[Johnathene]

I am a new member to this forum, but an occasional reader and long time Alfa owner. I am doing a rebuild of my 1600 engine and have come upon an issue I would like some help with. I have culled through the forum threads looking for a discussion on my particular issue, but cant find it, so I though I would start here to see if a) someone can point me to a thread where this was covered or b) someone has an answer to my question.

My issue is this: When I install the liners without liner O-rings, the liners protrude about 0.0015" above the block. With the O-rings I ordered from Centerline Alfa, they protrude about 0.020". This is obviously way above the spec value of 0-0.003". My question is, is this normal?

Reading through other threads on this topic, no one seems to discuss this issue. Any insight this group can provide would be most helpful.

Thanks,
John Behrens
'67 Duetto

 

[Gordon Raymond]

At some time, it may be someone took a "flattening" cut to your block deck to either remove imperfections or increase compression without milling the head. This was often done by racers in the 60's - 70's when we cut block decks about 1mm. This along with cutting liner tops or seats increased compression without milling the head. On GTA heads, milling moved the huge intake valve closer to the edge of the combustion chamber. That, in-turn, shielded early opening A/F flow with the inside edge of the liner. Power gained from increased compression was lost by fuel mix shielding with the liner. The solution was to mill the block deck for compression increase. Today, just buy good forged pistons cut for ratio increase.
In your case, FIRST be sure your block is true, upper and lower deck parallel, and main upper saddles all-in line and at right angles to the deck. Then carefully check liner seats in the block for flaws. Next measure EACH liner seat flange to top. Examine liner flanges for flaws. Without "O" rings, protrusion should be the same on all 4. You can use more than book spec protrusion but it must be the same on all 4. A Reinz headgasket 1.6 to 1.9 mm thick UNCOMPRESSED. Compressed it will be .5 to .6 or so thinner after torque and retorque, about 1.2 to 1.0mm or so. The fire ring in the gasket compresses similarly, so you have quite a bit of "room" here for liner protrusion. Gasket failure from very high liners will be oil leaks at the galleries to edge of block, most often seen on the exhaust side, but typically, not always. LOW liners are more likely to result in fire-ring failure, not good.
The head gasket interface on Alfa engines is a flexing seal as block, head and liners to not all expand and contract evenly with heating and cooling cycles. A GOOD headgasket, (Reinz) will allow this "flex" for a longer time than a not-so-good headgasket before failure leaks.
That's about the way it goes from my experience.

 

[Johnathene]

So I did buy a new Reinz head gasket. I also checked the fit with the old liner O-rings. with the old rings, the liner protrusion is about 0.0015". of course the old O-rings had been compressed and were asymetrical in cross section whereas the new O-rings are circular (~15mm in dia). That's why I'm thinking that the O-rings will compress and the liners will sit correctly after head installation?

its good to hear that there is "room" for excess liner protrusion and the ramifications are relatively minor (oil leak). when you say protrusion should be the same on all 4, is there a tolerance on that, say 0.001"?

 

[Gordon Raymond]

The "O" rings are designed to distort and fill gaps so no worry about them. Check protrusion with naked liners on the seats for protrusion. All should be the same with clean liner flanges and block seats. There is no mentioned tolerance here, I just try to get them all close.

 

[samakijoe]

This might be of value:

X's, O's and squares, best way to seal your head?

I recently got stopped in my tracks on a head gasket R&R when I discovered that a previous "mechanic" had installed the standard Reinz gasket without any of the oil galley O rings between the head and the block! No wonder why the engine looked like a bulkhead door stop for the Valdez! (and I...

www.alfabb.com

There was also information on brass inserts in place of the pins on the site not long ago
but I can not find it. It had to do with removing the roll pins..
Anyone remember?

 

[Gordon Raymond]

I did that. Maybe a week ago. I've several posts on this subject over the years concerning the problems and solutions with head gaskets.

 

[samakijoe]

Gordon: Please post the URL for this young man..
Searches on this site are not easy because...

 

[Gordon Raymond]

Just send me a message on the BB or an e-mail and I'll disclose what I've found to work. NO SECRETS!

 

[1750GT]

...There was also information on brass inserts in place of the pins on the site not long ago but I can not find it. It had to do with removing the roll pins..
Anyone remember?

I tried looking for the original thread but could not find it either. However I did use the same approach to remove a few of the spring roll pins that were stuck in my block and some that were driven down deeper into the oil galley by the PO. I tried the threaded route as well to no avail....so I created a simple extractor from a length of barbique skewers as in the photo below. Note that this photo was taken after the "tool" was used so it suffered some damage. Basically you need to find a flat rod whose O.D. matches the I.D. of the oil galley...and whose thickness is the same a the width of the roll pin slot....then a notch was filed into it whose depth is the same as the thickness of the roll pin. This allows the tool to be inserted through the pin then rotated 180 degrees and extracted by pulling up on the tool with a vise grip clamped to it and hammer. The skewer steel is probably not the best material to use as the steel is not very hard (tool steel would be ideal) ....nonetheless the roll pins still came out without too much difficulty though I did have to create more than one of these because of damage to the notch are (as the photo shows).

Good luck....not sure if this is what you were thinking of.

 

[samakijoe]

Really creative thinking.
The info was for the OP above. I was lucky enough to have pins installed and located correctally by the PO.

 

[fstntq]

I tried looking for the original thread but could not find it either. However I did use the same approach to remove a few of the spring roll pins that were stuck in my block and some that were driven down deeper into the oil galley by the PO. I tried the threaded route as well to no avail....so I created a simple extractor from a length of barbique skewers as in the photo below. Note that this photo was taken after the "tool" was used so it suffered some damage. Basically you need to find a flat rod whose O.D. matches the I.D. of the oil galley...and whose thickness is the same a the width of the roll pin slot....then a notch was filed into it whose depth is the same as the thickness of the roll pin. This allows the tool to be inserted through the pin then rotated 180 degrees and extracted by pulling up on the tool with a vise grip clamped to it and hammer. The skewer steel is probably not the best material to use as the steel is not very hard (tool steel would be ideal) ....nonetheless the roll pins still came out without too much difficulty though I did have to create more than one of these because of damage to the notch are (as the photo shows).


View attachment 1665157

Good luck....not sure if this is what you were thinking of.

Very cool idea but only really works if someone used the C type open ended roll pins vs the coiled roll pins, unless one can find a suitable rod that is both narrow enough and strong enough to do the same.

 

[Johnathene]

stepped away for a couple of days. you know, the holidays...

I checked my naked liner protrusions and all 4 are around 0.0015". so I think that tells me my liner to block fit is fine and additional protrusion due to the O-rings is normal and the rings will compress under the torque load of the head. Thank you for clarifying that for me.

I noticed that this discussion veered into the related topic of roll pin inserts into the oil passages between the block and head. I have read about their use to ensure the oil seals stay in place when installing the head on the block. When I pulled my engine apart it did not have those installed, and there were no signs of oil leaks between block and head. it seems to me they will restrict oil flow though, so I had not planned to install them. it sounds like their use may be advisable though.

my final question on this topic is reuse of the piston rings. the engine that I am rebuilding has about 5000 km (and 40 years) since the last rebuild. the pistons, liners, rings, valves, guides, etc were all replaced in that rebuild. I am considering reusing the piston rings simply because they are finally broken in and seal fine since they have so little mileage on them. I checked tolerances on them and they all passed. is this acceptable, or a fools errand?

John Behrens

 

[Gordon Raymond]

If it was Ok, and reassembled correctly, it will be as good as it was before disassembly. Some believe "while I'm in there...." while others feel "Don't mess with it if it's not broken".