I am looking to mill a pair of turbo valve covers to clear the trailing arms, How much do I need to mill off?

Here you go Pete, Happy Holiday. MarkClick to view attachment

We installed the engine without covers installed

Then milled to make certain they could fit on/off
Every chassis is slightly different

Smart

There was at least one other thread about this in the past. I learned the hard way when I ordered at of turbo covers and the engine was in the car. Selller said 'no problem, they fit fine...'. My milling process wasn't quite as neat, but I got it to work. You don't have to cut/mill the same amount on both sides.

You mill, grind or sand 5/16 off the entire piece, it should work fine but as shown earlier, there’s a couple ways of doing it.

I like this idea Brant! That is what I will do!

They don’t go on straight. Or as direct as you would think
If it’s your first -6. There is a trick of tipping them 90degrees to clear the swing arm nut. Then rotating back to position for install

I suppose taking extra off of the cover would make installing easier
But the more ribs machined down…. the less rigidity and strength of using a turbo cover

Duplicate

Great info!

I'm in the process of getting my six back in after an unexpected rebuild. The p.o. made some catastrophic mistakes. A couple of questions if you would.

Had lower valve covers ribbed type. No milling. My engine rebuilder put on a non ribbed set to get me to the finish line with the reinstall. Will non ribbed likely leak? Ribbed with the necessary milling to be able to remove them for valve adjustments a significant improvement vs. non ribbed type?

Thanks, Todd

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On a 6, if running the turbo lower valve covers, you need to have one side milled down to allow them to go on and off when the engine is installed. If you run standard valve covers, you can plane them on a piece of glass with fine sandpaper to make sure they are flat, flat, flat. Then use new gaskets and the correct washers and nuts, torqued to the correct specs to minimize leaks. You might get lucky.

I’ve never not ran turbos on the motors in this car

Designed to be less prone to warping
I would imagine you could sand stock ones to spec and get a long time before they warped. But have no data
Messy when they leak though ….. so a lot of folks are trying to avoid that

My clearanced cover is shaved down for half the length which is fine as I bought them in my country for 100nzd shipped so all is good,going to run them over a sheet of glass with wet and dry and check them for flat,that will cure 2 bad oil leaks.
Update ...lapped them on a glass panel and both pretty good but still needed it ,one needed a bit more than the other but fine,better than my old mag covers which I have done on the last 2 oil changes and they still drip,when i got my engine someone had fitted 2 gaskets on each of the lower covers and then did them up very tight .

Thanks for the info. I’ll chase down a pair of turbos to mill - another item on the “ I need to do this but have more pressing issues to do” list.

Here' my version for comparison. Tried to relieve as little as possible to maintain maximum rigidity. I used the remove a little and try fit it method. I used a surface grinder with a harbor freight flapper disk 60-80- grit aluminum. Removal goes very quickly. No need to pay for someone to mill it if you don't already have the machinery
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914043 - good to know. I was planning something similar. Glad it works.

Just pull the studs and use bolts, no machine work necessary. Some turbos don’t use studs.

I have found valve covers to be difficult to figure out the proper way to prevent leaks. Since they need to be removed for valve adjustment you do not want to permanently seal with something that will require a lot of work to clean, so lately I have been installing with just Curil-T on the gasket. I have made sure the covers are flat on milling machine. I have used both turbo style ( I have not used turbo style on 914 yet) and original style valve covers and had to tweak with each. In general i start by following factory torque specs (which seem really low) and hope for no leaks. I have not been able to get either type to seal with out leaks at this torque spec on any motors I have assembled yet. My current method is to torque to factory specs, heat cycle and hope for no leaks (again not worked yet) then tighten by 5 ft/lbs and check for leaks again. eventually I get to a point that the covers do not leak with both types. At this point once leak free they have remained mostly leak free (have had some slight weeping) until removed again. Plan to use Turbo covers on next build so very interested in machining guidance.

john

Well my turbo cover leaks on the driver side. Makes me mad. Time to mill flat and true