Everything was going fine till.......

[nismou20]

I'm in the final stages of getting my U20 back together when I encountered this issue. Head was resurfaced against my wishes, (communication issue with machine shop) but regardless they did a great job. In trying to install the head onto block I've noticed that the head bolt washer starts to bite into the Camshaft caps while torquing. My cam spins freely within the head journals fine, but when starting to torque down initial 44lbs my cam starts to bind. I thought initially that was because only the center head bolts were tightened. I went ahead and torqued them all to first turn of 44. The cam binds. I'm finding that the washer is almost impossible to keep from hitting the cam tower caps even when jamming a screwdriver. There's a nice gouge into the cam cap and its leading me to believe this pressure alone is hindering the cam from spinning, being that aluminum caps are soft and it may be putting lateral stress to cam caps. Does this make sense? Anyone encounter this in rebuilds? IS there a specific procedure or sequence to installing the head and cam? I'm not new to wrenching, I've done many import cars before. I'm thinking of getting smaller circumference washers just to avoid the binding. All suggestions are welcomed. I don't think the Mach shop ever removed the towers and it spins fine as long as it's not bolted to the head. I'm scratching my head on this one.

[notoptoy]

What do you suppose caused all that scoring on the tower? Something is torqued or misaligned obviously. Possibly you will need to have them align bore your camshaft bearing surfaces?

[fj20spl311]

My best guest is when they resurfaced the head it was warped and now when you torque the head down the cam towers are warped. They may need to have the cam tower bases resurfaced.
Some machine shops press the head flat before surfacing.

[nismou20]

Phil, I kinda thought that might be and that is why I didn't want the head shaved as my cursory flatness check was within parameters. I'm assuming now when I take it back they will torque the head down and then either shim one or more towers? Or just shave down the high towers? The scoring on the tower caps are from the washer digging itself into it when torquing head bolts. The washer only goes on one way but bites into the cap. It's almost impossible to torque head bolts down and cam caps after because the washer when tightening moves into the cap area. It seems machine shops just love to resurface heads like its a reflex action! Still, if it's perfectly flat and spins, why would it not when equal pressure torque is applied at all points?

[Gregs672000]

I have experienced the washer to cam tower issue, but I've never had it cause a problem with cam alignment. I do understand that you cannot remove the towers and torque etc. The towers are pinned but still have some potential for movement it seems. Looks like you're torquing the head with the cam installed. You could torque it with the cam removed or the caps off, doing your best to hold the washer in place (anticipate some turning! Or use a washer that won't interfere with the placement of the cap) then replace the cam and see if the binding goes away as you carefully and equally tighten the caps. I assume they removed the towers when they surfaced the head? As I said, they are pinned or should be, but they may be miss aligned if this doesn't work.

[nismou20]

Hi Greg, My instructions to the shop were don't resurface and not to remove the towers. I don't know if they heeded my request on the towers. I'm going to look for smaller round washers and give it a try. It's just harder than heck to keep washer from sliding forward with torque. You know. With smaller washer I can install cam after yes. I hope it works or it's another trip to the shop.