Hardway's 1971 240z #8011 - Build and Repair Thread

[wheee!]

Thumbs up for taking the safe route and inspecting everything properly. No shortcuts here!

Sent from my iPizzle ringy dingy device....

[240260280z]

You may consider flushing the oil bar with carb cleaner until only clear fluid leaves.

 

Use the straw to spray into each hole as well as through the cam oil holes.

 

Flush forward and backward and hold the bar up at 45 degrees with one end on the ground/catch pan then do the same with the other end.

[Hardway]

Good idea Blue!  No telling what else might be hiding in there.  No time like the present when parts are 100% accessible to take care of small jobs like that.

[Red7]

Really enjoyed reading this thread

[Hardway]

It has been over a month since my last update and some key events have taken place.  I dropped the cylinder head off at a local and recommended machine shop in Round Rock Texas, Glenn’s Machine.  A quick inspection of my head and pulling a few valves revealed what he already assumed.  The valve seats had been cut too deep in to the head causing the #4 intake valve to sit too high and thus not giving any room for valve lash.  After analyzing the seats we also discovered some of the valves were not cut correctly and not sealing correctly.  According to Glenn the valve should seal at the outer most edge.

 

Unfortunately most of my valves were sealing like in the picture below, basically allowing pressure and fire to get under the edge of the valve.

 

 

With the valves out also we also discovered the valve guides had been knurled.  Knurling pretty much makes the inside of the valve guide look like it has been threaded.  This is a process used by some machine shops to reshape a worn valve guide.  Knurling has two distinct schools of thought, the first being old timers who still swear by it as they have not had any issues with it and that it promotes better lubrication.  The second being that modern machinists do not use this method anymore as it has proven unreliable since it literally removes half of the surface area of the valve.  In addition it damages the surface of the valve stem over time and has not been found to promote better lubrication.  The pictures below help illustrate this.

 

 

Here are some better pictures with the valve guides cleaned and removed.

 

 

As you can see on the valve stems the impression of the knurling has been etched in to the valves.  It looks like something that would just wipe off but it is on there for good.

 

 

Another area of concern was the condition of the water jacket ports.  Many were dis-figured due to corrosion and in need of repair.  Since the head was off now was the time to address this. 

 

 

After talking about it the best way to approach the repair given what my plans were for the car he recommended getting a set of new 280z valves and turning them down to match the existing valve seats.  This was really the only feasible option as replacing the valve seats would have been $75/each times 12, do the math.  He was going to clean up the seats and felt 100% confident this was the best route to go.  The old valve seats would be replaced with new brass ones, the water ports would be repaired and reshaped, new valve seals installed, and the head would be resurfaced.  Total estimate, $1,180.00 with a wait time of three to five weeks.  I said let’s do it and put down a $600 deposit to get the parts ordering started.

[Hardway]

“A good machinist is a like a good lawyer, you don’t know one until you need one”

 

For anyone that has had to get quality machine work done knows good machinists are in demand and Glenn is no exception.  He had everything from a race ready BMW 4 cylinder w/dual Weber carbs in the dyno room to numerous SBC, BBC, BBF, and BBD blocks and heads he was working on.  However, the biggest attraction in the shop was a crankshaft for a Duesenberg Straight-8.  The pistons to it can be seen in the background of the picture above.  He took the time to tell me about it and explain all the unique characteristics of it.  The silver barrels bolted to the front are filled with liquid mercury to aid in balancing it while running in the car.  Glenn's passion for his work is second to none so it is no surprise that he remains a very busy man. 

 

 

 

[Hardway]

Three weeks go by and I receive a call from Glenn indicating he is done with my cylinder head and that is came out great.  He provided me with the following camera phone pictures while he was working on it.  You can easily see the cleaned up valve seats and new valve guides.

 

 

 

With the work paid for and the cylinder head back in the garage I took a minute to weigh it.  This is just the head with the cam and valve train installed.  No other studs, plates, etc. are on it.  I knew this thing was heavy so 56.2 pounds was not surprising.  If you ever need to ship one or are going to attempt to lift one off by yourself, keep this number in mind.

 

 

The pictures below show the final product.  You can tell the difference in the valves based on how much they were turned down.  The difference in color around the water ports show the repair work that was done.  As you can see almost all of them received some attention.

 

 

 

 

In this picture you can see just how thick the 280z valves are. 

 

[Hardway]

After a few degreasing wipe downs I shot some light coats of Rustoleum aluminum silver paint.  This really helps keep the aluminum clean and from getting dark from dirt getting buried in the pores of the aluminum.  I tried to mask off the valve train but no matter how clean I got the valve cover surface none of my masking tape would stick to it.

 

 

 

As I let the paint dry on the head I started cleaning the top of the block.  While I was at it I scraped off the carbon on the top of pistons #1 and #6.  Probably won’t make a difference but it certainly can’t hurt.

 

 

Then I went about cleaning out and chasing all the bolt holes with my tap.  For anyone that is wondering it is a M10 X 1.5 bolt size.

 

 

If you are doing this kind of work or anything similar to it, buy several packs of these long stem Q-tips.  I found these on Ebay but also discovered Northern Tool carries a variety pack of them as well.  They are priceless for doing detail cleaning and easily help clean out bolt holes.

 

 

That is all for now.  I recently received my new turbo head bolts and picked up a can of copper coat.  Once I finish cleaning out the rest of the bolt holes I plan to reinstall the head and go through the torque sequence.  I am taking my time with all of this work and trying to enjoy it as much as possible.  I encourage anyone doing this type of work to do the same as there are plenty of small tasks to take care of in between the bigger milestones.  Staying organized and being methodical is the best way to ensure success.

[Patcon]

I really don't like knurling. I had a head done many years ago and the guides were worn. Machinist suggested knurling as it was cheaper. With new valve stem seals it still had blow by because the knurling didn't hold up. Your head looks great by the way.

[madkaw]

I feel your pain of pulling a head off of a good motor:)

Hopefully your issue is simple. As far as HGs, it's hard to take anyone's word except for actual engine builders. Too many variables put there.

Nice build and good documentation.

[rossiz]

looks like quite a bit of work, and very nicely done.

 

not sure what you're using for paint and how it may affect the gasket sealing surfaces. you can use some 220 then 320 emery cloth and a very flat block (i have some leftover cherry hardwood flooring offcuts that i keep around for this) and lightly dress the intake/exhaust manifold gasket surface - but i wouldn't touch the head gasket surface with any abrasives, maybe some thinner and a rag to get off any overspray, same for the valve cover.

 

keep the posts coming - great writeup as always!

[Zed Head]

That's a lot of "Today" posts.  Nice to know that there are still some good machinists out there.

 

I notice that those 280Z valves look different from the 240Z valves, in shape.  What brand are they?  Are you going to measure combustion chamber volume?  Looks like it might be smaller than before.  Probably good to know.