Quattroporte III catch-all thread

Oh I think I understand you now. No, using the synchrometer to detect higher or lower rpms as a result of mixture adjustment is not possible. But for balancing airflow between the cylinders it's just fine.

 

Had another go at the carbs today, confirmed and tweaked the airflow a tiny bit more before putting everything back together, connecting the hoses back to the air pump, cam cover breather & manifold as well as microswitch. I also had adjusted the linkage so when the accelerator is floored the throttle plates are at 90 degrees to the venturi walls.

I noted that none of the hoses/switches seemed to affect idle at all, it was pretty much the same with/without them, plugged or unplugged. Also of note is that the microswitch doesn't seem to have any effect, but I need to get back in there and confirm that it's directly under the screw and is being completely depressed when the throttle shaft cam is at fully closed position.

Using the choke kills the engine. Too much gas? Not a huge problem as I've never really used it, and the car has always (until recently) started with 3 pumps on the accelerator before turning the key. After the carb rebuild, I need to mind the throttle the first minute or two if it's really cold outside.

Put everything back together, and went for a drive. Finally!

The engine pulls like a freight train and sounds smooth, no backfiring or spitting out of the carbs that I could notice, driving both on side streets and on the freeway. Acceleration was smooth with no noticeable flat spots, releasing the accelerator from WOT didn't cause any sputtering or irregularities. It may just be me, but the engine noise seems to be less in the cabin than it used to be. So driving (main circuit & accelerator circuit) seem to work fine.

The only problem remaining is the same problem I had before rebuilding the carbs, which leads me to wonder if the problem wasn't (just) the carbs to begin with. It isn't all that long ago they were rebuilt by the PO (hi Mike!).

The problem is still an erratic/irregular idle that shows up intermittently (both with cold and hot engine). It isn't that the engine hunts or changes rpms constantly, it's more that each start of a warm engine gives a different result rpm. Today I dialed in a perfect and smooth idle at 950rpms, did a bit more tweaking to match up the carbs even better than before. Put the car in gear and the rpms slowed down until the engine died. Other times the engine idles fine at 900rpms in D or R, but if I put it in P or N the revs shoot up to 1200 or even 1400! Even though only an hour earlier it was stable at 950. No difference with/without the smog stuff and various hoses connected.

So thanks again to everyone who's provided advice, tips and suggestions along the way. It isn't running any worse than when I got it back from the Dyno shop in the UK, and there too from time to time I had to hold in the brake while giving gas to keep it from stalling, but not consistently. Just like today. There weren't any vacuum leaks that I could find, although this seems like it may have something to do either with vacuum or timing.

I think I've gotten to the point where I need to find a specialist who can help me figure out what's going on and what I can do to fix it. There aren't really any here where I live, but I'll see what I can do with what I have.

It was great getting her out on the open freeway and flooring it! What a noise! What a feeling!

 

Congrats!

 

Congratulations!!!

Mike

 

Went for another drive today, started right up in 0C weather, but needed some throttle the first minute or two. Settled down and ran fine for an hour or two of spirited driving. Revs at idle in N were a bit high (1200-1400) so I dialed it down to around 1000 and ended up with a usable idle of 850 rpms or so when in gear, no stalling.

Engine is smooth, and testing out acceleration in various gears and situation, no flat spots that I can detect and everything seems to work fine.

So the keyword for today is inconsistency. Today she ran fine, idled ok (especially after a small adjustment to the throttle stop screw), yesterday not.

At least she runs!

 

Lovely 1986 Maserati Quattroporte III - EXTENSIVELY RESTORED AND BEAUTIFUL | eBay

OK I have taken the plunge. See what you think about the ad and what I could do or say to improve it. I put the reserve at 12k but it is way too low. Would be more value in new parts to break it!

I am hoping one of the German buyers will take a fancy to it as they are the ones that seem to have the appreciation.

Anyway. More later.

 

Jarle!

This is Charles Swanberg with the Merak Group... I didn't realized you got a QPIII. I haven't checked this forum in a while as I sold my last 1980 qp3 in 2012. I've owned 3 in the past besides the Merak and have probably over 150,000 miles behind the wheel of them. 2 of the 3 I've had were daily drivers... back when gasoline was a bit cheaper...
Regards.

 

Hey Charles

Have a QP3, Merak and a 1992 2.24v!
Well, it does use a bit of gas, but on the other hand it is a veteran car.
Cheap insurance and taxes make up for a bit of that!

I've covered 6000 kmtrs in mine last year without a hitch!
Even -20 it has performed flawlessly!

 

Mike u won!. enjoy

 

I thought I would post the brochure

 

Hello QP III guys :-D

I have just read for "houres" on this excellent thread. I know "CharlieA" very well as we are both two big Maserati enthusiasts. His QP3 was my car a few months ago, and I have gone through a lot of "late night thinking" when it comes to the tuning of these motors. The good thing is that now I know how everything works inside the engine and carbs.

One ting I noticed when you discuss the two different methods of tuning the carbs were that a US carb man (don't recall his name now) said to have the air balance screws out 1/4 of a turn. What that screw really does, is to make a "leak" of air into the engine, by opening a separate canal which draws an air/fuel mixture from the choke circuit. The choke air system (on the back side of the carb) have its own jet (inside the carb) which will allow the engine to run a RICHER fuel/air mix for cold start and during the first mile if going slowly in heavy traffic etc. Then you want an extra rich fuel/air mix. The balance screw "steals" air and fuel from the choke system and the result is that the air flow meter will show lower value (as it do not suck that much air anymore). That said, the way of balancing the carbs this way, will give richer mixture than the standard way. I am not sure if that is a good idea as the spark plugs can get too much deposits over time. OK enough about that!


I sold the Maroon Colorado met . QPIII, and only a few weeks went by before the hunger for a QPIII again kept me awake at nights. I love cars, and I must admit that the POWER and the sound of this V8 is just a real pleasure. And that fine ride and soft seats... Olalaaaa.

So I was lucky and found a 1983 Euro QPIII with only 41.000 kms from new! But it had not been on the road for 19 years! It has been out one time for a service back in 2009, but it was driven into the owners garage, and sat another 4-5 years before I managed to bring her to life.. That was pure love!!

It is in a workshop right now, but as soon as I get her back, I will try to tune the carbs to make it silky smooth if possible. That will be great fun now as I have read through this thread. I did in nearly that way with the previous car but I believe I can do it better now.

I read that you tune the car with the microswitch disconnected... WHY? I must admit that if it is adjusted with it on, it must make the car run more accurately? My opinion why this system is added is something like this: If the car has a fine idle in neutral or park, the idle will be much lower when you put it in Drive or Reverse (of obvious reasons), but if the this reduction in revs will also reduce the amount of vacuum applied to the spark retard actuator, the amount of retard will also decrease, so the outcome is that you get less retart and more power. That way the engine will manage to pull stronger when the load increases (aircondition on, full power draw with all lights on, turning the steering wheel/power steering brings down revs etc.). Can this be why MAserati added this? I have tried adjusting the carbs many times, but the different conditions make it difficult to adjust one setting that works fine for all situations....

Can someone tell me a good way to adjust the distibutor to get proper spark timing/setting? My car start to heat the exhaust manifolds to they become red hot at idle when the microswitch system is functional... That led me to believe the distributor has been adjusted to make the car run right (when the microswitch system is not connected). That will give the engine not enough advance in timing for the rest of the rpm. scale............. Am I thinking right?


THANK YOU ALL FOR GREAT KNOWLEDGE AND INFO. Post some pics of your Quattroportes please.. I attach a few myself!

 

The car of Michael Corleone when he is in Sicily in Godfather III (same color at least)
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Awesome pictures and good luck with the car!
Now I know what that new burning smell is when my car idles for a while! (euro version) You see my microswitch system never worked prior to me rebuilding the carbs. The screw was not turned in far enough to trip the microswitch at idle. Now that it does trip the switch (retarding the timing) the manifolds must be hotter. Even more so due to the air pump system removal.
Am thinking right?
Tony

 

It's for emissions emissions emissions!

It's very easy to deactivate it and see if you like the results.
Then set the ignition timing and idle mixtures and drive it like that for a while.
Easy and cheap to do.

You'll never find an absolutely "perfect" setting for the carbs for all temperatures but you can find a good compromise.

If you like that then look into recurving the distributor's advance.

Try that out and set what you think.

Read through that thread I suggested and you'll see a fellow QPIII struggling with his carbs but I think he's finally OK now.

BTW, I've known Jarle for many years now. We're fellow Berserkers! LOL

Where did the moniker "CharlieA" come from???

 

And the new car!
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Thank you

So emission is the answer...

My experince is that the car will drink a lot more fuel when the microswitch is active because the carbs need to open more to combat the reduced power when the timing is retarded. Does make much sense to me. Maybe the excessive heat wil make the exhaust burn more completely? The euro cars do not have catalyzers. But still forces air induction into the exhaust... My new car does not have the air pump connected. The good thing is that if the microswitch is connected, there is an exceptional throttle response as the timing is again advanced at the fraction of a second. I like that. The sound of the car is much better when the timing is retarded and it sounds mean! Just like another QPIII (the first one I saw live) many years ago.

I attached a few photos of the new one aswell. It has been at a workshop for some time now, and I am really eager to get it home now

 

I noticed your rear bumper. and easy fix. had my 400 bumpers fixed. $200 each and quick

 

Bob, a lot of my english speaking friends call me Charlie My surname is Adolfsen, so CharlieA it is

My QP3 runs better than any other carbed car I've owned, so won't spend more time tuning it unless something happens ofcourse. The throttle response is good enough, and it is not hot during my daily work trips, in fact it does run rather cool. It starts easily in -20C which is something most carbed cars will not. Soon 7000kmtrs covered and the car has been more or less troublefree!

Erik, personally I'd skip the switch completely. Setting fire to your car would be a tragedy. Emissions stuff is futile on old engines anyway, and the microswitch is not made to improve throttle response, it's like Bob says all about emissions..

 

Lovely cars! I want to buy another one….

 

Yes Jarle

I know the car consumption is greatly dependant on the mixture screw, so to have proper timing advance and lean mixture setting will make it burn less fuel, but then the revs start to climb when putting the car in N or P (because the idle stop screws nede to be a bit further in to make it run when in D and R stationary with AC and all power on. I will try to adjust the spark to 7 deg TDC stationary which is within the 6-8 deg reccomendation that Andy Heywood wrote on Enricos page. Then tune idle and mixture screws to make it run on the lean side and see if it works. The timing advance has very much to say for the power and to make the spark plugs keep clean. More advance = cleaner plugs and then they can ignite the immense amount of fuel that these carbs give when flooring it.... Jarles car pulls much stronger than the new blue car and I believe the blue car's timing is too much retarded. That's why the exhaust turns red hot. I like the idea of the vacuum variable retard because it will make more retarding when the revs start to climb when you put the car in park. And better throttle response on a green light because the spark plugs ignite on an earlier point where there is not so much fuel after the accellerator pump nozzles have filled the cylinders with fuel.

 

I think you may have a problem LOL

 

H a Ha. Yes I was looking at is as I really want to push forward on the 81 and it does not make sense to have 3 although that was not my intent. I had set out on the 86 when the "perfect" low mileage 81 came up which I bought from SA. Had I not started the painting on the 86 I would have sold it as is. The SA is a nice car and a 5 speed but after 30 years in SA even with low mileage it still needed everything to make it right. In some ways the 86 is better as it was well cared for, driven regularly and on good roads.

The car is the US was originally for parts but it was too good. In fact although US specs it may be the best of them.

I can see no business sense but it would be great fun to have a QPIII shop like they are doing for the Deloreans. Take a car and have all the fixes ready. The issue is that this would be great fun but not a money maker. I think the future, sadly, is a few cars left in good hands. The odd one in a lock up like above that comes onto the market and the rest lost. We do need to start capturing a few for parts before they are all gone.

 

I believe a chap named Joedro has been doing just that on this side of "the pond" for quite some time now. Capturing that is ...

The idea of a facility such as the Deloreans have is interesting. But first we need a blockbuster film to promote that car. I guess The Godfather didn't highlight the car quite enough?

 

Erik, I think the vote from most experts on this subject is that the microswitch is a part of an emission system that doesn't work and will possibly set your car on fire The wise thing would be to remove it's function completely, and tune the engine properly without it.. If any of the QP3 experts on the forum thinks otherwise, I stand corrected!

At this stage my car runs so nice, I won't even bother to check, but if it does engage the microswitch I will undo that for sure.

Colortune, balancing and adjust the distributor should be all you need to get the engine running as it should.

 

Hmmmm not quite the shop I had in mind!!! I was sort of thinking of the tuning shops that have "fixes" for new cars or indeed for old ones. There is an upgraded gearbox for some old Jaguars; an upgraded drive shaft for TRs etc.

For the Quattroporte we would have the things that need doing:

Front shock upgrade - done and available
Improved Radiator Fans - everyone is doing there own
Switch to manually turn on fans - everyone is doing and wiring in their own
New Tedel 101/102 - dogs breakfast
Drive joints etc - MIE has a parts solution for this

If you were doing a few of them in a shop what would be the cost of doing the complete rear end assembly? Send it in and get it back.

I think one of my key experiences has been dealing with shops. First, you are happy that someone will work on it, then there is the experience.