Cylinder head dowelling.

[Captain Pugwash]

Make some clear marks.



Pillar drill 3mm bit. Drill through. The holes need to be at the extremity of where the washer would sit, this is to make sure that when you drill the barrel you are not drilling into the barrel stud holes.



Check position of holes, then mark the gasket face (Only) with engineers blue or marker.





Bolt barrel and head together with four barrel studs 8 nuts and 4 washers.



With the barrel and head bolted up loosely spin the cylinder head fully one way and mark the barrel where it sits, then spin it back the other way and mark it again.





Next centre the head in the middle of the two marks to help align the studs, this will make it much easier to set the head on the barrel later.



Lightly tighten the head nuts, but be extra careful not to damage the spigot of the barrel.

Turn the assembly upside down, so now you can look down the barrel at the cylinder head, now using a very broad rubber mallet lightly tap the head to position it central so that no engineers blue can be seen. The head must be just loose enough to move.



When you are certain that the cylinderhead sits central, tighten all the head bolts.
Now recheck the marks you made earlier, if they are ok you can now remove the two barrel studs that sit over the pre drilled holes in the cylinderhead.

Now your ready to drill. Put the assembly back under the pillar drill and align and drill through to the head.


You need to drill just deep enough to sit the dowels into the head. The pillar drill has a gauge on the side so if you pull the drill bit down through the pre drilled hole now you have a start point, so now you can see how far you are drilling into the barrel.
Do not drill too deep or you will loose the dowels in the drilled holes.

Drill to suit the length of the dowels you use....
I use old crankshaft big-end roller bearings from old cranks I've pressed I find that there perfect for this.
Also a drill press with anything less than 50mm travel will make it difficult to drill to the depth that you need.



You only need a few mm protruding to centre the head, I've left about 5mm. I drilled approx 9mm into the barrel, the dowels sit in about 8mm deep.

Hope this is some use, Mark.

[a-teamlambretta]

excellent mark , was running out things to do as I have now run out of parts for other jobs . will have ago tomorrow aft. cheers and a happy new year. simon

[Toddy]

Great thread Mark thanks for sharing

[coaster]

Meticulous work again Mark but I don't understand this bit: "With the barrel and head bolted up loosely spin the cylinder head fully one way and mark the barrel where it sits, then spin it back the other way and mark it again." How can you rotate the head if it is bolted to the barrel Or am I just being dense

Colin

[Jamjo]

Great work Mark,
always good to see how the people who know what they are doing posting their.... How to do threads on here .
Thanks mate
James

[Eden]

excellent post Mark

[coaster]

Meticulous work again Mark but I don't understand this bit: "With the barrel and head bolted up loosely spin the cylinder head fully one way and mark the barrel where it sits, then spin it back the other way and mark it again." How can you rotate the head if it is bolted to the barrel Or am I just being dense

Colin

Just read it again and I was being dense, get it now

[modster79]

This is what I like about the forum, good useable information. Thanks Mark, excellent mate.

[LateAgain]

Meticulous work again Mark but I don't understand this bit: "With the barrel and head bolted up loosely spin the cylinder head fully one way and mark the barrel where it sits, then spin it back the other way and mark it again." How can you rotate the head if it is bolted to the barrel Or am I just being dense

Colin

Just read it again and I was being dense, get it now

I must be double-dense as I cant get my head (pun) round that. Spin the cylinder head? With 4 studs through it?

[carlos fandango]

Meticulous work again Mark but I don't understand this bit: "With the barrel and head bolted up loosely spin the cylinder head fully one way and mark the barrel where it sits, then spin it back the other way and mark it again." How can you rotate the head if it is bolted to the barrel Or am I just being dense

Colin

Just read it again and I was being dense, get it now

I must be double-dense as I cant get my head (pun) round that. Spin the cylinder head? With 4 studs through it?

The studs are a loose fit in the barrel and head holes, this is just away to make sure the studs are centered (ish) in the holes.

[HxPaul]

I think the confusion is in the word "spin".As far as I can make out,you move the head one way until it stops against the studs and mark the barrel,then do the same thing in the opposite direction,again mark the barrel.Find the centre of the two marks and the studs should be in the middle of the holes.