Raffles

Chrysler 323.5 Straight 8 Flathead

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 Try connecting the road draft tube to the air cleaner intake.

 It would act somewhat like a pvc  valve.

 It may eliminate the smell from the engine compartment.

 

 I installed a pvc on my 55 Chrysler in place of the road draft tube and I have no such smell.

 I have seen an engine that has such a set up and was sucking so much vapor from the crankcase that if you disconnected it  it would not idle.

Edited by Roger Walling (see edit history)

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I just want to add something more to my thoughts about the desirability of flexing the piston rings. While I mentioned that flexing the rings can help free them from sticking to the pistons in an older engine, I should have stated that the reason those steps are taken with a new engine is that it helps to seat the new rings against the cylinder wall and prevent cylinder wall glazing.

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Just had a fellow on another forum suggest installing a PCV valve - he has installed one on his flathead where the crank exhaust was. He very kindly provided a photo of his rig. Anyone else ever done this to their old engine?

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A PCV valve is a good way to cope with the problem. Finding a way to diminish the problem, first, would be a better way, however.

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Your description of sooty exhaust suggests it is running way too rich. Could just be the choke out of adjustment, if it only happens when starting from cold. Your engine has a Sisson choke which needs to be adjusted a particular way. Also they wear out over the years, I don't know if replacements are available but NOS ones show up on Ebay from time to time.

 

Could also be time for a tuneup and carb adjustment or carb rebuild. I would start with a compression test, and checking the oil pressure for an idea of what kind of shape the engine is in. If you have 35 to 45 PSI oil pressure @ 30 MPH and decent compression you should be able to tune it up to start and  run as well as a modern fuel injection car. I have done this on flathead Chrysler sixes and it is amazing how nice they run if everything is right.

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I have a couple of hot rods with first gen Hemis in them.

One parts supplier sells a kit that puts a PCV valve in place of the draft tube.

I did use one of those on one car and on the other I made a small tin box under the valley cover as its an aftermarket cover and doesn't accommodate a draft tube, then drilled a hole to accept a grommet for a PCV. (basically the same thing as the afore mentioned kit)

Vacuum source right out of the intake.

I have had absolutely zero problems with these.

The pic is the kit application however you cant see it in the pic. (all it is is a grommet that fits the original road draft tube hole) You can see the vacuum source though.

 

IM002854.JPG

IM002942.JPG

Edited by JACK M (see edit history)

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One thing that never gets mentioned in threads like this is that the PCV vapors need to mix properly with the fuel/air coming out of the idle jets. Just connecting to a random manifold tap screws the fuel distribution all up and requires you to run the idle way too rich, with the attendant plug fouling, driveability issues, etc.

 

Most modern carbs have a PCV port, and taking a close look at one will provide a good example of what to do if you need to make a plate to go under a carb that doesn't have a port. Ford used a separate plate under the carb in the late 60s and early 70s. Those are another good thing to look at to see what to do. Hint: usually the pcv dumps right under the idle jet or jets. Notice also that on the Ford PCV plates (and almost every other example of a pcv port) there is a big open cavity, and the only restriction is the last 1/8" or so right before it dumps in the throttle bore. If you ignore this detail the PCV will plug constantly.

 

Doing PCV as a band-aid for blowby is likely to be disappointing. There is an absolute limit to how much air/vapor you can move before the carburetor cannot work properly anymore. There is never enough flow. PCV is, after all, a huge vacuum leak. No PCV system, even on a healthy engine, can move enough air to work 100% of the time. There are times that vapor will blow backwards out the breather cap, or breather filter, or whatever the system uses to let clean air into the engine.

 

You might hit the limit for air movement even a little earlier by adding PCV to a carb that was not designed for it. The extra air coming through the PCV system means the throttle plate will be more closed than it was originally at the same idle speed. This means that the transfer ports in the idle system are going to be in the wrong place in the throttle bore relative to the throttle plates. The ported vacuum port for the distributor (if equipped) will also be wrong. Both will be late due to the more closed throttle. On some cars you won't notice a difference, on others it might be a big deal. You'll just have to try it and see.

 

Pick a PCV valve for an engine about the same displacement or a little smaller. For a stock, smooth idling engine start with a valve originally specified for smooth idling engine that had a lot of vacuum at idle. At 323.5ci, I would probably start with a valve for a Chrysler 318, and go to something smaller if it is too much flow for the carburetor to still work correctly.

 

 

Edited by Bloo (see edit history)
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Excellent advice X 2!

I'd also  say fix the engine with excessive blow by... don't band aid it. 

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Speaking about your oil quickly turning black, the soot patch on your gargae floor and the soot built up in your tail pipe does sound bad. Is soot a result from excessive oil burning?

 

My understanding is soot is extremely abrasive. It is suspended in the oil and pumped through all oil galleries and thru all bearings. It finely polishes tight clearances, enlarging them. Oil pump gears, housings, and bearings. Have you noticed a drop, or measured the engine oil pressure? I believe soot can plug up oil filters too. Further contributing to oil pressure reduction. How quickly the filter plugs can depend on the oil filter media efficiency. 

 

Does burning engine oil cause carbon build up on the upper piston ring gland too. Forcing the ring outward if it builds up behind the ring? Leading to broken top rings? Above the top ring, the carbon build up on the piston can cause scuffing on the cylinder wall.  Leading to further oil burning.  It seems when oil is buring, carbon and soot are destroying an engine from the inside out. 

 

Do these miracle oil additives help remove carbon build up? Fill micro scores in the cylinder walls? Prevent oil burn and also reducing soot?

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Soot is usually unburned fuel. Feel the black gook in the end of the tailpipe. If it is greasy and oily you are burning oil. If it is dry and sooty you are not burning the gas completely. Could be choke on too much, running too rich, engine misfiring and not burning the gas but, most likely choke out of whack.

 

If the tailpipe is dry with a gray or tan deposit that's perfect.

Edited by Rusty_OToole (see edit history)

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14 hours ago, keithb7 said:

My understanding is soot is extremely abrasive

This is a particular problem with turbocharged diesel engines on acceleration. The turbo charger does not spool up fast enough to supply enough air, briefly, during acceleration. Unburned fuel (carbon) finds it way to the sump. Oil companies have developed additives for oil to handle the additional soot and reduce the abrasiveness, since about CI-4 or CJ-4. e.g. https://www.lubrizoladditives360.com/soot-engine-oil-affects-wear/

 

Another reason to use CI-4 oil! :)

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