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Need HELP Engine Back Fired Blow off oil Fill cap and More

Started by Bill Balkie 24172, June 24, 2012, 07:16:56 AM

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62droptop

Quote from: gary griffin on June 24, 2012, 11:16:05 PM
W. Lee,

    I cheat on LBC's my Stag has a TR6 engine and a Toyota 5 speed transmission. My 1948 Triumph 1800 roadster will have a Tr 4 engine along with a Toyota 5 speed. The 5th gear in the Toyota is is about 1.2 to 1 which makes Triumph,s O K on the freeways.  My 1937 Lanchester is stock and not liking to go down the road much faster than 40 MPH in fact it probably likes 35 better. My Cadillac will be a freeway cruiser even though it origially had a 4:11 rear end I am trying a 3:26? . I expect it to be  a dog in town but a very comfortable cruiser which is what I expect to be doing with it

that will do it nicely
the stag v8 does sound nice,but expensive and problematic
i have a buddy in atlanta area with a 49 or 50  tr 2000 roadster,cool cars

62droptop

Quote from: TJ Hopland on June 24, 2012, 09:50:32 PM
That setup is basically how GM did it the first few generations of EFI.  By the time of OBD2 (1996) I think the computers just handle it because they obviously know if the engine is running or not and by that time were capable enough to handle extra functions like that.

ford also used the inertia switch with a ball bearing in it to shut down the pump in case of a crash
i have on wired into my mini from an old ford tempo
just have to remember it is there if you jolt the car as it may trip the switch and need to be reset


Glen

I have to agree with Phil here.  My father put an electric fuel pump on his 1938 Cadillac to solve vapor lock problems.  It was turned on and off with the ignition and it did not give any problems in the approximate 200,000 miles he drove the car after putting in the pump. I am planning on putting an electric pump on my 68 ELDO for starting after sitting for a long time.  I just need to find one that does not over power the float valve. 

There seems to be some misunderstanding of how a mechanical fuel pump works. 

When the cam bumps the pump lever it causes the diaphragm to pull fuel into the chamber of the pump through a check valve.  When the lever is off the cam the spring in the pump presses against the diaphragm creating a nearly constant pressure that is dependant on the spring strength and diaphragm size.  This pressure is only interrupted briefly each time the cam comes around to bump the pump lever.  Of course the pressure is matched to the carb to prevent flooding.  The carburetor is what regulates the flow of fuel; first with the float valve which fills the bowl.  The depth of the fuel in the float valve then provides the pressure needed for the rest of the carb systems like the Venturi(s).

In Bill’s case the only place that explosion could have taken place is in the crankcase.  Any explosion in the intake manifold would not have any effect on the oil filler cap or the valve covers.  Even with the intake valves open the explosion would only go into the cylinder where explosions happen hundreds of times a minute in a normally operating engine.   

The next question is what ignited the fuel vapors in the crankcase?  Liquid gasoline will not burn (it’s too rich) so only vapors burned.  Contrary to popular belief it requires a very high temperature to ignite gasoline vapors.  The MSDS says it takes a temperature greater than 530 degrees F (280 degrees C).  That requires an electric spark or a flame.  That would mean Bill has a bit of blow by as well as fuel in the crankcase.  That brings up the possibility that the fuel got into the crankcase by going past the rings. 

MSDS at:
http://www.mcohio.org/services/risk/docs/MSDS_for_Gasoline.pdf 
Glen Houlton CLC #727 
CLCMRC benefactor #104

Bill Balkie 24172

 Hello,
   I have a question on Pressure . The stock 57 Cadillac mechanical fuel pump should deliver 5 1/4 to 6 1/2 lbs of pressure  per square inch . Was the same pump used on both single and Dual carb set ups . i would think it does not matter because pressure is pressure.

Thanks Bill
Bill Balkie
1970 Coupe DeVille
2009 CTS

Bill Balkie 24172

#24
Hello Glen ,
   Your input is greatly appreciated . you raised the question about fuel getting into the crankcase by passing thought the rings .  leaked thru the needle valve into the piston and through to the rings and mixed with the oil i can understand that .( How did the spark get into the crankcase ?) however i drove this car without any problems the day before for a straight 20 mile drive . pulled into the garage and shut down the car . aprox.  18 hours later  Pow an explosion . I have two 1406 edelbrok carbs on my car . the one that sits next to the fire wall is much more used and to be honest looks  it could use a good cleaning . the carb did back fire a couple if time on the shop that had the car for a few months  before i drove the car home on Saturday . at this point i am really nervous about this happening again . after i changed the oil and replaced the  valve covers with a spare set that i had off another 57 Cadillac  engine i was reluctant to start the car again . however the car started right up , no oil leaks , ran smooth . went around the block and backed  the car in the garage with the front end towards the door .   New oil , new oil filter ,  installing a new  rebuilt  mecanical fuel pump    from Gould  and purchased a new edelbrook 1406 carb . i should be ready to fire the car up by the end of the weak . What are the chances of this happening again . I must of started my 57 Cadillacs  1000 times in the  3 years i never want to have something like this happen again . i am going to look for a spare set of valve covers just in case .  The bad thing is there is no warning.  It is like a car bomb going off .

  Bill
Bill Balkie
1970 Coupe DeVille
2009 CTS

76eldo

I have heard of this type of thing before when gas gets into the crankcase.  I don't know how the mixture gets ignited, but it can, and in the case obviously did.

Electric fuel pumps should always be wired through the ignition circuit so that when the key is on, the circuit is hot, and should still have an inline toggle switch to turn it off.

I don't have an electric pump on any of my 60 or 76, but have thought of adding it to cut down on cranking when the car has been sitting for a week or more.

On my Packard, I used it for cold starts after sitting a while, and only once in 100 degree heat for vapor lock.

Hope you get it all fixed!

Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

gary griffin

#26
   Having an electric fuel pump to charge the carbuerator with fuel after sitting a long time and to overcome vapor lock is a orudent thing o do.

   The mechanical fuel pump is approximatly 1 foot higher than the gas in the tank and when going up a steep grade even higher above the tank. When the fuel pump is drawing a vacuum of say 24 inches it decreases the evaporating point of gas and this along with higher temperatures causes rapid evaporation and subsequentially only fuel vapor is reaching the pump.

   Electric fuel pumps are useually installed lower than the tank and they are pushing the gas rather than drawing it by reducing pressure in the fuel line therefore they are much less prone to vapor lock AKA percolation of the gas.

   I know many cars today use electric pumps only with a great deal of reliability and many conversions to electric only work reliably for many years.

   I am a pilot (recreational onle since 1974) and have a preferance for keeping things as designed whenever possible. We don't hear of these random problems with mechanical fuel pumps (only vapor lock, slow starting after sitting extended periods of time and occasional failure) and many have devised complex and elborate fuel systems that are working just fine but they are still the sole fuel delivery system on their vehicles. I prefer the redundancy of a good mechnical fuel pump as designed by professional engineers with an electric back up and primer system on a manual switch that I have control over. To each his own !!
Gary Griffin

1940 LaSalle 5029 4 door convertible sedan
1942 Cadillac 6719 restoration almost complete?
1957 Cadillac 60-special (Needs a little TLC)
2013 Cadillac XTS daily driver

Bill Balkie 24172

 Good News ,
    Machanical Fuel pump installed , ( use electric only for priming ) new plugs , wires , cap , rotor . Oil change . Car starts right up , no leaks .  runs smooth . I consider myself very lucky . Thanks everyone for all your help , and have a great 4th of July .

  Bill
Bill Balkie
1970 Coupe DeVille
2009 CTS

gary griffin

Electric fuel pumps are not a problem normally but with an engineered design,  but just putting one on  a car because it is easier than rebuilding a original engineered fuel system can be problematic. There are a lot of different systems out there but getting the right one installed takes some knowledge.

How many PSI is required by your system? If a pump is installed providing higher pressure how will your system handle it? A PRV (Pressure Reducing Valve) set to your delivery pressure is always a good idea. 2 0r 3 PSI would probably serve most Cadillacs.

How many GPH (gallons per hour) would your car require at maximum load? I dont know for sure but probably 15 GPH would be the most a Cadillac would use?  A 5 GPM pump can deliver 300 GPH.

How will you keep from delivering fuel to the carbuerator when the engine is not running? A oil pressure switch is often used for that.

How can you prevent fuel delivery when the car is parked and you forget to turn off the switch if it only controlled by a manual switch? Wire it to the ignition switch so it cant operate unless the engine is powered up. (I would do this in addition to the oil pressure switch)

How can it by used for priming a car not operated regularily? A push button switch in addition to the oil pressure swich and the manual (If Installed) switch for priming.

Most installations have a pump with too much capacity and too much pressure and are wired to run without proper regard for the necessary safetys.

I will do a little research and determine which is the most reliable pump in the pressure range and GPH range for my car before I install a pump and it will be wired with the safeties I mentioned here

Possible a little over kill here but better safe than sorry.

Gary Griffin

1940 LaSalle 5029 4 door convertible sedan
1942 Cadillac 6719 restoration almost complete?
1957 Cadillac 60-special (Needs a little TLC)
2013 Cadillac XTS daily driver

Bill Balkie 24172

Hello Gary,
   i like your way of thinking , The engineers that designed these systems knew what they were doing and i agree i like things stock  Almost 100%.   The stock fuel pump always worked fine for me in my  57 Cadillac Seville that i had for 5 years .  The problem i had with the mechanical system was more in my mind . I always wanted the option of a back up pump just in case of Vapor lock or just a mechanical breakdown in the pump itself . Back in the 50's or 60's when your car broke down on the side of the road it was just another car broke down .  I can not imagine leaving my car on the side of any road today , and i am not a big fan of the tow truck . I purchased my Biarritz  10/ 30 / 11 and it only had the electric pump . ( should of changed it the next day ). My car was in a shop for 5 months January thouugh  June . Out of my control .  An excellent Mechanic that i respect very much called it the body shop blues , Only starting every other day or twice a week for just a moment to move the car 10 feet then back again . Although i did have the electric pump hooked up to an on / off switch ,I believe the car was left on maybe a handful of times with the ignition switch on and the pump running .  causing a backfiring condition Gas in the oil  and who knows what else . Although i had the  pull /push switch  tagged FUEL PUMP  on / off . they probably just disconnected the battery every time the moved the car and left the switch on all the time .  I also installed a solenoid made by the painless company that cuts battery power off with a pull /pull switch .  The good news is that my car is OK now . Running only on the mechanical pump with two seperate line comming off the fuel tank . one electric pump for priming only . controlled by a switch .

Keep it stock when you can , And thank you for taking the time to write to me i appreaciate very much .

    Bill       
Bill Balkie
1970 Coupe DeVille
2009 CTS