I has me beat .....any suggestions

[Baggy]

Hi All,

I've been struggling with a misfire / flat spot in my 3.5 v8 with CD 175 carbies.

I've been working through the issue and so far I have.

1) Replaced all manifold bolts with threaded rod and HT nuts and washersso I have no issues with leaking exhaust manifolds now.
2) Replaced the intake manifold gasket (only way I could remove carbies) until Ron sent me pic's of special bent spanner to remove carbie nuts.
3) Replaced all hydraulic lifters (had a noisy tappet) which I still have :mad:
4) Replaced coil.
5) Fitted new plugs Bosh WR8DC+ as recommended by ubeauty and set to32 Thou as per placard in engine bay.
6) Ive stripped cleaned and replaced gaskets, new main fuel jets in bowls,rubber diaphragms, checked float levels and set them to manufacturers
specifications on both carbies.
7) Throttle shafts are all in excellent condition (no wear) and all adjustingscrews on carbies now work to adjust air intake.
8) Purchased the special tool for adjusting main needles (through dashpots) and believe that I have them unscrewed (anti clockwise) as far aspossible without them disengaging from the adjusting screw itself.
9) Purchased Timing light.
10) As per other posts I have checked and to best of my knowledge theauto choke conversion to manual (while crude) is now working and is in the off position.
When engine is at operating temperature and you switch it off engine
will now restart - yippee.

In my previous posts engine that would only rev very high (2000 RPM's) with idle screw fully adjusted out.
I had at about the same time this issue started had only just replaced the electric fuel pump (was fiited with afternmarket unit) I purchased the same style and checked its pumping about 4-5 psi.

Replaced the large filter (tank end) and all hoses clips when pump replaced. fuel filter in engine bay is rasonably new.
(When I stripped the carbies they were both very clean and bowls did not have any sediment in them I normally only run BP Vortex fuel (98 Octane)

I now have an engine that will idle at 1200 RPM's, (can be adjusted lower) its an auto .....and revs drop to around 950 RPMs when reverse or drive engaged.

My current problem: As you accelerate it has a very noticeable misfire and vibration you can fee she's not running on all cylinders. When you pull up there's a very distinct strong petrol smell.

We've checked and reset timing several times.

6) If set to fire at TDC its has no power, you accelerate nothing just slowly picks up very flat acceleration.

7) Currently running at approx 6 degrees ATDC ?.what should the timing be set to....

Any ideas's on what the problem could be....

Cheers

Baggy

[clive22]

Hi I had a similar problem with my cd175 equipped v8. Turned out to be a bit of silicone goop in the fuel line attached to a thread that was blocking the needle valves moving back and forth depending on fuel flow.
Removed the needle valves cleaned em out and lived happily ever after.
The problem was I checked them but didn't remove them initially they flowed fine until fuel flow was high and the glob of silicone blocked one Carby and forced the engine to run lean.
Maybe put in a temp fuel pressure gauge.
Fwiw I spliced in my little outboard fuel tank into the fuel system to isolate the fuel tank pump side of things.
Clive

[Graeme]

I didn't see new spark plug leads, rotor button or distributor cap in the list.

[bee utey]

With 98 octane you can run up to 10 degrees BTDC advance no worries. As for your problem, it sounds a bit like its running on one carby only?

[Bearman]

Check that timing again. Should be BTDC not ATDC.

[Baggy]

Thanks everyone for your input,

Graeme - yes you are right havent changes leads, distributor cap or rotor as I did'nt believe (more hoping) that they could'nt fail all round the same time as my electric fuel pump and carbie issue but are on the list to replace.

Bearman / bee utey - rechecked timing was on 6 deg ATDC, reset it first to TDC and it had no power - nothing reset it to 6 -10 degrees BTDC accellerates better and while she still has a misfire she certainly does run better......thanks gentleman.

Clive 22 - I'm leaving your suggestion to last as it means pulling off the carbies again (bugger) although I did replace both needle valves with new ones. But I'm willing to strip them and check needle valves as suggested.

I'm also thinking as she has been sitting for a good 5 months, with the choke being on (now fixed) and it running very sooty could that be an issue.
Tonight afer resetting the timing it was the first time I actully felt comfortable doing a number of laps around my street and progressively going further out without the fear of breaking down.
Thinking could be about time I take her for a longer run to blow out some of those cobwebs ......

Its just nice to be in her and at least driving a short distance :D

Cheers

Baggy

[Baggy]

Hi Everyone,

Since my last post I have been driving the Rangy around my back streets with the engine misfiring.

I thought (as per my last post) that as she has not being driven much since Sept last year .... sitting around .....problems with auto choke stuck on (black soot from exhaust) that she may
need to be driven around to blow out the cob webs.

The carbies seem to be working, when cold, pull out the auto choke (turned manual) she starts.
She idles around 1100 rev's (it's a 3 speed auto) but when put into reverse or drive will drop to 850 rpms.....however there still is a rich fuel smell.
You can turn her off when she warm and she will restart with just a turn of the key ....something she wouldn't do before.

What's annoying is at times, not always it won't kick down or accelerate......you take off there's nothing.....it slowly starts to rev and eventually it will build up speed and ......away she goes.
I'm embarrassed as you hear this excellent burble from a V8 and the other night I was tailgated by a scooter till she eventually acellerated enough to pull away.:(

So last weekend I decided to step back and relook at the problem again.....

I pulled out the plug leads while engine was running and found spark plug No2, 3, 5, 8 would not make the engine run any differently. Pull out 1,4,6,7 leads and engine would noticeably shudder.

I then individually pulled out offending spark plugs (they were sooty) cleaned them, earthed and checked spark with engine running ... 2,3,5 had a yellow spark and number 8 was shorting off the side of the plug. ( these were new plugs)
Replaced number 8 with old plug and it now had a blue spark when earthed with engine running.

As per Graeme's suggestions I had the necessary $$$ to:

1) Replace Distributor cap with new Bosh replacement.
2) Replace Distributor rotor with new Bosh replacement.
3) Replaced spark plug leads.
4) Rechecked timing and set it to 10 degrees BTDC

I put a new coil in last year, swapped it over with the old coil and the result was still the same?.misfire.

Refitted the new coil back.

You can feel the vibration through the steering wheel.... it pulls away and when you get to into top gear it actually drives quite nicely.

The engine at idle sits and runs beautifully with no tell tale increase or lowering of rev's .....accellerate from under the bonnet it seems like a slight misfire when rev'ed up.

Where should I go from here ?...


Appreciate all suggestions


Cheers


Baggy

[101 Ron]

One carby running rich causing half of the plugs to fuel foul.
The motor will not idle and will clear its self at high load and rpm.
Check needle and seat/float level.
Also check for PVC valve and brake booster taking too much vacuum.
Block off the PVC and booster pickups on the manifold and see if it improves.
What does the jet adjustment tool look like that works though the dash pot and where do you get one from.
It is very unlikely to be a spark problem as it is running OK at high rpm which is when the spark would most likely fail if at fault.
Ron

[PhilipA]

Purchased the special tool for adjusting main needles (through dashpots) and believe that I have them unscrewed (anti clockwise) as far aspossible without them disengaging from the adjusting screw itself.

That is not how you set the needles!
You may have one carby full rich is you have screwed out the needles. the carbys work by the mixture being set by the gap between the main jet and the needle. The needle is tapered so that the mixture at idle is maintained through the demand/throttle range.
On those emission carbs, I would first set the needles about half way through their range. Then slightly lift each needle/piston with a small screwdriver with the engine idling . The engine revs should rise momentarily then stumble. If the engine revs rise and stay risen it is too rich, if they fall immediately without rising it is too lean. To adjust if rich, screw the adjuster clockwise or in to lean and vice versa.

This should be done after you have set the synchronization with a Unisyn or just a bit of tube in the carb throat just next to the piston. When the suction noise is the same the carbys are synchronized.

The best way to set the mixtures is with a colortune, which replaces one plug with a clear plastic spark plug and you adjust the opposite carb mixture until the combustion colour is blue with yellow flecks , just like a gas stove burner.
Regards Philip A

BTW, 727 auto 3.5s don't really accelerate, they just gain speed gradually! LOL . It is probably normal to be out accelerated by a scooter.

[PLR]

G`day ,

Right carb feeds 1746 .

Left carb feeds 2358 .

Your problem as you described is related to the left passenger side carb .

As your left carb is choke carb maybe your manual fit is not a hot worker and only works cold which would make sense as with your description .

[Baggy]

Hi All,

As far as I can tell both carbies are sucking air at similar rate due to sound (with tube) and also height of both pistons at idle are the same..... though my wife would challenge my hearing :D

PhillipA If you can (or others on this Forum) tell us if you can buy a colourtune in AU or best place to source one overseas would be appreciated.

I've set needles as per (RR factory manual) where they suggest that you fit needle with base of needle flat with piston on initial start-up.
I've made sure grub screw on side of piston is in the groove of needle and that if you (using adjusting tool with piston out of carbie) and turn clockwise (enriching) mixture that it will fully tightens and locks which is one of the check that they recommended.
You then back off (turning anti clockwise) and base of needle (brass section) rises so when piston operating at idle the needle is sitting lower to reduce amount of fuel being sucked into carbie.
Yes.... if unscrewed to far you can disengage needle as there is no "stop" on turning it anti clockwise.

They suggest that you can adjust needle with piston out so that you can tell accurately that the needle hasn't disengaged by unscrewing too far.

I'll recheck them but I believe that they are unscrewed as far as possible (anti clockwise without disengaging) and that's why strong fuel smell has me beat, but R H Carbie when you lift the piston rises but doesn't falter, so I'll check it again.

L H Side Carbie has choke on it and as I said on my earlier email the previous owner converted it to manual.
Now that I've got my head around how he set it up if it's on there is a noticeable black sooty smoke from exhaust with choke on and its virtually non-existent when off.
My searches suggest that the old earlier manual choke from earlier carbie (of which I now have a set) won't fit the later carbies I have on vehicle.
The older carbies I now have, have worn spindles on both and would need a complete rebuild :(

When you lift the piston LH Carbie, it will rev higher then stumbles so mixture seems to be about right.

My classic is fitted with a H/Duty Borg Warner 35 3 speed auto (factory option in Perth) and from all write ups at the time said that it covered the 1/4 mile in same time as manual though by today's standards she's not fast.

101 Ron: I've set floats as per factory manual and I may need to re look at this. Whoever had touched the floats previously had bent the arms that sit on fuel needles (which they recommend to do) I re straightened them and using aluminium washers (of various thicknesses) to bring out the main jets so that floats are sitting at factory specs.
It could be that the floats are rising (and with new fuel pump and pressure) they could be bending and flooding before shutting off the fuel needle.

I will also look at PVC valve and booster valves.

PLR - 1746 plugs were sooty and didn't alter engine running ....wouldn't it be the RH Side carbie being too rich? .....
Could you clarify what you mean by "hot worker"

Finally ....all your ideas and thoughts are really appreciated.

This journey with the fuel pump and carbies has really tested me.
Luckily she's not my daily driver as that could have made the difference and I think PhillipA you made a comment on a post of mine (quite a few years ago now) when you said that we have to be enthusiasts
(for putting up with the niggles that go with owning a RRC)

I've resolved that I won't let this beat me and I'll keep working of it (though my wife, kids and neighbours) would say get rid of it.

Cheers


Baggy

[Graeme]

Are the advance weights in the distributor free to move?

[Baggy]

Hi Graeme,

I'm spanner turner level 1 and don't know about advance weights in distributor ....excuse my ignorance, but please tell me more.

101 Ron - Attached is pictures of mixture adjusting tool I purchased from ebay.
Came ex eastern states from classic and race.
I also purchased my carbie kits from them.
Quality of gaskets including main jet was excellent as was service.

I'm working through everyones suggestions and will post results.

Cheers

Baggy

[superquag]

Just a quick look on evilBay, and here's a Gunson 'COLORTUNE'

Gunson Colortune 14mm Colour Tune Triple Pack FOR Twin Carburetors | eBay (http://www.ebay.com.au/itm/Gunson-Colortune-14mm-Colour-Tune-TRIPLE-PACK-for-Twin-Carburetors/121270628352?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%2 6asc%3D20140106155344%26meid%3D29c9b9ca353e417699b 05e57be243eb5%26pid%3D100005%26rk%3D1%26rkt%3D3%26 sd%3D111584294838&rt=nc)

This one is a triple pack, yes 3 of them, but the best value from that particular supplier (as far as I've looked...) He also has twin packs for $124 or so, making each one $62.
Buying the triple reduces each to $54.- Idea is you could flog one off for $?? - , cheaper than someone buying just one, best price on evilBay.au is around $84.

- Just a thought.:D

PS, , they come in more than one size, plus adapters are available. 14mm seems the most common.

- And, you have checked the condition of the vacuum advance gizmo on the side of your dizzy... ? they eventually leak, and can take a while to perforate completely and cark it. Suck it and see if it holds.

[350RRC]

........................
It could be that the floats are rising (and with new fuel pump and pressure) they could be bending and flooding before shutting off the fuel needle...........



Brass or foam floats? If brass, compare weights between the two to see if one has a leak. If foam do the same to see if foam on one has degraded. Does happen.

I assume you are happy with needle and seat sealing for float bowl level?

Sounds like electrical prob to me anyway, just giving you some more stuff to check. :)

cheers, DL

[PLR]

Hi All,

PLR - 1746 plugs were sooty and didn't alter engine running ....wouldn't it be the RH Side carbie being too rich? .....
Baggy

The way i read your description it was 2358 that were sooty you even said you replaced 8 with an old plug because of no spark .

I can only work on what i read or misread so i`ll leave you to it .

[67hardtop]

Anyone thought about doing a compression test???

Cheers Rod:wasntme:

[350RRC]

The way i read your description it was 2358 that were sooty you even said you replaced 8 with an old plug because of no spark .

I can only work on what i read or misread so i`ll leave you to it .

I read the same kinda.............

'I pulled out the plug leads while engine was running and found (pulling) spark plug No2, 3, 5, 8 would not make the engine run any differently. Pull out 1,4,6,7 leads and engine would noticeably shudder.'

Baggy maybe you're reading it wrong? If its running like crap and you pull 2,3,5 & 8 and things don't change they are the culprits.

Forget the soot on the other plugs until you find out what is going on with 2,3,5 & 8.

cheers, DL

[superquag]

Anyone thought about doing a compression test???

Cheers Rod:wasntme:



...Oi! let's not cloud the problem with .... information. :wasntme:

Edit: - on second thoughts, seeing that 2, 3, 5, and 8 are'nt doing much, whip 'em out and run the engine... easier to bung the comp. tester onto each hole as it lumps along....

[Rupert Prior]

cylinders 2358 work off one carb (i think passenger side)(follow the runners in the casting)
1467 work off the other carb . so it seems you have a carb fault.

[Baggy]

Hi All,


PLR - My humble apologies I can't read / understand my own post ....you are absolutely correct :D

superquag - appreciate the lead and thoughts on colurtune on ebay need run that past SWAMBO as I've spent a few dollars to this point.
That and a balancer for carbies will be on my wish list of must haves for my toolbox.....

RR350 - could the sooty plugs be causing misfire, I'm hoping its not the Distributor. There's not many RRC I see wrecking in Perth as I'd love to do distributor conversion as per bee utey suggestions. Prior to electric fuel pump being replaced there was no issue with misfiring in engine. I'd always had a rich mixture and not having the proper adjusting tool it was a case of if its working fine don't meddle with it :D
Rebuilding the carbies came about after fitting the new fuel pump..as engine would'nt idle any lower than 2000 rpms with idle screw backed right off and I did have a problem with leaking manifold (refer my earlier post) which are now all fixed.

I now have an engine that idles beautifully (higher and lower) and carbies that when I adjust the throttle screw on each will raise and lower revs individually as they were intended.

67Hardtop - Yes a compression test is the other thought (I don't have one) that's why I havent done one yet. If this misfire persists after all avenues exhausted, Ill borrow or purchase one and see what that shows.

Rupert Prior - I believe that you and PLR have hit it on the nail with sooty spark plugs and I'm hoping the source of the misfire.
I may look at removing the current manual /auto choke conversion,blanking it off and see how it runs.

Thanks everyone ....as a spanner turner Level 1 the problem faced by me is the more you take on doing it yourself for a) cost b) satisfaction in learning to do the job yourself - is that you have to buy the tools and gauges necessary to do the job and in my case slows the process down due to available $$$


Im hoping the carbie set up / sooty plugs is the reason for misfire as all was fine before replacement of fuel pump, but understand that Murphys Law it could now be something new.....


Again ....All suggestions posted will be looked at and its discussions like these that really help you work through the problem.

I'll post the results ......

Cheers


Baggy

[350RRC]

Quote ...........'Prior to electric fuel pump being replaced there was no issue with misfiring in engine.' .............Unquote

Was unaware of the fuel pump replacement............. You did install a low pressure one? High pressure pump (efi) will cause flooding / rich mixture.

Following on from that, find the single return line to the fuel tank (undo its cap), blow air down the line with a compressor to make sure it's not blocked. Be interesting if that line to the tank comes directly from the carb associated with the problem cylinders, after collecting excess fuel from the other carb.

Blockage is usually in the metal fitting that goes into the fuel tank at the end of the plastic line, it rusts or something.

cheers, DL

[Graeme]

I'm spanner turner level 1 and don't know about advance weights in distributorThe weights are below the points plate. Twisting the rotor button in the direction of rotation should encounter light then heavier spring resistance prior to a firm stop but inspecting the weights themselves for freedom to move is really required. 1 or both springs can break too but the weights not functioning correctly is more associated with poor power at low to mid revs under load due to lack of ignition timing advance.

[Meccles]

I brought a Petronix Flame thrower distributor to suit Rover V8 from Amazon over Christmas, was on special. US$250 delivered to door, really good units pretty well plug and play, already with good advance curves etc. Good replacement for stock units gets rid of points etc. They get good reviews in States. Cheaper than fitting a Piranha kit (I have used them before as well and it was good gear- lasted years).