Duetto engine removal - Page 5 - Alfa Romeo Bulletin Board & Forums
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post #61 of 197 (permalink) Old 01-20-2019, 12:30 PM Thread Starter
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Originally Posted by spiderserie4 View Post
those two are the alignment dowel pins.
the roll pins fit into the 6 oil passages.

iirc. there is a size difference for 1300/1600 or 2000/1750 engines (when ordering roll pins)

Yikes!!! None installed on my engine! I guess that would explain the oil leaks all around the head/block joint.
Iíll wait and see what Jim says before I look elsewhere for some.
Thanks for replying!
Mark
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post #62 of 197 (permalink) Old 01-20-2019, 01:31 PM
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Roll pins for the 6 oil passages were the orings go.

Measure the diameter of your hole and let me know the size. I might have some of the good ones.
Yes. Measure the diameter of the oil passage hole. I might have some of the good roll pins for your engine.

Alfa didn't start using roll pins in the 6 oil passage holes until sometime in the 70's. At that time they used split pins which help hold the oring in place but didn't help much with the eventual oil leakage. In the 80's Alfa started using rolled pins which don't have a slot down the side.

1969 1750 Spider Veloce w/dual webers, 1969 1750 Berlina, 1971 1750 Spider Veloce w/ dual webers, 1985 Spider Veloce 23,000 orig. miles, {Two} 1986 Spider Veloces, 1987 Spider Veloce bought new, 1988 Quadrifoglio, 1991 164S, Plus several more. I think they are breeding.
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post #63 of 197 (permalink) Old 01-20-2019, 03:14 PM Thread Starter
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Originally Posted by Jim G View Post
Yes. Measure the diameter of the oil passage hole. I might have some of the good roll pins for your engine.

Alfa didn't start using roll pins in the 6 oil passage holes until sometime in the 70's. At that time they used split pins which help hold the oring in place but didn't help much with the eventual oil leakage. In the 80's Alfa started using rolled pins which don't have a slot down the side.
Hi Jim,
The six small holes located along the long side of the head measure .188Ē. The corresponding holes in the block measure between .196Ē-.204Ē. The dowel pin hole sizes are referenced previously. Hereís a picture of the block serial number. Hopefully itís the original engine. The car vin begins with 66****.
Thanks for the help!
Mark
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post #64 of 197 (permalink) Old 01-20-2019, 03:17 PM Thread Starter
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Hereís a photo of the head holes iím Talking about and the engine serial number.
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post #65 of 197 (permalink) Old 01-20-2019, 07:40 PM Thread Starter
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Jim,
just to be sure we're on the same sheet of music: the six holes in the head (circled in red) measure .188". the two pins in the block (noted with a blue arrow) measure .317" & .319". the corresponding holes in the head measure .315".
thanks!
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post #66 of 197 (permalink) Old 01-20-2019, 07:49 PM
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Check both block and head for the 6 roll pins. Sometimes they end up in the head , even though they are supposed to be in the block.

74 GTV with 10548's and Ingram pump
71 Spider 1750 BOMBER ; 1995 LS 78K tight fast car
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post #67 of 197 (permalink) Old 01-20-2019, 09:36 PM
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Originally Posted by markgberry View Post
None installed on my engine! I guess that would explain the oil leaks all around the head/block joint.
Well, not necessarily. As Jim G wrote, "Alfa didn't start using roll pins in the 6 oil passage holes until sometime in the 70's." So your '67 wouldn't have had them originally, nor did Alfa engines built for the previous ten years. Those pre-70's engines didn't all leak oil at the head gasket.

Roll pins prevent the O rings from collapsing - they can become shaped more like a "8" than a "0" without something to hold them in a circular shape. Most engine rebuilders install roll pins in pre-70's engines. Either your Duetto engine has never been rebuilt or else it was rebuilt but no roll pins were added.

I would definitely recommend adding roll pins. But their absence doesn't necessarily explain your oil leaks.

What did the six O rings look like? Were they still circular? Might they have just become hard, taken a set, and no longer pressed against the head & block surfaces enough to create a seal? I always use the viton O rings from Spruell.

Jay Mackro
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'65 Guilia Sprint GT
'67 Duetto
'91 164L

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post #68 of 197 (permalink) Old 01-20-2019, 10:08 PM Thread Starter
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Well, not necessarily. As Jim G wrote, "Alfa didn't start using roll pins in the 6 oil passage holes until sometime in the 70's." So your '67 wouldn't have had them originally, nor did Alfa engines built for the previous ten years. Those pre-70's engines didn't all leak oil at the head gasket.

Roll pins prevent the O rings from collapsing - they can become shaped more like a "8" than a "0" without something to hold them in a circular shape. Most engine rebuilders install roll pins in pre-70's engines. Either your Duetto engine has never been rebuilt or else it was rebuilt but no roll pins were added.

I would definitely recommend adding roll pins. But their absence doesn't necessarily explain your oil leaks.

What did the six O rings look like? Were they still circular? Might they have just become hard, taken a set, and no longer pressed against the head & block surfaces enough to create a seal? I always use the viton O rings from Spruell.
some were still round, some looked like figure eights. there are no roll pins on the head or the block where those oil passages exist.
thanks for the explanation.
regards
Mark
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post #69 of 197 (permalink) Old 01-20-2019, 10:28 PM
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Alfa engines leak oil. Always have. But there are things you can do to lower the amount that they leak. Seals and gaskets get old. Using high quality gaskets and sealant where it needs to be used go along way to a long and very low oil leak engine.

The most common head gasket failure is oil in the coolant. The oil into the coolant comes from one or more of the 6 oil passages. By the time it starts leaking oil into the coolant its already been leaking oil to the outside. The roll pins will help reduce this.

I'll see if I have the correct pins ones for your car.

1969 1750 Spider Veloce w/dual webers, 1969 1750 Berlina, 1971 1750 Spider Veloce w/ dual webers, 1985 Spider Veloce 23,000 orig. miles, {Two} 1986 Spider Veloces, 1987 Spider Veloce bought new, 1988 Quadrifoglio, 1991 164S, Plus several more. I think they are breeding.
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post #70 of 197 (permalink) Old 01-20-2019, 10:52 PM Thread Starter
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Originally Posted by Jim G View Post
Alfa engines leak oil. Always have. But there are things you can do to lower the amount that they leak. Seals and gaskets get old. Using high quality gaskets and sealant where it needs to be used go along way to a long and very low oil leak engine.

The most common head gasket failure is oil in the coolant. The oil into the coolant comes from one or more of the 6 oil passages. By the time it starts leaking oil into the coolant its already been leaking oil to the outside. The roll pins will help reduce this.

I'll see if I have the correct pins ones for your car.
thanks Jim. i appreciate your help. you can Message me me about the pins if you want.
regards
mark
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post #71 of 197 (permalink) Old 01-21-2019, 09:58 AM
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I'm surprised you haven't been warned yet. Be VERY careful about not moving the crankshaft or any of the pistons. You will break the seal of the incredibly thin but large diameter o-rings at the bottom of the cylinder serves. If you do, you'll have to completely tear down the engine to remove the pistons, pull the liners, an replace these seals. You can save this disaster by putting a large washer over 3 or 4 of the head studs, and slide a section of 1/2" die pipe over that. Then just put the head bolts back on these and you will hold the sleeves in place.

Several of the suppliers make a tool that does this exactly.

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post #72 of 197 (permalink) Old 01-21-2019, 12:07 PM
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You can save this disaster by putting a large washer over 3 or 4 of the head studs, and slide a section of 1/2" die pipe over that.
Even a piece of heavy-wall PVC pipe will work (with the large washer at the base). There isn't a lot of force involved.

Is markgberry not removing his pistons & liners? With the engine torn down this far, replacing the rings and re-honing the liners would be an obvious job "while he's in there". Otherwise, the fresh valve job may increase compression enough to cause oil leakage past the old rings.

On the other hand, scope creep isn't always a good thing.

Jay Mackro
San Juan Capistrano, CA

'63 Guilia spider
'65 Guilia Sprint GT
'67 Duetto
'91 164L
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post #73 of 197 (permalink) Old 01-21-2019, 12:16 PM
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Question on this -

Many many years ago when I rebuilt my 1600 cylinder head, I remember one or two of the sleeves coming loose a bit as I pulled it all apart. I quickly put my washers and nuts on them to hold them all down.

Was I just lucky that it ran fine? That was over 25 years ago.

Thanks -

1967 1600 Spider
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post #74 of 197 (permalink) Old 01-21-2019, 07:43 PM Thread Starter
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Originally Posted by Alfajay View Post
Even a piece of heavy-wall PVC pipe will work (with the large washer at the base). There isn't a lot of force involved.

Is markgberry not removing his pistons & liners? With the engine torn down this far, replacing the rings and re-honing the liners would be an obvious job "while he's in there". Otherwise, the fresh valve job may increase compression enough to cause oil leakage past the old rings.

On the other hand, scope creep isn't always a good thing.
I really was hoping to not tear into the cylinders or bottom end bearings. Iím trying to avoid the ďsince Iím hereĒ syndrome that inevitably ends in a full rotisserie restoration. The cylinders have zero wear ridges at the top and the engine had good, even compression. No oil burn either. I dropped the head off at the machine shop this morning and they were aware of the roll pin issue these 1600ís have. Theyíre going to tear the head down and call me with their findings. Hopefully the valves just need to be cleaned and have new seals installed. They are going to resurface it as well. Iíll be careful not to move the crank too!
Thanks for all the replies!
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post #75 of 197 (permalink) Old 01-22-2019, 02:45 PM
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I found the roll pins and have sent you a PM.

1969 1750 Spider Veloce w/dual webers, 1969 1750 Berlina, 1971 1750 Spider Veloce w/ dual webers, 1985 Spider Veloce 23,000 orig. miles, {Two} 1986 Spider Veloces, 1987 Spider Veloce bought new, 1988 Quadrifoglio, 1991 164S, Plus several more. I think they are breeding.
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