so im building a 87 roller 305, and im zero decking the block, and running 0.030 over cast flat tops.i have a set of "416"s that are stock too.the question is;how much lift can i get safely with this set up? i dont want to exceed 5000 RPMS as well.any ideas???? any cam reccomendations? its gonna be a otherwise stock 86 tpi setup

 

With stock valves and retainers you can go 0.468" (small variations from casting to casting) before the retainers starts hammering the valve seals.
I have measured a lot of these heads and I have seen as low as 0.452" before contact with a 0.150" seal.
You can swap retainers, delete the oil shields & rotators, and gain enough to get you over 0.500" lift, and that's an easy fix.

If you're going cheap then you can use the Vortec V6 retainers without the oil shields or rotators.

Stock springs usually have around 0.570" movement between a 1.70" installed height and bind. You can easily use a 0.030" shim under the springs and still get 0.500" lift safely. Be sure to use hardened shims if you use the internal spring dampers that are stock.

There is more info in my signature links about modifying stock 416 heads.

 

Cams: The LPE cam in my signature link is great for stock TPI engines and computer friendly. It's a bit pricey new, but you might find one used.

the stock cams in the 1988 5.7 TPI cars might make a good swap for you if you can find a good used one.

Also, more info in this thread:
https://www.thirdgen.org/forums/tpi/...ore-power.html

 

Since you've got the motor apart, get yourself a vernier and measure. Every valve. There will probably be some variation - find out what the lowest clearance is, and work with that.

Can always cut the guide bosses down if you need more lift, or + 50 locks and spring shims.

 

As mentioned in the first reply, it's not just about lift. There's a lot of variables to check. The bottom of the spring retainer will probably hit the top of the valve seal or guide before you run into other clearance issues.

Then there's the rockers themselves. Unless you go to a roller rocker or a long slot rocker, a stock rocker will probably hit the rocker stud before it gets to full lift.

 

That's what it's all about, checking and measuring.

You can ask online all you like about what will fit and what won't, but in the end your particular parts are what they are, and you need to look and find out what measurements you actually have. Anything could have been changed since those heads were new.

Retainer to seal, spring bind, rocker bind, pushrod length & clearance, piston-valve etc etc.

 

Hey guys, correct me if I'm wrong here but with a STOCK set of 416 heads, small valves, chocked bowls & some what restrictive ports does it really help to go over .450 lift, especially with a 5000 max RPM?

On my 081 heads(center bolt valve cover, but same head) with 1.94-1.60 valves and allot of pocket & port work, once I get them flowed I'll worry about lift, if they flow good through .500 I'll be happy.

 

You're right. Nope, there are no significant improvements in flow between 0.450" and 0.500" valve lift unless you at least have some bowl porting and a good valve-job. It's not enough difference to be worth the trouble of running the extra valve lift. However, the power gain from pocket porting and valve size upgrade (on 305 heads) is worth the trouble in time/effort, and then the extra lift up to 0.500" pays off in flow improvement.