1968 DeVille Convertible - Restoration

[Bentley]

Nice work!

[DeVille68]

Thanks! Oh, well. I wanted to post earlier but did not find the time to do so. Here is a recap of the work done two weeks ago.

Picture 1: New main bearings and arp main studs
Picture 2: Rope seal for the rear main.
Picture 3 & 4: I used a block and hammer to pound the rope into the groove. I used a clap in order to achieve a nice cut of the rope end.
Picture 5: However the rope would not want to seat in the groove of the block.
Picture 6: So I had to order a different seal for the rear. Luckily there is a Neopren Seal available.

The crank is installed. Bearing clearance checked. Crank end play checked. All pistons installed without the rings to check bearing clearance and side clearance. All within specs. It took less than 2 Nm to turn the crank.

Then I installed to old 68 camshaft and measured again the lift with respect to crank degree. Then I installed the new camshaft and measured the same again.
Now I can really compare the lobes and lift of the two camshafts.
Here are a few pictures:

Picture 6: Degree wheel and dial gauge.
Picture 7: Comparing the camshafts.  On the left is the new cam on the right the old 68. Notice how the base circle is closer to the diameter of the camshaft rod. So it seems that the higher lift is gained by making the base circle smaller.
Picture 8: Lobe lift comparison. The curve with the higher lift and more area is the new camshaft. This camshaft has about the specs of a 72 camshaft. At least this is what I could tell from the shop manual information that I have available.

[DeVille68]

A full day was needed to gap all the rings and install the pistons.

I have installed oversize pistons. They are 40'' over.
So I would have needed to buy rings for a bore of: 4.340''. This would have been 2M695-40 from Hastings, which are the correct rings with a moly coating.

However, I found in that same catalog that there is a ring available for 4.342'' for a Chrysler 400. The profile and coatings are identical. Part number: 2M676

So this larger ring will give me about 0.002'' to work with or about 0.006'' in gap.

My goal was to gap the top ring to 0.016'' and the second ring to 0.014''.
Recommendations from Hastings and Egge was 0.014'' min and 0.026'' max. (for both rings).

When I installed the slightly larger rings into my bore I found that they were not consistent at all. The smallest gap was 0.005'' and the largest 0.016''. So I had to file all rings to achieve 0.016''. Would I have bought the "correct" rings the gap would have been probably somewhere between 0.014'' and 0.022''.

The oil rings ended up around 0.032'' to 0.036''. Factory recommendation is between 0.015'' to 0.050''. So with my ring gap I should have good oil control. Would I have bought the "correct" rings the oil ring gap would have been somewhere around 0.040''.

Here are a few pictures:
Picture 1: Ring filer from summit and a ring ready to grind.
Picture 2: Installing the ring in the bore to measuring the gap. I used an old piston with a ring in the second slot to push the ring down such that it would be flat in the bore.
Picture 3: I used a new ring compressor. However, I needed help, because the compressor would slightly jump up every time I pounded on the piston, which would result in the lower oil ring to escape and preventing the piston to go down.
So a helper pushed on the compressor and then a nice pound would move the piston down nicely.

If you have any questions or recommendations let me know!

Best regards,
Nicolas

[savemy67]

Hello Nicolas,

I could not tell from the photographs whether or not the top of the cylinder bore was slightly chamfered.  Chamfering the edge assists the insertion of the piston.  Your ring compressor looks to be of the correct style.  When I have inserted pistons, I slathered the inside of the compressor with oil, and then I used one steady push to insert the piston while keeping the compressor in contact with the block deck.  Keep up the god work.

Respectfully submitted,

Christopher Winter

[DeVille68]

I could not tell from the photographs whether or not the top of the cylinder bore was slightly chamfered. 

Hi Christopher,

Thanks! 
Yes, you are right. Looking at some other photos there is indeed a slight taper. I have not noticed it before, but this would explain my "difficulty" of installing the pistons with the rings.
It was difficult trying to do it alone, with a helper a nice pound would be all that was needed.

Best regards,
Nicolas

[DeVille68]

Today, I installed my three different valve springs, retainers and locks.
I have the original ones, one set from MTS and one set from CadCompany.

The first picture you see all the springs installed. From the bottom of the picture: original springs with original valves, original springs with new valves, MTS springs with new valves and in the back CadCompany springs with new valves.

What you notice from looking at it from above is that the new retainer (probably big block chevy?!) are a bit wider and cover the full spring. However, this does not pose a problem with the rocker arm, since it will clear those. The retainer is also a bit shorter in the middle, so more clearance to the valve stem seal. (if you use a positive type, or to the valve stem in the block for normal seal).

Next photo shows the difference in length of the intake to exhaust valve. The shorter valve in the middle is the intake valve. On the left is the MTS stronger spring and on the right is the original spring and retainer.
However, the difference is about 0.027 inches. This is fare more than the difference in the actual length of the valves with is only about 0.017'' (exhaust is slightly longer than intake). So I wonder if the valve seat is a bit more sunken into the head on the exhaust side?

Now, I don't like this, because this means that the rocker arm geometry or the contact point of the rocker arm on the valve stem is not exactly the same for the intake and exhaust valve. Possibly being offset and not in the middle of the valve.

I tried to measure this but was not able to do this alone, the paint on the stem would wash out because I would wiggle the rocker arms too much while trying to install and remove them. So I will have to wait for this analysis until I have a helper again.

Anyways, I need to wait for two head bolts, because the kit I got from a very well known Cadillac Performance Parts supplier did not include the two short bolts for the head?!?!

Next week or so I hope to be able the measure the spring rate and force those three different springs will give for open and closed valves. So, keep looking for this post.

Best regards,
Nicolas

[spolij]

Hi Nic. Where did you get the u channel finish ? for the leading edge of the top?

[DeVille68]

Hi,
Do you mean the paint? The channel is probably still original, but badly rusted because the weatherstrip was completely dry and in large parts long gone.
So I cleaned everything and put POR15 on top of the rusted metal. After that I glued new Weatherstrips from Steele on. No water issues anymore. So far it holds up good.

Best regards,
Nicolas

[DeVille68]

So here is a followup post on valve spring pressure.
I have three choices:
1) original springs and retainers
2) new springs and retainers with shims from MTS
3) new spring and retainers from CadCompany - Stage 1 kit

So I in my last post I showed you how I installed all those different choices into the head. I measured the installed height for each of those and they vary slightly, here is what I measured (mean value) :
Original specification is: 1.946''
Measured with the original springs: 1.980''
Measured with spring and retainer MTS: 1.943''
Measured with spring and retainer CadCompany: 1.942''

So for the later calculation I will use the original specification of 1.946'' or closed and my valve lift 1.464'' open (0.482'' lift)
I have no idea why I would measure a larger installed height using the original hardware?!

Anyways, I went to a local mechanics school and was able to borrow their spring pressure measurement tool. Please see the attached picture.

I measured all 16 springs from MTS and Stage 1 for pressure on seat and open, then I took the mean value and the results are:

MTS closed = 55 lb             MTS open = 182 lb              Spring rate: 267 lb/inch    Free length: 2.150''
Stage 1 closed = 28 lb        Stage 1 open = 157 lb         Spring rate: 270 lb/inch    Free length: 2.047''

Original specification according to shop manual: closed: 60lb - 65lb and open: 155lb - 165lb


Observations:
1) The MTS springs can be used without shims
2) The stage 1 springs need a shim to achieve proper closed pressure.
3) At least three or four shims of 0.030'' thickness would be needed to give 52lb - 61lb closed
3) The original springs have lost some of their stiffness they lost about -17% compared to specification.

MTS told me over the phone that their springs should give 90lb closed and 300lb open.
With is way way too high and not good for the original rocker arms. As you can see, someone figured out the correct spring pressure at MTS but that information was obviously lost.

Since I have a MTS #5 camshaft I will use the MTS springs and retainers.
I am not sure if I should use one shim or not.
I wanted to mention that I removed the internal spring dampeners. Below 4500 rpms they are not needed and only add friction.

If you have any more insights I would highly appreciate your input.

Best regards,
Nicolas

[Bentley]

Happy New Year Nicolas. Why did you choose the #5 cam, and does it require any other engine modifications?

[DeVille68]

Hi Wes,
Thank, to you too.
Other than new lifters there is nothing more required.
However, I also changed the timing chain, intake and exhaust valves, and the springs with retrainers and keepers. I also installed positive valve stem seals which required machining the valve stems. You could probably also use the original springs, but as you have been able to read above the original springs lost some tension over the years. So I am going with the springs that MTS supplied but use those without or with only one shim to stay in the region of forces that also the factory recommended. I don't turn the engine more than 4500 rpm anyways. More around 2000-2500 and there the stock springs / stock pressure is sufficient. On top it gives you a quieter valvetrain and less friction compared to the "chevy" specs. (90lb seat, 330 lb open)

Best regards,
Nicolas

[spolij]

Hi nick i have a 66 deville conv. i'm restoring. On the leading edge of the top over the windshield did you have a decorative u channel?

[spolij]

Nic the 66 deville has vacume switch.

[DeVille68]

Hi nick i have a 66 deville conv. i'm restoring. On the leading edge of the top over the windshield did you have a decorative u channel?

I can not follow what you mean. There is a chrome piece on top of the windshield frame. And then there is the front convertible top bow. This one has the front weatherstrip glued onto it (with plastic clips).
I have attached a factory drawing. Hope it help! Otherwise I will try to find some pictures of my front bow, they should be somewhere...

Best regards,
Nicolas

[DeVille68]

Update on the engine rebuild.
As I posted above I have measured all my springs and the corresponding valve pressure.
Since no one has a real clue about spring pressure and no one was able to give me a clear explanation of how much pressure is needed, I figured, that I can choose whatever I want, because I have also no idea. So, it apparently does not matter.

I have bought a MTS #5 and this camshaft is about the same as a 72 cam - from what I can tell from my measurements and from the specification of the 72 shop manual / information book.

The 72 has a lift of about 0.490'' and specifies 60lb-65lb on the seat and 163lb-173lb open.
As you can see above I have the MTS springs, and with one shim I end up with the following values:
61lb on the seat @1.946'' and 191lb open @1.465''.
This is exactly factory spec on the seat and about 14% more open.

So I think this will be fine considering to flimsy rocker arm setup.

The pictures below show how I first plugged the air passage in the head with a 1/16'' NPT set screw. The trapped air within the head will not pop out the caps at either end, because through the ideal gas equation the increased pressure of the trapped air should only create a force of about 1.2 kg.

Then I checked the valve seat area and then installed the shims, springs, retainers and keepers.

The heads are now done and would be ready to install.

However, I have to wait yet again about two weeks, because usps decided to return my package at the border - reason unknown. I suspect that they did not want to send me the assembly lube I ordered?!
Well, another unnecessary delay in the build...

Best regards,
Nicolas

[Roger Zimmermann]

If you don't get the parcel from USPS, I have assembly lube from GM.

[spolij]

Nic replace the spring. Get one from the hardware store, just a little stiffer than the originale.
I have a 66 convert. Did you have a decorative u chanell on the tip of the front cover?

[DeVille68]

If you don't get the parcel from USPS, I have assembly lube from GM.

Nice, I will get back to you eventually. Problem is, that also the two missing head bolts are supposed to be in this package! 

[DeVille68]

Nic replace the spring. Get one from the hardware store, just a little stiffer than the originale.
I have a 66 convert. Did you have a decorative u chanell on the tip of the front cover?

I still don't get what you are talking about, here is a picture attached that I have found.
The only decorative thing on the top is the chrome strip on top of the windshield frame. There is no channel in or on the front bow.

In the picture you see the black strip, this is the portion where the weatherstrip is supposed to go - you can see the holes for the clips.
The rest is just top material and metal.

[spolij]

I'll find mine and post a pic.