Porting the heads
- Thread starter 08BIGRIG
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Sounds Good !! Just got a price for my heads port ,polish and 3 angle valve job , so said do it , but now will be 2 weeks out !! The guy is taking vacation so i couldnt have timed it any better , well i guess it gives me more time to get some money together !! LOL
jdgleason
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Just to give you a heads up, an "angle" valve job, if anything, hurts performance in a diesel. The angles are designed to help atomize fuel in a gasser. Since diesels are direct injected, those angles can actually impede airflow.
I heard that once before and always wondered if it was true. Thanks for clarifying.
Tree Trimmer
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but depending on what angles you use, it takes the valve from having a, grabbing a random number bear with me, 2mm contact surface with the head, to having a 1mm contact surface, thus the same spring rate will hold the valve better, as the spring pressure is not spread out as much.
i probably murdered that explanation, so if someone can clarify that a tad for me.....
i probably murdered that explanation, so if someone can clarify that a tad for me.....
^^^ Great to Know Thanks JD , & Tree Trimmer , I will look into this more as also this may lower the price on labor a hair ? So Just a straight up port and polish is what i want done to the heads ? thanks for the gudiance , i have a little time so would like it done right !!! and can always count on getting the info i need on here !! Thanks Guys
jdgleason
Active member
We radius ours, but I understand what you're getting at. Either way, since the primary goal is airflow, the smoother surface, the better.
jdgleason
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Depending on your machinist, the cost is probably minimal and since you're going to port them, I say don't cut corners. If all he can do is a 3 angle, leave them be.
SSpeeDEMONSS
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Wouldn't there be more area of the valve that was under pressure from the intake air therefore the same spring wouldn't hold the valve shut as well? Though im sure either way the differences in area contacting one way or another wouldn't make a large enough difference on the spring.
Garrett
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Tree Trimmer
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the more surface contact the valve has, the less it actually seals, as the pressure from the spring is spread out more, rather than focused on a smaller area.
then when you do a three angle, it acutally beats itself into the head just a scootch, and creates a "custom seat" for itself.
take a 50lb feed sack and put it in your yard on a piece of plywood, or on the side of a piece of 2x4. same 50lbs but the dent in your yard tells you its pushing harder on the 2x4.
thats how it was explained to me.
this conversation i had with my guy, was more about sealing the valve in a high back pressure or boost scenario, than airflow characteristics.
then when you do a three angle, it acutally beats itself into the head just a scootch, and creates a "custom seat" for itself.
take a 50lb feed sack and put it in your yard on a piece of plywood, or on the side of a piece of 2x4. same 50lbs but the dent in your yard tells you its pushing harder on the 2x4.
thats how it was explained to me.
this conversation i had with my guy, was more about sealing the valve in a high back pressure or boost scenario, than airflow characteristics.
My analogy didn't make sense to me but I was trying to understand what you were saying....this last one does....so thanks, I appreciate it.
