Hi, I've been reading lots of forum for that last few years and I think I have a question that nobody asked yet! I have a set of 062 vortec heads that I what to swap in the 355 sbc.
My friend is teaching a CNC class at the local trade school and he can machine my heads for free! I'm not looking for anything crazy powerwise... I only need to satisfy my power need for a few years before I build a turbo 5.3 L33.

Heads are already magnafluxed. They will be also milled for straightness. I want to run a 0.500''-ish lift cam and not going to rev past 5800 RPM (Stock bottom 2bolt main).

0.500'' cam (Flat tappet)
PRW 1.5 self aligning rockers
Incognito studs
LS6 BeeHive spring
Lap the valves
Push rods (if the length is no longer good)

I know I can get away with some special retainer that I dont have to machine anything (w/ beehives) but I can for free.

Question!! If I simply mill down the valve guide boss to clear 0.500 lift with regular retainers, will the new valve seal fit?

Will there be enough exposed valve guide left to seat the new seals?

Sorry for my english! Frenchmen here from eastern Canada!

Thank you!

 

If you want to use conventional .550" lift stock diameter 1.26" ish high perf valve springs
EG Isky 235D or like (Howards, Summit, Elgin etc). you have to buy and use a special valve guide boss cutter machine tool. (Comp cams)
It has to match the new valve seals diameter and also cut the valve guide top shorter.
Then you need another cutter to cut the major diameter of the valve seat ID so that the damper in the stock diameter springs fits the spring seat.
Otherwise you have to remove the damper..

Why not just buy the Comp cams 787-16 special beehive size spring retainer.? and the beehive springs.
Now you are good to about 530" valve lift depending on (beehive) spring (1.80" default height) final installed height
eg 1.75" ish. No machining.

Full length valve guide height stem support vs cut down guide boss.

 

Why not just supercharge your 355 vortec engine when that time comes.?
A supercharged 355 vortec head SBC engine is 500+++ hp capable with say a Edelbrock E- Force 122 H blower or say a Torq Storm centrifical blow thru blower kit.

 

Just be aware that cutting the valve guide boss shorter ith stock length valves does increase max valve lift clearance. it also reduces the amount of valve stem SUPPORT by the shorter guide boss.
Just be aware of that.

When I cut mine I did it with the medium diameter cutter set to be ready for the medium size diameter 1.46" ish dual valve springs. (future dual spring upgrade ready)
I run the stock 1.26" diameter .550" springs /retainers on this fine.
Yiu don't need a machine shop. you can cut the guides with the cutter tool in a decent 3/8 drill.

But the Beehive spring/ comp 787-16 retainer method works great for most all hyd and moderate solid flst tappet cams and most all hyd rollers without any guide machining.
.530" range lift. Shim the beehive springs for seat and open pressure as required . leave .030" max lift coil bind height clearance.

 

If you keep within #90-115 seat and #290-320 open spring pressure with the beehive springs and 1.5 rockers and suitable hyd roller cams. you likely will have no issues with the stock GM vortec heads pressed in rocker studs.
They just don't seem to pull out like the older heads pressed in studs used to tend to do.
Thet are most likely fine as is.
Use long slot guided type rockers for high lift.
(Stock vortec rockers can be modded to lengthen the slot longer for more lift.) (rocker slot to rocker stud clearance at high lift)

 

Thank you very much for taking the time to reply.

let me answer some of your questions.

'' you have to buy and use a special valve guide boss cutter machine tool. (Comp cams)
It has to match the new valve seals diameter and also cut the valve guide top shorter.
Then you need another cutter to cut the major diameter of the valve seat ID so that the damper in the stock diameter springs fits the spring seat.
Otherwise you have to remove the damper..

I have a friend who teach CNC machining, so I could get everything done for free. So if I have the final specs of the boss (width/height) and the spring pad dimension I can get him to do it while teaching students.

''Why not just buy the Comp cams 787-16 special beehive size spring retainer.? and the beehive springs.
Now you are good to about 530" valve lift depending on (beehive) spring (1.80" default height) final installed height
eg 1.75" ish. No machining.''

I was thinking of going with the ls6 springs (cheaper than the Comp #787-16) Any reason not to?

''Full length valve guide height stem support vs cut down guide boss''

Is this a common failure point of cut down Vortec bosses?



For running a 0.500'' lift cam... I've seen no machining, ls6 spring (w/ matching retainers), 0.050'' offset keepers (w/ self aligning rockers grind down for cleareance on the retainers). But I dont like grinding away some of the ''self aligning'' part of the rockers...

Would you have the dimensions of the finish product? i.e.
1. Valve guide O.D. (for valve seal)
2. Valve guide Height from spring pdad)
3. Boss OD for clearing ls6 (dont think its needed)
4. Spring pad width


Thank you

Nick

 

Because it's only a 2 bolt main w/ 1000 miles on the drivetrain (TH-350). I've been a die hard sbc fan all my life... but the ls series is light years ahead. Thats why I'm going for aluminium block 5.3 turbo eventually

I'm not ready for a 550 hp build right now. I have 2 young kids and I dont want to spend $$$$ right now in my life lol. Soon. but not now...

 

I will be using hyd flat tappet w/ good break in oil and high zddp engine oil.

I'm still going to be using threaded studs for piece of mind.

Thank you very much for the info!! Really appreciate everything you wrote!

 

Well I'm going to go the 0.050'' offset keeper(crane #99095-1), comp retainer (787-16) route and ls6 spring for Hyd flat tappet with 0.500 lift. I like the idea of having more meat in the boss. Thanks!!

 

I have never had any issue with Machining down the Original Valve Guides...
(This was a common procedure for older OEM Iron Heads).

The ONLY time I have had an issue, is if the Valve Guide is worn...
In that situation, I remove all of the Original Valve Guide, and Install new shorter Guides for 8mm Stem Valves.

 

Thanks for the reply,

I'm going to try to salvage the oem valves, But I'm getting new guides no matter what.