Tuning Tips for PVC Equipped Engines

[meadowbrook]

Hi folks!

 

Delighted we had our 1st rain after this winter so now I can start driving the '50 Meadowbrook again.     :)    

 

I have purchased the required parts for a PCV installation and am looking for tips on tuning the vehicle. As I understand, the PCV is adding a small vaccum leak at the intake so I will likely need to play with the carb some, can folks respond to the questions I have below? Thanks in advance!

 

1- I believe I will need to richen the idle mixture screw, but will a main jet increase (or any other carb part change) be required? The carb is a Carter BB 1 barrel.

 

2- Will the existing hole used for the vaccum wipers suffice for the PCV line?

 

Thanks !

 

BTW anyone on the list live near Ann Arbor? Maybe we can meet.

 

 

[mlozier76]

My parents live in Ann Arbor, one of these days I would love to drive my Dodge from Idaho to there, and do the Woodward Cruise and Gilmore Museum, near Kalamazoo.

[DonaldSmith]

Meadowbrook, I live in Berkley, about three blocks from Woodward Avenue, the site of the DreamCruise, which culminates on August 15th this year.  

 

mlozier 76, Ann Arbor is about 40 miles from me.  The Gilmore Car Museum is west of Hickory Corners, Michigan, near Battle Creek and Kalamazoo, about 130 miles from me,and about 100 miles from Ann Arbor.  If you come this way from Idaho, you can skirt Chicago, see the Gilmore, and head to Ann Arbor.  Rest at your folks, and then mosey over to Woodward.  

 

(Edited to add:)  To get back to the topic, I added a PCV system to my DeSoto, and noticed that I don't get a very high vacuum reading.  Question:  Is this typical, or is the PCV valve letting too much air into the manifold?   

Edited March 26, 2015 by DonaldSmith

[martybose]

I made a small manifold to attach my PCV system into the vacuum wiper hose location.  My engine is nowhere near stock, but I didn't have to do anything to it when I hooked up the PCV system.

 

Marty

[desoto1939]

Meadowbrook, I live in Berkley, about three blocks from Woodward Avenue, the site of the DreamCruise, which culminates on August 15th this year.  

 

mlozier 76, Ann Arbor is about 40 miles from me.  The Gilmore Car Museum is west of Hickory Corners, Michigan, near Battle Creek and Kalamazoo, about 130 miles from me,and about 100 miles from Ann Arbor.  If you come this way from Idaho, you can skirt Chicago, see the Gilmore, and head to Ann Arbor.  Rest at your folks, and then mosey over to Woodward.  

 

(Edited to add:)  To get back to the topic, I added a PCV system to my DeSoto, and noticed that I don't get a very high vacuum reading.  Question:  Is this typical, or is the PCV valve letting too much air into the manifold?   

Don:  Did you know that the 2015 National Desoto Convention will be held in Kalamazoo this year in July?

 

I am planning on attend without my 39 Desoto might see you there.  Rich Hartung

 

Desoto1939@aol.com

[meadowbrook]

Great, keep me posted and we can make arrangements to convoy either to the cruise or the museum. Though I have a Dodge, I'd like to see the DeSoto meet. Some car, right?

[JohnS48plm]

Let me know when you go to Gilmores, I live in Battle Creek. I,m also close to Kalamazoo so I may run over to see the Desotos.

[blucarsdn]

On your question about vacuum for the PCV system you are planning on putting on your engine..

I have retro fitted  many pre '63 engines with PCV systems, generally V8's and inline OHV 6 cylinder engines. I have engineered a couple of systems for the flat head Ford V8 engine.. I plan on putting a PCV system on my '48 Merc engine in my '36 Ford.

I do not think that the vacuum port for the windsheid wipers will have enough volume for the average PCV.. The normal hose size for a PCV is 3/8" ID..

Assuming that you are using a flat head Mopar engine, you will have to block off rhe "road draft tube" on the side of your engine.

I would suggest that you make a fitting that would accept the PCV, attaching same into the road draft port in the block.. Make sure this port fitting has a baffle so that oil cant be drawn into the PCV. Vapor is OK, just not raw oil.

Make sure that the oil fill cap has a filter screen that will allow fresh air to be drawn into the engine.

In the past we generally leaned the fuel mixture out, down sizing the jet (s) a little because the addition of PVC would tend to make the engine run a little rich. In recent years we have found that the new unleaded fuels tend to be a little lean, therfore on engines, (312 Ford V8) which we had added a PVC to years earlier, we had to richen up the carb.

I think you are mistaken in your belief that the engine will have a vacuum leak with the addition of a PVC, It is true that the vaccum line to the vacuum advance will have to be disconnected and blocked off prior to setting the timing..

The one thing that most people do not understand about a PCV system is that under accelleration, the PCV must momentarialy snap closed, ergo valve, so that there will be vacuum for the vacuum advance on the distributor.  Bill

Edited March 26, 2015 by blucarsdn

[Don Coatney]

 

The one thing that most people do not understand about a PCV system is that under accelleration, the PCV must momentarialy snap closed, ergo valve, so that there will be vacuum for the vacuum advance on the distributor.  Bill

The ported venturi effect vacuum used for the distributor vacuum advance is separate and independent of the manifold vacuum. Follow the link below for a good explanation.

 

http://www.lbfun.com/warehouse/tech_info/timing%20&%20vacuum%20advance/vacuum_explained.pdf

[DonaldSmith]

2015 DeSoto Convention:  

7/16:  Driving tour to Binder Zoo

7/17:  Driving tour to AirZoo

7/18:  Car show on the field at the Gilmore Car Museum, 9-3.

 

(Sending PM to desoto1939, meadowbrook, and JohnS48plm)

[blucarsdn]

Many years ago I had a fairly late model vehicle with a 6 cyln engine. The engine would hesitate upon accelleration. I took the vehicle to the dealer, was told the engine needed a tuneup.

Later in the day I got the vehicle back and headed home.. Upon accelleration the engine would hesitate, I returned to the dealership, their service department was closed so I went home.

For many years I made it a habit to purchase the factory repair manuals when ever I purchased a new vehicle. I got out my 1964 repair manual and read up on engine "tuneups", etc. There was a secrion in the manual which addressed the PCV system, detailing the function and servicing thereof.. Low and behold a tuneup required the cleaning and checking of the PCV to ensure proper function.

I removed the PCV from my engine, checked it to see if the valve was working, it was not.. I went to a local auto parts store and purchased the correct PCV for my engine. After the PCV was installed I took the vehicle for a test drive, no hesitation..

In the afternoon of the next day I stopped by the new car dealership, I told the service manager my problem and how I solved it. I was told that they did not service emmision controls because they were factory mandated items.. In other words the service manager and tuneup man was clueless about the function, etc., of the PCV system, having most likely never even read their own repair manuals..  Bill

[meadowbrook]

Typical dealer 'service'.

[Ulu]

LOL...you got "serviced" all right.

 

I've had some clueless mechanics tell me similar stupid tales.

 

When they start calling it a PVC valve you pretty much know you're in trouble.

[Niel Hoback]

   Well, part of it is plastic.....................

[fstfish66]

a little off topic,,  ive been to wood ward,,what a ZOOO  plenty  of  wild  cars, and a great  display by  mopar,,and  others as well,,go as a spectator,  or you will be sitting in  traffic  for  most of the day,,you use to need to  register  for a parking  spot any  where near the  event,,

 

went to the  gilmore many years ago with the  barracuda owners club,, ide love to go again,,first place  i ever seen a real  tucker,,

[Niel Hoback]

If you come this way again, do the Gilmore and come down south to LaPorte Indiana county museum, there is another Tucker there in the blue color Tucker's wife ordered.

[fstfish66]

If you come this way again, do the Gilmore and come down south to LaPorte Indiana county museum, there is another Tucker there in the blue color Tucker's wife ordered.

geez thanks for that info,,  wish  ide of  known  when  i  lived in  ill,,,,now  eastern  PA sorry to  say,,,