Poor progression & Idle problems with dcnf on Montecarlo

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davelarcs
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Joined: April 20th, 2012, 1:41 pm

Poor progression & Idle problems with dcnf on Montecarlo

Post by davelarcs »

Hi, please be patient with me, I am not a competitor, just a lover of old cars.

I've owned my Monte (nicknamed sporty by my little girl) for about 13 yrs. In that time I have fully restored her (6 yrs hard labour). But I cannot get her to run right.

A brief history my be usefull, I hope not boring!

When I first put her back on the road, she was on the DATR carb as standard. When cold ran pretty crummy, as they do. When warm ran well, nice progression/full throttle etc. When in traffic, after a while was a nightmare, not overheating, but misfired, very jumpy on the throttle. But when stopped & come back to, back to normal. But sometimes after a good drive, around the twisty bits, she would again act up and if she was turned off, would only restart if I advanced the ignition?

I put up with this, as I only used her occasionaly, and rarely in traffic.

I then fitted a pair of 44DCNF's & Alquatti manifold that I had from an internet auction site (had bought along with a 'big valve head' that turned out to be just ported, as far as I can tell).

Totaly transformed the car, but soon blew the head gasket (cheap head set from local factors).

So, I took the opportunity to fit the 'new' head. I used an 8v Turbo head gasket and bolts. (seemed like a good idea, allthough after I wondered whether this may have dropped the CR)?

She ran OK, but did not have the sparkle as before.

I bought a colourtune and started to fiddle. Oh Dear. So it begins, many questions will follow I'm afraid. Having had the car so long, I am keen to get her running properly again.

The Engine spec is fairly basic:

1995 cc with .4 oversize 2 ltr pistons (Many thanks to Chad formally Montehospital for those, possibly one of the last available sets at the time)

Delta Turbo 8v head gasket and bolts.

Standard valves, with ported head (prev owner said he bought the head from someone who used to race a Monte)

44 DCNF's
145 Main jet
F22 Emulsion
60 Idle
160 Air corrector
36mm Chokes
Std Cams

Compression test - No 1 = 12.5 Bar
No 2 = 12.75 Bar
No 3&4 = 13 Bar

I have balanced the carbs with carbalancer.

Using the colourtune, have all cylinders at blue.

Numbers 3&4 seem to run better than 1&2, pull leads of 1&2 not much difference, but pull them off 3&4 and there is a big difference.

Will not idle unless has 35-40 Deg advance (that can't be right)?
But at that adv I can get a smooth idle but not below 1000 rpm. Free rev smoothly without hesitation.

On the road, at part throttle she spits and pops and generally runs really badly. If I go full throttle after a little hesitation, pulls cleanly, but not as well as before.

Out of desperation I have refitted the DATR, will not tickover smoothly below 1200 rpm, again requires 35-40 deg adv. On the road still will not accelerate smoothy, but not as spitty as the DCNF's. Full throttle, huge flat spot, then pulls but very sluggish.

I have double & tripple checked the cam timing, std cams, on std sprokets, all marks linning up where they should.

Am I missing something very obvious here? When I rebiult the block, I did not check that the gaps in the piston rings were not linning up, should I have done, am I losing compression down through there, or do the rotate around anyway?

I am begining to loose sleep over this, and that cannot be healthy.

Any help and advice would be very much apprecaited, I would love to get her on the road for summer.

Thanks, Dave.
Guy Croft
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Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by Guy Croft »

The comp test indicates modest variance betw cyls. It is on the low side but it won't be due to the ring gap placement. If it was done hot engine wide open throttle plugs out then do it again with a bit of oil in the cylinders see if the compressions jump up. If it wasn't tested under those conditions it needs to be.

Quite honestly - apart from the air correctors being too small (they should be 185) I can't see much wrong - except for that ignition timing. A TC with 35 deg adv at idle would be almost impossible to start never mind run.

Please advise the exact type of igntion system fitted.

If any member can offer suggestions here feel free.

GC
Urbancamo
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Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by Urbancamo »

Hi there Dave.

I would like to know too what ignition you are using. This all cannot be just fuel related problem.

Second thing i'd like to know is what kind of fuel pump you're using?
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Guy Croft
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Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by Guy Croft »

INCIDENTALLY...

... if that turbo Delta head gasket originated from me it will be right but it is important to use the carb version one (Lancia Delta HF Turbo) as the coolant gallery layout on the ie version with reversed-port head is wrong. Using the wrong one generally causes detonation due to overheating.

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davelarcs
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Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by davelarcs »

Hi Gents.

Thank you for your comments so far.

I am using Luminition sports ignition as bought from Montehospital, black module and coil.

I'll double check the timing, I'm borrowing a strobe light from my brother in law that has a dial on the back, when that is at 35deg the pointer on the flywheel is at tdc mark on the bellhousing, but I may be using it wrong so will try again.

Is it possible to fit the pointer incorrectly? It was a few years ago I rebuilt the bottom.

I am about to put the DCNF's back on, I much prefere the sound they make over the somewhat asthmatic sound of the DATR.

Guy, you said I can oil the bores to check them, sorry to sound a bit dim, but what is the best way to do this? Engine warm, cold, simply pour some down the plug holes??

Also I forgot to mention, I have had the distributor reconditioned by H&H but not re-curved.

Thanks again, Dave.
WhizzMan
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Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by WhizzMan »

It's fairly easy to see if the TDC mark is where it should be, if there is one. You should be able to just take the #1 or #4 plug out, put the mark on the indicator and use a screwdriver in the plug hole to feel the bottom (top) of the piston. If you move the crank just a little bit now, you should be able to tell if the piston is really at it's top dead center when the marks for TDC align.

In general, dials on the back of strobe lights indicate the angle that the points are closed/opened (dwell angle), not ignition advance. I'm not familiar with the exact type of engine myself, but in general, there are usually several markings on the fly wheel to use to check your ignition timing. TDC is fairly common to be there and also a mark that is usually between 5 and 10 degrees before TDC. This is usually for idle (800-900RPM most of the time, for stock engines, check specs for your application) and should often be set with any vacuum advance disconnected from the distributor. So for most cars, the procedure is to make sure the engine runs smoothly at the correct idle speed, have the vacuum advance disabled and the strobe should be illuminating the idle timing mark and the static mark aligned. Someone will no doubt post here and tell you the exact details your engine needs to be adjusted to and what timing marks to use and all that.

I wonder if your cam timings are really what they should be. You wouldn't be the first to align marks that weren't meant to be aligned. Putting cams in that were marked for a different configuration, or just marked plainly wrong is something that happens more than you'd think. I'd try and find the correct opening and closing angles, get a degree wheel and double check that the markings are really what they should be. You are at a point where you think you have everything set up right, but your engine still runs like unacceptable, so my advice to you would be to verify the truth you think you have by an alternative method.
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tmvolumex
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Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by tmvolumex »

You may have a vacuum leak affecting cylinders 1 and 2. In fact, it may be the carb gasket or insulator for carb mounted over cylinders 1 and 2. Also DCNF's tend to drip fuel at idle. If you look down the carb bores when it running if you see fuel dripping out the accelerator pump jets you need to fix that. If you do have fuel dripping out of the jets you may have leaned it out on the idle / low speed circuit if you made your changes based solely on the Colortune. If so, you have no low speed circuit for fuel on the leaky carb (cylinders 1 and 2). Count the number of turns in on the idle adjustment screw on all 4 carb screws. They should all be similar. If 1 and 2 are way different than 3 and 4 that indicates a problem.
I would also check the distributor advance weights. The distributor is 35 years old and they wear out at the distributor weight pivots and slots. Check this I am sure it is shot, if the car has many miles on it. If so try to find a better distributor or weights. As the weights wear the amount of total advance increases. In addition the weights stick in the advanced position. As a minimum make sure the weights and pivots are clean and lubricated and move freely.
Not sure what type of triggering a Lumination ignition has but if its a "one size fits all" optical slotted rotor I would junk it. I bought a Fiat 131 with a Crane optical triggering system and it had a one size fits all optical slotted rotor and there was 10 degrees difference in timing between cylinders 1 and 4. The rotor did not and would not self center on the distributor cam thus the timing error between cylinders. Clip your timing light on cylinders 1 and 4 and check their respective timing at idle and 4,000 RPM. Both cylinders should indicate similar ignition advance values for a given RPM.
Good luck,
Tom
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davelarcs
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Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by davelarcs »

Urbancamo wrote:Hi there Dave.

I would like to know too what ignition you are using. This all cannot be just fuel related problem.

Second thing i'd like to know is what kind of fuel pump you're using?
Hi, sorry, I forgot, I am using the standard Montecarlo electric pump, it was fine before.
davelarcs
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Joined: April 20th, 2012, 1:41 pm

Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by davelarcs »

tmvolumex wrote:You may have a vacuum leak affecting cylinders 1 and 2. In fact, it may be the carb gasket or insulator for carb mounted over cylinders 1 and 2. Also DCNF's tend to drip fuel at idle. If you look down the carb bores when it running if you see fuel dripping out the accelerator pump jets you need to fix that. If you do have fuel dripping out of the jets you may have leaned it out on the idle / low speed circuit if you made your changes based solely on the Colortune. If so, you have no low speed circuit for fuel on the leaky carb (cylinders 1 and 2). Count the number of turns in on the idle adjustment screw on all 4 carb screws. They should all be similar. If 1 and 2 are way different than 3 and 4 that indicates a problem.
I would also check the distributor advance weights. The distributor is 35 years old and they wear out at the distributor weight pivots and slots. Check this I am sure it is shot, if the car has many miles on it. If so try to find a better distributor or weights. As the weights wear the amount of total advance increases. In addition the weights stick in the advanced position. As a minimum make sure the weights and pivots are clean and lubricated and move freely.
Not sure what type of triggering a Lumination ignition has but if its a "one size fits all" optical slotted rotor I would junk it. I bought a Fiat 131 with a Crane optical triggering system and it had a one size fits all optical slotted rotor and there was 10 degrees difference in timing between cylinders 1 and 4. The rotor did not and would not self center on the distributor cam thus the timing error between cylinders. Clip your timing light on cylinders 1 and 4 and check their respective timing at idle and 4,000 RPM. Both cylinders should indicate similar ignition advance values for a given RPM.
Good luck,
Tom
Hi Tom, thanks for your suggestions, the distributor has been reconditioned by H&H, and there is no dripping of fuel into the chambers, as far as I can see. I have set the floats as per weber directions.

As for the rotor, had not thought of that, I believe the setup is designed specifically for the Monte, (baseplate, rotor, pickup ect). But when I get it running again, (half way through putting DCNF's back on) I will check on that.

Thanks again.
Guy Croft
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Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by Guy Croft »

I just H&H (they do a lot of work for us) and they - like me - don't think it can actually be running with the advance you state.

Check timing marks, try a different timing light etc is the drill here..

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nabihelosta
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Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by nabihelosta »

Hello Dave

From my experience on my 2 liters Fiat TC, I can tell that these units are very sensitive ignition-wise. They respond obviously to the slightest change in ignition advance. On a twin carbed unit, 12-14 deg BTDC at idle gives you the best overall performance. Go down to 10 BTDC, you will feel an obvious lag on the low and midrange RPM. Go beyond 15 BTDC, you will hear clearly the pinging and knocking between 2500-3500 RPM full load. Of course based on the distributor's advance curve. I'm talking about the exhaust cam driven Marelli electronic distributor.

The thing I can tell for sure, is that at 35-40 BTDC at idle, it will NEVER start. Maybe won't crank too. As if the battery is empty.

I advise you to check two parameters here:
1- The timing marks, on the crank pulley and on the cambelt cover. Maybe you are using a cambelt cover borrowed to another motor (1600, 1800?), or the crank pulley has a random mark elsewhere than true TDC, maybe a scratch or hammer mark that you're mistaking to be the TDC mark?
2- Try another strobe light, a trusted part from a trusted brand, better try it on another car that you already know the true timing, as a reference.

Thank you

Nabih
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davelarcs
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Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by davelarcs »

Hi All,

Once again, thanks, this is a very helpfull forum, I did not expect so much help so soon!

I am in the middle of refitting the DCNF's, between work and other comitments I only manage to work on the car now and then, and then it maybe only for an hour or so, hence why it took 6yrs to restore it :).

So it may take a bit of time to resolve this, but with your help, I hope we get there.

I will keep you updated as and when.

By the way, when I get the time, would any one be interested in my restoration piccys, and have loads I could upload.

Some of them are pics I took as I was taking the car apart, to remind me how to put it back together again, these may be of use to someone.

Dave.
Guy Croft
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Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by Guy Croft »

You are welcome to document the resto but please do it in the Readers' cars section.

The 'wet' comp test is done by squirting about 1/2 thimble-worth of oil down each plug hole in turn. Hot engine, plugs out, wide open throttle. You keep cranking till the gauge stops rising basically which should only be a few strokes.

Have been 'mulling over' your setup and the only thing I can usefully add is that if you're on contact breakers (which I don't suppose you are unless it's a contact-assisted system) and they are set dramatically wrong you can end up erroneously dialling in way too much ignition advance to get the motor to run right. I saw this recently on a unit where the coil was mismatched to the distributor and the condenser could not cope with the breaker-open event and the contacts rapidly burned and closed up. That reduces the dwell period so much that tons of advance has to be put in. All wrong of course, once the coil was correctly rigged (with a ballast resistor) normal service resumed (10 deg static).

It may just be be that your coil is not actually matched to the amp unit and the electronic dwell is not working right. That would lead you to enter far too much advance.

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davelarcs
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Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by davelarcs »

Hi Guy,

Right, I have the DCNF's refitted.

While they were off I checked the throttle plate action, carb feeding 1&2 must have had a slightly bent spindle as one plate was completely passing the first progression hole before the other.

So with a bit of gentle teasing they now both pass the holes together. That can't of helped things.

Turned all idle screws out 3 full turns, and got the engine running without any problems.

All throttles are pulling at 4 on the carb ballancer (after a little playing) at 1000 rpm.

Now have the timing at:
1000 rpm - 15 deg adv
2000 rpm - 26 deg adv
3000 rpm - 30 deg adv

It does help -of course- if I had read the timing light properly the first time, sorry to have sent you a red hearring there.

Once hot I then checked the compression as per your instructions. Previously I had checked it cold.

Those were: Engine hot, plugs out & full throttle.
1 - 13.25 Bar
2 - 14 Bar
3 - 14 Bar
4 - 13.74 Bar (I must have had 2&4 mixed up before)

I then added a little oil:
1 - 14 Bar
2 - 14.5 Bar
3 - 14.25 Bar
4 - 14.5 Bar

Once warm it Idles smoothly at 1000 rpm and revs freely without any hesitation. But after a while it starts to stumble and die off, but if I hold it at 1500 rpm for a few seconds it then goes back to smooth idle for a while again, I suspect the plugs are fouling up? And a bit of a rev cleans them?

On the subject of plugs fouling, especially during stop start traffic, what can be done? Does a different temp plug help? I have BPR6ES in now, would a 5 be better or a 7?

Have not road tested yet as it is raining, and my Monte rusts in protest :).

Will keep you further informed.

Thanks. Dave.
Brit01
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Re: Poor progression & Idle problems with dcnf on Montecarlo

Post by Brit01 »

On the subject of plugs
I have BPR6ES in now, would a 5 be better or a 7?
These are NGK right?

5 is hotter - lower the number the hotter.
But 5 is very very hot. You shouldn't have fouling with a 6 which is considered hot.
I have an Alfa boxer and found the 6 NGK rating too hot.
7 is good all round. Maybe for short trips in traffic I could get away with 6 but on longer runs no.

So if you have fouling with the hot 6's then sounds like the idle circuit is too rich and/or you have too much oil in the firing chamber.
My 2 cents.

Did you set the idle mixture screws to borderline rich? Did you use a colourtune plug?

As Guy said he doesn't see anything wrong with the jet set ups (except the air correctors which don't come into play at lower revs), maybe your idling mix is too rich.
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