Re: Anyone ever go faster with less lift?
[Re: polyspheric]
#3016177
02/16/22 09:50 PM
02/16/22 09:50 PM
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Joined: Jan 2003
Posts: 1,796 Windsor, ON, Canada
Diplomat360
top fuel
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Windsor, ON, Canada
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increasing the lift brings the valve closer to the cylinder wall
Did you typo this? It's backward. Nope, I literally see it as the valve getting closer to the cylinder wall as the lift increases. Yes, the starting angle is such that the valve intially starts on-center, but that very angle also has it moving towards the exterior cylinder wall. I mean theoretically if you kept on going it would simply run into the wall. Having said that, I suspect that given the lift ranges most of us are talking about (street builds), so maybe .650-.700 at most (?), this probably does not hinder the air flow much. Further on, I suspect that the shrouding due to valve diameter size has a much bigger role, especially the part of the valve head closest to the cylinder wall. This I believe is part of the reason why doing a de-shourding cut on the combustion chamber often helps with the flow.
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Re: Anyone ever go faster with less lift?
[Re: lancer493]
#3016282
02/17/22 12:06 PM
02/17/22 12:06 PM
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Joined: Dec 2021
Posts: 1,398 Loudoun County, VA
Brad_Haak
pro stock
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pro stock
Joined: Dec 2021
Posts: 1,398
Loudoun County, VA
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Y'all are following the trail that leads to relocating the cylinder heads farther inboard to get the open valves away from the exhaust-side of the cylinder walls. If link below works, it'll take you to a pic of a head that Jesse Robinson ("RAMM") modified for an older EMC event to offset the head... looks like about .100" to me, FWIW. This is one of those things where other engines (non-Mopar) can have an advantage cuz their heads have the valves located closer to the center of the bore. IIRC, it's one of the revisions that B1 heads (not B1-BS) have compared to the OEM architecture. PICTURE
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
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Re: Anyone ever go faster with less lift?
[Re: lancer493]
#3016304
02/17/22 01:09 PM
02/17/22 01:09 PM
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Joined: Mar 2003
Posts: 9,119 Rogue River, OR
Jeremiah
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master
Joined: Mar 2003
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Rogue River, OR
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As a point of interest, a 2.30 intake valve will hit a 4.375 bore at a little over .800" lift.
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Re: Anyone ever go faster with less lift?
[Re: mopar dave]
#3016504
02/18/22 10:58 AM
02/18/22 10:58 AM
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Joined: Jan 2003
Posts: 14,545 So. Burlington, Vt.
fast68plymouth
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I Live Here
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Posts: 14,545
So. Burlington, Vt.
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Didn’t know that was a problem on these heads They’re not any different in that regard than any other heads that retain the stock valve placement and angle....... in other words......”most” of them.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Anyone ever go faster with less lift?
[Re: Jeremiah]
#3016617
02/18/22 07:08 PM
02/18/22 07:08 PM
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Joined: Jan 2003
Posts: 31,261 Oregon
AndyF
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I Win
Joined: Jan 2003
Posts: 31,261
Oregon
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As a point of interest, a 2.30 intake valve will hit a 4.375 bore at a little over .800" lift. Doesn't surprise me, 2.30 valve is pretty big and 4.375 is kind of small for an engine that needs a 2.30 valve. Typically you would want a 4.500 bore for that big of a valve. It might not pay to put a 2.300 valve in a head if the bore size is only 4.375.
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Re: Anyone ever go faster with less lift?
[Re: AndyF]
#3016636
02/18/22 08:45 PM
02/18/22 08:45 PM
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Joined: Jan 2003
Posts: 19,609 Las Vegas
Al_Alguire
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I Live Here
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Las Vegas
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Since we are talking points of interest. We run a 2.300 intake valve in a 4.25" bore in the Vette. Non wedge of course. But NONE of this math works in that situation save one persons source Oh yeah a lot more lift than the OP's source sites as well, a LOT more.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: Anyone ever go faster with less lift?
[Re: AndyF]
#3016696
02/19/22 06:52 AM
02/19/22 06:52 AM
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Joined: Mar 2003
Posts: 9,119 Rogue River, OR
Jeremiah
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Rogue River, OR
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As a point of interest, a 2.30 intake valve will hit a 4.375 bore at a little over .800" lift. Doesn't surprise me, 2.30 valve is pretty big and 4.375 is kind of small for an engine that needs a 2.30 valve. Typically you would want a 4.500 bore for that big of a valve. It might not pay to put a 2.300 valve in a head if the bore size is only 4.375. Upon my discovery I came to the same conclusion. I also learned that stock valve spacing limits you to I/E valve sizes of 2.250/1.81 or 2.30/1.78. Not enough radial clearance for 2.30 and a 1.81. Nothing super technical in that experiment, just mocking up parts on hand. This is for my -1 tunnel ram 511 with a little over .800 lift.
Last edited by Jeremiah; 02/19/22 06:53 AM.
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Re: Anyone ever go faster with less lift?
[Re: GTS340]
#3016713
02/19/22 08:24 AM
02/19/22 08:24 AM
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Joined: Oct 2007
Posts: 4,219 New York
polyspheric
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master
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New York
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That was my point: facts matter less than "how you feel about it"
Boffin Emeritus
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Re: Anyone ever go faster with less lift?
[Re: mopar dave]
#3016760
02/19/22 12:02 PM
02/19/22 12:02 PM
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Joined: Jan 2003
Posts: 1,796 Windsor, ON, Canada
Diplomat360
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Posts: 1,796
Windsor, ON, Canada
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umm...sort of a strange "turn" to this thread...and I'm not quite following the under-current since the most recent remarks seems to WANT to say "I disagree" but they just can't seen to get to actually making that point! lol @polyspheric: I replied to your commentary re: my assertion the valves actually open towards the cyliner bore as opposed to the center, I even included a Mopar small block cut-through...I see that your original post, to which I responded, has now been editted by you, and is gone and has been replaced be a rather terse "Never mind"??? So the whining and complaining from @GTS340 and '@Harry's Taxi 2' is exctly what? I mean, does that actually contribute anything to this discussion??? If any of you have an answer, ney, even an opinion based on supporting evidence as to what '@mopar dave' original post is about, I would love to read about it. [now where is that "shaking my head with disbelief" icon]
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