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Engine Stuttering under load

Discussion in '"Stock" Alpine' started by alpiner, Feb 2, 2016.

  1. pruyter

    pruyter Donation Time

    If you have done the Webconconversion which means both the new Alpine manifold plus the Weber 32/36 then the stalling is caused by the PCV valve which is situated at such a place on the manifold that the gasses from the sump pan influence the mixture in the manifold.
    The cure is: block the PCV valve!


  2. RootesRacer

    RootesRacer Donation Time


    Block the PCV, where does the blowby go now?
  3. pruyter

    pruyter Donation Time

    You can do two things with it: I have connected a little K&N filter at the end of the hose which comes from the tappet cover, so the fumes are passing this filter and are then entering in the open air.
    The second possibility is: take of the hose which comes from the tappet cover and then block off the hole in the tappet cover or.....try to get a tappet cover from a Rootes car from the Hunter range because this cars did not have an air breathing from the tappet cover. So in the end Rootes discovered that this kind of breathing was to no use.
    But the question is: do you have a real Webcon conversion?
    Up til now several owners who did this conversion have now blocked off the PCV valve. If you take your Alpine to a rolling road you actually can see the disturbing of the mixture by the oil fumes!
    I think I was about the first of owners with this conversion who experienced this error and although I found the solution I did not found the real cause. I was in the opinion that the PCV valve had an air leak but Tim Ray, who is just as I am a member of the British SAOC, found the real cause when his Alpine was placed on a rolling road. He reported about this on the forum of SAOC.
  4. alpine_64

    alpine_64 Donation Time

    Peter the early alpines had a road tube that vented the crank case directly outside, the series 3 started to use the pcv system and iirc the hunters also used the pcv system slightly modified with a different sized flame trap filter.

    The pcv system extends the life of the engine significantly... Not sure why you would want to remove it from the car. I am surprised that you would remove it with the webcon conversion, perhaps it's producing a different amount of vacuum to the factory setup and requires a different valve ... But ditching it all together seems a retrograde step.
  5. 65beam

    65beam Bronze Level Sponsor


    the hunter range cars that came to the states and were equipped with dual carbs did have the flame trap coming off the valve cover. the vent used a larger flame trap than the one used on alpines and this was connected to the air filter housing. there was not a PCV.
  6. pruyter

    pruyter Donation Time

    Yes 65 Beam you are right in that and that means that venting from the tappet cover was deleted at the Hunter range with the consequence that the tappet cover had no tube on it any more.
    The reason for blocking off the PCV valve when a Webcon conversion is installed is the following: at the standard inlet manifold the PCV valve is situated in a kind of gallery that services alle the 4 cylinders while at the Webcon manifold this valve is situated right in front of the 4th cylinder. The conseqence is that the mixture becomes that weak that the engine stalls.
    To answer the remark from Alpine_64: I agree that the venting of the engine prolongs the life of the engine significantly, but when Rootes deleted with the start from the Hunter range the venting from the tappet cover and relied only on the venting from the rocker cover I assume that Rootes knew what they were doing.
    But most important of all: the stalling from the engine disappeared right away when the PCV valve was blocked.
    If you are interested in the discussion on the SAOC-forum look for the thread "engine stalling during gear change". This tread can be found under "Alpine technical problems/Help"
    Last edited: Feb 15, 2016
  7. RootesRacer

    RootesRacer Donation Time

    PCV is one of the few features that came with the 60s and 70s emissions push that is beneficial. It's the main reason that engines suddenly jumped from 50,000 mile lifetime to what it is today. Sure motor oils improved a lot over that timeframe, but PCV eliminated the problems from acid and sludge formation in the crankcase.

    I run twin 40 DCOEs and modified the intake to to run a balance pipe with PCV feeding it (to all 4 intake ports). Running a 2bbl DGV or DFV with a common log intake makes PCV that much easier to setup and jet for.

    If you are having "stall" issues, my recommendation is to find someone that understands carburetors and knows how to jet them before deleting a perfectly functional PCV system.
  8. pruyter

    pruyter Donation Time

    Ai, Ai that is a rather harsh reaction! If you are willing to take a look on the forum of SAOC and also are willing to check about the facts of the Webcon conversion you might change your opinion. I am mot doubting the advantages of the PVC system, but.....the design of the new inlet manifold causes the trouble with the PVC as a rolling road test proves without any doubt. Second: Rootes him- or herself changed the breathing system at the start of the Hunter range to a system that deletes the venting through the tappet cover and so did I now. So what am I missing here?
    I am open to any debate and to any discussion and if I hear any comment that is reasonable I am the first to admit that I am wrong, but I prefer a discussion in a kind of gentleman way...


  9. 65beam

    65beam Bronze Level Sponsor


    this is not intended to upset anyone but engine oils have been greatly improved. they now contain additives to control and prevent sludge, anti corrosion additives, foam suppressants and other additives not in use when these cars were being built.
  10. RootesRacer

    RootesRacer Donation Time

    I dont see anything ungentlemanly about my response. My final sentence may be giving you some grief, but lack of proper tuning is probably the crux of the issue. Isn't webcon the UK distributor for carburatori weber? One would think they could get a setup to work (rootes did with the 2bbl solex in a nearly identical configuration). If the new intake is the cause for your problem, then there you are... I am not really sure what was so wrong with a modified solex intake running a 32/36 (or a 38dgas) weber. Its been done for nearly 40 years as nearly a bolt-up leaving all other systems intact.

    Lack of PCV will cause the crankcase pressure to increase, which will in addition to the well known sludge and acidic oil will also increase the engines tendency to weep. With the rootes engines scroll seals it doesnt take much in way of blowby to cause a great deal of oil leakage.
    In any case, simply blocking off the PCV flow is a horrible idea since you would then lack the capability of even having a "road tube". At least install a proper vented side cover so the crankcase gasses have somewhere to go besides fouling the carb/intake with untrapped oil vapor.

    Yeah, we've seen the hunter engines with the PCV delete, it was done near the final gasps of Rootes, probably as a cost reduction exorcise. That they did it does not make it the right thing to do.
    Even with all the wonderful oils available today, its kind of odd that pretty much every gasoline engine produced today has some form of PCV (from lawnmowers to automotive).
  11. pruyter

    pruyter Donation Time

    Yes it was the last sentence that I did not like very much, but I agree with all what you say about the advantage of the PVC and yes I have connected a tube with a K&N-filter at the end to the side cover as I have mentioned in one of my reactions below.
    Webcon has with great help of the Britisch SAOC designed the new inlet manifold and the advantages are great. It is not that the standard inlet manifold doesn't do the job but it does it not efficiently. On the website of SAOC you can spend some time with reading about this conversion. The great advantages are a much better fuel economy, better drive ability and however not very important a gain of about 17% more HP.
    So yes the standard inlet manifold plus the Weber 32/36 or as earlier used the 28/36 works fine but not as good as with the new inlet manifold.
    I was very disappointed indeed when I had to find out that the new inlet manifold causes problems with the PVC. As I mentioned below I found the solution for the stalling but not the culprit. It was britisch SAOC member Tim Ray who experienced the same trouble who brought his Alpine to a rolling road where they discovered the real cause of the problems.
    So now I have a few options: return to standard and forget about the new inlet manifold, accept the stalling, or delete the PVC and use a tube with a filter on the end so that there is some way of breating from the side cover.
    If you have other suggestions so please tell me. The jetting is the result of much work of both Webcon and SAOC on a rolling road so changing the jetting is no options. What else can be done?
  12. RootesRacer

    RootesRacer Donation Time

    If you are bound determined to keep the intake (I have to believe there is a tuning solution but perhaps not at the hands of webcon) then install an exhaust based vacuum ventilation system like this:

    BTW the new carbs available from weber/webcon may not have appropriate progression holes for PCV since the carbs available now are a "universal" application.
    PCV requires the ability to close off the throttle a bit more (with a progression holes still in play) and needs the ability to add more fuel at closed throttle to offset the lean mixture as the result of a sizeable percent of air dilution from the PCV.
    OEM PCV applications usually had more and larger progression holes than the earlier non PCV apps.
    This is why selecting a carb from a similar displacement engine (that had PCV) is always a better starting point to get a carb than one that is for a universal application.
    The key to getting idle to work with PCV is usually in the idle jets emulsion well. This emulsion and the progression holes are what "makes" the OEM tuning work like you expect.
  13. pruyter

    pruyter Donation Time

    Thank you very much for this comprehensive explination! I know that both Webcon and SAOC have done a lot of work and have spent many hours in designing the inlet manifold, but it seems that they have not properly tested the PVC system with the result of stalling that I and others are experiencing now. So if will give your information a very big thought and I have some work to do. So again: thank you very much for your time and information!
    That said I should nearly forget that this thread started with a question of a member who also experienced stalling problems. I have asked this member if he has done the Webcon conversion, but up til now he did not answer that question. If he has not done this conversion then we can forget the discussion about the PVC valve. Very strange that he is not reacting while forum members try to help him...it is a pity!
  14. alpine_64

    alpine_64 Donation Time

    The reason for blocking off the PCV valve when a Webcon conversion is installed is the following: at the standard inlet manifold the PCV valve is situated in a kind of gallery that services alle the 4 cylinders while at the Webcon manifold this valve is situated right in front of the 4th cylinder. The conseqence is that the mixture becomes that weak that the engine stalls.[/QUOTE]

    Well that's a very poor design outcome, we all know it should come from a common point so as not go drag heavily on 1 cylinder. I wonder why they didn't locate it better?

    They did... Cutting costs... Basically any new car from 60's has a pcv and its proven to increase engine life.

    As for the webcon thread on the saoc, I had read it during the testing and promotion... And I mean promotion of the webcon setup. While its great that a company decided to build and develop new parts for our cars and i applaud the effort, many of the comments as to why people wanted to make the switch were dubious. Lots of people complaining about the twin 150CD setup saying they were to hard to keep in tune, hard to get running right or suffering flat spots etc. Most of the complaints were classic signs of worn out carbs, or people who thought fitting a gasket kit was a "rebuild" they would have got the reliability and drivability they wanted from a proper rebuild of the carbs.. And indeed in many cases the linkage as people complained about slop in the original... They are 50 year old rotating parts with bushes... They need to be rebuilt/replaced over time.

    I empathise with people running the twin downdraft zenith carbs, rebuilding them correctly is difficult due to parts availability and the fact you often need to rebore throttle bodies and shafts and make new ones. Then they will still weap as they did new and still wear quicker than other setups ( though most peoples usage would allow them a long life)

    The biggest issue I had with the whole saoc thread was the heavily biased nature of the promotion ( it was not discussed really just aggressively defended)

    As for the setup, I think it looks horrible... The performance gain while apparently decent according to their reported results will not make the alpine a much faster car. As for economy, well setup stock options are not thirsty so fuel consumption given most driving millage is not really a primary concern.

    The line for me though (and I'll admit it concerns the factory single setup as well) is that it's such an ugly installation. The manifold is heavy looking and ugly... But that's driven by its design for flow.. So fair enough, but the filter setup is offensively ugly... It looks like a cheap rice cooker stuck under the bonnet and has no aesthetic appeal or period relevance. Why not make the filter housing at least somewhat period?

    Rootes did a nice looking motor, particularly the early separate header tank setup and then put this on there and make it look like someone kitchen utensils.... If be embarrassed to open the bonnet at a show ....

    Im bias, I run twin dcoe Weber's.. I do it for the performance... But just as much for the look and sound.. They do give good performance, they are reliable and yes they use a lot more fuel than any stock setup... But I love them for all the aforementioned reasons... I didnt buy a sunbeam because I wanted an efficient modern car... I bought it for looks sound and fun.... And I did drive it as a daily drive for 4 years with the dcoes in a major city.. So I can vouch for reliability and drivability... But the best part was the smile on my face when I touched the throttle pedal or opened the bonnet...
  15. RootesRacer

    RootesRacer Donation Time

    As the OP is in the U.S. and because the webcon carb and intake is not directly available here (and its also rather expensive) I would venture that the OP does not have the webcon setup.
    I am unaware of anyone running one here in the states.

    Pierce manifolds has a similar intake (though surely with a lesser pedigree) that is known to work fairly well.
  16. RootesRooter

    RootesRooter Platinum Level Sponsor

    My SV has some of the same Weber symptoms but am running a Series IV manifold.


    Nevertheless, I will try plugging off the PCV just to see what happens.
    Last edited: Feb 15, 2016
  17. pruyter

    pruyter Donation Time


    I emphatize with your reaction and you are right in saying that there was a lot of agressive promotion on the SAOC thread regarding the Webcon conversion, I did not l like that at all.
    The looks....yes it is not exaxtly pretty, I agree with that too. The argument of the fuel economy? Well as the owner of a Sunbeam Tiger I know what exessive fuel consumption means and.....I don't mind because I enjoy the roar of the V8 and that means a lot to me.
    Well, why have I installed the Webcon conversion? I own besides the Tiger also a 1965 Sunbeam Rapier series 4 with the dreadfull Solex carburettor for which parts are unobtainable. At my brothers series 4 Alpine is also installed this Solex carburettor and one of the emulsion tubes is broken and it is impossible to get a new one. So he and I decided to get rid of this carburettor which was installed by Rootes in order to cut costs. At this point a Weber carburettor came in sight. In the beginning I was looking for the 28/36 carburettor to be installed on the standard inlet manifold, but....I did not succeed in finding one. Then in august 2013 I bought the Rapier, the only LHD Rapier in my country the Netherlands and originally sold here in 1965. I discovered an inlet manifold that was leaking water, so I had to do something about that. I preferred to find a good used one since new ones are unobtainable. And again I did not succeed in finding one. Then I red about the Webcon conversion and decided to go for it. And to be honest, it changed the drive ability for the better.
    And yes Michael I agree very much with your comment "why did they not locate the PCV valve in a better place?". I have wondered about that a lot and I still have no any answer. On the SAOC forum nobody reacts on that comment, so the owners of Sunbeams with the Webcon conversion are now only looking for solutions for the stalling and up til now it is: blocking off the PCV valve.
    In my case I reckon that I am not driving that much kilometers and the only thing I can do in order to make things not worse is changing oil and oilfilter regularly. When and/or if the times comes that I am forced to overhaul the engine, so be it. That should happen not more then one time since my age is 66 and I am not driving that much. The weather in the Netherlands is a lot like it is in the UK and that means that I drive my Sunbeams only from the beginning of march to the beginning of december.
    Thanks for your opinion. I really appreciate that!
  18. George Coleman

    George Coleman Gold Level Sponsor

    One note is that the Weber can not handle high fuel pressure, check that no more than 2 psi is a good start, and also no one has seemed to confirm fuel flow and volume. :cool:
  19. alpine_64

    alpine_64 Donation Time


    You could have easily bought one of the factory rootes DD manifolds even the later curved runner one from UK very cheaply, I'm very surprised you couldn't find one, or from USA, Australia new Zealand which would be more postage for you being in Europe , but still available. Also as mentioned Peirce in the USA offer them new as do sunbeam specialties.

    Anyway as long as you are happy with what you have.. But having to block off the pcv indicates to me something is not right with the webcon kit... They need to work out if it has to much/ little pressure and find a suitable replacement pcv to get it to work.

    Good to hear you have so many rootes cars running there....

    As for the tiger... You can get good mpg and save engine wear with a 5 speed... And now they have the bolt in tko500 kit that requires no body mods.... That is a fantastically developed aftermarket modern product for the cars
    Last edited: Feb 16, 2016
  20. pruyter

    pruyter Donation Time

    Hi Michael,

    Could you explain for me what you mean with DD manifold? It must be my lack of the English language that makes that I don't understand this abreviation. Also I don't know what you mean with the later curved runner from the UK. I was and I am aware of the Pierce manifold in the USA.
    As I said I was not happy with the discovering that Webcon/SAOC have not thought about a proper PVC system, but that is something I found out after I had installed the Webcon conversion. In retrospect I could have made another decision, but that is not helping much now.
    This conversion has certainly made the drive ability a lot better, but I have to think about a solution for the PVC system. Well I have got some input now and I have to think it all over.
    I know about the 5 speed possibilities of the Tiger, but the use of this car makes that I am not making that much kilometers with it that I have bothered to do something with the fuel economy. I bought the Tiger in october 1995 with LSD diff, 289 cc engine and a SS exhaust. The Malory distributor and coil I have sold to Tristan Bradfield in the UK who installed it in his racing Tiger and I installed in my Tiger a Lumenition electronic ignition plus standard Ford distributor.
    Here in the Netherlands are rather much Rootes cars around and in the period 1968 - 1977 I have driven 5 of them as my daily driver. Even my father and brother drove Rootes cars. Even though I changed later on over to a totally other profession I have worked 3 years as a car mechanic at a Rootes dealer. Perhaps this experience has feeded my love for Rootes cars.

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