Forum Discussion
Lynnmor wrote:
I gave up on the stupid test when they didn't understand that some OHC engines have no rocker arms, but instead directly operate valves with only a bucket and adjusting shim.
It's kind of like some government exams I have written, You need to know the kind of answer they are looking for, not necessarily the technically correct answer.- Del
- I gave up on the stupid test when they didn't understand that some OHC engines have no rocker arms, but instead directly operate valves with only a bucket and adjusting shim.
Lynnmor wrote:
45Ricochet wrote:
travelnutz wrote:
Timing advances to before TDC as the RPM's increase. However, as far as technical/technology being the question, for the engine to even start to run, the actual spark must occur after TDC and into the combustion stroke or the engine would run backward. Pre-ignition would occur! Think about it!
Very common with a 1970's 80's Detroit diesels in OTR tractors. I ran one backwards once in San Francisco after a picking up a load of Best Foods Mayonnaise. Heavy load.... HUGE hill.... Wrong gear :E
Many gasoline engines spark before TDC when starting, some small engines have fixed timing that is BTDC.
Never could find the spark plugs in a Detroit diesel. :?
Very true. the only time they fire ATDC is on the older hand crank cars with the timing adjuster in the middle of the steering wheel. you would turn it to ATDC when starting so you didn`t lose an arm or have the crank smack you in the face! after it started you then turned it to BTDC. when electric starters came out the manual timing adjustment went away and it was fixed. they slowly went from 0-2 degrees BTDC in the very early years to 7-10 degrees nowadays. no car that I know of puts timing to ATDC when starting.
I`de love to see that site explain how OBDII systems work! :EOH48Lt wrote:
The answers to questions 7 and 13 are wrong.
Spark plugs fire on the compression stroke, several degrees BTDC, just before the power stroke begins at TDC.
Pistons are connected to connecting rods, not the crankshaft.
Thank you. And a steam engine is not an internal combustion engine. the combustion is a one time sequence then it just makes steam. the steam is what moves the cylinders. There were a few others I questioned, but forgot what they were because I gave up.45Ricochet wrote:
travelnutz wrote:
Timing advances to before TDC as the RPM's increase. However, as far as technical/technology being the question, for the engine to even start to run, the actual spark must occur after TDC and into the combustion stroke or the engine would run backward. Pre-ignition would occur! Think about it!
Very common with a 1970's 80's Detroit diesels in OTR tractors. I ran one backwards once in San Francisco after a picking up a load of Best Foods Mayonnaise. Heavy load.... HUGE hill.... Wrong gear :E
Many gasoline engines spark before TDC when starting, some small engines have fixed timing that is BTDC.
Never could find the spark plugs in a Detroit diesel. :?wnjj wrote:
wilber1 wrote:
When did steam engines all of a sudden become internal combustion engines?
I thought the steam engine was the answer to a question of what was NOT an internal combustion engine but I may not have remembered it right.
Not impressed with the thing either.
I miss read the answer, it said Stenson also built America's first steam engine. Also, it seems like only about half the questions were actually about engines.
I did the engines quiz after and got all of them.- It's quite obvious some posting negative comments about the quiz didn't read and/or comprehend the question or the 3 choices given. The quiz was about engines as in general but some seem to put their own nebulous into the questions asked. Basically shows their lack of documented formal education gained.
For instance: There are 4 distinct stroke cycles in a 4 stroke engine. 2 beginning at piston TDC and 2 at BDC. 2 distinct stroke cycles in a 2 stroke engine. The "fire in the hole" burn creating the expansion of gasses occurs only after the spark plug fires and occurs only in the power stroke which begins after piston has passed TDC from the compression stroke which is what was asked about in the quiz. Timing signal for the current to be sent to the spark plug to create the explosion is only relevant to and by the RPM the crankshaft is turning, not the piston's actual location. There's a time lapse that requires the signal/current setting required to be advanced before TDC! The power stroke only occurs AFTER piston reaches TDC. wilber1 wrote:
When did steam engines all of a sudden become internal combustion engines?
I thought the steam engine was the answer to a question of what was NOT an internal combustion engine but I may not have remembered it right.
Not impressed with the thing either.- I wasn't impressed with the quiz in the least. As mentioned above, they had incorrect answers as the correct answers, the had questions that couldn't possibly have a correct answer (hp on the 454) and less than half the questions actually had nothing to do with what MAKES an internal combustion engine WORK.
Pretty evident this quiz was not made by someone with an engineering/mechanical background.
