Food for thought re roll pins

[Mr. C.]

I recently replaced the head gasket on my 1300 engine. The engine while built in 1975, did not have roll pins installed to hold the O-Rings. There was no oil leakage and the gasket was replaced due to a coolant leak. The gasket that was on the engine was not an original factory part. So I don't know if roll pins were removed when the gasket was changed or if they were never installed.

HERE is the interesting part - prior to my changing the gasket and installing roll pins, oil pressure ran 45 psi on the dash gauge and when the cam cover was removed, the galleys under the cams were totaly full of oil. With the roll pins, the pressure reads 50 psi and the galleys are, at most, half full. It appears that the pins do present a restriction to oil flow. Well I guess we suspected they would didn't we. I can see now why a lot of other methods of holding the O-Rings have been tried.

I wish I could see an O-Ring that failed. The roll pins are definitely a good fix but I like lots of oil everywhere. A bigger oil passage and roll pin would need a different O-Ring a thinner "pin" is a challenge to hold in place.

So my question is "What else has been used or tried?".

[PSk]

Why are we using roll pins?

Roll pins are thick walled things, if something really is required then why not purchase a very small thin wall tube and use that instead. No great strength is required and even a 0.25mm wall tube will not fail in this installation. If you bought thin wall tube that was bigger than the hole, drill the hole out so there is a step (in head and block), split the tube lengthwise ... then the tube will have to be compressed to get in the hole and spring out against the wall and never move passed the step ... thus trapped perfectly.

Also has anybody looked at machining grooves in the head (and maybe block?) to hold the O ring.

Pete
ps: Roll pin looks like a bad idea to me ... very restrictive. Infact machining up a little tube out of alloy and machining the block to accept this tube. Ensuring the ID of the tube is exactly the same as the original hole sounds like a feasible solution ... the roll pin NOT.

[VeloceOne]

Greetings All,
As far as roll pins go, I think that they are a poor idea, I throw them away.
I much prefer the square section o rings in conjunction with the ferrules that float with them and are not set in the block. I still have some around, but can't rember who sold them. Regards, Ian

[Jim K.]

Long time ago I had an O-ring split and lost about 2qt of oil in 5 miles. Since then, I have come up with a permanent fix that probably doesn't even require o-rings any more (haven't tried it without though). When the engine is being rebuilt, I drill out 1/4" wide and 1/4" deep in both head and block. I then buy 1/4" aluminum tubing and cut 6 pieces 9/16" long. Next, chamfer both ends of these little tubes so they taper nicely to their ID. When ready to assemble, place head gasket on block, push the tubes in place and slip the o-rings over them. You now have 6 little tubes standing about 1/4" proud of the block. Carefully lower the head and coax any one that doesn't like to line up perfectly, using judicious force. When the head hits bottom, the thin lips of the tubes are squeezed to conform and seal the oil connection perfectly. Its a simple fix that requires very little work (make sure you airblow any swarf from drilling!) and is 100% guaranteed !! The only thing you must watch is to be fairly exact with the drilling depth and even if you screw that up and go deeper, just make a longer tube !
Factory roll pins are a half-*** fix, as they don't seal and most times you find them pressed down anyway. BTW, if that happens, don't bother trying to pull them out as it is sometimes impossible, just push the new pin on top of the old one.
Jim K.

[beatle_bayly]

Mr C,

I've seeen a stuffed Alfa 4cyl engine with the oil galleries peened closed to raise oil pressure for a quick sale !!!!!!

[George Willet]

Hydralically O Rings will not seal if there is a "fourth force" ,other than oil pressure, on the inside on the O Ring. The O Ring works by the containment of the outer diameter, the upper, and the lower surfaces, and liquid pressure in the inner diameter.

Place the O Ring over the roll pin, and you'll see that it doesnt come close to the inside diameter.

The purpose of the roll pin is to restrict the oil pressure to the O Ring, and the volumn of oil to the cam area. Lessens "windage" at the crank from drainage. NO LOSS of cam/follower life.

I use the square O Rings from Centerline Alfa, with no leakage. Carefully insert the O Ring in the head gasket, gently lower the head.

Of course, one must change the oil, as old oil and acids will deteriate, O Rings, seals, etc.

[Lee Hjelsand]

Any body try these

[Mr. C.]

Lee, What is that ? If you can, please show the o-ring's orientation in relation to the piece. In other words where does the o-ring go? I am hesitant to drill the bolck to fit an "oil tube" if the head also has to be drilled. I just don't have a way to insure alignment. The device that you show certainly looks like a very good solution if it can be installed without a lot of special machining. Where can these be purchased?
Thanks

[Lee Hjelsand]

The "O" ring goes around the shoulder in the normal position in the head gasket. No machining is required to fit these, They are a replacement for the standard roll pins. The only reason I said to debur the hole in the head is because after surfacing there may be some burrs in the hole. No machining is required in the block either. Only to make sure the hole is round with no burrs. I have a few of these left. If you wish I will sell for $1.00 each (6.00) plus 1.50 for shipping in the US. If you don't like them or see a problem I will refund your money.

[torcia]

Pulled out my two blocks today to see which one I'm going to build-up. both of them have old roll pins in the short block. I purchased a few of Lee's special roll-pins so I want to pull out the old ones but I'm not sure how I'm going to do it. I tried grabbing the little bit that is sticking up with some pliers but don't want to bugger up the mating surface so that didn't work. Short of drilling them out I'm kind of at the head scratching phase. Any ideas on how to get the old pins out?

Thanks,
Mike

[VeloceOne]

To Pull roll pins, slide a nut or washer over, and have it tig welded on and pull the pin...
Regards, Ian

[Lee Hjelsand]

Use the method I described, A ss sheet metal screw with the finest thread you can find. Carefully screw into roll pin, May take a few tries to get a good bite. I have never failed to get them out doing it this way, period. Patience is required, and if I was close to you I would do it for you, but I assure you this method will work.

Lee

[mghamms]

I used 1 5/8 fine thread drywall screws to remove the roll pins. The minor diameter fits well into the pin and the thread is hard enough to cut into the pin without expanding the pins. Then pry out with a cats paw or small pry bar with a piece of wood to protect the head.

[Andrew]

Jon Norman makes/sells those brass stepped fittings pictured above to replace the roll pins.

Andrew