Talk:Overhead valve engine

message: Why was the pushrod page moved and why wasn't the move discussed first? Overhead valve can also be used to describe an overhead camshaft engine, so this page should be moved back or it should be moved to I-head. IJB TA 15:04, 16 April 2007 (UTC)
replies: text: I agree, it's better to have a short page here that says "'overhead valve' from a technical standpoint encompasses several engine types, including overhead cam engines and pushrod engines, though now is most commonly used to refer to pushrod engines", and have the larger articles elsewhere.  --Interiot 20:04, 17 April 2007 (UTC)
replies: text: So I guess the question becomes whether to move this page back to pushrod engine or to a new page called I-head. IJB TA 15:41, 18 April 2007 (UTC)
replies: text:  That's something that should be discussed at Talk:Pushrod engine...  can we split them back out now?  --Interiot 22:26, 3 May 2007 (UTC)
replies: text: I would, but I'm not really sure what to do with the redirects. IJB TA 21:29, 5 May 2007 (UTC)

text: I think it should be pushed back to "Pushrod" LOLHI  IM  AHANIX 05:28, 5 December 2007 (UTC)

text: Is nels ornate onmandela-am an architect and still kill this mechanical phenomena and shit.  — Preceding unsigned comment added by Nels ornate onmandela (talk • contribs)  18:13, 6 October 2019 (UTC)
thread_title:  [[Pushrod engine]] merged here 

message: "Comparing engines is not an exact science. This table shows the comparison of some of the most important features when looking at an engine"
I think it's somewhat misleading to say comparing engines is not an exact science. I would argue that it is an exact science, however I understand what the author was trying to communicate, which is that its not possible to accurately compare engines using only a few figures such as peak power/torque figures and rev limits etc. I would put forward a more accurate phrase such as "There are numerous factors to consider when comparing engines. Some of the key features are described in the following table"
—The preceding unsigned comment was added by 60.242.154.34 (talk) 12:59, 9 May 2007 (UTC)
replies: text: Go for it. IJB TA 14:49, 10 May 2007 (UTC)
thread_title:  Comparison of engine configurations and types wording 

message: I immediately noticed in this article that when comparing engines, some of the OHC engine benefits/examples were those using pneumatic valve springs, which are decidedly different than the standard coil springs used on the other examples. Can pneumatic valve springs only be implemented in OHC engines, or is it possible for an OHV engine to use them? None of the articles in question give any indication.
If pneumatic valves are independent of valvetrain, I suggest the examples be removed from the article.
If they are specific to OHC, I suggest that they be listed as a benefit, but set apart from standard coil spring OHC engines. Scott Paeth (talk) 10:22, 9 February 2008 (UTC)
replies: text: Pneumatic valve springs could be used in a pushrod engine but wouldn't offer any benefit. The use of pneumatic springs came about because metal springs begin to shatter at a certain RPM, well over the maximum RPM of any pushrod engine. Pushrods are limited by the high mass of the valvetrain, not the valve springs. IJB TA (talk) 06:03, 17 February 2008 (UTC)
replies: text: Thanks for the feedback. I'll edit the article to reflect this. Scott Paeth (talk) 05:09, 19 February 2008 (UTC)

text: Not true, pneumatic valve return systems (PVRS) can be used in an OHV or OHC engine but wouldn't offer any benefit unless it is in a "race" type engine with current technology.  Teams in Prostock wanted to use PVRS just like F1 does but the NHRA preemptively banned it unlike in F1.  The use of it is because springs that are stiff enough to control the valve in those engines do not last long.  It is pointless to talk about them in general terms between OHV and OHC especially if refering to production engines.LrngCrv (talk) 04:55, 25 September 2008 (UTC)
replies: text: You should really read my comments before replying to them. I just said almost the exact same thing as you. IJB TA (talk) 02:39, 27 September 2008 (UTC)
thread_title:  Use of Pneumatic Valves unbalanced? 

message: While it is common to have only one cam in a pushrod motor I think it's worth noting that GM did design a twin cam VVT 3 valve pushrod motor called the XV8.  The intent was to maximize the potential benefits of a pushrod motor.  That is maximize the displacement you can get in a small total engine package size.  The concept is described here:
http://www.acarplace.com/brands/gm/xv8-engine.html
and here with pictures:
http://theautoprophet.blogspot.com/2005/06/redemption-of-pushrod.html  —Preceding unsigned comment added by 129.59.246.28 (talk) 17:43, 28 March 2008 (UTC)
replies: text: So its the same size as a V6 and makes as much power as a V6, what are the benefits? IJB TA (talk) 06:31, 31 March 2008 (UTC)
replies: text: It's actually smaller than the average V6 and makes more power than the average V6.  The benefits are in more than just the obvious.  What's the benefits of a DOHC, it is larger than a OHV and makes as much power?  It's a rhetorical question, I don't want a response it is just to make a point.LrngCrv (talk) 05:23, 25 September 2008 (UTC)

text: It seems to be ridiculously over complicated. A V6 with DOHC and VVT would have a considerably lower part count. IJB TA (talk) 05:11, 1 April 2008 (UTC)
replies: text: I don't see how your opinion is relevent, how does that even add to the discussion?LrngCrv (talk) 05:23, 25 September 2008 (UTC)
thread_title:  Multi-cam pushrod motors 

message: In the introduction it implies that a 1949 engine was the first OHV engine.
Well hardly.  The curved dashed Oldsmobile produced well before WW1 and almost all Buicks ahd 'valve-in-head' engines.
The first Chevrolet 'Stovebolt Six' came out in 1927 and the second in 1939.203.26.122.12 (talk) 06:33, 25 November 2009 (UTC)
thread_title:  First pushrod engine 

message: See Wikipedia:Articles for deletion/Cam-in-block  Andy Dingley (talk) 10:18, 14 April 2012 (UTC)
thread_title:  [[Cam-in-block]] at AfD 

message: Maybe somebody can help me to understand the staggered valve arrangement?  When I saw a picture of one side of a big block engine a few days ago, I didnt know about the staggered valve arrangement,  Now that I know, it might be still not making sense.  When you look at an overhead photo of the valves, you see six valves in the center, one valve by itself on one end, and one valve by itself on the other end.   In total, eight valves makes sense:  four intake valves, and four exhaust valves.    But the thing Im not fully fully understanding is the staggered arrangement.   It seems really, that of eight valves, only two are staggered.   One valve at each end is set at an angle.  Am I correct?  The valves in the two middle cylinders are closer together, than each valve set in the end cylinders.    Am I correct?  Or am I missing some facts here?  Marc S., Dania Fl 206.192.35.125 (talk) 13:50, 8 March 2013 (UTC)
replies: text: Do you have a photo or a link?  Andy Dingley (talk) 13:55, 8 March 2013 (UTC)
replies: text:   http://WWW.MOTORTREND.COM/FEATURES/CONSUMER/1301_CHEVROLET_CORVETTE_60_YEARS_AMERICAN_ICON_PART_1/PHOTO_17.HTML  Marc S.  Dania fl.  206.192.35.125 (talk) 19:42, 8 March 2013 (UTC)
replies: text:  Looks like a perfectly straightforward valve layout. The valves are in pairs, per cylinder, and what's a little confusing is that the pair for one cylinder are the widely-spaced pair, whilst the closely-spaced pair are across two adjacent cylinders. All four of each bank, inlet (central) and exhaust (outer, towards the rear of the engine), are simply in line. Andy Dingley (talk) 21:00, 8 March 2013 (UTC)
thread_title: Mark IV 396 big block of 1965: the staggered valve arrangement.

message: I propose that the section "1994 Mercedes/Ilmor Indianapolis 500 engine" be either deleted, or moved to a new page linked to this one. Arrivisto (talk) 15:01, 29 December 2014 (UTC)
thread_title:  1994 Mercedes/Ilmor Indianapolis 500 engine 

message: This also compromises the spark plug location, since it is not possible to have a centrally located spark plug in an engine with two valves per cylinder.
This is plainly false. While most (possibly all) two-valve engines have the sparkplug offset to allow for maximum valve size, nothing prevents the designer from placing a sparkplug in the center and simply making the valves smaller.
Of course, this effectively gives you about half the flow of a four-valve engine, but that's just inefficient, not impossible.
AI0867 (talk) 13:01, 27 January 2020 (UTC)
replies: text: A great deal of this article is false and unsourced, based on vague ideas from someone with no real breadth of knowledge of the subject. This is a typical example. Andy Dingley (talk) 13:20, 27 January 2020 (UTC)
replies: text: After a quick lookover, I think it's safe to say that there are more "interesting" things that might need fixing. The variable displacement explanation is written in a way that suggests that it is related to OHV; I'd say that it's "temporarily disabling fuel supply" rather than variable displacement, if I'd mention it at all. And OHV actually does allow variable valve timing (if you will): Many older Diesel engines have flip switches that change the outlet valve timing so that the valve doesn't close anymore. This significantly reduces the engine turning-over resistance and is used to ease hand-cranking all these engines that otherwise would only start with the help of a starter motor. Even bigger old Diesel engines used variable valve timing for adjusting intake air flow whilst starting up or for changing the crankshaft turning direction from counterclockwise to clockwise or vice versa. This is not really related to "modern" variable valve timing, but if it isn't varying the valve timing, what is it? --Johannes (Talk) (Contribs) (Articles) 00:01, 28 January 2020 (UTC)
thread_title:  Two-valve central spark plug