vortec head modifcations??
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From: Catlettsburg, Ky
vortec head modifcations?? I recently aquired a set of '98 model vortec heads (062's). I've got a cam sitting on the shelf that is going with my motor.
dur. @.050" is 212/218 and valve lift on a 1.6:1 rocker is .523/.528 and is ground on a 112LSA... it is a comp 501 hyd. roller.
I've also determined that a set of comp 918 spring will be used for their proven performance, and the fact that I do not need to open the spring seats up any.
I have a a 5/8" counter bore tool with an 11/32 pilot to cut the height of the guides down. is it necessary to cut down the diameter of the valve guide itself? I was under the impression that this only needed to be done if a double valvespring set was used.
do I need to do anything other than cut the guides down .080 to .100", and open the pushrod holes up to 1/2" while using a 1.6 rocker?
thanks, rob
dur. @.050" is 212/218 and valve lift on a 1.6:1 rocker is .523/.528 and is ground on a 112LSA... it is a comp 501 hyd. roller.
I've also determined that a set of comp 918 spring will be used for their proven performance, and the fact that I do not need to open the spring seats up any.
I have a a 5/8" counter bore tool with an 11/32 pilot to cut the height of the guides down. is it necessary to cut down the diameter of the valve guide itself? I was under the impression that this only needed to be done if a double valvespring set was used.
do I need to do anything other than cut the guides down .080 to .100", and open the pushrod holes up to 1/2" while using a 1.6 rocker?
thanks, rob
you wont have to cut the diam. of valve guide unless dual springs, as for the 1/2 holes make sure you run a self aligning rocker arm or you can have screw in rocker studs put in and run guide plates
Thread Starter
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From: Catlettsburg, Ky
Originally Posted by My01SSCamaro
you wont have to cut the diam. of valve guide unless dual springs, as for the 1/2 holes make sure you run a self aligning rocker arm or you can have screw in rocker studs put in and run guide plates
I wonder how complicated it is to remove the factory press-fit rocker studs? see.. all the machining, I can do myself, and if needed I COULD drill and tap the stud holes for screw-in studs, but if they are not absolutely needed, then I don't intend on doing it.
this motor is going in to a 4wd truck (the one in my sig) so it's not going to see much over 5500rpm anyway. I don't think the cam or the 1 5/8" headers will let it breath much past that anyway..
I contemplated the guide-plate/standard NON-S.A. rocker idea, but the price of the new studs, plus guides was not really cost effective when I could buy the very same rocker only for a S.A. application for roughly 40 to 60 bucks more--- I went through this on my car, and it already has screw-in studs factory.
the information you gave me really makes me happy, now all I have to do is cut the height down, drill the pushrod holes, get a valve job done, and buy springs. hell, I do have a set of stock rockers laying around somewhere that I could put on it for the time being, and then switch to 1.6:1 down the road (I think the 1.6:1's help torque out a little bit anyway due to more valve lift with a similar duration.)
thanks, rob
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From: Champaign IL
I tell you a trick I learned from an old timer that I know. He cuts them off. You can just stick the head in the mill, and mill the stud off, mill 3/8" off of the stud boss to compensate for the "nut"/hex-head and guideplate.
After that, the remaining part of the stud can be pressed out throught the bottom into the intake ports and water jackets. I have done this before, its quite simple. I did it to my Iron L98 heads. Works great, 10x easier than trying to pull them out as some try to do.
After that, the remaining part of the stud can be pressed out throught the bottom into the intake ports and water jackets. I have done this before, its quite simple. I did it to my Iron L98 heads. Works great, 10x easier than trying to pull them out as some try to do.
^^^never heard that trick before, but it sounds like a good idea! I would definitely upgrade to screw in studs for reassurance since you're upping the lift w/1.6's....may not be totally necessary but it's "cheap" insurance against a stud pulling out.
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From: Champaign IL
after they are cut off, (I cut mine with a die grinder, then had my machinest mill the bosses) YOU MUST mill the bosses before pressing them out! Otherwise the pieces in the intake port hang up. They end up being a c*nt hair too long. Soooo, make sure you mill them after hacking them off before pressing them out. Good luck, and IT DOES WORK! By far the easiest way to do it. 
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You need to reduce the diameter of the valve guide boss down close to the head if you use small springs with an inner flat wire damper. Or take the damper out of the spring. If not they will bind.
The pushrod holes should already be 1/2" since they came with factory SA rockers.
And I would not cut the studs off on an older head (if someone reads this while doing a search), most center bolt heads have studs that go through to the intake port but most, if not all old heads don't.
The pushrod holes should already be 1/2" since they came with factory SA rockers.
And I would not cut the studs off on an older head (if someone reads this while doing a search), most center bolt heads have studs that go through to the intake port but most, if not all old heads don't.
"you wont have to cut the diam. of valve guide unless dual springs"
^^^This is wrong stock diameter springs will not work properly with stock diameter guide bosses and the dampner will break all to pieces during the binding sure to occur. 918's will clear but have a taller spring height 1.8 instead of 1.70 for most SBC springs.
After having the guides milled for retainer clearance I would:
>I would just put a standard diameter type spring on the heads competition products,Howards as well as other companies have stock height and diameter springs that handle .560-.600 lift. The cam you are specing really isn't a big cam at all.
>.comp cams sells a tool that will take the diameter of the guide boss down... while you are taking the guide boss height down for retainer clearance. It will also open the pockets up for double springs if you want that option.
Also stuff in this list to clear up misinformation in thread.
>918's don't have an inner wire they are behives
>I wouldn't pull the inner dampner on a single VS It is there to reduce harmonics which could and most likely will break the VS.
Pulling studs by stacking and using and a impact doesn't take long ... doing it manually will take a while though.
^^^This is wrong stock diameter springs will not work properly with stock diameter guide bosses and the dampner will break all to pieces during the binding sure to occur. 918's will clear but have a taller spring height 1.8 instead of 1.70 for most SBC springs.
After having the guides milled for retainer clearance I would:
>I would just put a standard diameter type spring on the heads competition products,Howards as well as other companies have stock height and diameter springs that handle .560-.600 lift. The cam you are specing really isn't a big cam at all.
>.comp cams sells a tool that will take the diameter of the guide boss down... while you are taking the guide boss height down for retainer clearance. It will also open the pockets up for double springs if you want that option.
Also stuff in this list to clear up misinformation in thread.
>918's don't have an inner wire they are behives
>I wouldn't pull the inner dampner on a single VS It is there to reduce harmonics which could and most likely will break the VS.
Pulling studs by stacking and using and a impact doesn't take long ... doing it manually will take a while though.
On The Tree
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Sorry, dont mean to hi jack thread, but I was wondering if there would be a substantial gain in getting my set of iron Vortec heads ported and port matched. Someone told me that there wouldn't be much of a difference. If I it is worth it, can anyone suggest someone to send them to?
thanks.
thanks.
The Vortec heads respond well to a mild bowl blend and quality valvejob.
There is no need to go "hog" wild with the port work.
I have been very happy with the few motors I have used them on.
One engine is a stock 350 2-bolt shortblock with a HOT cam and a
150 shot of NOS. The heads got a very quick bowl blend and LT4 springs.
This setup went 11.15 at 120 in a 1938 Ford pickup!
Not to shabby for an "on the cheap" build up!
There is no need to go "hog" wild with the port work.
I have been very happy with the few motors I have used them on.
One engine is a stock 350 2-bolt shortblock with a HOT cam and a
150 shot of NOS. The heads got a very quick bowl blend and LT4 springs.
This setup went 11.15 at 120 in a 1938 Ford pickup!
Not to shabby for an "on the cheap" build up!
Thread Starter
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Joined: Feb 2006
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From: Catlettsburg, Ky
wow... I forgot about this thread until now!
so basically, my comp 501 on 1.6's with 918's and beehive retainers will be just fine if I mill the guides down .100"?
and screw-in studs are not mandatory, but are like playing russian roulette with my engine without them, correct?
so basically, my comp 501 on 1.6's with 918's and beehive retainers will be just fine if I mill the guides down .100"?
and screw-in studs are not mandatory, but are like playing russian roulette with my engine without them, correct?
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From: Champaign IL
Originally Posted by 8a8mfh
And I would not cut the studs off on an older head (if someone reads this while doing a search), most center bolt heads have studs that go through to the intake port but most, if not all old heads don't.
Double humps, before aftermarket heads were available. I have extremely bad luck followed by amazing luck 10 secs to late, most of the time. I should have been killed at least 3 different times but that is where that amazing luck comes in.
Originally Posted by moge11
ACTUALLY.... John, the guy I learned this from, has NEVER done this to new heads, only I have. The method is something he used when he used to modify OLDER heads, Double humps, before aftermarket heads were available.
Double humps, before aftermarket heads were available.What confused me is the big cut out or pocket in the inside of the intake port around the stud on later model heads.