I have a ’69 Coronet wagon. The odometer reads 67,000 miles, and the car was regularly serviced and garaged. I couldn’t leave well enough alone and began modifying the wagon shortly after I got it to make it into a cool street cruiser. First, I lowered the suspension all around, and then I added a nice vintage set of mag wheels and 235 60R-15 front tires to the front, and 275 60R-15 tires to the rear. Next, a shift kit went into the factory 904 transmission, and finally, my attention turned to the engine to get more power.
The car originally came with a 318 two-barrel, and I found a Holley double pumper 750 and an old Edelbrock Torker 340 intake. Since I was working on a tight budget, and the price on these parts was a deal, I soon had them bolted to the 318. Next, I added electronic ignition that I pieced together from OEM parts, and a new control box. This seemed to help, but the single exhaust was restrictive, so I added Hedman Hedders, and a 2½-inch exhaust system with Flowmaster mufflers. This really woke the 318 up and I was pretty happy with the improvement, but I wanted some more cam to give the engine a lope at idle. I went with an MP “Hemi Grind” cam that a buddy ran for a while in his Duster, until he switched to a solid, and added a set of 360 heads.
The little 318 now had some serious attitude, but I found the low-end to be soft. It wouldn’t even burn the tires. The car had an 8¾ rear, so I swapped the gears to 3.91’s and added a 3,000 rpm stall converter. Now it could smoke the tires, but the car just sucks down the fuel. I can’t believe that a 318 wouldn’t do better, even with the performance modifications. Cruising around, the wagon gets me an average of just around 8 mpg, which seems to be worse than a big-block. Before I messed with it the car would at least get me in the mid teens in mileage. I love the wagon, but with gas prices where they are, I can hardly afford to drive it anymore. Is it a lost cause, or can I improve the economy of the combo?
Frank, that big wagon and that combo is not going to be the best setup for fuel efficiency. I have to say that the parts selection you went with doesn’t help matters, from the double pumper carb to the single plane intake, to the deep gears and converter, and then the long duration MP cam. You pretty much have put together the anti-mileage combination. The fact that the stock 318 was fairly low compression and the big-chamber 360 heads dropped the ratio by about another full point is just the icing on the cake. If you want to keep the 318, you really have two choices right now, and that is to either try to make the best of the parts you have, or start over with a parts list that will result in a more efficient engine.
Looking at the first option, you really have to work on the tune. Those old double pumpers were notoriously heavy on the fuel use, and it will take more than a simple jet change to really dial it in. You are best off with a wide-band lambda gauge, and a good Holley tuning book. You can also expect a serious effort to dial it in. The ignition will also need work, particularly with a low-compression engine and a stock distributor. You are going to need way more advance at initial, and a much shorter mechanical advance, maybe as much as 18-28 degrees initial and 36 degrees total. You are also going to have to dial in the vacuum advance. Finally, the cam would benefit from about 6-degrees of advance, putting it in at 102-degrees intake centerline. I am confident that the tuning changes alone can net a worthwhile mileage increase.
The other option is a full rework of the combo. Since you mentioned that you were working on a tight budget, I’m not sure of how practical this would be, but I would start with a set of small chamber heads to get the compression up. An Enginequest iron head would give you a tight chamber, and flow better than the stock 360 heads. Next, a two-plane intake will be better than that ancient Torker. The standard Performer will get the job done, but even a RPM or AirGap intake is better than the single-plane. The Holley double pumper will be hard to work with for economy. As a replacement, I have found the Edelbrock AVS to be very good in efficiency when tuned. Then, we have the MP cam. A stick with 20-degrees less duration would definitely help the fuel consumption situation, but you might lose that boulevard lope. Finally, you can attack that deep gearing a few different ways to cut the rpm. You can do this with an overdrive swap, using a 500 or 518 four-speed, or by adding a Gear Vendors overdrive to your existing trans. Even if you make all of these parts changes, your results may vary, since the tune is one of the most important factors.
Valve Clearance Clarification
I have a ’73 Duster that I’ve been building into a strong street/strip machine. The car was originally Slant Six–powered. I built a 408-inch stroker combination, and the engine has stock Edelbrock heads, dished pistons for 10.0:1 compression, an Edelbrock AirGap intake manifold, old style Holley 950 HP carb, and a solid flat-tappet Crane Powermax cam, with 238/248-degrees duration at 0.050-inch, and .480/.500-inch lift. My question is about setting the valve lash. The instructions from Crane call for 0.022-inch lash on both the intake and exhaust. I have the old Direct Connection manual, and there are a couple of different procedures that I can follow for setting the lash. The one I use is called the Four Position method. There is also the Eight Position method, and either way, it tells you where to park the crankshaft and then which valves get adjusted.
I use the Four Position method because it involves less turning of the crankshaft, which is hard to get to. I hear that the Eight Position method is more accurate, so I’m wondering if my engine would like that better. What do you think is the better system?
John, either one of those systems will work with your cam, and really are just shortcuts based upon lobe positions versus crankshaft position. The key is having the cam lobe on the base circle where the lobe has no lift while it is being adjusted. The base circle comprises a very broad sweep of a given cam lobe, so it is a pretty big target. There shouldn’t be any variation in the base circle diameter, so either method will likely provide the same result. The problem with those methods is that it is tedious turning the crankshaft to the right spot, and then you have to be careful not to get mixed up on which rockers to adjust. Direct Connection and MP used to sell an under hood decal that were popular so that the valve adjustment reference was right there in front of you while you adjusted the valves.
I prefer to use another technique which is quicker, easier, accurate, and doesn’t involve all that wrenching on the crankshaft snout. The system is the exhaust opening, intake closing technique. Looking at the pair of valves for any cylinder, when the exhaust valve begins to open, the intake on that cylinder is always on the base circle, and can be adjusted. When the intake valve reaches fully open and begins to close, the exhaust valve on that cylinder is on the base circle and can be adjusted. I use a remote starter button and just bump the engine around, starting with number one, and do all the intake valves following the firing order sequence, and then go back around and do all the exhaust valves. This is the way most professionals set the lash. It saves time, and minimizes the potential for mistakes.
Headers or Manifolds
I have a ’71 Challenger that originally came with a 383, and now I’m fixing to drop in a hot 440. The 440 has the Stealth heads, a Comp XE285HL cam, JE flat top pistons, and a factory forged crankshaft. It also has a Performer RPM intake manifold, and a Quick Fuel 850 mechanical secondary carb. The ignition is MSD, with a billet distributor and a 6AL.
Even though the engine is built, I have painted the heads and intake stock orange, and I am going to run the stock dual-snorkel air cleaner. I have the stock valve covers off the 383. What I am undecided on is the exhaust. I am trying to decide between using the stock exhaust manifolds, or run a set of Hooker 17⁄8-inch headers. The stock manifolds from the 383 Magnum are the HP type, and I think they are the same used on the 440 engine. I like the idea of manifolds, because of the stock look, and also to avoid the hassle of header leaks. I’ve been told the HP manifolds flow just about as good as headers, and that there wouldn’t really be much power difference. What do you think?
I hate to say it, Jason, but the manifolds are going to be giving up a significant amount of power and torque compared to the headers. Even on a stock 440 Magnum, headers are good for about 30 hp and torque throughout the curve. On a modified engine with much more cam and the other mods you have, the difference can be 50-60 horsepower or maybe more. There is no question that the headers flow significantly better than those stock HP manifolds. However, there is more to the added power from headers than just the flow. The length of the pipes helps scavenge the cylinders, and improve the cylinder fill. This effect is magnified with more cam timing and overlap. That said, if you are intent on the stock look of the manifolds, you engine will still be a strong combination, but be assured that the power will take a big hit compared to the potential with headers.
I have a 440, and am thinking about making the change to a solid-lifter cam. The cam in it now is hydraulic, a Comp XE269H, and I am thinking about swapping to a Mopar 528 solid. When the engine was built, I got new factory-style stamped steel rocker arms. These are supposed to be the heavy-duty version. I think I can change to the Mopar solid cam without having to switch my Comp number 911 valvesprings. I would also like to keep the same rockers. I have an old set of adjustable Mopar pushrods that will fit, but would like to know if you would recommend using them instead of getting new rockers.
Clive, if you are asking if it is possible to run the adjustable pushrods, I would be forced to answer yes, but I definitely would not recommend them for a solid cam. The adjustment is just not precise and positive enough, and the second problem is I have to question the long term durability. I would strongly recommend changing out the rockers and getting a matched set of pushrods.
I just read the April ’13 issue’s Performance Clinic, “To Stroke or Not.” I am putting together a stroker LA 360. I’ve got a 4-inch stroke forged crankshaft, 6.123-inch Eagle I-beam rods, 360 Magnum heads, an Edelbrock 750 carburetor, Air-Gap intake, headers, and a recurved distributor, with 30-degrees of advance that is all in by 1,500-1,800 rpm. What cam would you recommend? This is going in a ’73 Challenger street car with an automatic, and a 3:23 rear.
Mike in Iowa
Mike, it is going to be pretty hard to give you a direct recommendation without knowing a little more about what you want from the camshaft. The first question that needs to be answered is what kind of camshaft you want, hydraulic, or solid flat-tappet, or hydraulic or solid roller. For a true street application, either flat-tappet, or a hydraulic roller will all work quite well, depending upon your objectives and budget. I would stay away from a solid roller for a real street application. A solid flat-tappet will give the most rpm potential of the remaining choices, though with a stroker engine and the relatively small cylinder heads, your engine will want to make peak power at an rpm range below where a solid’s benefits really come into play. This leaves the hydraulics, in either roller or flat tappet configurations. Many builders do prefer the hydraulic roller, and there are advantages in a build like yours, such as the potential for making more power and virtually eliminating the potential for premature cam failure. However, a hydraulic roller is much more costly than a flat tappet. I’m going to have to take a shot here and presume you want to go with a flat tappet.
The next question that needs to be considered is the engine’s specs. Again, this will depend upon what you want out of the engine. If you are looking for a relatively smooth, stock-type idle with plenty of torque, something in the 214 degree intake duration area would do the job. The Crane PowerMax 272 is one that I like for this kind of application. Stepping up from there, a cam in the 224-230-degree duration at .050-inch range makes a good streetable cam. Here the Comp XE268 or the higher-lift offerings from Hughes Engines work well. On the other hand, some guys want a hard-hitting cam with lots of lope. If that’s what you are after, something in the 240-250-degree duration at .050-inch range will make the noise. Of course, the bigger nastier cams will want more converter stall, and deeper gears would be a plus. I’d suggest getting in touch with the cam manufacturer of your choice and going over your end goals in more detail to find a stick to get the job done.
I recently took my Dart out for a test drive, and the heater core started to leak, causing my engine to overheat. I was able to get it off of the road before any major damage happened, but now when I start it, the bearings rattle for a second or two, and the then it stops while idling. They rattle more when revving the engine up. I had a mechanic pull the pan, and he said the crankshaft (it is forged), has blue heat-marks on it, and that it should be replaced. This is a big hit to my budget. All the info I can get on the net is that blue marks are normal. Will it be ok to just replace the bearings and keep rolling with the same crankshaft?
James, I can only go by what you are telling me, and that is that you got it off the road before any major damage occurred. To me, this means that it was shut down before getting really hot. If you got it hot to where it would do damage to the crankshaft, it had to be heated to the point of nearly seizing the pistons. At that point, the oil in the engine will have been so hot, that it would be bellowing smoke from the breathers due to overheated oil. This kind of heat can cause the oil film to break down and blue the journals, and if it is that hot, the bearings will be toast, and the rings will have also likely overheated and lost tension. You are not going to get that kind of damage if you didn’t get it really hot.
I would personally inspect the journals, and see the extent of the heat damage, along with the condition of the bearings. From there you can decide whether you really have blued the journals. If so, the bearings will normally be severely heat damaged, and you will have to decide if you are willing to try and patch things up with just a fresh set of bearings, or go in for a full freshen of the engine. The bottom line is this, if the journals really did get that hot, you will be wise to go for a tear down and rebuild.
I have a ’72 Charger that originally had a 318 engine and a 904 transmission. I got a 440 out of a mid-’70s motor home, and built an engine with about 500 horsepower. The engine features flat top Probe pistons, H-beam rods, Edelbrock heads, a Comp hydraulic cam, and an Edelbrock RPM intake with a Holley 950 HP carburetor. I put in a 727, and an 83⁄4 rear. The thing that has me worried is that the driveshaft has the smaller 7260 U-joints. I know the big-block cars had the big 7290 joints, which I hear are much stronger. I already have a yoke for the larger joints in my junk pile, but I am worried about the rear. Even though it is the 83⁄4, it has the small yoke. It is a 489 case, which I understand uses a crush sleeve to set the pinion bearings. I am afraid to pull the yoke and mess up the gear set up. On the other hand, I am worried about spitting out the driveshaft. I never run the car on the strip, and only tear around the streets on 275 60R-15 tires. I was told on street tires I should have nothing to worry about, but I can’t help but want to upgrade.
Frank, I would definitely feel better about the bigger joints, especially if you are regularly hammering on that heavy Charger. I would bite the bullet and upgrade the driveshaft if it was my car. In fact, I would also suggest replacing the crush sleeve in the centersection at the same time with a solid spacer and shim arrangement. Although this was not a stock arrangement with the 489 case, you can get a kit for this upgrade from rear end specialists such as Randy’s Ring and Pinion. Use a high quality U-joint and you should never have a problem with this setup on street tires. The solid spacer will help the rear sustain a much greater level of abuse without failure. mm
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