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How much lift can my stock heads handle?

6K views 19 replies 8 participants last post by  Alwhite00 
#1 ·
1970 400 Small block - What's the max lift they can handle?

Thx.

LK
 
#2 ·
are you talking retainer to valve seal clearance here?
Piston to valve with stock pistons? Valve size comes into play too
Something else?
 
#4 ·
I don't mind a spring swap, I really don't want to pull the heads if I don't need to. I want to put a roller in it and was just curious on the max I could push the valves. Not going with anything radical for a cam, Maybe a performer.

LK
 
#11 ·
What throws everyone off is the 70 400ci...everyone figures "stock".

As for the flat tops... on what rod and how far in the hole ??

Stock 400 rods, No idea how far in the hole - I built this motor 15 years ago for a street rod, Never fired it and sold the rod & the guy did not want the motor in the deal, Sat on an engine stand for 10 years and I eventually put it in my chevelle. I know it's not some high dollar motor but I love the torque it has, Just want to change it up a little. I believe the paperwork said it was right around 9.5:1 CR with the TRW forged slugs.

LK
 
#12 ·
I want to put a roller in it
Why? Stock 400 heads don't flow enough to make much power with a flat tappet cam--you'd be better off to take the money a roller would cost and buy a set of heads; it'll make more power with less cam. Then, if you still think you need a roller, you'll be able to make even more power!
 
#16 ·
Got a source for the heads?
A set of stock Vortec heads will make far more power than what came on a 400, or damn near any stock production head. New they are about $600, but you need a Vortec style manifold to do it right.

A set of Patriot aluminum heads is $795--some people will moan about the imported stuff being junk, but I've used Patriots and Pro Comps, and for the money they aren't bad. You'll spend at least that much on a roller cam and kit, and the heads will make far more power than a roller with your stock heads.
 
#17 ·
A set of stock Vortec heads will make far more power than what came on a 400, or damn near any stock production head. New they are about $600, but you need a Vortec style manifold to do it right.
QUOTE]


I would love to do that but the chambers are too small, I'm already at 9.5:1 CR

LK
 
#18 ·
With aluminum you could easily run 10.5:1 compression on the street. I had a SB 400 in high school, great engine. Mine had big valve 186 heads and those really woke it up, kept snapping motor mounts.
 
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