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Recent content by franzh

  1. franzh

    valve seat recession on LPG

    Generally speaking, if the engine in question is capable of operating on conventional unleaded gasoline (petrol), and if the vehicle is driven in normal operation, no modifications are needed. I have operated several vehicles well in excess of 200,000 miles and never had the cylinder heads off...
  2. franzh

    Advice needed re suitablity of Impco 425 lpg/propane carb for a particular engine

    Al: The last part of your question is against this forum's policy. Take a look online for other means of contact. Franz eng-tips, by professional engineers for professional engineers Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
  3. franzh

    Advice needed re suitablity of Impco 425 lpg/propane carb for a particular engine

    I am not particularly a fan of the 300, mostly due to the susceptibility to vacuum leaks and its size. However, there are two sizes of the 300-A, the smaller of which works relatively well on engines in the 3.0-5.0 L range. Franz eng-tips, by professional engineers for professional engineers...
  4. franzh

    Natural gas vs Propane hp derate

    Gaseous fuels displace air at stoich, about 10% for NG and about 5% for LPG. Displacing any air has the effect of derating an engine by that relative amount. Taking an engine designed for gasoline and simply substituting the fuel will result in lower output unless the engine is optimized for...
  5. franzh

    Advice needed re suitablity of Impco 425 lpg/propane carb for a particular engine

    While not exactly the proper engineering topic for this forum, lets see if we can work through this project. The Impco 425 is a moving air-valve air-fuel mixer that modulates gas flow depending on the relative airflow through the mixer body. The mixer operates by a pressure differential above...
  6. franzh

    Is turbocohen still onthis Forum?

    Tek, most LP distribution pulls from common pipelines with the distribution closest to a particular refinery or gas plant having a higher concentration of either a desirable or less desirable product. No company to my knowledge is knowingly selling an inferior product, it would be harder to get...
  7. franzh

    Is turbocohen still onthis Forum?

    The reason most exchange cylinder companies are selling cylinders with less total product is they have little control over how or where the cylinder is stored. A properly filled 20 lb cylinder could expand to 100% full if allowed to overheat in a garage or other enclosure. The easy way to...
  8. franzh

    LPG max total ignition advance

    Wow, I have that book! It was written in the late 80's and references basic technology available at that time and has no real relevance today. This book is great material for basic level tinkering but doesnt contain any real engineering sciences. eng-tips, by professional engineers for...
  9. franzh

    piston ring position

    I too have torn down hundreds of engines of all shapes and sizes. Rings do move around to circumference of the piston. This puzzled me for quite some time, and one old-timer (I've got to watch that term, I'm one of them now) told me that rings are twisted around the piston during installation...
  10. franzh

    Calculating Fuel Fitting Torque

    Hemi is right, especially if you are considering the failure modus of the component (as your handle implies). Consider that if an M10 bolt of the same length as your fastener has X-value torque, a hollow bolt fastener of the same size would have a drastically different torque value. If the...
  11. franzh

    cranking a diesel engine by hand

    My first boss told me that in the days of the Model T, farmers were told to have their wive learn how to crank the engine. In case the crank spun backwards and broke her arm, she could still do house work with one arm, while a farmer would have difficulty working with one arm in sling! True...
  12. franzh

    red hot valve springs

    Although Prostock and straight line drag racing is impressive, I have to shudder on the valve train stresses an F1 or Indy car engine experiences during a 2 hour run. F1 was just completed about an hour from my house and I could hear the shrieking engines if the wind was just right. 18,000 rpm...
  13. franzh

    digital flow benching, smoke query-esque.... sorta thing....

    I heard what appeared to be a high velocity blower (suction) and cigarette smoke? I think a slower velocity would make the smoke more dense. In college, we used an oil based smoke and experimented with variable speed blowers. Boundary Layer Adhesion was an interesting study/demonstration and...
  14. franzh

    US EPA stationary engine emission certification

    I have worked with and used SWRI for many years and are totally satisfied with their justification for their pricing. There is a reason they are expensive. They are used to varying fuel blends and there isnt anything they havent seen already, just in case you think you have the holy grail in...
  15. franzh

    Intake/exhaust valve diameter ratio on older OHV8s

    A lot of early (1963 and up) SBC heads had the 1.94/1.6 valves, on 327 and really stout 283 engines. Some of the built 327 engines in 67 went to the 2.02 heads (they were called the 327 Fuelie heads). They really didnt work well on the street as the intake air velocity would drop the gas...
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