I have a ’68 Barracuda with a 340 engine, and it is modified with the usual aftermarket goodies. The engine has no emissions equipment, and it runs just great. I want to further upgrade the engine, and I am now thinking about adding an aftermarket fuel injection system. I read about the FAST EZ-EFI, and it seems like a simple upgrade, with the injectors in the throttle body just replacing the current Holley carburetor, and the self-learning programming. I’m debating whether to go with this system, or just run a full EFI system with the injectors in the manifold. What are the pros and cons of the two types of systems?
Henry, FAST can provide you with either type of system, and perhaps your best bet would be to discuss the virtues of each with the manufactures by calling them on their tech line, 877/334-8355. The throttle body will be less complex, easier to install, and more cost effective. A full multipoint injection system will offer more tune-ability and more precise metering, but is a more involved conversion.
I have a ’72 Demon, that has accumulated quite a few miles, and a buddy suggested flushing the engine with transmission fluid. He is experienced with working on engines, and said it would clean out all the sludge and muck in the engine, and make it clean as new.
We drained the crankcase, added four quarts of transmission fluid, a quart of motor flush from the parts store, and a pint of diesel fuel. We drove the car for about an hour until the oil was working well up to temperature, and everything seemed normal. We then went and drained the oil and it was plenty dirty! We decided to repeat the treatment, and did the process all over again. We drained the oil again, and then changed the filter and filled the engine with 5-15 synthetic. This oil was way more costly than regular oil, but my buddy told me that these modern oils are way better and would give the engine more power, make it wear less, and prevent sludge from coming back.
Now my problem is the engine seems to use a lot more oil. I used to run about 600-700 miles on a quart, which wasn’t great, but now it uses a quart every two hundred miles, and the oil cost is three times as much as the cheap stuff. It seems like I’m getting some oil leaks too, and the engine is ticking like the lifters are making noise. Do you think I hurt something? Should I just change back to the old 20-50 Valvoline I used to run?
Jonathan, I hope running that witches’ brew didn’t do any real damage to the engine. Those kinds of old-fashioned backyard tricks are okay if the engine is a junker that you really don’t care about, but this is not something I would do to my Demon, even if the engine is tired.
The thin synthetic oil is much more likely to leak when put in an older engine, and it will often result in oil consumption. Another problem is that many of these modern oils are formulated for roller cam engines, and do not have sufficient additives for a flat tappet camshaft like the one your engine has. The tappet noise is what really has me worried, since it can mean a camshaft that is going away. If that is the case, you may be looking at a rebuild before everything is back to normal. I would remove the valve covers and inspect every rocker for clearance while the cam at TDC with the valves closed for the cylinder being checked. I would look for wear or scuffing on the cam lobes. If there is excessive clearance wear in any of them, the intake will have to be pulled and the cam and lifters inspected more closely. The only cure here is replacement of both the cam and lifters. If everything looks fine, I would suggest changing oil back to the heavier mineral based lube, and keep my fingers crossed that the noise and oil consumption clears up.
...many of these modern oils are formulated for roller cam engines, and do not have sufficient additives for a flat tappet camshaft like the one your engine has.
DART DRIVETRAIN SWAP
I have a ’68 Dart, with a Slant Six for power. Unexpectedly, I actually like the car with the six. Eventually I am going to swap to a small block, and have been gathering parts. What I have so far is a 360 and 727 out of a ’77 Dodge truck. I pulled the 360 apart and re-ringed and re-gasketed it, and added a Crane 272 Powermax cam. I had a valve job done, milled the heads .040-inch, and added 2.02-inch intake valves and new springs. The engine was detailed, and it is now sitting on the engine stand with a Performer RPM intake and 750 AFB carb.
I cleaned up the transmission, and installed a shift kit. I also threw in a new filter, and think that is all it will need. For the rear, I had trouble finding an A-body 83⁄4 that fit my budget, but I found a complete A-body 81⁄4 and added a limited slip. The rear has 3.55 gears. I also got a complete K-member from a rusty V-8 Dart, along with the motor mounts. I have a few questions though. How much power do you think my 360 will make? How can I increase the rpm at which the transmission shifts automatically at wide open throttle? I know stock, these truck transmissions shifted at about 4,000 rpm with full kick down, and would like to step that up. Finally, do you think the 81⁄4 will be enough rear?
Peter, I think the stuff you’ve gathered together will make a really nice street machine. A 360 like the one you’ve put together should make 320-350 horsepower with headers and offer very good drivability. The upshift speed of the transmission will be higher than stock, due to the increase in line pressure from the shift kit. If you want more, your best bet is to go with a higher upshift governor. As for the rear, if you’re planning on really beating it up at the strip with drag slicks, it might prove marginal. However, on the street with an automatic it will live a long and healthy life.
FRUSTRATING VALVE FLOAT
I’m the owner of a ’78 Aspen with a four-speed overdrive manual transmission. Up to this point, I’ve replaced the 318 engine with a 400 horsepower 360 with an Air Gap intake, added headers and exhaust, Edelbrock aluminum heads, and a hotter camshaft. To keep up with my results, I’ve become a regular at the chassis dyno, and currently the engine is producing 303 horsepower at the rear wheels. Without a doubt, I think these Mopar small block engines are the best bargain for performance since the big blocks of the ’60s.
During my last dyno session, which by the way was the occasion when the engine finally crested the 300 rear wheel horsepower number, there seemed to be a high rpm problem. At roughly 6,100 rpm, the power curve dropped off sharply, with the engine definitely sounding unhappy. My tuner identified the problem as valve float, and limited any further pulls to below this rpm. I’ve heard the term valve float before, and know that the answer is usually an upgrade in the valve springs, but am not really sure about what causes this condition, technically speaking. Can you provide some information on valve float, and if possible, provide me with a recommendation on what valve springs to get to solve this problem. I think the engine will make even more power if I can get it to rev higher. Thanks
Louis, valve float is kind of a broad term for a loss of control in the engine’s valvetrain. Operating the engine above an rpm where float occurs, creates the potential for catastrophic engine failure, so it needs to be avoided or corrected. The ability to maintain valvetrain control is one of the challenges and limitations in pushrod engine performance, and as a result, it is one of the most highly developed areas of an engine. Starting with the basics here, in a pushrod engine, the camshaft profile determines the motion of the valves by virtue of the shape of the lobes. The tappets (lifters) are raised and lowered by the lobes, which in turn operate the pushrods, transferring the motion to the rocker arms that actually operate the valves. Essentially, the valvetrain in a pushrod engine represents a system of linkages to connect the valves to the camshaft, providing the mechanism to open the valves. The valve springs act against the valvetrain to control the system and close the valves.
As rpm increases, the demand on the valvetrain becomes exponentially greater. Any part of the system that imparts false motion or instability can create or exasperate problems with valvetrain control. Classic valve float is a situation where the loads provided by the valve springs are not high enough to ensure that the valvetrain follows the profile of the camshaft accurately. Typically, insufficiencies here will show up as the valves bouncing or oscillating on the seat upon closing. It also allows the lifter to lose tension on the camshaft as the lobe goes “over the nose,” or through the full-lift position, changing direction to begin closing. With more rpm or more intense camshaft profiles, the inertia of the valvetrain components becomes higher, resulting in higher demands on the valvetrain. So the key factors to balance are valvetrain inertia, vs. the countering valve spring loads.
Clearly, more spring load is the most obvious solution to valve float problems, however, there are other factors at play that affect valvetrain control, such as inertial and deflection. A reduction in valvetrain weight can reduce the demands, via a reduction in valvetrain inertia. The Mopar small block engine offers plenty of room for improvement with things like lightweight valves, springs, retainers and low inertia rockers. Improvements to the valvetrain can be accomplished with more refined aftermarket pieces, such as titanium retainers, and aluminum roller rockers. False motion stemming from deflection can be reduced with stiffer pushrods and.
To summarize, a successful valvetrain utilizes low-deflection components, is light weight, and has adequate spring loads. Actually, there is a further level of complexity involved in the dynamics of an operating high-rpm valvetrain, where other sources of false motion such as valvetrain harmonics and spring surge are explored. Top aftermarket firms invest in sophisticated testing to help design their components to minimize the negatives of these effects. Cutting-edge designs such as Competition Cams’ “beehive” valve springs are the result of such development.
HITTING THE BAR
I am restoring a ’64 Polara, and I need to get the torsion bars out. I am going from the stock 318 to a 426 Wedge. Do I need to replace the torsion bars with bigger bars for the bigger engine? If I do, I can hammer them out with the pipe-wrench method, or will need the special tool to remove them properly. Where can I get the tool? Also, what is the maximum “safe” cylinder bore for that engine? Currently it is 4.25-inch
Bill, I like to remove the tension by backing the adjuster all the way off. I then remove the shock, and take the nut off of the lower control arm pivot shaft, and at the strut rod. Remove the clip at the back of the torsion bars. To make things easier to handle since you are going to go through the whole suspension, you can separately unbolt the brakes, and then detach the lower ball joint and pull the upper a-arms and spindles. You can then just use a large pry bar to push the lower control arm along with the torsion bar back until the bar pops out of the rear cross member once free at the rear, the bar will usually slide easily out of the lower control arm socket. If not, some taps forward on the socket where the bar goes in with a heavy brass mallet will free it. I found this system to work much better than the factory tool.
About the over bore dimension, I wouldn’t be looking for the “maximum” overbore, but the minimum. Since it is a factory bore now, you should be fine with a clean-up overbore and rebuild. If your plan is an unusually large overbore for a substantial increase in displacement, you are going to need to have the block sonic tested to find out how much meat is available.
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