Will There Be A Big Power Difference On A Mildly Modded AMC 258 Straight 6? - Engine Power S8, E1

Hello guys, thanks for watching our programs. We are very close to reaching one million subscribers and we would love you to help us. Hit the subscribe button, take us there, and follow us on Instagram to stay up to date with the latest giveaways and contests. like the corvette, you can enter to win right now. Stay tuned for more technology you can use. If this old postal jeep is going to go from hauling mail to hauling it, he'll need some

engine

work or at least a spray overhaul. Welcome to Engine Power, today we have another Dare to Be Different project in the workshop to see what we can improve.

We always give a lot of love to the big three manufacturers on our projects and that mostly consists of two pushrod v8 valves because that's what is commonly used on hot rods, but we've proven that pretty much anything can be upgraded to hot rod status. rod with the correct assembly of parts and a good old-fashioned dyno session. That said, there is one automaker from the past that sometimes gets overlooked. but it has produced some formidable

power

plants that can hold their own. That company is amc american motors corporation had its own entries in the muscle car field with high performance models like the javelin amx rambler rebel and the hornet, just to name a few V8s ranging from 290 cubic inches to 401 cubic inches place them right in the middle of the horse

power

wars of the late '60s and early '70s, unfortunately this is not one of them, what we have here is a simple and

straight

forward 232 cubic inch six-banger.

It has the same basic architecture as the more popular 258, which later evolved into the modern 4-liter variant that powered several Jeep models until 2006. This particular power plant was removed from a late 1990s Postman Jeep. 70 rough-looking building found in The Building at the moment Carcass has some interesting plans for it. Our first task is to see if it works and then make some simple improvements and hand it back to the guys at Carcass who are helping out today. He is the newest member of power. The national team's Frankie Foreman graduated from Unoh, where he built

engine

s for the school's dirt track and drag racing teams.

We had a 4 liter jeep on the superfloat docking car a few years ago so we know this amc

will

bolt up great. We use the jeep. 4-liter flywheel because this engine was originally paired with an automatic transmission. I have it. You're like a bull in a china shop, regardless of the engine. It was like a clean floor to see where it dripped and from where, so it's spicy. Right there, I should probably take out this flow inhibitor because it's an older engine. The dyno setup is very simple and smooth, with one small exception, to get the stock throttle linkage to work on our dyno, we had to do some soft fabrication on an angled piece. aluminum and some one inch dom tubes create a support and spacer, full throttle, I can feel it, yeah, well loaded, yeah, that's pretty smooth, full throttle, oh, that's more than I expected, damn Wow, that's more than I expected. 88 horsepower. thinking like 60 maybe like oh I didn't mean that's something cool, 171.8 lb-ft of torque, remove the air filter but at the same time cut the exhaust, oh yeah, cut it, cut it in front of the muffler and Run it again now , I'm not saying I'm going to do anything with something that makes this kind of power, but it hurts, oh that's more, oh yeah look at that, oh and it still has 97.8 oil pressure and 178 lbs. -foot, I know.

It may sound crazy, but if we're going to try to eliminate some energy-stealing things, take away the fan, something to make these guys read my mind, yeah, it definitely charges better without the aerodynamic system, what do you think of that? So crazy, yeah, that's amazing, that's amazing, 101 horses, 182 pound-feet. I knew I had it by removing the fan. We backed that run and the numbers were consistent: 101.8 horsepower at 3600 and 183.1 pound-feet of torque at 2000. The next few years of dirt and grease we found a pleasant surprise, then refreshed the amc and put it back on the block. cells with a modest max power of around 100 the amc inline won't surprise anyone but what's impressive about this engine is how well it runs after all those years in a postal jeep as we don't want to break the block but we do We want to know if the cylinders are sealing well, we decided to do a compression check, the numbers look great.

When trying to remove decades of built-up grime, you'll need all the help you can get, so we grabbed a can of CRC Pro Strength Degreaser. Dissolves oil and grease, but is still safe for painted and plastic surfaces. It is waterproof. based leaves no residue and is biodegradable after letting the degreaser soak for 10 minutes we pressure washed the engine the results were impressive it is much better yes it took a little work but it is all clean now it sounds like if something had broken, well we have our first broken part, look how this one goes holy, they are in good condition so it is definitely a reuse and although it is a little rusty, it is a relatively recent water pump, very nice , half the time when you are destroying something you

will

find other things. what people have done may or may not be right, like this bolt was too long, it bottomed out and started to come off, that's why it looks like it's all gold on one end, same goes for half of the other fasteners that have been rounded. or whatever is typical of high maintenance things, like a racing gutted male jeep thermostat that is sometimes used as a restrictor, but I didn't know male jeeps got that hot.

I love the reveal about the valvetrain because I know how this thing works so it's Always nice to see what it looks like besides being dirty it looks fine interesting that only a few seem to be lubricated the others don't get any oil and it still worked well and sometimes didn't make any noise when working on old vehicles. things are not always what they seem, for example this engine when the power was removed and we looked up casting numbers, it is actually not a 232 inch engine but a 258 which is great because it will run better with the changes that we plan. doing but to make those changes we have to continue with the disassembly and that means removing the cylinder head.

You can see that the oil cap was changed once because the boxes that hold it there is an extra one so that it does not get chewed. but it's not supposed to have a cup. This is what you're not supposed to see at the bottom of a flat faucet. The lifter is not supposed to be concave even though the engine was running fine, we are seeing some discouraging signs. like the worn timing chain and cupped lifters, although this project is called an aerosol overhaul, we'll have to dig a little deeper into the 258 to find out the true condition of this power plant.

Next, what started out as a spray overhaul gets a little more complicated, the original plan for this six-cylinder was to clean it up a bit, put some cool parts on it, and return it to the guys and the shell, like any other hot rod project. , things change quickly the deeper we dig into this. The project was getting worse, so we made the decision to renew it a bit, rings and bearings, and although it's not a racy V8, we knew we could get all the parts we needed at the peak races, this adds a bit of cost and time to the build. build, but it's worth it considering how the old parts look, so we went ahead and polished the crankshaft and polished the cylinders for a new service and put in our new parts since we had to replace the camshaft.

Anyway, we decided to go with something a little sportier, so we called Summit Racing and got a complete cam kit. It comes with everything we need. This is a hydraulic flat tablet and the duration at 50,000 on the intake is 206 degrees and the exhaust is 212. with 113 degrees lobe separation it also comes with retainers and timing gear spring locks plus lifters , everything that matches the profile of the cams. As for lift, we're going to have a little bit more because we decided to use our 1.7 ratio rocker arm, so the lift at the valve is around 500k. This hydraulic flat cam tappet requires specific lubricant on the lobes for proper break-in and comes with the kit on the journals.

We are using break-in oil. Timing clearance is not adjustable. but we still go ahead and grade the cam, it comes in at 110 degrees from the intake centerline, which is three degrees advanced dramatically, the freshly sandblasted original timing cover bolts up, followed by the clean original harmonic balancer and painted, more lubricant is spread on the bottom. of the lifters before assembly, they are then gently placed into the lifter holes, it is tempting to use a magnet to install them, but if the magnet has attracted small metal particles, they can end up in your engine, the original replacement head gasket is the Next, there are no pins to align the gasket so you have to do this by hand, go slowly and check your work making sure both the gasket and head are properly aligned, only one bolt from the head goes to the water jacket , must be sealed with thread sealant, the head is Tightened in three steps to a final value of 100 foot-pounds using high pressure lubricant, the original pushrods ended up being the correct length, so they go back in.

These scorpion full roller rocker arms offer greater durability and less friction than the stock rocker arm configuration they have. It's a bit overkill for this engine, but if more high-performance modifications are made in the future, we'll be ready to go after the rocker arms are torqued to 30 foot-pounds, the valves are adjusted a half-turn past zero play before the oil pan cork gasket comes loose. down below we'll put some black weatherstripping adhesive on, the rubber end gaskets are next, finally the original tray continues, we now have the engine reassembled to a point where we can apply some colour, hence the name spray review what do you think because the the intake and exhaust are on the same side they share a gasket the pegs will keep it aligned the boss header has to work first it's a six in one style with a primary tube diameter of one inch and a half for induction which we chose to splurge a little on Offenhauser's dual port 4 cylinder intake manifold ensures the intake and exhaust bolt flange height is the same on both pieces so the manifold bolts on cleanly and seal properly.

We are using a one inch spacer for linkage clearance for the good street stuff we are running. A 450 cfm QFT carburetor with an electric choke from where we started to where we finished, we made a big improvement, we did it, we did it, we hit the dyno room to see what the AMC 258 will do while keeping the timing accurate. As a billet distributor for MSD Pro along with their 8.5 millimeter superconducting cables, we also installed a new MSD Blaster 2 coil. It won't be used for dyno testing, but we'll see a lot of use later on the street.

Well, here comes some fuel. Once the fuel level has been checked, we will start the engine and adjust the timing to 32 degrees. We will check for leaks and break the flat tappet cam. That's a good time to let the paint on the head burn off and also run the engine smoothly. 1500 to 2500 rpm cycling it for 20 minutes, okay, so we're ready to race again here, if there is such a thing, okay, here's the deal: We initially thought this engine was a 232, because that's what It said on the fender, the problem with that. It was only made like a hundred horsepower and like 180 foot-pounds?

We talk about very little 180, but it's actually a 258, we actually cleaned and measured everything, so it made the engine even duller than it was before. it was wasted, we had to put some parts on it, re-ring it, bare it again, polish the crank, easy stuff, we didn't change a piston or anything like that and we put a couple of things on it like the manifold and the faster rocker arm of the carburetor. but we had to put a camera on it anyway, so we put a slightly bigger camera. 206 to 50 is not a big cam by any means so any predictions of what it's going to do other than telling you the truth, I don't even know what it's going to do because it's not a big motor, I'm going to 158.

I hope it works , yeah, I was going to say somewhere, I think that's probably a fair assumption, so now we have 32 degrees of total timing, it's a 450 cfm qft carburetor, a very good carburetor, so it's sitting here at idle at uh 14, approximately for air andfuel, so it works fine, it responds, yeah, here we go, okay, that's not bad. What did you do? let's say it was 158 oh 158. look at this, yeah 156 that's pretty good it's kind of dumb on the bottom just because the new carburetor isn't tuned for the application we'll have you retune for that because it's, uh it's got a little bit bigger camera we're going to have to adjust it a little bit but it's nice and smooth 156 at 4500 that doesn't fall out at all wow amazing I'm impressed it's super easy super simple I mean. the jeep itself isn't much to begin with, right, we didn't ask for much less much better, that's what we thought we wanted to get running again, so this is a little better, I think we're going to put a little bit of timing, uh right now, 32 degrees, we're going to jump to 34 degrees sync, so okay, we'll do it right now because this is low compression, it's going to take some time, so here. we're going good it did 216 lb-ft at 3500 160 at 4500.

Awesome that's great oh my gosh oh my gosh I love doing this stuff and yeah you broke 200 with torque yeah we broke I mean , the torque is good, um. we broke 160 on power and are still going up as the jump to 34 degrees full sync worked great, we're going to advance it to 36 degrees full sync for the next run. Wow, it sounds better, yes, much better. Oh, I did. the Pokey fool up there, right at the top of 217 foot-pounds, although that's okay, I mean, we'll take it, I don't think so, because look how he gained a little bit, okay, I think we're there in time, but what? did you know? let's do it now, let's turn it up, see if we can get this, they'll make 5000. so, you're starting to pull at 25 yup and you're taking the brakes off. back a hole at 5000 okay, this is going to sound a lot spicier are you 100 percent ready?

I know I get emotional and I swear I don't do drugs I just drink a lot of coffee okay here we go it was kind of complaining about things with low cylinder pressure like this this has a calculated compression and a measured compression ratio from 8.13 to 1. When you drive something with this amount of power that is low, any incremental change is a big percentage gain, okay, so we were at 101 horsepower. Before now we were at 162. That's our power

difference

there, holy cow, now it's a different engine or it's a different engine. Wow, that's awesome, that's fun, but all said and done, that's a bad little guy, I don't see it.

Why wouldn't that work perfectly for us? Yes, any increase is huge for us. Now the paint job was my idea because the Jeep is green and I wanted to look cool when you open the hood and say, "Oh my God, you know I'm not." Hoping this is there, you know, and it'll also run a little sportier than it's supposed to, so, yeah, I think it'll be a perfect engine for us to cruise if you compare where we started and where. We end up with the slightly modified 258, which has a little more than 61 horsepower and 31 pound-feet of torque at its peak and average power from 2500 to 4500 rpm increases by more than 41 horsepower and 68 pound-feet of torque, which is a nice gain for some.

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