Valve clearances
Discussion
Has anyone ever done their own 500 mile valve clearance checks on the SBC ? I'm keen to have a crack at it unless it is a specialist job ? I can't see any advice under historic threads ...
Anyway, I have the cylinder layout and clearance figures and from my limited knowledge of these things think I proceed as follows :
Turn the engine in the rotation of normal operation
Turn until the rocker on piston 1 is "rocking"
Adjust the value clearances on the valve opposite in the firing order (e.g. piston 1 (front top) opposes piston 6, 2 vs 3, 4 vs 7 and 5 vs 8)
Continue around all 8.
Inlet and Oulet clearances checked together.
Not sure exactly what "rocking" means, the mechanical roller cams may look different to my Ford Capri's rockers ! Will find out if I take the head covers off, but would appreciate some feedback before I venture into the unknown ....
Regards
Tony
Anyway, I have the cylinder layout and clearance figures and from my limited knowledge of these things think I proceed as follows :
Turn the engine in the rotation of normal operation
Turn until the rocker on piston 1 is "rocking"
Adjust the value clearances on the valve opposite in the firing order (e.g. piston 1 (front top) opposes piston 6, 2 vs 3, 4 vs 7 and 5 vs 8)
Continue around all 8.
Inlet and Oulet clearances checked together.
Not sure exactly what "rocking" means, the mechanical roller cams may look different to my Ford Capri's rockers ! Will find out if I take the head covers off, but would appreciate some feedback before I venture into the unknown ....
Regards
Tony
Found this on the net - seems to make a lot of sense.
http://www.centuryperformance.com/valveadjustment....
Tony
http://www.centuryperformance.com/valveadjustment....
Tony
Bit of a "one man thread" this, but a few tips from my recent experiences for completeness :
1) Valve adjustment is actually quite simple, so long as you know what to adjust.
2) The bolts to adjust the clearances may have a locking nut inside (allen key job). Mine did, so beware.
3) For roller cam engines, do not automatically follow the "open one valve to the max, adjust the opposite valve" method as per my earlier link. The method here is as follows :
Set one cylinder at a time. To set intake valve, rotate engine over until the exhaust valve starts to open. Then set the intake lash on that cylinder. For exhaust valves, rotate until intake valve opens and goes through entire cycle; just before it closes set the exhaust valve lash.
4) MOST IMPORTANTLY, make sure you check with your engine manufacturer and do not necessarily rely on anything you read (case above for my engine, I did the "opposite valve" adjustments then needed to redo them all). Gail Trent is the contact at AS (0013097643601).
Regards
Tony
1) Valve adjustment is actually quite simple, so long as you know what to adjust.
2) The bolts to adjust the clearances may have a locking nut inside (allen key job). Mine did, so beware.
3) For roller cam engines, do not automatically follow the "open one valve to the max, adjust the opposite valve" method as per my earlier link. The method here is as follows :
Set one cylinder at a time. To set intake valve, rotate engine over until the exhaust valve starts to open. Then set the intake lash on that cylinder. For exhaust valves, rotate until intake valve opens and goes through entire cycle; just before it closes set the exhaust valve lash.
4) MOST IMPORTANTLY, make sure you check with your engine manufacturer and do not necessarily rely on anything you read (case above for my engine, I did the "opposite valve" adjustments then needed to redo them all). Gail Trent is the contact at AS (0013097643601).
Regards
Tony
Tony, thanks for the web link to Century Performance as I've been looking for the compensation figures for setting valve lash on a cold engine following a rebuild, just the ticket... cheers.
In case you're wondering, I do not normal get into posting messages on forums, just don't have the time! I'm currently overhauling the top end of the SBC in my GTR... T81GJF due to cooling issues. Thought it was a head gasket following compression tests which resulted in coolant being blown out of No.6... but gaskets are fine!!! Suspect leak via cracked/porous casting within the inlet port, so next step is pressure test heads? Fingers crossed it can be repaired as they are Dart alloy race heads!
Regards,
Trevor.
In case you're wondering, I do not normal get into posting messages on forums, just don't have the time! I'm currently overhauling the top end of the SBC in my GTR... T81GJF due to cooling issues. Thought it was a head gasket following compression tests which resulted in coolant being blown out of No.6... but gaskets are fine!!! Suspect leak via cracked/porous casting within the inlet port, so next step is pressure test heads? Fingers crossed it can be repaired as they are Dart alloy race heads!
Regards,
Trevor.
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