Re: replacing piston rings in 74 SB
What rods?
Yancey
Re: replacing piston rings in 74 SB
Yancey wrote:
What rods?
Yancey
The pushrods.
Re: replacing piston rings in 74 SB
Ok, low compression on cylinder 1, and it seems like you covered most of the bases. Put a teaspoon of oil into the cylinder 1 sparkplug hole, and redo the compression check. If it makes little or no change in the reading, you have a valve or cylinder head sealing problem (cracked head, leaking head gasket). If the test results come up, like from 115 to 130 for example, then I'd say piston rings. The oil cap bouncing while doing the check on cylinder 1 would tend to support a ring problem: air compressed in the cylinder would escape past the piston rings into the crankcase, which would cause pressure fluctuations at the oil cap while the engine is cranked.
Paul
Re: replacing piston rings in 74 SB
Yeah if it feeel's low on #1 Pull the head I hand Crank warmed up motor's coupla brisk turn's by hand feel the compression.
Sure Spark plug is tight < lose Compression obviously ? < check any how
If feel's low try pullin the head ?
Head's can be both visually inspected and tested for seal .
Quite easy scrape carbon if any off the Combustion chamber being carefull not to remove any metal .
Look between Spark plug hole and Valve seat's for Crack's < blueing if you need ?
But pour gasoline in each port !
Exhaust port < check that Exhaust Valve !
Pour in gas watch valve < if valve take's 20 second's or more to become wett < good seal !
If Gas runn's thru quickly ? Not sealing !
Mark the Badd valve !
Now if this head was rebuilt ?
Most likely you can remove the Valve's !
But on a runn in head < Most likely you cant remove the valve's because the Keeper's will mushrooom up the Valve stemm Keeper groove's .
This Enlarge's the Diameter of the Valve stem and keep's the Stemm from passing thru the Valve Guide < tear's them up !
So you grind the stemm keeper groooves and replace with new Valve .
Do not reuse a valve that has been Filed around the Keeper's .
But if it is the Good Head < supposedly rebuilt that is #1 < badd Cylinder < Gas leak's thru it ?
Remove valve and hand lapp it in too see if you can get a good seal < might get Lucky Lil suction cupp on a Stick some Valve lapping compound ?
As to re- Ringing <, Not that hard but understand not all Cylinders and Piston's are good candidate's for re- ringing .
but test all port's and valves with gas .
Check Cyl to Head matte surface << Head should be smooth not all grooved up from cyl.
Look for gas mark's or burn mark's indicateing hott escapeing gas .
If Cyl groove is ?? Lil grooved up ?
Post again there's trick's ?
Do not lapp cyl. intoo head with lapping compound < Usually make's worse !
Sean