Cylinder Head

[Ralf001]

4 minutes ago, MangoKorat said:

In 25 years in the motor trade I have never known anyone have a block skimmed.  If things got that serious, I'd be fitting a s/h engine from a write off.

ok.

[BarraMarra]

20 minutes ago, Ralf001 said:

car engines typically do not have a barrel.

The original didn't inform us it was a car Engine or a bike.

[Ralf001]

7 minutes ago, BarraMarra said:

The original didn't inform us it was a car Engine or a bike.

Bike forum is a different sub forum than motor forum.... kinda gives it away.

[Daffy D]

3 hours ago, BarraMarra said:

Whats the point in skimming the head if the barrel is worn? you wouldn't put 1 brake shoe in Daffy would you ? you put a pair in. Thead or barrel can be damaged so you skim both.

Cylinder head skimming has nothing to do with wear. Cylinder heads don't wear, they warp from overheating or get pitted from water or exhaust gas leeks, then need to be skimmed, removing a small amount of metal to get it all clean, smooth and perfectly flat surface again. 

 

Sometimes in a bad case the top of the block, where the head bolts onto also needs to be skimmed and that is an altogether more complicated job. 

 

Skimming gives a ever so slightly increase in compression ratio, but so little as no to be mentionable  

 

Barrel, actually the name is cylinder/bore, is where the pistons go up and dawn and they do wear. Fixing that is call a Re-Bore.

 

Warning motor head trivia:-

The word "barrel" is usually used by motorheads when referring to carburetors, "its with fitted a 2 barrel Webber"

 

Cylinders can also be referred to as "pots" - "it's got a 6 pot lump (block) with twin 2 barrel Webbers and goes like the clappers"

 

[HauptmannUK]

Speaking as someone who's had many cylinder heads skimmed over the years (probably into the 100's) here's my take on it...

1. Get the head chemically cleaned and pressure tested prior to skimming. No point in skimming a defective head.

2. Petrol cylheads can usually be skimmed with valves in-situ.  On most Diesels the head is flat and valves project beyond the head surface so the head will need to be stripped.

3. Since most Diesel heads are flat skimming does not increase compression ratio.

4. Some aluminium Diesel heads have hardened steel inserts in the head casting. These heads cannot be skimmed.

5. Blocks can be skimmed, and the machine shop I use in the UK can accommodate large V-blocks, but its relatively rare and may not be possible with linered or 'insert' engines.

6. Takes under an hour on the miller to measure and skim a head. Cleaning and pressure testing also well under an hour (assuming the head has been stripped).  I would think in Thailand a couple thousand Baht would be more than enough.