Retainor to valve clearence.

[Steve V]

I am looking for max lift you can run on a stock exhaust guide with a stock valve spring retainor. 204/214 cam that is very popular has exhaust lift of .472 at the valve. By my measurements on a spare head this going to cause the retainor to hit the guide. Can I have the machine shop take a little off the bottom of the retainor?

If I have to cut the guide,then I am going to need 6 new exhaust valves.

I've seen machine shops use retainors that are thicker than stock. I know I have a few motors I need to check over....and I thought that only when going roller the exhaust guides need to be cut and valve changed.

 

[bison]

I am looking for max lift you can run on a stock exhaust guide with a stock valve spring retainor. 204/214 cam that is very popular has exhaust lift of .472 at the valve. By my measurements on a spare head this going to cause the retainor to hit the guide. Can I have the machine shop take a little off the bottom of the retainor?

If I have to cut the guide,then I am going to need 6 new exhaust valves.

I've seen machine shops use retainors that are thicker than stock. I know I have a few motors I need to check over....and I thought that only when going roller the exhaust guides need to be cut and valve changed.

Really? Id think you would coil bind before you hit the guide. Even when its cut down you still would put a seal on it even though it didnt come with one which would put it back up where it was without the seal uncut.

 

[turbofabricator]

Really? Id think you would coil bind before you hit the guide. Even when its cut down you still would put a seal on it even though it didnt come with one which would put it back up where it was without the seal uncut.

You CANNOT run a seal on a stock exhaust valve. There is a groove machined into the valve stem, where a seal will ride. This groove will prevent the seal from even contacting the stem. Won't work. If you NEED to increase retainer to guide clearance, you can remove about .050" from the top of the guide and the stock "oil pump" built into the stock exhaust valve will still work. You can also remove a small amout of material from the bottom of the retainer, too. Be VERY careful with this type of mod, though. If you have to cut the guides down more than .050", then you MUST replace the exhaust valve with a smooth stem valve, aka Stainless Steel aftermarket valve, (or stock TTA valve) so the seal will ride correctly on the stem.
Again, a seal installed on a STOCK exhaust valve, even if you cut the guides down .250", will NOT work. You WILL loose oil control. Usually, when installing a new spring/cam combo, you will replace the retainers, too. The aftermarket retainers improve the retainer to guide clearance issues. The factory retainers hang WELL below the keepers, reducing retainer to guide clearance. Usually, with aftermarket retainers (i.e. bee-hive springs/retainers) you will be OK with less than .510", certainly with less then .500". Check the actual clearance with your new retainer, spring combo, though.

 

[bison]

You CANNOT run a seal on a stock exhaust valve. There is a groove machined into the valve stem, where a seal will ride. This groove will prevent the seal from even contacting the stem. Won't work. If you NEED to increase retainer to guide clearance, you can remove about .050" from the top of the guide and the stock "oil pump" built into the stock exhaust valve will still work. You can also remove a small amout of material from the bottom of the retainer, too. Be VERY careful with this type of mod, though. If you have to cut the guides down more than .050", then you MUST replace the exhaust valve with a smooth stem valve, aka Stainless Steel aftermarket valve, (or stock TTA valve) so the seal will ride correctly on the stem.
Again, a seal installed on a STOCK exhaust valve, even if you cut the guides down .250", will NOT work. You WILL loose oil control. Usually, when installing a new spring/cam combo, you will replace the retainers, too. The aftermarket retainers improve the retainer to guide clearance issues. The factory retainers hang WELL below the keepers, reducing retainer to guide clearance. Usually, with aftermarket retainers (i.e. bee-hive springs/retainers) you will be OK with less than .510", certainly with less then .500". Check the actual clearance with your new retainer, spring combo, though.

Good info

 

[Steve V]

My machine shop used new retainors that reduced my clearence from about .500 to .430 ,engine has .449 exhaust lift and it smokes at start up almost everytime. Engine did not smoke before overhual.

Motor is out,heads are off going back to machine shop tommorrow.