How much lift can my stock heads handle? - Chevelle Tech
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post #1 of 20 (permalink) Old Dec 19th, 09, 9:10 PM Thread Starter
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How much lift can my stock heads handle?

1970 400 Small block - What's the max lift they can handle?

Thx.

LK
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post #2 of 20 (permalink) Old Dec 20th, 09, 1:41 AM
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Re: How much lift can my stock heads handle?

are you talking retainer to valve seal clearance here?
Piston to valve with stock pistons? Valve size comes into play too
Something else?

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post #3 of 20 (permalink) Old Dec 20th, 09, 7:48 AM
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Re: How much lift can my stock heads handle?

With a spring swap I was running a 280H CompCam (230 @ .050 and .486 I/E lift)

I would't trust 1970 springs with a new "bigger" cam

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Last edited by DOUG G; Dec 20th, 09 at 3:25 PM.
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post #4 of 20 (permalink) Old Dec 20th, 09, 8:07 AM Thread Starter
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Re: How much lift can my stock heads handle?

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
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post #5 of 20 (permalink) Old Dec 20th, 09, 3:19 PM
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Re: How much lift can my stock heads handle?

Quote:
Originally Posted by Alwhite00 View Post
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
since when do you have to pull the heads to change the springs?
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post #6 of 20 (permalink) Old Dec 20th, 09, 3:26 PM
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Re: How much lift can my stock heads handle?

Quote:
Originally Posted by curley8788 View Post
since when do you have to pull the heads to change the springs?
X 2 (unless machining is involved)

68 Camaro~406ci
RedЯum <-Pics
11.304 @ 119.05 ~1320' NEW (3/19/11)
http://youtu.be/48OfD_C4JWU <-11.36 Vid.
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post #7 of 20 (permalink) Old Dec 20th, 09, 3:53 PM
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Re: How much lift can my stock heads handle?

Wouldn't the bigger issue here be piston to valve clearance, and not the which heads you have? And of course the valve springs.

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post #8 of 20 (permalink) Old Dec 20th, 09, 5:45 PM Thread Starter
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Re: How much lift can my stock heads handle?

Quote:
Originally Posted by curley8788 View Post
since when do you have to pull the heads to change the springs?

That's why I said I don't mind a spring swap but did not want to pull the heads. (machining)
I am running TRW flat tops with the 4 valve reliefs and stock size valves.

LK
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post #9 of 20 (permalink) Old Dec 20th, 09, 7:06 PM
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Re: How much lift can my stock heads handle?

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 ??

68 Camaro~406ci
RedЯum <-Pics
11.304 @ 119.05 ~1320' NEW (3/19/11)
http://youtu.be/48OfD_C4JWU <-11.36 Vid.
Some days all you can do is just smile
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post #10 of 20 (permalink) Old Dec 20th, 09, 7:48 PM
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Re: How much lift can my stock heads handle?

Any other work done on the heads, get to big and the studs get funny, to much lift and you get coil bind. All sorts of minor details come into play when you change things.

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post #11 of 20 (permalink) Old Dec 20th, 09, 8:45 PM Thread Starter
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Re: How much lift can my stock heads handle?

Quote:
Originally Posted by DOUG G View Post
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
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post #12 of 20 (permalink) Old Dec 20th, 09, 11:35 PM
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Re: How much lift can my stock heads handle?

Quote:
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!
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post #13 of 20 (permalink) Old Dec 21st, 09, 7:55 AM
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Re: How much lift can my stock heads handle?

Quote:
Originally Posted by bowtie0069 View Post
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!
I agree with the heads holding you back. I went from home ported 400 heads (13.2 @ 102) to out of the box 200cc Protopline Iron Lightnings (12.3 @ 110) and no other changes (heads did bump comp up .3 though).

68 Camaro~406ci
RedЯum <-Pics
11.304 @ 119.05 ~1320' NEW (3/19/11)
http://youtu.be/48OfD_C4JWU <-11.36 Vid.
Some days all you can do is just smile
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post #14 of 20 (permalink) Old Dec 21st, 09, 12:15 PM Thread Starter
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Re: How much lift can my stock heads handle?

Quote:
Originally Posted by DOUG G View Post
I agree with the heads holding you back. I went from home ported 400 heads (13.2 @ 102) to out of the box 200cc Protopline Iron Lightnings (12.3 @ 110) and no other changes (heads did bump comp up .3 though).
Got a source for the heads?

LK
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post #15 of 20 (permalink) Old Dec 21st, 09, 5:56 PM
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Re: How much lift can my stock heads handle?

RHS owns them Now.

http://www.racingheadservice.com/Cyl...st%20Iron.aspx

68 Camaro~406ci
RedЯum <-Pics
11.304 @ 119.05 ~1320' NEW (3/19/11)
http://youtu.be/48OfD_C4JWU <-11.36 Vid.
Some days all you can do is just smile
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