How much is a 3 angle worth on a stock head
02-01-2005, 09:07 PM
#1
How much is a 3 angle worth on a stock head How much power can be expected out of a stock 853 or 241 head if I had them 3 angled when I refresh them. I just got a set of LS6 valve (thanks Louis) and was thinking about just lapping them if it''s not really worth it to spend the money now. I'm planning on heads in the future, but the car has 102,000 on it now and I need to change the lifters out for a cam swap.
02-02-2005, 07:43 AM
#3
every stock chevy V8 head since the late 80s/early 90s has had a 3 angle valve job.
its not a performance upgrade. it used to be in the 70s, but its FACTORY today. heck, alot of engines come stock with 5 angle jobs.
if you dont get atleast a 3 angle, its WORSE then factory.
its not a performance upgrade. it used to be in the 70s, but its FACTORY today. heck, alot of engines come stock with 5 angle jobs.
if you dont get atleast a 3 angle, its WORSE then factory.
02-02-2005, 10:57 AM
#5
you heard wrong.
what each "angle" is, is a additional cut in the head... ideally you want a perfect curve into the valve seat. but we can only cut straight angles accurately (not true anymore, but go with me on this)
testing has shown its not benificial to go any higher then 7 angles, except in extreme cases like F1 cars and such.... but all a valve job is, is cutting the head for the valve to seat, and then cutting the head leading to the seat so it flows into it.
it used to be cost prohibitive, thats why single angle jobs were the norm... but with cheaper modern machining, 3 and even 5 angle jobs are done all the time. its better for street driving, daily driving, racing and even your lawnmower.
this isnt a pic from a LS1, but it'll give you the idea... notice that all thoes angles make a nice curve into the seat.
my edited pic next to it shows a single angle... notice the much nicer and better flowing curve of the multiangle valve job.. no sharp edge.
so yea, if all your machinest can do is a 3 angle, thats perfectly acceptable... but if hes able to do a 5 or even a 7, thats a better valvejob.
what each "angle" is, is a additional cut in the head... ideally you want a perfect curve into the valve seat. but we can only cut straight angles accurately (not true anymore, but go with me on this)
testing has shown its not benificial to go any higher then 7 angles, except in extreme cases like F1 cars and such.... but all a valve job is, is cutting the head for the valve to seat, and then cutting the head leading to the seat so it flows into it.
it used to be cost prohibitive, thats why single angle jobs were the norm... but with cheaper modern machining, 3 and even 5 angle jobs are done all the time. its better for street driving, daily driving, racing and even your lawnmower.
this isnt a pic from a LS1, but it'll give you the idea... notice that all thoes angles make a nice curve into the seat.
my edited pic next to it shows a single angle... notice the much nicer and better flowing curve of the multiangle valve job.. no sharp edge.
so yea, if all your machinest can do is a 3 angle, thats perfectly acceptable... but if hes able to do a 5 or even a 7, thats a better valvejob.
02-02-2005, 11:07 AM
#6
10 Second Club
so for a daily driven vehicle a 5 r 7 will be ok. the reason i am asking is i am rebuilding my motor in my truck to pull my race car to and from the track. or would just a three angle be all i need, all i have is a 302 so i need all the umph i can get out of it, i will be pulling at times up steep inclines and for one haul it will be a 1000 mile round trip.
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02-02-2005, 01:42 PM
#8
Originally Posted by Cal
I would just lap them and put it back together if the seats are in good condition.
but if it needs the valvework, get a 3angle valvejob... if your machinest cant/wont do it, you need to find another machinest. its been the norm for years.
02-02-2005, 06:56 PM
#9
Ok. I was thinking (or read somewhere....rumores) that the 5 or 7 would wear out faster because of less material on the surface for the valve to sit on. I'm still thinking that if the heads are ok I'm just going to lap them, but if there is a chance for a good improvement in airflow (ie 15+cfm) to support the cost of the 5 or 7 angle, I might wait, save up and get that done.
