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Series 3 ST vent hose routing

rixter

Gold Level Sponsor
Hello,

I am trying to make heads or tails out of a series 3 ST that has been sitting for years and I have no knowledge of how it ran before sitting. Can anyone post an engine compartment photo of an original Alpine series 3 ST with the twin Zenith carbs? Specifically I'd like to see a stock setup for the hose routing for the crankcase ventilation. I had assumed they utilized the draft/road tube on Alpines through series 3, but my car has the up swung tube on the tappet cover. It would not surprise me if the set up on my car was not original, but I also think it is possible that this is stock. What is odd is that there is no PCV valve I can find. The mesh screen filters on both carbs have hose ports. One goes to the oil filler neck side port and the other hose goes to the tube on the side tappet cover. How would this arrangement flow? There also appears to be no protection against backfires from the carbs to get to the crankcase.

Any study of PCV systems has always had me spinning more than the flow of the gases. On a series 5, I assumed the flow was from the air filters, through the flame trap, through the oil filler neck on the valve cover... then out the tappet cover pipe to be pulled through the PCV into the intake manifold. Someone correct me if I have that wrong.

I think on cars prior to the series 3 the flow was in through the vented oil filler cap and out the draft tube on the tappet cover to the atmosphere. No hoses, flame traps or PCV implemented.

Was the series 3 with dual Zeniths some kind of in between method that I am not understanding or is my set up just wrong?

Thank you
Rick

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RootesRacer

Donation Time
I am not familiar with the specifics of an SIII PCV, but if its done as the SV was, the air cleaner hoses go the oil filler riser through a flame arrestor, providing clean air to the valve cover, then the side cover will have a hose that goes to the PCV valve on the intake. You could reverse it all and it would also work.
 

husky drvr

Platinum Level Sponsor
After looking at the parts manual, I don't think the actual PCV system was adopted until the introduction of the Solex twin choke carb and associated intake manifold. As best I can tell, the twin Zenith intake manifold only had provision for a check valve for a vacuum line to the brake booster. The Solex manifold had provisions for both PCV and brake booster. The twin Zenith air filters were also different front and rear, probably one with a hose connection and one without. I'm not sure how things were actually laid out.

I think it was Jim Stone who posted a picture of his S3 engine that had a small breather filter on the tappet chest cover in the area of the oil filter and no tube port.

YMMV,
 

alpine_64

Donation Time
I think the pcv system was perhaps started with GT cars batwing ( which differed to the sI/II batwing) ...

An easy check would be the change in parts book at the side cover and see when it swicthes from the atmospheric breathing road tube to closed system.

A S3GT for reference

 

rixter

Gold Level Sponsor
Here are 2 photos of a stock early S3 ST setup.




I saw these photos above in the gallery but it only shows a hose to one filter and I can't see if there are connections to the tappet cover. If this is stock, then mine is incorrect, but I'd like to see "the rest of it". Am I wrong in thinking that when looking at this picture there is no "circulation" shown. In my view, a hose connected to the carb filter from the filler would be pulling gases from the valve cover when suction is created at the carb because there appears to be no other way suction would be created to move gasses the other way. On my setup, the brake booster is getting its vacuum from the same spot on the manifold, but the routing is via a rigid line wrapping around the back of the motor, along the firewall, then up to the booster.

Going to a parts list as suggested is where I will go next I guess.

This photo below is of a later 3 or a 4 with the Solex setup. It can be seen that the intake manifold has provisions for two vacuum ports. Looks like the yellow marked goes to the brake booster, the green marked goes to the tappet cover and the red marked goes from carb filter to filler neck.

Rick

solex hose set up.jpg
 

Alpine 1789

SAOCA President
Diamond Level Sponsor
I think it was Jim Stone who posted a picture of his S3 engine that had a small breather filter on the tappet chest cover in the area of the oil filter and no tube port.
I'm pretty sure it wasn't me. My S3 engine is still sitting on an engine stand. But, FWIW, I just took at look at it and it just has the standard early engine tappet cover with the long breather tube pointing down. I have another S3 engine, which came out of a GT and is complete, and that one has an unvented cover on it. That said, I have no idea what is original on ether engine.
 

rixter

Gold Level Sponsor
Jim,

I spent hours combing through the parts list and don't see any tappet covers with no "vents". The three they show are with a down pipe (draft tube), which is series 1+2 and early 3, with no tube, but a breather cap (a vent I assume... later series 3), and an up swept pipe (series 4 + 5). So by no vent do you mean no pipe?

The photo posted by alpine_64 (also in the gallery), appears consistent with the parts book for the items I can see for an early series 3 ST. That is to say there are two different screen filters for the carbs. One with no pipe (front) and one with a pipe (rear). The rear carb pipe goes to the valve cover oil filler neck side port... no flame trap. No PCV is shown until they went with the Solex carb as was mentioned above by husky drvr.

So with respect to my mess:

1) The front filter is incorrect. It should be a screen filter with no pipe or hose.

2) The rear filter, oil filler neck with side port pipe and the connecting hose with no flame trap appear to be stock.

3) The up swept pipe on the side tappet cover is incorrect. It should be a down pipe/draft tube tappet cover.

I still want to understand how this arrangement works. My assumption is that it is an early attempt at re-circulation of some gases to the carbs for re-burning. It was only implemented a short time. Maybe that is a sign it didn't work so well. I suppose I could install a draft tube tappet cover, change out the oil filler neck to one with a vent and no side pipe and replace the screen filters with the series 1 + 2 style and say goodbye to this odd arrangement. I just don't know if the jetting was different between series 1 +2 and the series 3 Zeniths related to this. Back to the parts list.

Thanks

Rick
 

John W

Bronze Level Sponsor
Someone went to some trouble to put a hose on each carb, whether factory of after. That "bat wing" has a hose to both carbs.
 

rixter

Gold Level Sponsor
I think I sort of figured out the evolution of this system. Before venting, built up blow by crankcase exhaust gases had no choice but to force themselves out through engine gaskets. Once a vent was installed in the crankcase, the gases would exit out that way. This was via the draft tube. Some suction is created at the bottom of the draft tube as air flow from the moving vehicle passes the bottom of the tube (Venturi effect?). An additional vent somewhere else in the crankcase would aid the flow out the draft tube. So with the Alpine 1 & 2, this was via the vents in the oil fill cap. So airflow across the top of the motor due to motion of the vehicle combined with air flow from the fan, and in combination with air draw at the bottom of the draft tube, would facilitate the exit of the gases. This arrangement would still not be introducing "clean" air into the process as the filler cap vents would in theory be in a dirty environment. Enter the inclusion of the hose from the clean side of the air filter to the oil filler neck instead and you get what the early series 3 had. Apparently the conclusion was that retrieving clean air from only one of two air filters was necessary. Perhaps with the batwing arrangement and later on the dual Strombergs, they learned that changing the air flow dynamics of one carb intake without doing so with the other may have created some imbalance.

So the early series 3 crankcase exhaust gases circulation system is not a true PCV system. Being as airflow is from air filter to oil fill neck, in my view there should have been a flame trap implemented.

Rick
 

alpine_64

Donation Time
Rick,

The SI/II alpines dont have a vent in the oil filer neck.. They had a spring fitted push down cap ( that said its not a perfect seal as any blow by creates an oil mist on the rocker cover at the base of the filler neck.
The twist on filler cap starts at series 3. It has the small vent tube in the neck to connect the hose and seal the system.
At some point ( def siv .. But maybe on the solex equiped s3) they fit the flame trap into the system.
 

RootesRacer

Donation Time
I think I sort of figured out the evolution of this system. Before venting, built up blow by crankcase exhaust gases had no choice but to force themselves out through engine gaskets. Once a vent was installed in the crankcase, the gases would exit out that way. This was via the draft tube. Some suction is created at the bottom of the draft tube as air flow from the moving vehicle passes the bottom of the tube (Venturi effect?). An additional vent somewhere else in the crankcase would aid the flow out the draft tube. So with the Alpine 1 & 2, this was via the vents in the oil fill cap. So airflow across the top of the motor due to motion of the vehicle combined with air flow from the fan, and in combination with air draw at the bottom of the draft tube, would facilitate the exit of the gases. This arrangement would still not be introducing "clean" air into the process as the filler cap vents would in theory be in a dirty environment. Enter the inclusion of the hose from the clean side of the air filter to the oil filler neck instead and you get what the early series 3 had. Apparently the conclusion was that retrieving clean air from only one of two air filters was necessary. Perhaps with the batwing arrangement and later on the dual Strombergs, they learned that changing the air flow dynamics of one carb intake without doing so with the other may have created some imbalance.

So the early series 3 crankcase exhaust gases circulation system is not a true PCV system. Being as airflow is from air filter to oil fill neck, in my view there should have been a flame trap implemented.

Rick
That the engine can burn the fumes is not a design consideration, the intent of the system is to evacuate vapors from the crankcase, which prevents the oil from turning acidic and sludging up.
You really would rather not consume any of these fumes as they also contain some oil vapor which in higher blowby cases results in lower effective octane from your fuel and possible engine knock (plus undue carbon deposits in the combustion chambers).

Hipo aftermarket setups route the chamber vapor into a venturi in the exhaust, where it is not burned, but still keeps the engine oil clean.
 

rixter

Gold Level Sponsor
Rick,

The SI/II alpines dont have a vent in the oil filer neck.. They had a spring fitted push down cap ( that said its not a perfect seal as any blow by creates an oil mist on the rocker cover at the base of the filler neck.
The twist on filler cap starts at series 3. It has the small vent tube in the neck to connect the hose and seal the system.
At some point ( def siv .. But maybe on the solex equiped s3) they fit the flame trap into the system.

Correct... SI/SII have no vent port on the side of the filler neck, but air can get in around the push down cap from the bottom. The "cloverleaf" shape of the cap as viewed from the bottom illustrates this.

My believe is that the flame trap was implemented at the same time as a PCV valve.

Rick

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Alpine 1789

SAOCA President
Diamond Level Sponsor
I spent hours combing through the parts list and don't see any tappet covers with no "vents".
Sorry I created so much work for you. The only thing I know about my S3 GT engine is that it was removed from the car (I am guessing at least 15-20 years ago) by an owner who was planning on creating a Tiger clone. As far as I know, that owner and car were never heard from again, so I assume that car is yet another victim of the "how hard can it be?" syndrome. That said, I have another ventless cover someplace and was told a long time ago that they came from a different Rootes car that used the same block but didn't require a vent. Perhaps someone here will know where they came from.
 

rixter

Gold Level Sponsor
Jim,

No worries... one can learn a lot from the parts list diagrams and the associated notes on the part numbers that signify when changes were made. Of course the parts list doesn't take into account previous owners making changes. Ha. I have told people often that the research required to figure out what actually is the correct set up for a 50+ year old vehicle that I've obtained is both a frustration at times and a fun challenge. I appreciate everyone's input.

So by ventless you mean pipeless? The first photo below shows the two cover types pre PCV. I was wondering if you had the type to the right.

With the introduction of the Solex carb in series 3 came the PCV system (and flame trap I see), along with the up swept tappet cover pipe.

Third photo is the two oil filler neck types with the side port type being used in PCV systems.

Rick

tappets cover1.jpg
solex pcv.jpg
oil filler necks.jpg
 

Alpine 1789

SAOCA President
Diamond Level Sponsor
So by ventless you mean pipeless?
Yes. My S3 has the first one and my SV has the second. But, Rootes definitely made some without any pipe - I have two. Here is as good a photo as I can get at the moment off of the S3 GT engine. Lovely color, isn't it? I have the calipers from the car and they have the same paint.

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rixter

Gold Level Sponsor
Jim,

That is interesting. It doesn't appear in any diagrams I found. So what is up top with respect to the oil fill pipe and carb hoses? If they aren't venting blowby exhaust gases somewhere, it would seem they went backwards from earlier models in that regard and would be contributing to increased gasket leaks and the oil sludge as pointed out by Rootesracer.

Rick
 

Alpine 1789

SAOCA President
Diamond Level Sponsor
the S3-GT engine is currently in a fairly inaccessible place (the photo I posted took some contortions and was about as good as I could get), so it might be a little while before I can get better access to it. I'll bump it up in priority if you need the information quickly, but otherwise will file it away for something to do as soon as I can get easy access to the engine.
 

ALC 68A

Donation Time
My Series 3 GT B9203246 with its original engine has the tappet chest cover with the down pointing open vent tube. The oil filler has a rubber breather tube that connects to an inlet on the batwing air filter. There is no flame trap in between, as fitted to the later cars. On an ST with the mesh air filters, this breather tube connects to an inlet on the body of the rear filter. The filters from the Series I and II do not have the inlet connection, but presumably one could be modified, if the correct S3 one is missing.
 

rixter

Gold Level Sponsor
Hi,

My situation is that I DO have the correct rear pancake air cleaner with the pipe and hose going to the filler neck, but my front carb also has a pancake air cleaner with a pipe... one of a slightly larger diameter. This larger diameter matches that of the tappet cover up swung pipe and a hose connects them. This particular front air cleaner with the larger pipe I have seen in photos of Zenith carburetors for Alpines, but not in a vehicle. The front and rear pancake filter diameters are smaller than that used in the Series 1 & 2. I have a set of the earlier pancake filters. They also had extra holes on the underside where the Series III ones I have do not.

I am suspecting that this implementation, while odd and not documented anywhere I can find, isn't something that a previous owner dreamed up. And if so, why would there be at least two of these arrangements that I've located floating around? I am still researching it. I am wondering if this arrangement is from a UK set up (Home A/Cleaner). The series III of course had within it's short life a carb/manifold change and different arrangements for ST and GT when it came to air cleaners. This all in the middle of migrating to a PCV system. A bit of a mystery still.

Photos below are first of my Zenith C1809 setup... then a C1744 Zenith carb that was on eBay showing the identical front air cleaner I have... and finally a couple photos showing the slanted nature of the filters and their diameter compared to the earlier series.

Rick

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zenith C1744 ebay.jpg
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