XER lobes and Valve Seat Longevity
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ok,so we all know that with a good dual spring,you can run an aggressive XER or similar lobe and have good spring life.but,how much harder are they on the valve seats? how long before the seats are pounded out,or how many miles between valve jobs?this would be on a street car that sees the strip a few times a year,not an all out drag car.just wondering as i haven't seen this discussed too much.
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Once spring pressure drops 20% from installed pressure on the seat you better change them. This is when the valve tends to bounce on the seat and power drops. Anyone going very aggressive on cam profile needs to solid roller. This way adequate spring pressure can be used and possible lifter failure can be avoided.
Chris
Chris
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Originally Posted by Cstraub
Once spring pressure drops 20% from installed pressure on the seat you better change them. This is when the valve tends to bounce on the seat and power drops. Anyone going very aggressive on cam profile needs to solid roller. This way adequate spring pressure can be used and possible lifter failure can be avoided.
Chris
Chris
Shawn
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Yes, change the springs. The valve spring is the most critcal part in an engine. That $6 part or $30 part can destroy an engine. The hyd roller is a valve spring nightmare due to the fact it is heavy as hell and you are limited to how much seat pressure you can apply to it to control its inertia before you overcome and collapse the hyd valving.
As I have stated time and time again the hyd roller is wonderful for making power in pushrod engines under 6K rpm. It is a nightmare for making power above or for extended runs over 4K rpm. If you don't believe me as Mercury Marine.
It's not my place to comment on what is aggressive and what is not. My advice is you better go with good valve springs and make sure the keeper does not move in the valve groove up and down.
Chris
As I have stated time and time again the hyd roller is wonderful for making power in pushrod engines under 6K rpm. It is a nightmare for making power above or for extended runs over 4K rpm. If you don't believe me as Mercury Marine.
It's not my place to comment on what is aggressive and what is not. My advice is you better go with good valve springs and make sure the keeper does not move in the valve groove up and down.
Chris
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Originally Posted by JCMGTO
What are you considering an aggressive cam profile? Exceeding what specs? Deciding on a cam right now and just wondering. Looking at XE-R 224/230 581/588 114LSA.
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Originally Posted by Cstraub
Yes, change the springs. The valve spring is the most critcal part in an engine. That $6 part or $30 part can destroy an engine. The hyd roller is a valve spring nightmare due to the fact it is heavy as hell and you are limited to how much seat pressure you can apply to it to control its inertia before you overcome and collapse the hyd valving.
As I have stated time and time again the hyd roller is wonderful for making power in pushrod engines under 6K rpm. It is a nightmare for making power above or for extended runs over 4K rpm. If you don't believe me as Mercury Marine.
It's not my place to comment on what is aggressive and what is not. My advice is you better go with good valve springs and make sure the keeper does not move in the valve groove up and down.
Chris
As I have stated time and time again the hyd roller is wonderful for making power in pushrod engines under 6K rpm. It is a nightmare for making power above or for extended runs over 4K rpm. If you don't believe me as Mercury Marine.
It's not my place to comment on what is aggressive and what is not. My advice is you better go with good valve springs and make sure the keeper does not move in the valve groove up and down.
Chris
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Let me put this in simple terms:
aggressive lobe + heavy hyd roller lifter= very hard on valve spring life.
Valve spring gets weak + rpm = valve bouncing on seat
bouncing valve + continued running = cup valve and beaten seat possible cracking.
So as I said, if you don't monitor the seat pressure of the valve spring then you will beat the SEATS out of the head.
Chris
aggressive lobe + heavy hyd roller lifter= very hard on valve spring life.
Valve spring gets weak + rpm = valve bouncing on seat
bouncing valve + continued running = cup valve and beaten seat possible cracking.
So as I said, if you don't monitor the seat pressure of the valve spring then you will beat the SEATS out of the head.
Chris
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Originally Posted by Cstraub
Let me put this in simple terms:
aggressive lobe + heavy hyd roller lifter= very hard on valve spring life.
Valve spring gets weak + rpm = valve bouncing on seat
bouncing valve + continued running = cup valve and beaten seat possible cracking.
So as I said, if you don't monitor the seat pressure of the valve spring then you will beat the SEATS out of the head.
Chris
aggressive lobe + heavy hyd roller lifter= very hard on valve spring life.
Valve spring gets weak + rpm = valve bouncing on seat
bouncing valve + continued running = cup valve and beaten seat possible cracking.
So as I said, if you don't monitor the seat pressure of the valve spring then you will beat the SEATS out of the head.
Chris
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Originally Posted by Cstraub
No. In a perfect world they are not harder on seats, but the world is not perfect. If you go aggressive just monitor the SPRING pressure. I have seen Sportsman 2 heads that were hyd cam engines where the seats are beat all to hell do to lack of seat pressure.
Chris
Chris