How Camshaft Timing Affects Engine Performance - Engine Power S8, E7

[Music] you're watching powernation it's not just how much power your engine produces where your engine makes power matters too today on engine power we talk camshaft timing welcome to engine power today we're going to be building a very popular combination and you've seen a few of them come out of the shop before it's going to be a 383 cubic inch small block chevy but with a twist we've ordered some special parts to show you some cool tech on the dyno now i know what you're thinking these guys are building another stroke small block chevy are they stuck in the 80s well yes and no but that's a different conversation anyway we are doing this for two different reasons one there is a vehicle in the building that requested this exact combination and two we're going to show you some stuff on the dyno we haven't shown you in a while we're going to show how the camshaft's intake center line affects the power curve of an engine whether the cam is advanced or a bunch and you are going to be interested to see the results a few weeks ago when we heard that music city trucks was turning a 1991 suburban into a 10 000 pound off-road rig it piqued our interest this is we're calling it unbreakable this is the ultimate off-road rig that you drive to the off-road park wheel all weekend and drive it home nothing breaks so you want to be reliable that's a tall order and when they wheeled in they used up stock engine we said thanks but no thanks that's far enough that's far enough what is this contraption this is the 350 out of our suburban project what's it doing here uh i want you guys to build it this particular engine well i mean this is what we got okay if you name your vehicle unbreakable the engine better be rock solid based on the age and condition of the stock power plant we suspected it was better to start from scratch when mark told us a little bit more about their engine needs we knew this was a good plan it's going to live its life in the low to mid rpm range okay sometimes higher rpm if we want to do like a really you know high rpm run through the mud or something like that but for the most part low in mid rpm range is where it's going to lift it's fortunate that we already have a 383 project in process that way we don't have to tear apart their engine and we have parts already in-house it starts with a fully machined small block chevy this is a late model tall lifter roller engine that has already been board honed a line home cam bearings and freeze plugs installed and then clearance for the bigger stroke and that leads us to the parts that were all available off the shelf from summit racing it starts with an eagle rotating assembly with a 4340 forged crank with a three 750 stroke a set of molle power pack pistons with a five cc valve relief and a one millimeter one millimeter two millimeter ring pack the connecting rods are a set of eagles forged 4340 i beams with a six inch center to center length and a bushed pin end for induction we used a set of afr220 eliminators because we were going to do something different earlier but we can make it work for the application we also have one of their high-rise single plane intakes for valve train we'll be using a comp cams solid roller we were using a solid roller on our other application and we can still use it for this one we just have to back it down on lift and duration we also have a set of harlen sharp 1.6 ratio rockers and it's all held together by arp fasteners now we're going to go through our normal process of measuring clearances and filing rings but we're going to show you a little bit less of it so we have more time for our tech on the dyno and to do that we're going to use these we picked up this comp cams billet double roller timing set from summit racing we chose this over other designs for its ease of use and increased accuracy it has up to six degrees advance and six degrees built in in order to use this setup on the dyno we also picked up a three piece billet aluminum timing cover set it has a top piece that is removable for easy access to the cam gear adjustment and the bottom piece is aligned by dowels and comes with a front cover seal already installed every good engine build starts with careful measurement of clearances and pre-fitment pat usually worries that if we don't show you the work being done you might just assume that we didn't actually do it like i said before we're going to save some time by showing you the work in a high speed time lapse that way we don't have to worry about pat's blood pressure and we'll have more time to focus on camshaft timing in a little bit with everything looking good the crankshaft is placed on the slicked up bearings the arp main bolts are torqued in sequence to 70 pound-feet i tell you that i was uh reading a book about anti-gravity no it's impossible to put down coming up on the engine and in the dyno cell we'll show you how camshaft timing affects performance [Music] when you are looking for a new set of spark plug wires for your project there are a few different options to consider depending on your application basically there are two different types of spark plug wire construction solid core and spiral core solid core wires are for when you want the maximum voltage with the least amount of resistance to your spark plugs they are readily available in either pre-made sets or in sets that are not terminated at the distributor end so you can make them fit your particular engine the only drawback to this design of wire is that it sends out lots of rfi when it is operating and that will affect other electronic systems in the vehicle the other type is a spiral core wire also available in pre-made or universal sets this design wraps the core with a blend of stainless copper and tin to suppress that rfi noise the only drawback to this style of wire is the more the core is wrapped for rfi suppression the more resistance the wire has to send maximum voltage to the plug but it is better for vehicles with sensitive electronic equipment making up a custom spark plug wire is an easy task with a few tools you can get through summit racing here we have two different styles of crimping pliers to do the job both will produce a good quality crimp to ensure your wires perform to their maximum capabilities our 383 stroker build continues with a comp cams solid roller camshaft this is smaller than originally planned but since the guys from music city trucks wanted lower rpm power it fits the bill nicely the comp cam's billet timing set slips on next held in place by arp fasteners that will be torqued later at this point we're mocking up the engine so we'll install the number one rod and piston assembly without rings for now true tdc is set on our degree wheel the cam is degreed at 110 degrees of intake center line which is straight up a set of lifters are installed in the number one lifter bore location and the cylinder head equipped with checking springs comes next two harlan sharp 1.6 ratio rockers are added with a set of comp cams push rods cold lash is set at ten thousands on the intake and twelve thousands on the exhaust the point where the exhaust valve is closest to the piston occurs at 10 degrees before top dead center on split overlap we have 122 thousands pissed into valve clearance for the intake valve the clearance is 177 thousands at 10 degrees after top dead center on split overlap so we have a ton miles miles of intake clearance that means we can really advance the cam i mean a ton more than you would ever think you could and still have safe valve cleans to start off checking clearances we are installing the cam in straight up at 110 degrees of intake center line which is the same as the cams lobe separation we are going to try to advance or the cam as much as we can as long as we have sufficient piston to valve clearance when you advance the cam the intake valve gets closer to the piston and the exhaust valve gets further away the opposite happens when you the cam the exhaust valve's clearance gets closer and the intake valve increases so we will vary it to see how much we have safely in each direction and that's where we're going to run it on the dyno we'll the cam as much as we think is safely possible and recheck our clearance now that's 90. [Music] 90 000 clearance for piston to valve on the exhaust side is a bit on the tight side normally you would want 100 to 120 thousandths just for safety purposes in our case we're going to be okay because we will be using a thicker head gasket when we assemble the engine for real the one we have now is 10 000 less than we will be running so that will put us in the good so we will mark that position and then we will advance the cam as much as we think we can and we'll check the intake valves piston to valve clearance and see what we have [Music] well the camshaft in at 100 degrees intake center line which is 10 degrees advanced we'll check the exhaust side which should have increased by a lot so it's out at 190 293 switching it to the intake side at a 10 degrees advanced still have basically a hundred thousands clearance all the piston rings have been file fit with gaps of 22 000 on the top ring and 24 000 on the second to ensure proper break-in we're lubing up the rings and cylinders with total seal assembly lube things go way smoother with a tapered ring compressor from arp especially with modern thinner ring packs torquing the rod bolts to 75 pound feet yields four and a half thousands of rod bolt stretch which is in spec for the arp fastener as always we check all the fasteners the three-piece timing cover is next it requires only a thin film of rtv to seal it a little goes a long way our summit racing sfi approved balancer presses on using a harmonic balancer installation tool not a hammer the comp solid roller lifters are lubed and slid into place they must go in before the cylinder heads are bolted down afr adjustable guide plates are mocked up along with the rest of the valve train so we can align the rockers precisely on the valve tips then they are tacked in place using our forney tig machine now the studs get thread sealant and are reinstalled they are torqued to 55 pound feet with everything set up the rest of the valve train is installed in the engine's firing order our afr single plane intake manifold finishes out the big pieces it's held in place by arp fasteners with a black oxide finish we like our engines to be snazzy so we'll shoot our engine with a plain red base coat followed by a metallic red engine enamel the color is red fire [Music] we sprung for a billet o-ring seal oil filter adapter from summit racing which is a big upgrade over the cast aluminum stock piece we bought our oiling system as part of a summit pro pack kit it includes the oil pump drive shaft pickup one piece oil pan gasket and a six quart baffled oil pan initial timing is set at 30 degrees the engine is warmed up and hot lash is set at 16 on the intake and 18 000 on the exhaust up next we dial in the power band of our stroker for maximum performance on the trail [Music] all right so we've gone through and ran the engine we've set the valves and made a few initial pulls to get the carburetor and the timing in the right range so at 34 degrees of timing we're going to make a sweep from 3 500 to 6 500 at 300 a second [Music] 503 477. dang how about them apples that's sweet i mean for yeah for the cam that's in it what a spectacular little street engine here yeah it's got about an inch of manifold vacuum not bad at the very top that's oil pressure is good we are two and a half degrees on the camshaft right now so what i'd like to do is where it's at right now now that's at operating temp let's uh shut it down before we do anything with the cam let's do a cranking compression test because this engine is 10.95 to 1 static but with a cam backed all the way up like that the dynamic compression is something like eight point zero that gets around where it was this would be a good way to show what actually changes when you actually move the cam from a target to advance right so i'll let's do that right now strong cranking compression is a sign of a healthy engine ours tests at 170 psi later when we advance the camshaft's intake center line both cranking and dynamic compression will increase you can find several online calculators to help determine your engine's dynamic compression to get to the camshaft we just have to drain the block and remove the water pump the top half of the timing cover comes off next giving us access to the camshaft timing adjustment after breaking loose the outside locking bolts we will change the center line by rotating the crankshaft instead of using the adjustment tool we do this since the cam is under full valve train spring pressure no need to use the degree wheel because we've already set up our timing marks during engine assembly the camshaft is now at 100 degrees intake center line which is 10 degrees advance the outside locking bolts get re-torqued to 14 pound feet and after applying silicone the timing cover is resealed and reinstalled since the engine is still warm we can test our cranking compression again and it has increased from 170 psi to 205 the cams intake center line is in at 100 previously 112. yeah i've never done this on the dynamic 10 lsa yeah i've never done this on an iron four so this is going to be pretty interesting so me neither timing because you had to move the cam you have to move the timing back to be the same so we're still at 34 degrees are we ready [Music] [Music] it did exactly what it was for so i think i think it tilted the curve oh yeah pumped up the torque 491.9 pound-feet of torque and 483 horsepower so drop some horsepower but what happened is when you switch the intake center line it changes where the intake valve closes build cylinder pressure earlier so you will sacrifice some top end but pick up some bottom and we were at 477 to 491 yeah and if we if we overlay them you can see where it is oh yeah you'll you'll be able to really see where it tilts there yeah look at that you could actually take the curve if you could unhook them from the screen and you just put them together it's the exact same pull it's just now it makes more torque down a little less power up top we can't get it any further on the on the other side so we couldn't go further and show a bigger gain because we've hit the valves at some point you can get these advanced so far you can really put the engine into detonation we're at 93 octane gas we're still okay so uh this is a great great illustration of doing this on the dyno to show what it does for power high performance engines live or die by ignition timing and when we're tuning our engines on the dyno we need a timing light that's both versatile and accurate one of our favorites is this timing light that we picked up from maco tools it has six foot detachable leads that hook right up to 12-volt power like our dyno battery and a spring-loaded clamp style magnetic pickup that is easy to put on and take off it has a rotating head for easier access into engine bays and one of the nicest parts of this light is the digital display the backlit screen is super easy to read even in direct sunlight and it has readouts for battery voltage timing advance rpm and even dwell it can show up to 90 degrees of timing advance and works on two and four stroke applications with 2 to 12 cylinders making it perfect for anything we throw on the dyno you can find this and any other tools you need at macotools.com up next the guys from music city trucks have a decision to make what do you think they will choose it's a no-brainer it's a no-brainer isn't it that's no brainer all right all righty guys the uh the engine is done we wanted you over here not only just to see it run but you're going to have to make a decision about how it runs if that's cool with you so here's the way it's going to be in the truck we used your headers and uh that does affect power and we've done some stuff with the cam that will affect power also you ready i'm ready you ready let's do it [Music] those short headers don't throw a little fire back out okay so that's what our power is now we fuzzed a little bit more timing into it and uh did a couple little things we're at 490 horsepower at 6300 but 492 pounds of torque 0.7 492.7 but look how flat your torque curve is right yeah okay i want you to keep that in mind you want power in a specific range now the first run that we've done with the engine before all this we had the cams intake center line in at 112 and a half which is two degrees so we've ran it like that to get a power number and then we take it and take in the cam and advance it as far as we can what is allowed by the actual equipment and now it's in at 100 so it's 10 degrees so we have 112 and a half degree swing on the intake centerline from very very you know uh advanced to uh slightly so um but what it does to the power is it tips where it makes power i'm gonna pull a graph up here on our first pull i'm going to overlay it while you're doing that i just want to say the engine looks awesome that's a frankie picasso there he uh man that looks good i'm going to get it to match your truck a little bit but it can't be dull so i had to throw a little something extra at it okay notice the difference in our graph okay if you took this graph and you unhook these two lines you could actually see their shapes you could squeeze them together and they're actually they make the same curve so the torque is high and it trails off down low right the power starts off higher and trails off up top with the cam in the position it starts off a little bit lower on torque but carries further and makes more power up top then that's around you know 5500 if you uh if you have the engine that runs below 5500 for the majority of its time it will absolutely make more average power peak numbers are one thing average power is more important 99.9 of the time so we can change it if you want us to change it back if you want this big number or if you want to leave it so you have more torque you almost have 500 pound feet of torque yeah i mean i like to torque more than the horsepower on that yeah well down low look how much more torque at say 3 500 it has i mean 455 versus you know 482. i know you're not you this this is comparing apples to oranges but what potentially would the difference in peak torque as you go lower in the rpm range be greater so it would it would exacerbate it more when when you have the cam that far advanced you're trapping air earlier in the cycle the the intake valve is closing sooner building more cylinder pressure we did a cranking compression test on it and it was from 170 uh with the cam in at 112 and a half to it was 205 pounds at uh at 10 degrees advance wow so on average below that 5500 mark we would be averaging at least 15 more pound feet yeah yeah possibly even more and lower in the rpm range that you didn't even sample right it has more torque and it has more horsepower it's a no-brainer it's a no-brainer all right changing where the cam's position is definitely affects where it makes torque and where it makes power oh yeah and i've seen entire cam swaps that didn't make that big of a deal yeah yeah so this is that's cool this was a fun one to do so uh we didn't want to hold you up too much okay you guys got stuff to do but uh we'll you'll see this in a little bit appreciate it thanks guys awesome for more information on anything you've seen today visit [Music] powernationtv.com

Channel: POWERNATION

Views: 608,033

Keywords: Car, PowerNation, howto, how-to, diy, automotive, cars, trucks, automobile, do it yourself, automobiles, auto, powerblock, engine power, horsepower, suburban, small block, engine build, first-generation Chevy Small Block, chevy, chevrolet, timing, camshaft timing, old-school stroker, 383 stroker

Id: wimUgFd0Qkg

Length: 21min 35sec (1295 seconds)

Published: Sun Apr 18 2021