cams on d-50 g54b

[robertson5347]

Are the cams the same on a 1980 d-50 and a 1988 d-50 g54b 2.6l?

[camoit]

No there different sizes on the journal. Or at least I think they are, 90% sure. The head are cut different too. Large cam bore VS a small cam bore. The 80 used splash and spray for lubrication while the 88 has oil galleys and hydraulic adjusters.
You can always contact clear water heads and double check with them.

[pennyman1]

The change in the heads was in 85 when they went to hyd lash adjustors - the whole valvetrain changed and the cams are also different. You can use mechanical rockers on a hyd head, if you use a mechanical cam with them. The valves are different lengths also, with different locks and retainers, due to the different rocker arms.

[robertson5347]

Cannot figure out how 3 out of 4 exhaust valves got bent. Redone the head and valves were removed and lapped, all worked smooth and checked for sealing. I put the head back on, set the cam timing as shown in manual (#1 cyl. exhaust and intake valves closed and worked freely@ tdc). Started the engine and the #1 exhaust valve started sticking open. Pulled the head and showed the valve had hit the piston which would bend the valve (?due to valve sticking), but no other marks on the other pistons. Replaced all exhaust valves and connected the cam gear back just as I had removed it (crank had not been disturbed). It appears the exhaust valves are not touching the pistons by rotating the engine manually. Am I correct in figuring the compression stroke as follows: Rotate engine until The #1 cyl. exhaust valve opens and piston returns to tdc, the intake valve opens and returns to tdc. This is the compression stroke with crank at tdc and plug fires driving the piston down? In this position both valves are free and camshaft sprocket pin is in 12 o'clock positon and the camshaft lobes are pointing in the direction of their respective valves.

Point of interest: It appears that Rockauto has the only exhaust valves left for gen. 1 2.6 liter engines up to 1982. The manufactures has closed them out and no specifications are listed with them or Rockauto. I only found the specs. through a company by the name of S.B. International which cross referenced the size measurements to the beck/arnelly part no. and clevite/perfert circle part no. So if anyone thinks they might need some of these valves, might be a good time to pick up some extras. I was unable to find any other sources.

[BradMph]

This image shows TDC areas correctly.
Cam gear pin at 12 and timing mark lines up with mark on casing both at 9
Distributor pointed #1 terminal
first 2 valve rockers will be loose and rockers will be on flat area of cam

click on image to enlarge
TDC.jpg