake and coolant temps have you got when its playing up?
what sort of ECU?
what plugs/heat range and leads? age/condition?
when does it knock? free rev, light load, high load, hot, cold, all of the above.
all cylinders or just a few/one/two?
cooling system correctly filled/bled/working?
engine age? does it have chambers full of carbon?

- Double check the cam install, ensure it is not massively retarded or advanced.
- accurately asses the mixtures with a known meter
- check the ignition advance while free revving the engine as a base confirmation that its working as it should, also check that what you think is TDC on the balancer really is TDC, you'll figure this bit out when your checking the cam install anyway.

Overfuelling can cause an engine to knock aswell as under or poor fuel
Set your base maps up free revving the engine then copy the fuel curve shape and for every 500 rpm load point adding 5% fuel should give you a driveable baseline mapping provided the mechanicals are ok and the injectors/fuel pressure is about right for the engine, assuming programmable injection.

Have fun
Daryl

Give us some more info and we might be able to help more.

I would start by checked the compression ratio properly the pressure reading isn't accurate enough.
We had a similar problem with a blown commodore engine we had to Dyno.I couldn't stop it pinging I noticed that the inlet and manifold temps were way hotter than they should be.When we asked the customer what the comp was he said it was 8.5: 1. He had just payed $8000 on it getting it built. I ended up pulling a head off to check the compression myself and it ended up being 10.3:1. We machined the pistons got the right ratio and everything is fine now.
Just my 2 cents worth.
SAM

ok run down on motor
20,000 k if it is lucky .
speed tech in mitch has done the dyno twice on it with all the sensors up the pipe etc
it is running a wolf 3d v4 ems which controls everything ( has been back to wolf to be checked out already once is working fine)
igniton is all computer controlled using the dissy as a pick up point
runs Premium unleaded , 45 psi in the rail , mallory adjustable fuel reg , and a series 1 disco injection manifold
the heads are reco rover one which have been hand ported out to a little more then standard leyland heads
the cam has been degree
not sure what the leak down is
doesn't matter what the temp of intake or coolant is it still knocks
i have tried hotter and colder plugs 1/2 and 3/4 inch thread
knocks under medium to heavy loads not matter what the temp is both high and low range in same spot
the engine coolant is fine doesn't over heat etc .

we have pulled the motor down and going thru checking everything agian . there was a slight carbon build up nothing to worry about . Also one other thing we seem to foul plugs but only on 2 pots 2 and 7 , strange thing is that the injectors are in 4 banks of 2 and pots 2 and 7 are on different banks. injectors are all working fine bench tested them all so it is not a injector stuck open . this fouling has not set pattern to it either u can go 1200k not a prob then foul number 2 or 7 twice in 20 minutes . Wiring loom has all been replaced a second time already as it was suspect . The motor doesn't like to rev over 3000rpm either and the cam is rated to 4200 yet it is not starved for fuel .

ok did the pot test for compression it turned out to be around the 9.7:1 which is too high i believe so we are going to knock it back to 8.5:1 and hopefully this will fix the prob

Thanks for all the insight and advice

Joe

your fouling on 2 and 7 with batch fired injectors is more of an indication of fuel distribution and exhaust efficiency issues. The intake manifolds are pretty good for factory items as far as distribution goes. What sort of exhaust manifolds/system?

@9.7:1 premium unleaded should have kept it happy.


using the dissy as a pick up, have you locked the advance out?

have had bad experiences with warm/aerated fuel and knock/ping too. If your running a pump that is way over rated or have poor line placement etc this could be a prob. checking flow rate and temperature of return out of rail will give you a good idea.

Hope your getting somewhere.

Cheers
Daryl

I agree 9.7 should be alright on premium fuel.
Derangerover has the right idea check with a timing light what the advance is doing on the dyno at the time when it is pinging.

SAM

after listening to all the advice and ideas from here and a few other people i had a new motor built . we reduced the comp ratio from 9.3:1 down to 8.6:1 all going well it will fire for the first time tomorrow hopefully all the probs are gone .
Thanks to all who offered advice and ideas to me .