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[Pitchfork]

I never recall having seen a failure of an engine in a Motor cycle or Car, failing because of a push-rod problem or failure!
So - why do we now have over-head camshafts, & perhaps
more critically, camshafts driven by rubber-bands?
Seems to me that if you do have to have OHC, that chain driven are more reliable/ economical to maintain (e.g. Traktors, Nissan Micras) than these wretched belt-driven lumps (unless of course they provide a good excuse for a Beery weekend get-together for readers of the ultra-right Daily Mail!)
Discuss :-?

[maria]

OHC engines are capable of much closer valve/piston clearances than the OHV/pushrod engines, hence incresing power output and efficiency.

Cambelts, on a plus point, are MUCH easier to replace than a timing chain (which pushrod engines also have!)... and cambelts are also reliable if changed on schedule.

Given all the pro's and cons, I would rather change a rubber belt every 40k miles, than have to struggle to do a timing chain every 100k....

[Pitchfork]

OHC engines are capable of much closer valve/piston clearances than the OHV/pushrod engines, hence incresing power output and efficiency.

Cambelts, on a plus point, are MUCH easier to replace than a timing chain (which pushrod engines also have!)... and cambelts are also reliable if changed on schedule.

Given all the pro's and cons, I would rather change a rubber belt every 40k miles, than have to struggle to do a timing chain every 100k....
 

The question was rhetorical (& I was not anticipating serious answers)
But in answer to your point, who ever needs to change a timing chain apart from those who patently ignore servicing schedules to the point of crass negligence, & would not the same people cheerfully miss the recommended cam-belt change intervals too?

[maria]

OHC engines are capable of much closer valve/piston clearances than the OHV/pushrod engines, hence incresing power output and efficiency.

Cambelts, on a plus point, are MUCH easier to replace than a timing chain (which pushrod engines also have!)... and cambelts are also reliable if changed on schedule.

Given all the pro's and cons, I would rather change a rubber belt every 40k miles, than have to struggle to do a timing chain every 100k....
 

The question was rhetorical (& I was not anticipating serious answers)
But in answer to your point, who ever needs to change a timing chain apart from those who patently ignore servicing schedules to the point of crass negligence, & would not the same people cheerfully miss the recommended cam-belt change intervals too?

Interesting points... but not having oil immersed timing chains has contributed towards car manufacturers being able to increase servicing schedules  

[Pitchfork]

OHC engines are capable of much closer valve/piston clearances than the OHV/pushrod engines, hence incresing power output and efficiency.

Cambelts, on a plus point, are MUCH easier to replace than a timing chain (which pushrod engines also have!)... and cambelts are also reliable if changed on schedule.

Given all the pro's and cons, I would rather change a rubber belt every 40k miles, than have to struggle to do a timing chain every 100k....
 

The question was rhetorical (& I was not anticipating serious answers)
But in answer to your point, who ever needs to change a timing chain apart from those who patently ignore servicing schedules to the point of crass negligence, & would not the same people cheerfully miss the recommended cam-belt change intervals too?

Interesting points... but not having oil immersed timing chains has contributed towards car manufacturers being able to increase servicing schedules  

....and inserting expensive, time-consumming & profitable cam-belt changes into the shedules!!

[VXL V6]

OHC engines are capable of much closer valve/piston clearances than the OHV/pushrod engines, hence incresing power output and efficiency.

Cambelts, on a plus point, are MUCH easier to replace than a timing chain (which pushrod engines also have!)... and cambelts are also reliable if changed on schedule.

Given all the pro's and cons, I would rather change a rubber belt every 40k miles, than have to struggle to do a timing chain every 100k....
 

The question was rhetorical (& I was not anticipating serious answers)
But in answer to your point, who ever needs to change a timing chain apart from those who patently ignore servicing schedules to the point of crass negligence, & would not the same people cheerfully miss the recommended cam-belt change intervals too?

Yep probably very true.

Chains are known to stretch over time and the guides tend to break up around 100K.

[theolodian]

Chains can go too (or more to the point guides/tensioners).  A mate's V8 Diesel self destructed at 88K miles 10 days ago when the chain slipped.  

Chains are often at the back of the engine, so it's an engine out job to replace them.  Not that belts are a great solution.  At least it's pretty easy to change on the miggy.

As James said, pushrod engines have chains too.  Those guys will convert the chain to gears for near absolute robustness.

[maria]

OHC engines are capable of much closer valve/piston clearances than the OHV/pushrod engines, hence incresing power output and efficiency.

Cambelts, on a plus point, are MUCH easier to replace than a timing chain (which pushrod engines also have!)... and cambelts are also reliable if changed on schedule.

Given all the pro's and cons, I would rather change a rubber belt every 40k miles, than have to struggle to do a timing chain every 100k....
 

The question was rhetorical (& I was not anticipating serious answers)
But in answer to your point, who ever needs to change a timing chain apart from those who patently ignore servicing schedules to the point of crass negligence, & would not the same people cheerfully miss the recommended cam-belt change intervals too?

Interesting points... but not having oil immersed timing chains has contributed towards car manufacturers being able to increase servicing schedules  

....and inserting expensive, time-consumming & profitable cam-belt changes into the shedules!!

 

Tbh, I think it's swings and roundabouts.. there are pro's and cons of each. but I think going back to the original Q, the reason for implemenging OHC engines is because they are mroe capable of delivering the power and efficiency that the market requires..

[Pitchfork]

OHC engines are capable of much closer valve/piston clearances than the OHV/pushrod engines, hence incresing power output and efficiency.

Cambelts, on a plus point, are MUCH easier to replace than a timing chain (which pushrod engines also have!)... and cambelts are also reliable if changed on schedule.

Given all the pro's and cons, I would rather change a rubber belt every 40k miles, than have to struggle to do a timing chain every 100k....
 

The question was rhetorical (& I was not anticipating serious answers)
But in answer to your point, who ever needs to change a timing chain apart from those who patently ignore servicing schedules to the point of crass negligence, & would not the same people cheerfully miss the recommended cam-belt change intervals too?

Yep probably very true.

Chains are known to stretch over time and the guides tend to break up around 100K.

Poll?  How many Traktor owners on the forum have had to replace a timing chain?
I'm at 140K currently

[maria]

As James said,

James hasn't posted on this thread - he is outside cleaning out the car    

[VXL V6]

OHC engines are capable of much closer valve/piston clearances than the OHV/pushrod engines, hence incresing power output and efficiency.

Cambelts, on a plus point, are MUCH easier to replace than a timing chain (which pushrod engines also have!)... and cambelts are also reliable if changed on schedule.

Given all the pro's and cons, I would rather change a rubber belt every 40k miles, than have to struggle to do a timing chain every 100k....
 

The question was rhetorical (& I was not anticipating serious answers)
But in answer to your point, who ever needs to change a timing chain apart from those who patently ignore servicing schedules to the point of crass negligence, & would not the same people cheerfully miss the recommended cam-belt change intervals too?

Yep probably very true.

Chains are known to stretch over time and the guides tend to break up around 100K.

Poll?  How many Traktor owners on the forum have had to replace a timing chain?
I'm at 140K currently

I was really referring to the Senator / Carlton 24V straight six petrol lump, afraid I know little / nothing about the BMW straight six deisel.

[Pitchfork]

OHC engines are capable of much closer valve/piston clearances than the OHV/pushrod engines, hence incresing power output and efficiency.

Cambelts, on a plus point, are MUCH easier to replace than a timing chain (which pushrod engines also have!)... and cambelts are also reliable if changed on schedule.

Given all the pro's and cons, I would rather change a rubber belt every 40k miles, than have to struggle to do a timing chain every 100k....
 

The question was rhetorical (& I was not anticipating serious answers)
But in answer to your point, who ever needs to change a timing chain apart from those who patently ignore servicing schedules to the point of crass negligence, & would not the same people cheerfully miss the recommended cam-belt change intervals too?

Interesting points... but not having oil immersed timing chains has contributed towards car manufacturers being able to increase servicing schedules  

....and inserting expensive, time-consumming & profitable cam-belt changes into the shedules!!

 

Tbh, I think it's swings and roundabouts.. there are pro's and cons of each. but I think going back to the original Q, the reason for implemenging OHC engines is because they are mroe capable of delivering the power and efficiency that the market requires..

What does that do for society & our Carbon-Footprints??

[Andy B]

.......As James said, pushrod engines have chains too.   .......

Unless it's a Ford Essex/Cologne V6. They use gears, originally one of them was fibre, for quietness, however they had a tendancy to be very quiet when the fibre gear shed its teeth and the engine stopped!    

[theolodian]

OHC engines are capable of much closer valve/piston clearances than the OHV/pushrod engines, hence incresing power output and efficiency.

Cambelts, on a plus point, are MUCH easier to replace than a timing chain (which pushrod engines also have!)... and cambelts are also reliable if changed on schedule.

Given all the pro's and cons, I would rather change a rubber belt every 40k miles, than have to struggle to do a timing chain every 100k....
 

The question was rhetorical (& I was not anticipating serious answers)
But in answer to your point, who ever needs to change a timing chain apart from those who patently ignore servicing schedules to the point of crass negligence, & would not the same people cheerfully miss the recommended cam-belt change intervals too?

Interesting points... but not having oil immersed timing chains has contributed towards car manufacturers being able to increase servicing schedules  

....and inserting expensive, time-consumming & profitable cam-belt changes into the shedules!!

 

Tbh, I think it's swings and roundabouts.. there are pro's and cons of each. but I think going back to the original Q, the reason for implemenging OHC engines is because they are mroe capable of delivering the power and efficiency that the market requires..

What does that do for society & our Carbon-Footprints??

OHC has much better control over the valves and allows variable cam timing (and even lift) which is important for start-up emissions and balancing power and efficiency.

[Pitchfork]

As James said,

James hasn't posted on this thread - he is outside cleaning out the car    

Who is James & why has he not posted anything??