stupid ? about exhaust valve guide

[JDSfastGN]

I have ported stock iron heads with 1.77/1.50 Manley SS valves. does this mean that the valve guides have been machined down already? If you have bigger valves is this a required modification? I wasn't sure if this mod had to be done for bigger valves. When I get back home this weekend obviously i can see if they are machined for seals or not, but i'm away and trying to figure out what else i need to do to convert to a roller setup.

 

[Jerryl]

I have ported stock iron heads with 1.77/1.50 Manley SS valves. does this mean that the valve guides have been machined down already? If you have bigger valves is this a required modification? I wasn't sure if this mod had to be done for bigger valves. When I get back home this weekend obviously i can see if they are machined for seals or not, but i'm away and trying to figure out what else i need to do to convert to a roller setup.

Great question!
The valve guide mod for increased lift is not required when installing bigger valves.

 

[charlief1]

X2 with Jerry

 

[turbofabricator]

Not required when installing them IF you don't mind alot of oil down the exhaust guides. With a smooth stem aftermarket valve, the exhaust NEEDS to have the guides cut for a positive seal. The stock exhaust valve has a step in the stem that pushes oil out of the guides. With a smooth stem valve (all aftermarket valves are smooth stem) there is no step/groove and it will not control oil. Make SURE they did cut the guides for positive seals. Having more clearance helps, too. This is standard proceedure if they are a reputable shop.

 

[Jerryl]

Not required when installing them IF you don't mind alot of oil down the exhaust guides. With a smooth stem aftermarket valve, the exhaust NEEDS to have the guides cut for a positive seal. The stock exhaust valve has a step in the stem that pushes oil out of the guides. With a smooth stem valve (all aftermarket valves are smooth stem) there is no step/groove and it will not control oil. Make SURE they did cut the guides for positive seals. Having more clearance helps, too. This is standard proceedure if they are a reputable shop.

Always willing to share your wealth of knowledge.

 

[JDSfastGN]

Not required when installing them IF you don't mind alot of oil down the exhaust guides. With a smooth stem aftermarket valve, the exhaust NEEDS to have the guides cut for a positive seal. The stock exhaust valve has a step in the stem that pushes oil out of the guides. With a smooth stem valve (all aftermarket valves are smooth stem) there is no step/groove and it will not control oil. Make SURE they did cut the guides for positive seals. Having more clearance helps, too. This is standard proceedure if they are a reputable shop.

Thanks turbofabricator, This could be good news for me if they are already done. They were a reputable shop that is pretty well known locally for their buick heads. The heads have over 60000 on them and don't smoke or have any known issues, so maybe they are cut down and have the seal. A few years ago I did the valve springs and for the life of me I can't remember if they had seals on the exhaust:redface: