well we're both right. in a packaging sense pushrods are great, but you can make more efficent power with overhead cams and valves.



mike [/quote]

well all pushrod engines are overhead valve. [/quote]

not so. flathead ford v8's are pushrod (i think) and not overhead valve



mike

 

Not true flat heads have valves in the block itself, some models had the cam up high but Ford and Studebaker I know for sure did not.



Citroen had a variable valve timing system based upon hyrdaulics opening up at the correct time and filling the lifters giving a higher open time with a push rod engine. Bizzzaarreee.



Otherwise mechanically simple is the best bet plus the aforementioned compact size...although they've gotten pretty good about sinking the cams down into the head further.



There was also the loophole the in old Indy rules that allowed a pushrod engine more boost to make up for the lack of valving/intake. Penske/Mercedes took advantage of said rule and blew the rest of the field away.



They of course changed that rule shortly after.



The problems with pushrods include plugged pushrods if they transfer oil, lifter noise, misseated pushrods, bad valve adjustments with solid lifters and flex at high speeds. Mostly fixed of course

 

yea push rod engines are cool and make alot of power, but like they said over head cams were done for less moving parts............ then came the rotary engine and the world was like... " What no pistons, pushrods, valves, hell not even a block of some sort?" so every one ran from the idea and here we are pioneering the rotary engine with 1000 + horspower with 1.3 liters!!! who would of ever thought?

 

the first car was 1896. the dual overhead cam 4 valve per cylinder was 1912. the rotary is 1963? 64?



mike