Help!!

D

Daxklynsmith

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I dont know if I have done something stupid, My ongoing saga with the rebuilt head on my 73 3.0 CSA (Carb)continues.
While I am trying to find out what is still wrong I decided to swap the head from my donor 75 3.3L(Carb) E3,
Are the camshaft and valve lengths the same?
My valves are touching the pistons?
Am pretty sure I set them both on Compression TDC before removal?
I see that the E3 has Piano top pistons while my CS has half-moons?
Please help guys
Regards
Dax
 
All pre-1988 (or so, whenever the M30B35 hit the line) stock BMW heads are the same as far as combustion chamber shape, size and valve size and config, regardless of engine displacement. The rocker arms are all the same so unless you have a significant high lift cam you should not have piston and valve contact unless the cam timing is off. The piano top pistons will not hit properly timed valves.

If you have the head off, set #1 to TDC visually (there is no compression or exhaust stroke for the bottom end, just strokes), then set up the head for a compression TDC on the #1 valves and bolt it all up. You can check the clearance with clay before committing if you're unsure. It doesn't take much -- one or two teeth off will bend exhaust valves.
 
Help

Hi Tony, Thanks,just struggling here, set all up at TDC on #1 and still touching,am going to fiddle with it and move it 1 tooth at a time till I get it right,I guess I'll have to go to a Gym to get the other bicep to the same size
To x_atlas, , nope, bores are the same @ 89mm
Re the Crank, I am in Ireland and that's a Heavy mother
Regards
dax
 
Dax
From what you have said it definitely seems like the valve timing is off.

One trick is to remove the chain and very carefully turn the engine and the cam a little at a time until you know that you have TDC on number one and number one valves are closed. Turn the engine and the cam in the correct direction and remember the ratio of the crank to cam, the cam turning "slower" than the crank

The only other possibilities I can think of are
The headgasket is incorrect, there were differences between FI and carb ones
The head has been skimmed beyond its limits - then you need a thicker gasket
Make sure the valve clearance is correct ie they are adjusted already.

HTH
Malc
 
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