Another option for a better breathing head?

chessterd5

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pmuller9":2rojir89 said:
The biggest problem with the LS3 heads that we are looking at is they position the pushrods halfway outside of the 300 six pushrod cover.
This would require a special side cover to enclose the pushrods all the way up to the head.
Yes sir, I agree that is a problem but, it's fixable. It is not however the two major problems that I mentioned before.
 

pmuller9

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Tbone3366":393fmw2l said:
an avg quality PS6.7 head flows 440 cfm at .500 120 @.150
Impressive flow numbers.
The 300 six wouldn't need crazy valve lift to make big power which is good on such a long camshaft.

What flow bench did you use?
 

guhfluh

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pmuller9":c6fuvqd4 said:
The biggest problem with the LS3 heads that we are looking at is they position the pushrods halfway outside of the 300 six pushrod cover.
This would require a special side cover to enclose the pushrods all the way up to the head.
This is the one thing I can't picture sealing up on the conversion. I've read the talk about using plates to bolt to the side of the block and bottom of the cylinder head and grinding the side of the deck out above the lifter bore for pushrod clearance. But, what I can't figure out is how to seal from the pushrod side cover up the side of the block to the deck. It's a rough cast surface there. It's not pressurized, so I'm wondering if the plan was to just use a build up RTV type sealer on the ends like a China wall or actually machine the block and plate to mate better together, or ?

I don't see the 6.7L PSD head as viable, unless you're building an extreme race engine, tractor puller, etc.
 

pmuller9

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guhfluh
I'm not real happy with the pushrod position either.
What we really need is a head that is a retrofit head requiring NO block modifications.
 

guhfluh

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pmuller9":3etpbsze said:
guhfluh
I'm not real happy with the pushrod position either.
What we really need is a head that is a retrofit head requiring NO block modifications.
I'm not saying it's a huge problem, I just thought you had a better idea of how Gramps and others had planned on sealing it or done it in the past. I do agree a direct bolt on replacement would be a dream come true.
 

CNC-Dude

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That's a big issue for guys using a V-style hybrid head. Trying to seal up that huge gap that is left by the cylinder head overhang. There is not really anyway to make that look attractive unfortunately....
 

Firepower354

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Doesn't the 300 lifter cover nearly meet the deck?
An aluminum block/wedge shouldn't be a big deal.
The pre-gen 5 ls heads have a smaller headbolt between each intake port at the manifold flange, to draw the cover up.
 

Firepower354

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Yes
The upper two corners are rounded and there is a very small valley making sealing less than ideal at those two spots but a good sealant should handle it.

Aftermarket LS heads also have 5 bolt holes that can be used to pull the cover up tight.
https://www.dropbox.com/s/9yuo17x9ozhwn ... .JPG?raw=1

Those are the ones I meant.
The 4 studs under the intakes(as well as the outer 4), on the aftermarket 6-bolt ones aren't likely relevant.

The newest DI heads eliminated all but the end ones, of the 5, but should still hold a cover.
They reversed the valve layout too, but with a custom cam, intake, header, not an issue, I'd think.
And, with LS3 stuff at 340cfm@.500 that should suffice.

Thoughts on how the short pivot length on the LS rockers, and relatively high lift, works as well as it does? tip travel?

And, thoughts on shifting the bore centerlines in the block, to make "3 groups of 2", more closely matching the head segments?
A .040 over, split .005/.035 is still only taking .020 from the thrust side. Less if the bores are also shifted to the driver side.
All pending sonic check, of course.
 

pmuller9

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Thoughts on how the short pivot length on the LS rockers, and relatively high lift, works as well as it does? tip travel?

And, thoughts on shifting the bore centerlines in the block, to make "3 groups of 2", more closely matching the head segments?
A .040 over, split .005/.035 is still only taking .020 from the thrust side. Less if the bores are also shifted to the driver side.
All pending sonic check, of course.
The LS roller rockers are frequently used with .600"+ valve lift. I don't see a problem.

If you are doing a 3 segment head, just let each cylinder pair straddle two bores evenly.
You may have to offset the head bolt holes a little.
 

CNC-Dude

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Something else that should be mentioned regarding the "wedge" at the top of the side cover. It actually is a whole new side cover that needs to be fabricated. This has also been discovered on the Chevy inlines as well when making a hybrid head. Due to the V-style valve spacing from the pushrods, the pushrods are actually moved beyond the deck to literally be on the outside of the engine at or near the deck. So to now be able to fully enclose the lifter area to the underside of the head, a "wedge shaped" side cover will need to be made. Not just a "wedge shaped" piece to fill in the gap at the block/ head mating surface. So it will be a little more involved than people may be thinking, but well within many of the folks skill set to accomplish. Notching the outside of the block along the deck surface may also be needed to have adequate pushrod clearance to prevent binding or rubbing the block as the pushrods move throughout their travel.
 
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Firepower354

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Something else that should be mentioned regarding the "wedge" at the top of the side cover. It actually is a whole new side cover that needs to be fabricated. This has also been discovered on the Chevy inlines as well when making a hybrid head. Due to the V-style valve spacing from the pushrods, the pushrods are actually moved beyond the deck to literally be on the outside of the engine at or near the deck. So to now be able to fully enclose the lifter area to the underside of the head, a "wedge shaped" side cover will need to be made. Not just a "wedge shaped" piece to fill in the gap at the block/ head mating surface. So it will be a little more involved than people may be thinking, but well within many of the folks skill set to accomplish. Notching the outside of the block along the deck surface may also be needed to have adequate pushrod clearance to prevent binding or rubbing the block as the pushrods move throughout their travel.
Of course. I meant "wedge" as in tapering from the bottom of the lifter cavity.

It's not gravel driveway type work, but well below the level of the Sizemore head, or some of the cool same-era stuff in the warehouse when I was at Batten. SBC head converted to U-flow with a HUGE intake port brazed in on the wrong side of the head. 4cyl sprint stuff, I think. etc
 

CNC-Dude

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That wasn't directed towards anyone in particular. It's just that with the hybrid head discussions that have gone on here recently, very little subject matter has been discussed past making the cylinder head. While a few of us do know what all else goes into finishing out a hybrid head project, many do not. Thanks Paul for taking the time to post a picture of the block mods required for the pushrod relocation phase of a hybrid head install. Now, many that aren't familiar with what was meant by the "wedge" modification necessary, hopefully the picture posted will start to fill in the blanks for those that couldn't quite picture was is needed.
 

Firepower354

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Firepower, What kind of engine do those covers fit? 292 XFLO?
Chevy, but the shorter 250.
 
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