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Aragorn

V8 Performance Oddness

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Yep, thats why the image above shows it smashed to bits! Didnt help though.

It needs to be pulled out. I'm hoping the 10mm drill and M12 stud will sort it, need to get to the DIY store and buy a drill bit though, my set only goes up to 8mm and i cant find the 10mm i baught a few months back for drilling out the galv on my chassis. :angry:

Checked the valve lift on cylinder 7, measured a peak of 5mm give or take.

Anyone got the specs of the standard cam? I know from working on old vauxhall 8v's they ran anything from 4.5 to 6mm lift depending on tune, so its not a wildly bad figure?

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I know it is not an OE spec profile but Kent Cams mild road profile shows cam lift of 6.83mm and valve lift of 10.89mm

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I know it is not an OE spec profile but Kent Cams mild road profile shows cam lift of 6.83mm and valve lift of 10.89mm

That is pretty much the same as OE lift and calculates correctly for 1:6 rockers…….

Once you get above 12mm of valve lift then the guides need machining by 100thou to stop spring bind. Top end race cams are about 13.2mm lift…………..

Kev ………. You need a new cam !

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Or i'll just whistle along happily and ignore it :P

I'm sure that without those nasty restrictors and with the carbs set up properly its going to make a huge difference to performance anyway!!

Its pissing down today, so no drilling of the other restrictor nor reassembling.

The DMF on the A4 decided to spit the dummy last night too, cars still drivable, just doesnt like pulling away or reversing much, so i'm going to have to dump some money into that and get the replacement engine fitted sooner rather than later. I really want to get the disco running before i take the A4 off the road though!

Once my funds have recovered from that i might look at doing something with the engine, but tbh, i should be spendin some money on the defender!

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Wooooooo.

Finally got the other restrictor out this evening. Managed to grip the thing with a pair of molegrips well enough to tap it out to M12, then used the Aux belt tensioner from my spare A4-1.8T motor and some M12 screwed rod as a puller to get it out!

If it ever stops raining i'll see if i can get the thing put back together!

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Right an update finally.

I've refitted everything, set the carbs to their default setting as per the manual and tried to start it.

Cold weather and a battery thats not been used for a while means it only cranked over for perhaps 30secs before saying "no more!" but it didnt fire, and theres also no smell of fuel anywhere in the engine bay or at the tailpipe.

I'm wondering if the fuel system needs primed somehow?

Afaik its got an electric pump, but what tells this pump to run? Anyone got a circuit diagram so i can see whats going on and perhaps bridge the relay or whatever to get the system primed?

I tried pulling the fuel pump fuse, and something over in the passenger footwell clicked, and clicked again when the fuse was back in, but i dont have any kinda circuit diagram to work out whats going on there...

Cheers.

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IIRC the pump is in the tank............. as its carbs, its only a low pressure pump so disconnect the fuel feed to the carbs and turn on the ign ...... should be a decent flow...............no priming required

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What i assume is Fuelpump relay is a funny thing...

http://www.lr90.org/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=353&g2_serialNumber=1

Thats i diagram i've put together from looking at the relay pinouts and what the wires do.

The fuel pump fuse appears to apply power to 87a and 85, and 86 appears to be grounded, so with the ignition on the relay latches open and connects 30 to 87, however neither 30 or 87 have any voltage on them...

I know this relay is somehow tied into the oil pressure switch, presumably for accident safety, if theres a crash and a fuel line is split, you want the pump to stop even if the ignition stays on.

So i'm going to guess that 85 is the oil pressure switch. That would mean that with power on and oil switch conducting (ie no pressure) the relay connects the pump (30?) to the white wire on 87. When the oil pressure lamp goes off, the relay coil powers down, and 87a is connected to 30, providing power to the pump from the fuse. So the question is what is the white wire at 87 doing?

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If it was working before you pulled the carbs then what would cause it to stop now apart from a lot of bad luck ?

If the battery volts are low then it will probably cause the relay to drop out under cranking ....... also it will take time to fill the float bowls so it may take a fair amount of cranking to get it to fire ..............

Stick the battery on charge and go buy a tin of easy start ............

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Yep spot on. Took a different approach though.

Bridged the relay contacts using my assumption that 30 was the pump, meter was showing a 1a draw and a bit of a listen near the tank confirmed a nice whirr.

Left it like that for a few mins (i'd changed the filter as well as doing the carbs, so lots of filling required) then turned the key. Battery was almost done but it only turned over two or three times before it caught and spluttered a bit give it some gas and it fired up :)

Been "tuning" it now, it seems quite rough and spluttery at idle, not quite as even as it was before, but maybe thats a side effect of removing those restrictors. I've come in for a break and some food, but i'll head back out in a bit and see if i can get it running smoother.

From what i can gather, i want to adjust the mixture screws (from the tweaking so far it seems to like them going in the way, turning them out made it die) until i get the highest idle?

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Aye that seems to make sense.

I started turning the screws anticlockwise (lean) and it died out immediately, so turned it quite a few turns clockwise (rich) and the revs came up, then another turn or so it stopped increasing perhaps even dropping a little, but did seem to get smoother, so i left it at that.

Trying to balance the carbs just isnt happening, I listen and the hiss is different, but twiddling the screws doesnt change it in a way that makes the noises more similar. Offside carb is slightly deeper sounding, if i try and adjust nearside to match it it only seems to make its hiss louder or quieter...

Anyone have a flow meter they could lend me?

It revs up nicely now, and idles alright, but then it did before too!. Just need to wait for the missus to see if its any good out on the road to see if all of this has been worthwhile!

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Have you set the linkage ? that must be done first.

Then get an evenish idle and listen to the air flow ........... lean off the carb with the loudest & higher pitched hiss until they are the same and then adjust both carbs evenly until you have a good idle. The just tickle the throttler stop screw on either carb slightly to provide a final adustment as they will not be quite identical. ....... job done ;)

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lean off the carb with the higher hiss?

Manual says the mixture should be adjusted by the same amount on both carbs, and only the throttle stops (and linkage) gets adjusted to balance the carbs?

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Yes, you can do it that way ......... my way assumes that the butterfly's and linkage has already been set ........ I have also edited my previous post to be clearer...........

Slightly louder, very slightly higher pitch is often a rich carb ......... well, it was on HS6's :lol:

TBH they dont need to be deadly accurate ......... carbs are like dizzy's ....... a compromise. :P

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ye, its a bucket with a hole in the bottom.

I just want to ensure the hole is optimally sized :P

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Whats with the random thread move? :angry:

Its not a question about a discovery, its a generic question about setting up a rover V8, thats been in the international forum for well over two weeks...

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also very interesting, and i have learnt a lot about V8's (being a derv man thinking V8's just dont do anything apart from sound, power and fast) :P they are also tricky.

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As I said to you in my PM, I've been having massive PC Issues for a while, and now back on line

You have a disco V8, hence why I moved it along with a rnage of other posts to other forums, V8s tend to be Disco, Def and RR, International is for posts that don't really fit any of the other forums, yours does, if I had not had the PC issues I have had on and off :( I would have mobved it quicker, its more importnat that members try to think re posting in the sub forums, a - so as not to have them almost not used, and everything in International, b - many members are specialist and read a variety of forums, and c- posting in a sub forum will often see a huge number of replies from specialsit knowledge, and you post last longer before driopping to obiivion :)

Its is more for members to think about where they post, if a A&M Team member thinks it should be moved it most likely will be, but the workload for mods here is heavy already (most members have no idea of the time spend by mods on here for the benifit of the forum) so those concerned may, or more liley may not get a PM of "Explanation"

^^^

But as per my PM to you plus a tad more

Nige

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* have you checked there is fluid in the dashpots?

* check your tappet clearance too.

* i would look at the fueling before making the decision that the camshaft is trout- it probably is worn as most are not in best condition.

get some injector cleaner or some kind of engine friendly(combistible) cleaner and clean out the carbs as the needles may well be gummed up. 10k boost is ok if you spray it in but it is qite expensive considering.

* if it is good at top end, not bottom end, then the camshft is probably ok as high lift is for top end not bottom end, which suggest there is some profile on the cam lobes.

* if the dizzy has been replaced, the dizzy cap could be 180 out as they will fit both ways around, and check your leads are connected to the correct cylinders too. a good way to check if you dont know much,is to take off the dizzy and turn engine to see which way the rotor arm rotates, then find which point is no.1 position. the firing order is 1-8-4-3-6-5-7-2. so if you follow the points on dizzy cap around in the direction of travel of the rotor arm, the firing order will be the placement of the leads to their respective plugs.

--- i would go for clean out carbs and check dashpots have fluid in them first though-------

regards

richard

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Moby: yes there is (now) fluid in the dashpots (wasnt before).

Carbs have been cleaned out and reset to factory settings, then fitted and "tuned"

The manifold has had its restrictors removed too as its clearly not the original and had some Series spec restrictors in the inlet.

Not had it out on the road yet, but revving it on the drive it does sound a bit more purposeful than it did previously so i'm hoping thats a good sign.

Will post back once i've managed to get out for a drive in it!

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Moby: yes there is (now) fluid in the dashpots (wasnt before).

Carbs have been cleaned out and reset to factory settings, then fitted and "tuned"

The manifold has had its restrictors removed too as its clearly not the original and had some Series spec restrictors in the inlet.

Not had it out on the road yet, but revving it on the drive it does sound a bit more purposeful than it did previously so i'm hoping thats a good sign.

Will post back once i've managed to get out for a drive in it!

And???????????????

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Righty, inlaws left today so we wheeled it out and took it to Tesco to see what the score was.

Its better for sure, but still doesnt quite meet my expectations.

Maybe i just expected too much but i've taken a few videos while we were out today for people to look at and give their opinions on:

http://friesian.lr90.org/gallery2/main.php?g2_itemId=37

Low revs is still dissapointing but definately less so that it was. If you plant the foot to the floor at 45mph in 5th for instance, it just does nothing.

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