Cam timing gear tooth damage from link chain
02-09-2019, 07:38 AM
#11
Registered
Common wear pattern on high hour/ mileage silent style timing chains and gears.
Someone was just too lazy to change the set.
The old school trick of drilling the gallery plugs will haunt you . Dont do it.
Those old wet sump motors have so much oil blowing around in the crankcase
the extra oil from the drilled holes is a waste. Also the oil coming from around the cam bearing and journal supplies plenty of oil
The hole helps create a
vacuum break , allows the oil in the gallery to drain back quicker .
Results in longer oil pressure build time , especially with hot oil. Clicking hydraulic lifters etc. etc. etc.
That old trick came about when roller chains first appeared on the market , metallurgy wasnt
quite up to par and the chains would wear prematurely at elevated RPM. The short
term fix was the drilled galley plugs. Just like the trick of filing a slot on the distributor lower
pilot OD to oil the cam gear! Complete waste of time , and causes more problems than
it fixes.
Someone was just too lazy to change the set.
The old school trick of drilling the gallery plugs will haunt you . Dont do it.
Those old wet sump motors have so much oil blowing around in the crankcase
the extra oil from the drilled holes is a waste. Also the oil coming from around the cam bearing and journal supplies plenty of oil
The hole helps create a
vacuum break , allows the oil in the gallery to drain back quicker .
Results in longer oil pressure build time , especially with hot oil. Clicking hydraulic lifters etc. etc. etc.
That old trick came about when roller chains first appeared on the market , metallurgy wasnt
quite up to par and the chains would wear prematurely at elevated RPM. The short
term fix was the drilled galley plugs. Just like the trick of filing a slot on the distributor lower
pilot OD to oil the cam gear! Complete waste of time , and causes more problems than
it fixes.
02-11-2019, 10:01 PM
#12
Registered
Thread Starter
Line honing has nothing to do with what main caps you have. You cut some off the top of the caps and then re cut the holes by using a line hone.
this causes the crank bores to be slightly closer to the cam bore causing slop in the timing chain.
They make a chain that is shorter for blocks that have been line honed and need it.
this causes the crank bores to be slightly closer to the cam bore causing slop in the timing chain.
They make a chain that is shorter for blocks that have been line honed and need it.
new timing set came in today, gonna see how the chain tension is and go from there. Hope I don’t have to pull these out and rebuild them myself it’s about to be boating season!
02-11-2019, 10:09 PM
#13
Registered
Thread Starter
Line honing has nothing to do with what main caps you have. You cut some off the top of the caps and then re cut the holes by using a line hone.
this causes the crank bores to be slightly closer to the cam bore causing slop in the timing chain.
They make a chain that is shorter for blocks that have been line honed and need it.
this causes the crank bores to be slightly closer to the cam bore causing slop in the timing chain.
They make a chain that is shorter for blocks that have been line honed and need it.
I would not be surprised when the past owner "rebuilt" the motor they left the gear on the crank. Either it was worn or not the same exact dimension as the replacement gear and it let the chain flop around. On any motor I open up I dump that single crap and put a double roller on it.
Also there is metal missing and it went somewhere.
Also there is metal missing and it went somewhere.
i ran a magnet in the pan and didn’t pick anything up. You are right it’s somewhere, hopefully the filter or in the last oil change I did, and the oil pump isn’t torn up.
