When I put a mild cam into my 92k mile 1995 Z28 I noticed more than normal wear on the front cam bearing. The history of my engine is that it is on its fourth water pump. Do you think that binding up water pumps contributed to cam bearing wear by the wp gear pushing downward on the cam gear, or is this common to LT1's for other reasons? I currently still have 20# of oil pressure at hot idle running 700 rpm, but I am sure there's a loss thru the worn bearing.

 

Not sure but I believe the water pump is why the front is worse then normal.

 

i have noticed standard sbc's do it as well. (different waterpump)
so i would rule that out. my guess is the timing chain loading causing bearing wear on the front cam bearing.

 

That would be my guess as well.

 

Correct. My 89 L98 at 60K had front bearing wear.

 

The front bearing gets the least amount of oil compared to the rest.
The water pump does not help.
The timing chain does not help.
If that one is bad most likely the rest are too.

 

Do you have proof of this statement? I'd like to hear more as mine was showing some wear when I did the H/C swap. That's one of the reasons I went with an electric water pump.

 

My thoughts are if the wp gears are installed correctly, there should be no downward force on the cam gear. Most of the cam bearing wear is going to be contributed to the timing set/valve train...as the crank turns clockwise, the right hand side of the chain will be tight..the left side will be slack since the right is pulling downward to rotate the cam gear.
The heavier/stiffer/more seat pressure your valve springs are, the harder it is to rotate the cam gear...thus the more downward force is needed to rotate the cam gear...thus causing more cam bearing wear on the lower half of the cam bearing.
The wp gear will add to that force needed to rotate the cam gear, but if your wp bearings aren't seized, it will be minimal force compared to that to rotate the cam.

Not to mention the lifters/valve train are pushing in a downward force all the time on the cam also.

 

Timing Chain is a big part of it. wrd1972 got it right.

 

My "proof" is simply based on common sense here:
The front cam bearing is the farthest from the oil pump, therfore it cant get as good of oil pressure as the #5 bearing.
The water pump load is not transmitted to any cam bearing but the front.
The timing chain load is not transmitted to any cam bearing but the front. Tighter chain makes it even worse.
If one is shot then it is very likely that the rest are shot, was in my case.

SBC's are hard on the front bearing, just the way it is.
Also if the water pump drive stub is installed funky this will create bad gear mesh and additional load, I checked mine closely for good backlash and tooth contact.