Valve Performance diy Modifications & Why I'm NOT Back-Cutting My Valves

hey how's it going today we're modifying valves [Music] [Applause] to back cut or not to back cut that is the question well not really for me i already know what i'm going to do basically based on some advice i got from another guy because of my cam shaft i am not going to back cut and that's the most popular valve modification people do you see they'll add another angle which helps with low and mid-lift flow but with my camshaft and then the overlap it has i don't really want to increase that low lift flow because it could result in more reversion and here's here's a prime example i have an intake over here that was off the car with the cam i'm going to use and you can see here these ports are pretty dark and that is exhaust it's not amy it's not pvc i run open breathers so just so you know it's not oil it's exhaust so clearly i have some reversion and i don't really want to back cut my valves now what i can do is i can radius the head of the exhaust valves a little bit to help some flow now technically i've already done this video before but i screwed up so i got to redo it again and i just need to get done so prepare yourself for rambling chaos because i'm just going to wait let's just get it done here we go okay over here i got some valve set up and let's start off with back cutting you can see here are two used manly valves and on this one right here there is no backup i'm looking at the wrong valves sorry over here i got valves valves and more valves so just bear with me over here we have two used manly valves you know take two and you can see this one here is not back cut this one i've given a little bit of a back cut and basically what it is is you have your your your your 45 face seat and adding the back cut is just the top that you add a little bit of a 30 cut you know 30 ish you know depending on you know what you you know you you what your flow results show or whatever i don't i'm not a flow specialist i just know that 30 degrees is popular but some people will tweak it to get a little more and i don't have a lot of fancy equipment so 30 is good enough or close to 30 is good enough for me anyways moving on to back cut your valve you can you know there's various ways the way i like to do is i will chuck up the i will chuck up the valve in my drill press oh is it that way that's the wrong way think i'll get it here in a second i will check the valve just just snugly in my drill press and i will take a file and run it across as i said you know you have your 45 and you're just going to add a little bit of a 30 and give it a little more of an angle see over here i got a diagram i almost forgot and you can see right here here's the 45 and here's a 30 inch back cut and a lot of valves will also have a little bit of a head cut and that's what we're going to get into here in a minute i just want to point that real quick but normally you'll get the valve and sometimes it'll be like just like this bam just a straight cut others will have usually this these days but over here you can see the reason i said these valves out is they do not have a head cut let's restart take two you were warned this video is not about back cutting valves what i want to demonstrate is raising the head of my exhaust valves well you see over here i drew an example we have the exhaust flow coming out of the cylinder and around the valve into the port and you can see over here this is like you know some aftermarket valves and usually an oem valve you just have like a sharp edge and what we're going to be doing is radiusing the edge on the head side of the valve to make the you know of course the exhaust flow around it easier now a lot of valves these days i've noticed have somewhat of a cut here so we're just gonna be racing it slightly and i got some examples over here real quick you see these are some old manly valves and you should be able to see that they have a little bit of a cut on the edge of the heads here's some sportsman valves sorry some valves i got on my sportsman two heads the same thing a little bit of a cut here's some other ebay valves same thing and of course the elgin valves i just got oh and the even the the reman vortec crate engine valves have a bit of a cut on them you can see right here on the intakes and the exhaust and here's one of the algebra there's the whole set of the elgin i'll be radiusing i'm only racing the exhaust because in my opinion well the exhaust is dry flow so you don't have to worry about you know it's just it can be smooth but for the wet flow of the intakes you want to be sharp to shear the fuel as it comes out so we're not going to be touching the head side you know of the intake valves just the exhaust over here you can see this is an old manly valve out of this sportsman two heads that were on my car and it does not have any head cut to it it's just a 90 degree so give me a minute here and i will chuck up one of those exhaust valves and give you a demonstration okay one more thing i want to point out before we start this modification is over here i forgot to mention i have drew a diagram and now in my opinion because i don't have a flow bench you know we have the flow coming out of the cylinder into the port so that's the major benefit of this modification but also we have the flow coming out of the intake port and it comes across you know the edge of the exhaust valve so i set up an example over here so you can kind of see better what i'm talking about you can see right there the is exhaust valve the flow comes out and this is you know a oem head you know just vortec you know one nine valve for the intake and one five i think for the exhaust so with larger valves like you know a 202 or 208 and a 1 6 exhaust they're going to be closer so just something else you know i think is a benefit but back to over here we're all set up and now i'm going to be using the this the smooth cut file for the for the exhaust valves because you don't really need to do much it's already you know as we showed earlier there's already a cut on the end so we're just going to radius that a little bit more and we'll get to this this larger bastard cut file later so here we go to the tripod now once again my valve is just snug in here i need to loosen just slide it in and snug it up don't crank it down no need to break out the chuck that's good enough we're not going to put any extreme pressure right now we're going to be more going up but if you're doing a back cut you don't want to put too much down pressure you want to mostly let the file do the work and you can use another method to do this some people will use a lathe others will take a drill and use like you know run the drill so it's on the grinder you know hit the grindstone but i'm not you know this is the method i prefer to do so here we go turn the drill press on [Applause] i'm going to take my file and start on the bottom and as i go i'm going to roll it because we're just trying to not remove a ton of material just we're trying to radius it i don't want to go you know over you know 90 and get into that 45 we're going from you know the other plane or whatever you want to call it so here we go we'll do a few cuts we'll stop and check it and inspect it okay give it some more that's if i go else if i go the right way i was going over the first time and here we go okay yeah let's check our progress here that's getting there a little more a little more on the flat side now maybe i did use the bastard file last time let's try the bastard another thing i forgot to mention is i went ahead and i read online it's good to chalk them up so i stole some of my niece's sidewalk chalk and i went and chalked the file up [Music] that way the metal doesn't load the file up okay let's see what we got here it's looking pretty good do a little more so let's see that should be good i think yeah it's got a nice little radius to it and that's pretty much it got seven more to do i keep going the wrong way [Music] well i got all the exhaust valves done last night i mean i went in for a snack afterwards and started watching videos and you know how that goes so here they are here's all the elgins nice and radius and the vortec exhaust valves you'll just have to trust me on those ones i ran out of room but i think they turned out nice i mean a few notes before i move on um since the algin valves are stainless i don't have to worry about oiling them but these oem valves they're steel whatever so i definitely want to oil them up so they don't rust on me while until i get to use them also the oem steel were definitely softer and they fall down much easier so just you know just so you know yes these valves are harder valves the chalking and the files i guess it helped i mean they still kind of loaded it up pretty decent but brushing them off was easier you know quicker or whatever so you know you know i'll keep doing it you know we'll see i did at least make my shavings nice and prettier i guess anyways moving on the last thing we're going to do is mess with the vortec oem replacement intake valves because they have this little bit of a lip on them as you can see and basically let's go over to the diagram here real quick my last diagrams you can see where we got the you know the the intake runner here we've got the flow coming in you're more on the long side as opposed to the short side and it comes across the back of the valve so over here i've drawn you to show you you can see a little bit of a lip as the flow comes across it's going to get a little bit of a hiccup so basically by removing that lip you know flow better across the valve it would flow even better if i back cutted it but you know because of my cam and so on you know so next we're going to set up and i'll demonstrate you know you know not back cutting but i guess leveling out you know removing that little lip on these intake valves over here i have an example of what i've already done and if i really want to i could polish the whole back of the valve but you know i don't want to put the time into these valves so you know oh and also before i forget here's an example of the lip on the exhaust valves these ones i don't want to remove that lip because you know over here you know as the flow tries to you know reverse and you know back out you know that little bit of lip would actually help stop it so the exhaust valves were good intakes you know not so good so let me set up the tripod and we'll get started on those intake valves there we go this time we're going to try a different valve angle and once again you want to just you know snug your valve not crazy tight just snug don't need the key or nothing to crank it down just that's good so i forgot to know earlier also the rotation of the valve you know we're working on the side that's going towards me so you're going we're pushing away you know running the file across we're not going back and forth you know you classically see a files your files are technically supposed to be only used in one direction so you know valve's coming towards me and we're going across you know we're going against against the rotation to help cut so this time i've reached out my file and we're going to be going you know pretty much this level you're not back cutting just level take that lip off so you know here we're going to zoom in here real quick too i think i got this pretty much centered yeah we'll give a nice close-up shot of this okay here we go on the inside let's check our virus well that looks pretty good i'll just do a little more just to be my oh what a smooth cut i haven't chopped it we'll hit with a smooth cut [Music] okay yep that's it we're good man now i hope this helps if i should zoom out wrong way there we go this is really supposed to be i'll be how to just showing you well how i do it and what i'm doing explaining why so as always i hope this helps thanks for watching keep it real [Music] you

Channel: BOOT

Views: 26,335

Keywords: Action Auto diy BOOT, Performance Valve Modification, backcutting valves, back-cut valves, how to valve modification, valve flow mods, improve valve flow, valve flow improvements, high performance valves, stainless steel under cut valves, 2.02 1.6 elgin valves, back cut valve

Id: aTj1j28mWdk

Length: 18min 12sec (1092 seconds)

Published: Sun May 24 2020