Help spec'ing out a new small block

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pittsburghracer said:
Ok I said I was out on this post but I better clear a few things up. Number one those heads are already cnc ported as delivered. Number two you better get an after market block so the valves clear the cylinder walls.
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Can the block be notched ?
I had to notch my 4.375 bore 400 for my trickflows about .100 .
 
MOPARMAGA said:
Can the block be notched ?
I had to notch my 4.375 bore 400 for my trickflows about .100 .
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I believe so....what a pain. So much easier to throw nitrous at it (no I am not going to do that) :steering:

This is what is stated in their instructions.

If these heads are used on small bore engines, valve-to-bore clearance
should also be checked, and the top of the bore notched for clearance if
necessary. A minimum of .100” is recommend.
 
-Boosted- said:
I believe so....what a pain. So much easier to throw nitrous at it (no I am not going to do that) :steering:

This is what is stated in their instructions.

If these heads are used on small bore engines, valve-to-bore clearance
should also be checked, and the top of the bore notched for clearance if
necessary. A minimum of .100” is recommend.
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It's easy. I'd gladly drive over and help you
 
2.15 X 1.60 = 3.75 in the bore minus valve to valve clearance.
 
Isn't anything less than .200-.250" valve to wall clearance, cause valve shrouding?
 
273 said:
Isn't anything less than .200-.250" valve to wall clearance, cause valve shrouding?
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In theory most of the air fuel mix is going to the high speed side of the valve which is heading to the most unshrowded area in the middle of the cylinder, but at low speed, which this engine probably won't see too much of it could shroud a bit.
 
I am a rookie (but old!) bigblock racer, but believe in a couple of things. Max cubes, based around a centerweighted crank for long life and to bring rpm down for a long life, many run motor that is a bit easier on valvetrain parts.. Also i run .9 mm rings and methanol, with a primer plus system for warmups, clotz fuel lube in the methanol. i also run mechanical injection because it is so dirt simple.
 
-Boosted- said:
So in theory, it’s a non-issue?
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depends where the intake valve sits in the bore, from what I hear at .200-.250" the wall no longer shrouds the valve. So ideally, Wall, .250", 2.15 valve, space?, 1.60, space?, Wall. 4" plus the other 2 spaces.
 
MOPARMAGA said:
In theory most of the air fuel mix is going to the high speed side of the valve which is heading to the most unshrowded area in the middle of the cylinder, but at low speed, which this engine probably won't see too much of it could shroud a bit.
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Right! Low lift is over the short side. Where this is depends on the head design.
-Boosted- said:
So in theory, it’s a non-issue?
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To a degree, IMO, yes because valve shrouding isn’t good for the A/F mix and burning of it but I wouldn’t get caught up in it a ton. As the saying goes, the LS guys aren’t concerned with it.

For sure an improvement can be made by avoiding it.
273 said:
depends where the intake valve sits in the bore, from what I hear at .200-.250" the wall no longer shrouds the valve.
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I think a case can be made for more or less of which I don’t know any specific figures for this. For certain more clearance the better. But where does it hurt and where does it become a detriment?

I think this will depend on more things than a short list provides.
 
Newbomb Turk said:
Nope. The W7 they require a MINIMUM of a 4.150 bore and 4.185 is better. A notch doesn’t work well enough to bother.
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Newbomb Turk said:
Nope. Because some of us do “wrong” things to try and get the full port to work at high lift, high air speeds and that’s even if the flow bench says you lost some flow, especially low lift.
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Bingo! Just because you notch the cylinder, it doesn’t mean you have fixed the issue. Sometimes it’s living with the short comings along with the plus side of things. A catch 22 if you will.

The bigger the bore the better the cylinder head can breath.

If you could have a SBM stroker @ 426 cubes, the further you go the shorter stroke and big bore route, the better the head breaths. The short stroke is great for rpm’s and more the merry when creating hp.
 
This is a made up B/S set up. IDK if you can get a B/RB crank with a 3.15 stroke, but it’s an interesting day dreaming combo with a big block head in the head.


IMG_1691.png
 
rumblefish360 said:
This is a made up B/S set up. IDK if you can get a B/RB crank with a 3.15 stroke, but it’s an interesting day dreaming combo with a big block head in the head.


View attachment 1716187266
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If you could get a B block with a 8.8 inch deck I would build that. But you better like RPM because that’s going to 9k plus to make power with that stroke.
 
I had to notch my bores so my combustion chambers were not shrowded by the bore itself.
As in combustion chambers on intake side were larger diameter than the bore.
I can't say exactly what it did because I made multiple changes but I know it didn't hurt and the engine makes plenty of power for a stock block set up.
 
Stock mopar valve spacing 1.87", 2.08/1.6 = 3.71" / 2.02/1.6 = 3.68" / 1.88/1.6 = 3.61"
W7 " " " 1.936", 2.15/1.6 = 3.81"

Victors valve spacing ?
 
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Newbomb Turk said:
Any head I know of with larger than a 2.100 valve (and a 1.6 exhaust) requires moving the valve centers to get the valves to fit.

I just used the W7 as an example but that the rule.
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I get what you're saying. I wish Edelbrock would just come out and say what is required to run these heads on a stock block with 4" bore.
 
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