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1725 Blow-by? Dead Cylinder? Both?

M

mferris

Donation Time
On my 1725 with Weber 32/36 - I'm venting the side cover and oil filler to atmosphere and have a question about the amount of air and smoke should be coming out of both.

Is this blow-by? Or do I have a dead piston/cylinder?

Hard to describe:

- There is a strong, constant puff of air coming out of both side-cover and oil filler vents, and smoke puffs coming out of the side-cover vent.
- A white piece of paper held against the exhaust gets wet with black soot - although no smoke is visible
- When I pull #4 plug wire - little changes (all other wires almost kill the engine) - haven't tried a vacuum change check on it yet.
- Pretty sure I had 150psi on all cylinders when I was trying to get it started, need to check again.

Other things that might confuse the issue:
- All valves are moving up/down, I've done valve adjustment a few times now.
- I randomly get shocked when I touch the distributor (pertronix, with new wires/distributor as far as I can tell)
- Adjusted the Weber 32/36 idle mixture/screws to ~800 rpm at idle and timing (2-3 marks e.g. 12degBTDC since it brought the idle up)
- running 20-40psi on the original oil gauge, no idea if this is accurate.
- I've put 20w50 Castrol in it as of this weekend, same smoke before and after.

The side-cover vent (with a hose attached) puts out some puffs of smoke which dissipate within a foot of the outlet - but If I'm at a stoplight, I can see smoke coming in the cabin (no top on the car for my health so far) and out of the engine department (I don't think this is spilled oil from the oil change I did). It all dissipates within a foot of the car or so and is only visible in the right light.

I put about 25 miles on it this weekend, it starts and runs. I can easily keep up with traffic, it doesn't stall out at idle ever. I have a slight stall when I romp on it - but I presume this is a jetting issue (using stock webercarbdirect.com model).

Generally seems usable - but I'll have to decide whether I rip the good V6 out of the other car I have or not and use here. I'd rather just drive this one originally for a while.

-Mike
 
R

RootesRacer

Donation Time
A question I would ask is what side cover are you running?

The early side cover has a long tube with a slant cut on it that uses the vehicle
speed to create suction on the road tube for ventilation.
The side cover has a baffle to prevent oil loss during vent evac.

If you run a later side cover that goes to a hose, this has no baffle and oil droplets will exit the tube. The side hose on the later side covers is the fresh
air intake, not a vent, this is why its not baffled like the earlier.

Other things to consider are:
1) Is the flow out the vent unidirectional? This is hard to test and tell. Often the flow out the vent pulsates, but reverses flow as the pistons go up and down and pressure builds and reverses in the crankcase.

2) Are you waiting for the engine to be at temp before testing this?
Rings may not fully seal until the pistons are up to op temp.
Your "smoke" may in fact be water vapor.

3) Excess fuel will make the vent gas smoky and have a gassy smell.

4) Did you provide a fresh air inlet for the crankcase?
The oil filler cap on the atmospheric vented engines is different (rightly so) than the closed cap used on the PCV equipped engines.
You should not use the closed cap on a road tube vented engine as there
is no pathway for air to evac the crankcase.
 
J

johnd

Donation Time
RR - Is it OK to use a loose fitting (old style) oil filler cap with a later model side vent tube that connects to the air filter used in Weber applications?
 
R

RootesRacer

Donation Time
johnd said:
RR - Is it OK to use a loose fitting (old style) oil filler cap with a later model side vent tube that connects to the air filter used in Weber applications?
Click to expand...

Not really.

The long tubed side cover is long for a reason.
It generates a vacuum in the road tube (due to the vehicles speed and the angle the tube is cut at) that provides fresh air flow through the engine.

Connecting the side output to the inside of the air cleaner is not going to be particularly effective as there is not much depression there unless you are at wide open throttle.
A functional PCV is much more effective.
 
J

johnd

Donation Time
RR - Does this mean that I would be better off fitting the later model "sealed" oil filler cap to the valve cover?
 
R

RootesRacer

Donation Time
You are best off doing it right.

Choose a method and do it completely and correctly.

Option 1, install long pipe side cover and early valve covers oil cap assy.

Option 2, use short side cover (with hose). That goes to the filtered air side of the air cleaners and provides clean air to the engine. Connect flame trap to the oil fillers output nipple and then connect the flame trap output to the PCV valve installed in the intakes common log.

Option 3, install a crankcase evac venturi (moroso makes some) in your exhaust pipe and connect that to the short pipe side cover. Use the early oil filler cap for air inlet.

As I said before, I am a fan of PCV so I would do option 2.
 
sunbby

sunbby

Past SAOCA President
Donation Time
RootesRacer said:
You are best off doing it right.

Option 2, use short side cover (with hose). That goes to the filtered air side of the air cleaners and provides clean air to the engine. Connect flame trap to the oil fillers output nipple and then connect the flame trap output to the PCV valve installed in the intakes common log.
Click to expand...

I think that's not quite correct. The tappet cover connects to the PCV valve and the oil filler/flame trap connects to the air filters.

the PCV valve "sucks" the crankcase fumes (combustion blow-by) out of the crankcase and the air filter/flame trap/oil filler supplies the fresh air to replace the combustion fumes.

see page 33 of the Engine section in the work shop manual - WSM145
http://www.sunbeamalpine.org/downloads/WSM 145 SV Manual/5 Engine (B-1).pdf
 
R

RootesRacer

Donation Time
sunbby said:
I think that's not quite correct. The tappet cover connects to the PCV valve and the oil filler/flame trap connects to the air filters.

the PCV valve "sucks" the crankcase fumes (combustion blow-by) out of the crankcase and the air filter/flame trap/oil filler supplies the fresh air to replace the combustion fumes.

see page 33 of the Engine section in the work shop manual - WSM145
http://www.sunbeamalpine.org/downloads/WSM 145 SV Manual/5 Engine (B-1).pdf
Click to expand...

WSM 124 says the opposite (first paragraph pg. 59).

Doesnt really matter though (except sucking vapor from the side cover will have more oil in it than the oil/flame trap).
 
J

johnd

Donation Time
Page 33 describes the PCV valve as being "screwed into the inlet manifold". The Pierce manifold I'm using in conjunction with a Weber carb does have a threaded orifice into which I suppose a PCV could be screwed into - but I thought that orifice was for brake booster vacuum. ?? Also, how many areas are there that are "...used for entry of clean air into the engine crankcase"???
 
R

RootesRacer

Donation Time
johnd said:
Page 33 describes the PCV valve as being "screwed into the inlet manifold". The Pierce manifold I'm using in conjunction with a Weber carb does have a threaded orifice into which I suppose a PCV could be screwed into - but I thought that orifice was for brake booster vacuum. ?? Also, how many areas are there that are "...used for entry of clean air into the engine crankcase"???
Click to expand...

Do you have a brake booster fitted?
If not then buy a PCV that is for a similar application and put it inline to the fitting in a hose at both ends.

IIRC there is a common toyota 1600cc PCV that has metric pipe at one end and a hose barb at the other. Both sides can go into rubber hose though the pipe threaded end is a bit larger.

I use this PCV on a twin 40 DCOE setup and put 4 small hose fittings, one in each runner.
 
J

johnd

Donation Time
I have a SII - so no brake booster. Would you happen to know what PCV valve would fit the Pierce orifice?
 
R

RootesRacer

Donation Time
johnd said:
I have a SII - so no brake booster. Would you happen to know what PCV valve would fit the Pierce orifice?
Click to expand...

probably none.

The fitting installed will probably be 1/8 or 1/4 NPT.

Most PCVs are a fine metric straight thread or tapered.

I would just install it inline.
 
M

mferris

Donation Time
Thanks guys. Page 33 cleared things up for me pretty well. I'm going to order a v100 pcv and install it inline from the tappet cover. Then install the flame trap between the oil filler vent and the carb unfiltered air intake. Although I took page 33 saying it works either way.
 
T

Tom H

Platinum Level Sponsor
RootesRacer says
"WSM 124 says the opposite (first paragraph pg. 59)
Click to expand...
.

Note that the description is for "A.C Crankcase ventilation" for earlier engines. The rest of the section says: "the crankcase ventilation air enters the crankcase through an intake on the engine tappet cover plate" . This is a description of the open pipe used on earlier engines. It is the later Positive Crankcase Ventilation that uses a completely closed system. On the 1725, the flame trap is between the oil filler post and the dual air filters , using a special molded dual / split hose. The PCV valve is screwed into the inlet manifold and the other end connects to the tappet cover.

When I installed a Weber, I used a SIV manifold, installed a port in the manifold, and fit an aftermarket PCV valve in the middle of a hose from manifold to tappet cover. I think there are two ports in the SIV manifold, one for my Brake booster and one for PCV.

Tom
 
R

RootesRacer

Donation Time
Tom H said:
RootesRacer says .

Note that the description is for "A.C Crankcase ventilation" for earlier engines. The rest of the section says: "the crankcase ventilation air enters the crankcase through an intake on the engine tappet cover plate" . This is a description of the open pipe used on earlier engines. It is the later Positive Crankcase Ventilation that uses a completely closed system. On the 1725, the flame trap is between the oil filler post and the dual air filters , using a special molded dual / split hose. The PCV valve is screwed into the inlet manifold and the other end connects to the tappet cover.

When I installed a Weber, I used a SIV manifold, installed a port in the manifold, and fit an aftermarket PCV valve in the middle of a hose from manifold to tappet cover. I think there are two ports in the SIV manifold, one for my Brake booster and one for PCV.

Tom
Click to expand...


Tom,

Read it again.
That whole section is for the early closed PCV system.
It appears earlier PCV equipped engines were run differently than the later.

No matter, it still provided clean air and positive flow through the crankcase into the "AC brand" PCV valve on the intake.
 
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