When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
To accept that lift (.480) might be possible with stock heads, valves, seals, springs and retainers but that's about the limit.
Adding Comps 26918 or 26915 springs and retainers, that will drop in over the factory seals, can be used to gain added retainer to seal clearance. There are other springs and spring packages out there that will do the job however my experience lies with the Comp parts.
This is not to mention the need for screw-in or pinned rocker studs and that the OEM or similar self guiding rocker arms are required.
[QUOTE=skinny z;6108898]To accept that lift (.480) might be possible with stock heads, valves, seals, springs and retainers but that's about the limit.
Adding Comps 26918 or 26915 springs and retainers, that will drop in over the factory seals, can be used to gain added retainer to seal clearance. There are other springs and spring packages out there that will do the job however my experience lies with the Comp parts.
This is not to mention the need for screw-in or pinned rocker studs and that the OEM or similar self guiding rocker arms are
http://www.competitionproducts.com/H.../#.VZN89BtViko these qre the springs i have now.. what other components do i need to make my xm270hr comp cam work.
Last edited by happyhapka; 01-31-2017 at 10:31 PM.
To accept that lift (.480) might be possible with stock heads, valves, seals, springs and retainers but that's about the limit.
Adding Comps 26918 or 26915 springs and retainers, that will drop in over the factory seals, can be used to gain added retainer to seal clearance. There are other springs and spring packages out there that will do the job however my experience lies with the Comp parts.
This is not to mention the need for screw-in or pinned rocker studs and that the OEM or similar self guiding rocker arms are required.
or do you have part numbers i can use to buy what i need would be a super big help. Thanks.
Last edited by happyhapka; 01-31-2017 at 11:11 PM.
Piston to valve clearance should not be an issue but there more clearance checks that need to be done.
If lift is too great, the bottom of the spring retainer can hit the top of the valve seal.
A stock stamped steel rocker may not have a slot long enough to allow enough rocker travel. Roller rockers solve this problem unless you decide to go really inexpensive with long slot rockers.
With increased valve lift, you should have springs designed for the camshaft. They need to provide enough seat pressure to keep the valve from bouncing off the seat (valve float) and need to have enough space between the coils when at max lift so that the springs don't bind. Higher spring pressure also have a tendency of pulling the pressed in rocker studs out of the heads. That's why it was mentioned to get the rocker studs pinned or to use some screw in studs.
Piston to valve clearance should not be an issue but there more clearance checks that need to be done.
If lift is too great, the bottom of the spring retainer can hit the top of the valve seal.
A stock stamped steel rocker may not have a slot long enough to allow enough rocker travel. Roller rockers solve this problem unless you decide to go really inexpensive with long slot rockers.
With increased valve lift, you should have springs designed for the camshaft. They need to provide enough seat pressure to keep the valve from bouncing off the seat (valve float) and need to have enough space between the coils when at max lift so that the springs don't bind. Higher spring pressure also have a tendency of pulling the pressed in rocker studs out of the heads. That's why it was mentioned to get the rocker studs pinned or to use some screw in studs.
I wouldn't spend that for a set of roller tipped rocker arms.
Screw in studs will require a machine shop to pull the existing studs and drill/tap your heads. It is extra insurance.
Im running stock heads with ls6 valve springs, some comp retainers, and a set of scorpion roller rockers with the lt4 hotcam. Im still running the stock press in studs.
I'm not sure if the Howard's springs has a large enough inside diameter to fit over the stock seals. The sheet you posted lists them at .860". The Comp 26918 and 26915 springs I've used (and continue to use) have an .885" inside diameter. I'm not sure if the extra .025" is a deal breaker or not.
I'll give a little background on my first Vortec build.
Bone stock (right over the counter from GM) and installed on a new 350 short block. Cam was a hydraulic flat tappet (Clevite) with .454" lift and 218 @ .050". I ran this with the pressed in studs and stock springs. That was until a missed shift put a couple of valves into the pistons.
Next step was the full treatment for the Vortecs:
Comp 26918 springs.
I used retainers that are on the spring spec sheet. 774-16.
Had the heads machined for screw-in studs and also fitted with guide plates.
The pushrod holes were enlarged to ensure that there was no binding due to the guide plates or the added lift for the 1.6 ratio rocker arms.
I also stepped up to a hydraulic roller with .570" lift and 224 @ 050".
Now here's the thing that needs attention. These springs drop over the factory valve stem seals however this precludes the use of a spring locator. You have to rely on the outside diameter of the spring pocket to keep things together. Plenty have done it. In my case, I pulled the original seals, cut the guides down to fit a traditional Viton seal and prior to installing the seals, I used Comps 4705-16 spring locator. Then it was a matter of making sure the spring was installed close to the proper height using a variety of shims and off-set valve locks.
Keep in mind, as I stated earlier, it's not a 100% necessity to go that far.
If it's possible, see if the Howard's springs you have will fit over the factory seals and register in the spring pocket with a good fit.
The screw-in studs you posted are as good as any in as far as I can tell. I see that they have no base which excludes using guide plates. That's all good as I see you've selected a self-aligning rocker. I went the guide plate route but it's not necessary.
You may be able to use the Howard's springs and retainers over the factory valve guide seals, add the screw-in studs and call it a day.
The specs on your Howard's springs are pretty weak though.
90 @ 1.70" with a 305 lb/in spring rate.
The 26915's are 105 @ 1.80 with a 313 spring rate.
The 26918's are 125 @ 1.80" and 372.
Notice the difference in the installed height.
The 26918 will easily handle a hydraulic roller.
I would use nothing less than the 26915.
I can't say for sure if the Howard's spring is up to the job.
Do you already have the cam?
I will be buying the cam soon, a member on here told me to go with the howards springs. And mentiond to take out the inner dampner and install them like that... the cam is XM270HR from comp cam. I dont have it yet but will be getting it very soon. Ill get the retainers you showed me and if need be the springs... i figured the springs would be good enough as the cam has a .493 .503 lift and max it can handle are .520.
ill get the comp rollers i posted, screw in studs, those retainers, im using the stock pushrods, not sure if those rockers come with retainers but ill still get the ones you mentiond.. i want to do it right.
and its a roller engine.. came out of a 98 suburban.
definitely roller.. do i need both the shim kit and the seals? I think the roller rockers i posted before come with the seals. Or do i need these.
I would replace the seals if these are a better value go for it. The shim kit is not 100% required but it is nice to make sure they are all the same installed height.
I would replace the seals if these are a better value go for it. The shim kit is not 100% required but it is nice to make sure they are all the same installed height.
ok thanks ill get the shims not sure on the valve seals because looking at the rollers im getting, it looks like it comes with the seals..
Sounds like i may need to get conformation on the springs. And if need ill get the other ones thats on this thread.. they seem stronger too for extra security.
Do you have the heads? It's an easy job (providing you have the tools) to pull a valve spring and measure the outside diameter of the valve stem seal. You haven't stated the history of the heads. It may be that the seals have already been done.
That said, as I mentioned earlier, I'm not certain that the Howard's springs are up to the job. Comps recommendations are the 986 or the 26986.
986: 132 @ 1.750, 293 @ 1.250, 322 lb/in
26986: 109 @ 1.800, 284 @ 1.175, 280 lb/in
Howards: 90 @ 1.700, 230 @ 1.250, 305 lb/in
You can't use either of the Comp springs as the outside diameter is larger than the spring pocket in the Vortecs.
The substitute that's used, with great success, are the springs posted earlier. Comp 26915 or 26918.
I've never used the Alex parts posted earlier so I can't comment on them other than to say the specs look OK. It would be nice to know who's springs he uses. He advertises them as having 130 lbs of seat pressure. Again, that more than the Howard's springs.
As for your roller tip rockers, I don't think that they come with seals. Rocker ***** and lock nuts yes. But no seals. (It would be odd if they did).
You will have to check the valve train geometry with the new parts installed. Do a search here at thirdgen and there are plenty of posts. Some good. Some...not so much.
Lengthening or shortening the pushrod affects the geometry. Stated a different way, changing any of the valve train components may require the use of a different length pushrod to get the rocker tip motion and position where it needs to be.
Originally Posted by happyhapka
Ok just bought the alexis kit with the shim kit and seals.
Not sure if the seals supplied in the Alex kit will fit over the OEM guide or if the guides will have to be cut to accept the new seals. The use of valve spring shims almost always dictates that the seals be removed. You have to measure (with the spring removed) the distance between the head the bottom of the new retainer. That value will determine whether or not you add shims, offset locks or both.
Originally Posted by happyhapka
What are guide plates and what are they for? Should i get them?
Guide plates are a performance improvement for keeping the pushrod where it belongs. Older versions of OEM heads used the pushrod holes in the head as a guide. High performance versions use a guide plate fastened under the rocker stud instead of the hole in the head. Vortec used a rocker arm that has guiding "rails" built in. Any cylinder head will use one of the three. But only one. Using two may introduce a binding condition in the pushrod travel. If you've selected a "self-guiding" rocker arm, then you should be good to go. No guide plates should be used.
You will have to check to see if there is any binding with the pushrod and the head with the addition of the new cam.
if you click on the link of the HR alex kit lokk under the description. I states that it all is machined and cut specifically for the vortec, if you would like to check that out and let me k ow that would be great. But i sounded like and i took it as "its a drop in and go, no machineing"..
Yes, Alex does say that all of the parts drop in with out machining.
It doesn't provide valve guide seals though.
But again, Alex says that the springs will fit over the factory guides so that settles that.
I have a good friend that litterally gave me a fully dressed vortec 350 out of a 98 suburban with 68,000 miles. Nothing was wrong with the engine, the guy pulled it to drop a 454 in it and said here, get rid of your weak 305, ( my 86 130,000 mile lb9 305 put down 170hp and 250 tq on the dyno) so hes been busting my ***** about how weak it is. But regardless a free healthy vortec 350 y not, i would have been a fool to of turn it down. So im making it into a 383.
At only 68k for mileage they should be in pretty good shape. (Hopefully the engine was never overheated in it's lifetime. The Vortecs are prone to cracking).
That said, according to my engine machinist (a race shop, not a re-man shop), "The Vortec valve guides are cast iron. They last forever".
So, aside from having to remove the seals to add the valve spring shims (should that prove necessary after measuring) new seals probably aren't needed. They are however cheap insurance and it's something that's routinely done at this stage of an engine build.
A 383 you say? How did you go about making your cam selection?
I figured it was a good selection due to a couple of factors. I know the tpi intake even with the as&m runners still dont flow enough for high rpm so the cam is designed dor i believe 5200rpm wich is ok because shell run out of breath around 4500 or so. So no need for a higher rpm cam, the cam is designed for tourque but with a 224 exhaust duration i am able to tune it. And on stock vortec heads i was informed that this cam would compliment the build nicely and drivability would be great with awsome response. If im not wrong it would..
that and its a ton better than the stupid peanut cam i have in my LB9.
Last edited by happyhapka; 02-03-2017 at 03:13 PM.
01-31-2017, 08:08 PM
