were there pre-disco era non-interference engines?
were there pre-disco era non-interference engines?
(OP)
I'm thinking non-interference engines were developed shortly after timing belts became popular.
Looks to me like if a valve on any of these 40+ year old OHV engines was left open 0.3 inches or more at TDC the piston would get all Rocky Balboa on it.
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Yet I don't recall folks building passenger V8s having to replace parts for other than wear reasons.
Aside from the occasional plastic overlayed timing sprocket losing teeth outright, it seems like chain wear would make starting and running so poor that the car was either fixed or thrown away before actual chain breakage would cause the engine's interfer-osity to be tested.
Then again, there are likely to be only a few preferred at-rest positions of the camshaft that would occur naturally due to balance of spring pressure stuffing the lifters against the lobe.
Looks to me like if a valve on any of these 40+ year old OHV engines was left open 0.3 inches or more at TDC the piston would get all Rocky Balboa on it.
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Yet I don't recall folks building passenger V8s having to replace parts for other than wear reasons.
Aside from the occasional plastic overlayed timing sprocket losing teeth outright, it seems like chain wear would make starting and running so poor that the car was either fixed or thrown away before actual chain breakage would cause the engine's interfer-osity to be tested.
Then again, there are likely to be only a few preferred at-rest positions of the camshaft that would occur naturally due to balance of spring pressure stuffing the lifters against the lobe.





RE: were there pre-disco era non-interference engines?
Of course, all the (even older) flat head designs are non-interference.
RE: were there pre-disco era non-interference engines?
RE: were there pre-disco era non-interference engines?
As I remember (or mis-remember) history, the phrase 'interference engines' didn't even enter our collective vocabulary here in The Colonies until OHC rice rockets began showing up in volume. There may have been Italian interference engines on our shores before then, but the valves burned so quickly that nobody ever ran one with a really old timing chain..
Mike Halloran
Pembroke Pines, FL, USA
RE: were there pre-disco era non-interference engines?
Regards
Pat
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RE: were there pre-disco era non-interference engines?
On GM inline sixes similar in principle to Chevy side plate engines, I have also seen gear drives fail and bend valves when the gear drive was made of reinforced phenolic compound.
Regards
Pat
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RE: were there pre-disco era non-interference engines?
RE: were there pre-disco era non-interference engines?
It would usually last until the engine needed to come apart for other reasons, though. Good old days?
RE: were there pre-disco era non-interference engines?
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RE: were there pre-disco era non-interference engines?
RE: were there pre-disco era non-interference engines?
RE: were there pre-disco era non-interference engines?
Surprising it was the inlet valves. Worn timing chain = later valve timing = more clearance for the inlet valve not less. Were the problems associated with loss of chain tension as well? (Allowing oscillation of the camshaft and thus both early and late timing.)
Engineering is the art of creating things you need, from things you can get.
RE: were there pre-disco era non-interference engines?
RE: were there pre-disco era non-interference engines?
My recollection is that early American 4-cyl OHC engines were all non-interference; Chrysler 2.2, Ford 2.3, etc. Seems like the first domestic interference engine was the awful engine in Escorts?
RE: were there pre-disco era non-interference engines?
RE: were there pre-disco era non-interference engines?
Which way do you turn a camshaft to retard the timing? Which way will a camshaft rotate in relation to the crank with a badly worn chain?
RE: were there pre-disco era non-interference engines?
Sorry for the non-helpful post:
I think the flat head in the '49 Merc I had during my high school years in the 70s was non-interference.
Dick
RE: were there pre-disco era non-interference engines?
I'm not entirely certain that engine counts as "domestic", does it?
RE: were there pre-disco era non-interference engines?
2. Which way will a camshaft rotate in relation to the crank with a badly worn chain?"
1. Backwards
2. Backwards
Engineering is the art of creating things you need, from things you can get.
RE: were there pre-disco era non-interference engines?
Regards
Pat
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