Intake Valve Suggestion
#1
Intake Valve Suggestion
Having just rebuilt the engine in my '87 4Runner, I have run into a _major_ problem with the valve train.
I installed a new camshaft (LCE "Pro Torquer"), new oversized valves both intake and exhaust, new valve springs matched to the cam (valve seat pressure should be OK), and a complete new rocker shaft and rocker arm assembly (again LCE).
After a few thousand mile of operation I lost compression on the #4 cylinder, and discovered that valve lash had gone to 0 so the cam was holding the valve open. I thought this to be strange as I had set lash according to the cam card on assembly. I figured that things might move once, so re-set valve lash on all valves. Note that all of the intakes had tightened up.
A few hundred miles later and same problem. Adjusted again. 20 miles later same problem. So obviously the intake valve was drawing up into the head. This is a BAD situation since if it draws up too much it will eventually fail and breaking a valve gets really expensive.
Removed the cylinder head to find all intake valves in terrible condition. See below...
Valve on the left is from #4 intake and obviously junk.
I have spoken to the tech folks at LCE and the installed height on the springs is within spec, if not a little loose (barely). Seats look perfect. Guides within spec. Rockers and cam lobes look perfect. LCE, me, and the shop that cut the valve seats (oversized valves) cannot fathom what is going on.
My question, anyone have a source for great quality valves other than LCE? LCE uses "Ferrea" brand valves which are (according to the shop that cut the seats) very good quality valves. I am just wondering if I got a "bad" set from LCE so investigating other sources/brands.
No intent to "blame" LCE here, just recounting my experience.
I installed a new camshaft (LCE "Pro Torquer"), new oversized valves both intake and exhaust, new valve springs matched to the cam (valve seat pressure should be OK), and a complete new rocker shaft and rocker arm assembly (again LCE).
After a few thousand mile of operation I lost compression on the #4 cylinder, and discovered that valve lash had gone to 0 so the cam was holding the valve open. I thought this to be strange as I had set lash according to the cam card on assembly. I figured that things might move once, so re-set valve lash on all valves. Note that all of the intakes had tightened up.
A few hundred miles later and same problem. Adjusted again. 20 miles later same problem. So obviously the intake valve was drawing up into the head. This is a BAD situation since if it draws up too much it will eventually fail and breaking a valve gets really expensive.
Removed the cylinder head to find all intake valves in terrible condition. See below...
Valve on the left is from #4 intake and obviously junk.
I have spoken to the tech folks at LCE and the installed height on the springs is within spec, if not a little loose (barely). Seats look perfect. Guides within spec. Rockers and cam lobes look perfect. LCE, me, and the shop that cut the valve seats (oversized valves) cannot fathom what is going on.
My question, anyone have a source for great quality valves other than LCE? LCE uses "Ferrea" brand valves which are (according to the shop that cut the seats) very good quality valves. I am just wondering if I got a "bad" set from LCE so investigating other sources/brands.
No intent to "blame" LCE here, just recounting my experience.
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priest16
84-85 Trucks & 4Runners (Build-Up Section)
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08-06-2015 07:43 AM