Valve choices

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MOPAROFFICIAL

MOPAROFFICIAL

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What's everybody using for bigger valves anymore? I still have a set of 1.70 1.44...
But watching all this hype lately got me thinking how about an 8 mm stem 1.89 LS valve cut down to 1.70 -1.72 and then a cut down 1.55 to 1.45.
Its .087 & .050 total off the o.d.
Then a re face and back cut.
The length is only around .070 longer, maybe knock .020 off that. I've taken .030 off of stems before ,no issues with hardness.
Is it easier to wait on SI to make more.
The ford valves are terrible peices..heavy
 
MOPAROFFICIAL said:
What's everybody using for bigger valves anymore? I still have a set of 1.70 1.44...
But watching all this hype lately got me thinking how about an 8 mm stem 1.89 LS valve cut down to 1.70 -1.72 and then a cut down 1.55 to 1.45.
Its .087 & .050 total off the o.d.
Then a re face and back cut.
The length is only around .070 longer, maybe knock .020 off that. I've taken .030 off of stems before ,no issues with hardness.
Is it easier to wait on SI to make more.
The ford valves are terrible peices..heavy
Click to expand...
Which Furd valves?? There are late-model 2.3-2.5L Ranger 4-banger valves w/7mm stems that have been used, forgot the dia. I plan on raising/moving the shaft, & using Toyota 3F-3FE 4.2/4.0L valves, longer with 8mm stems. 1.81"/1.48" w/tool steel LS retainers and beehives. The exhaust heads are heavy, may work on that. The intake valve combo weighs less than the stock 1.60"/retainer/spring...
 
Killer6 said:
Which Furd valves?? There are late-model 2.3-2.5L Ranger 4-banger valves w/7mm stems that have been used, forgot the dia. I plan on raising/moving the shaft, & using Toyota 3F-3FE 4.2L valves, longer with 8mm stems. 1.81"/1.48" w/tool steel LS retainers and beehives. The exhaust heads are heavy, may work on that. The intake valve combo weighs less than the stock 1.60"/retainer/spring...
Click to expand...
I THINK he's talking about the Ford 300 I6 valves, if I'm not mistaken. and of course, I could well be. lol
 
Killer6 said:
Which Furd valves?? There are late-model 2.3-2.5L Ranger 4-banger valves w/7mm stems that have been used, forgot the dia. I plan on raising/moving the shaft, & using Toyota 3F-3FE 4.2/4.0L valves, longer with 8mm stems. 1.81"/1.48" w/tool steel LS retainers and beehives. The exhaust heads are heavy, may work on that. The intake valve combo weighs less than the stock 1.60"/retainer/spring...
Click to expand...
When comparing, it's an awful amount of bore shrouding the valve. The slant has the most of all.
 
MOPAROFFICIAL said:
When comparing, it's an awful amount of bore shrouding the valve. The slant has the most of all.
Click to expand...
The avg piston is so far away from the top, that's not a problem, as long as the head gasket is big enough, same as other long-stroke engines. Unfortunately, it appears the large-bore Aussie gaskets have become difficult to obtain, so the limit is the current ACL @3.55"(-.020"). Printoseals being @3.53"(-.020"). Unlike SBC & BBM, Slanty valves are pretty well centered in the bores, less of an issue.
 
Killer6 said:
The avg piston is so far away from the top, that's not a problem, as long as the head gasket is big enough, same as other long-stroke engines. Unfortunately, it appears the large-bore Aussie gaskets have become difficult to obtain, so the limit is the current ACL @3.55"(-.020"). Printoseals being @3.53"(-.020"). Unlike SBC & BBM, Slanty valves are pretty well centered in the bores, less of an issue.
Click to expand...
I don't know what all the hooplah is about the Aussie "big bore" gaskets. Almost every gasket I have here measures 3.55". I guess maybe if you bore one .100" then you might be concerned. I'd go to Cometic though, before the overpriced Aussie piece plus paying shipping from down under.
 
RustyRatRod said:
I don't know what all the hooplah is about the Aussie "big bore" gaskets. Almost every gasket I have here measures 3.55". I guess maybe if you bore one .100" then you might be concerned. I'd go to Cometic though, before the overpriced Aussie piece plus paying shipping from down under.
Click to expand...
The top of the bore is an extension of the chamber, & can be relieved in kind above the ring travel, done it on other similar long-stroke smaller-bore mills. De-shrouding is key to large valves. At higher lifts the side shrouding encourages swirl depending on port orientation, and the form that is cut.
 
Killer6 said:
The top of the bore is an extension of the chamber, & can be relieved in kind above the ring travel, done it on other similar long-stroke smaller-bore mills. De-shrouding is key to large valves. At higher lifts the side shrouding encourages swirl depending on port orientation, and the form that is cut.
Click to expand...
Yeah yeah. I've read all that. How much do you think the gain will be? I'd like to see some comparisons. Might be more hair splittin.
 
Killer6 said:
The top of the bore is an extension of the chamber, & can be relieved in kind above the ring travel, done it on other similar long-stroke smaller-bore mills. De-shrouding is key to large valves. At higher lifts the side shrouding encourages swirl depending on port orientation, and the form that is cut.
Click to expand...
...and no, it's not "just" the top of the cylinder. The WHOLE cylinder is the chamber.
 
Killer6 said:
Lol, as far as the valves are concerned, predominately the top.....better??
Click to expand...
That's what everybody pays attention to, but the whole of the cylinder with the head on is technically the chamber as well. Combustion occurs at the top, yes, but the whole cylinder is also a part of that. The LS valve thing is really interesting though.
 
RustyRatRod said:
That's what everybody pays attention to, but the whole of the cylinder with the head on is technically the chamber as well. Combustion occurs at the top, yes, but the whole cylinder is also a part of that. The LS valve thing is really interesting though.
Click to expand...
The 3.8 60°V-6 around '04 had 8mm stems near the correct length, 1.89" int., 1.4-something exh. Wonder if They even checked into those, prob more $$$ even for stock ones.
 
Killer6 said:
The 3.8 60°V-6 around '04 had 8mm stems near the correct length, 1.89" int., 1.4-something exh. Wonder if They even checked into those, prob more $$$ even for stock ones.
Click to expand...
I think the stem diameter makes more difference than might be expected. I know Justin's done some playin around with it and come up with some interesting numbers. I guess wanting to get the most flow you'd certainly look into it.
 
RustyRatRod said:
I think the stem diameter makes more difference than might be expected. I know Justin's done some playin around with it and come up with some interesting numbers. I guess wanting to get the most flow you'd certainly look into it.
Click to expand...
That's not all, more pocket volume for stored inertia, & superior valve control=more output. All good with quality components, no downsides.
 
Killer6 said:
The avg piston is so far away from the top, that's not a problem, as long as the head gasket is big enough, same as other long-stroke engines. Unfortunately, it appears the large-bore Aussie gaskets have become difficult to obtain, so the limit is the current ACL @3.55"(-.020"). Printoseals being @3.53"(-.020"). Unlike SBC & BBM, Slanty valves are pretty well centered in the bores, less of an issue.
Click to expand...
If you take valve diameters sb, bb, then slant deduct from their bore sizing..the others have .200 or more room. Its tight in comparison.
 
MOPAROFFICIAL said:
If you take valve diameters sb, bb, then slant deduct from their bore sizing..the others have .200 or more room. Its tight in comparison.
Click to expand...
Questions is there any merit to the rule thumb that intake valve should be 52.5% Max of bore dia. ?
 
I can tell you an 500" NHRA Pro Stock engine uses 4.75" bore and run a 2.50" intake valve. if you use the 52.5% it calculates out to a 2.49375" size valve.

So I am going to say it's probably a pretty accurate percentage if you have the right ports and chamber design.

Tom
 
PROSTOCKTOM said:
I can tell you an 500" NHRA Pro Stock engine uses 4.75" bore and run a 2.50" intake valve. if you use the 52.5% it calculates out to a 2.49375" size valve.

So I am going to say it's probably a pretty accurate percentage if you have the right ports and chamber design.

Tom
Click to expand...
That's pretty much dead on, talk about a big bore guess the stroke got to 3.52" ish.
 
Using that formula on my slant build I get 1.7914, so the 318 valve size is right on top of it.
 
You can buy 7MM valve stem blanks from SI and create your own custom valve if you have the capability. I've done it for several V engines before. The 7MM stem really improves flow by reducing the valves footprint in the bowl area. That coupled with a reduced diameter and shaped guide gives you almost as much gain in flow as a mild ported head without having to mildly port it. Just imagine if you ported the head and swapped to the 7MM valve. You likely exceed the flow of a radically ported head with only mild porting....I'm sure other companies sell blanks as well....
 
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