Think you've taken on a big job? How 'bout this photo from the guys at Goodmark Installati
Rust Never Sleeps
Scott Jordan, Columbus Junction, IA: I recently acquired a '71 Nova that was about fenderwell deep in a pasture. The car is relatively sound with the floorpans and the front frame among the pieces that are OK. However, the driver-side rear framerail is rusted clear through behind the shackle, thus causing the bumper mount to rust out as well, and now the bumper is falling off. How hard is it to replace a framerail like this? Will I need a full rail installed and then also have to have a piece fabbed up that ties both sides into each other? I ask this because I can't find a shop that supplies the piece that includes the bumper mounts. I'm capable of doing most repairs, however I have never had a body off a car and would rather not try to do it either. What are my options, and where do I look for parts? I live in Iowa, so the selection of people doing major projects like this are few and far between. Any help would be great!
Jeff Smith: We talked to Craig Hopkins at Goodmark Installation Center (Goodmark, the sheetmetal restoration company) about saving older musclecars from the ruthless ravages of rust. Hopkins had some great suggestions that can save your Nova, Scott. First of all, a Nova is not a full-frame car like a Chevelle or an Impala. The Nova uses a removable subframe in the front, but the rear "frame" is really a unibody design where the rear framerail is integrated into the sheetmetal floorpan that supports the rear of the car. This repair will require some cutting and welding, so grab your cutoff wheel and MIG welder and follow along.
First, you will have to find a donor car because you are correct that no one makes replacement framerails for these unibody cars. As far as we know, Nova rear subframes from '68 through '74 are all the same, so look for a car that has a nice framerail in the area you need. If you really want to use new material, we know that Detroit Speed offers new framerail sections as part of a minitub kit. You might be able to talk them out of some material, but double-check the size before you buy. Or, if you have access to a sheetmetal supply company, it's possible you might be able to find a section of rectangular tubing close to the size you need, and then it could be sectioned and welded to fit.
Assuming you use a donor-car frame piece, this rail section will have to be removed. The best way to do that is with a cutoff wheel and an air-operated die grinder. Short of that, you might get by using an electric Sawzall with a metal blade. Cut a much longer section than you need to replace, with at least 2 to 3 inches ahead of where you intend to splice the new rail in place. This will give you room to trim.
Next, support your car with jackstands and remove the rear bumper, gas tank, and complete rear-axle assembly. Before cutting the old section out of the car, Hopkins suggests making multiple triangulated measurements to establish the precise location of the old framerail so the new rail will replace it accurately.
Here's where we test your fabrication skills. Hopkins recommends building a sleeve that will fit inside both the new rail from the donor car and the end of the existing rail in your car. This sleeve needs to be 2 inches long and can be made out of a portion of the donor framerail or out of new sheetmetal. If you are using a portion of original framerail, it will require sectioning the rail down the middle in both directions (vertically and horizontally) to make it smaller so it fits tightly inside both ends of the framerail splice with roughly a 1-inch overlap. Once the sleeve is constructed, drill a hole in the top of the old framerail that will be intersected by the sleeve. This will serve as a plug-weld connection. If it is not possible on top of the rail, the next best place would be the bottom. This plug-weld will maintain proper position on the sleeve and serve to improve the strength of the repair. Don't weld yet, however.
Test-fit the new framerail and clamp it in place. Hopkins suggests leaving a slight gap between the original frame and the repair that will ensure sufficient joint strength. With the sleeve, this will easily become the strongest portion of the car's rear subframe. Duplicate your measurement technique to ensure the new framerail is properly positioned. This may also include the rear shackle mount for the leaf spring. It might even help to make sure the bumper will bolt up. If you are within 11/48 inch of the original factory specs, this is probably better than the factory performed back then. After tack-welding the repair in place, you can perform the plug-welding and then measure again to ensure nothing moved. With everything square, the entire repair can be welded, with attention paid to not putting too much heat into any one area. If aesthetics are important, you can grind the welds down slightly, but not enough to sacrifice weld integrity.
Finally, we'd suggest blasting and painting this entire area to prevent further corrosion. If all this is too much work for you, we're sure there are body shops in your area that could handle this effort, especially if you located the donor framerail. But don't be intimidated by the fab work. Consider this: For the amount of money you would spend to have a body shop do the work, you could afford to purchase a 110-volt MIG welder from Sears/ Craftsman, Lincoln, Miller, or any other reputable welding company and own the welder once you're done with the project. We did that several years ago with a trunk floor repair with very little prior MIG-welding experience. Who knows, you may actually enjoy the experience of saving your car with your own two hands.
It's a Dog
Eliot Stepka, via CarCraft.com: I am 17 years old and seeking advice. It has taken me two-and-a-half years working on and working to pay for my '70 El Camino to get it to this point. It runs and drives now. I am having some problems tuning my motor, a '99 5.3L Gen III. I converted it to a carburetor using the intake from GM Performance Parts for the LS motors along with the standalone ignition system from MSD. I am also using a Holley 750-cfm vacuum-secondary (PN 80508S) with 70 primary jets with a 65 power valve. In the secondaries, it has a fixed metering plate with no power valve and a 25 squirter on the primary side. I have tried tuning the carb and changing the timing chips, but nothing seems to help. It sounds great when it's not under load, but when I drive it and nail the throttle, it falls on its face. I've also discovered the secondaries are not opening, and I know the vacuum diaphragm is OK because I just changed it and tried a softer spring and it does not seem to help. It has 20 inches of manifold vacuum at idle. Can you think of a reason why the secondaries aren't opening?
My drivetrain is a race-built TH350 with a custom-built adapter converter by Cone with a 2,000-stall. The rear gear is a 2.73, so I know it's not going to be perfect, but it should still light them up. It also has custom-built headers from Street and Performance in Arkansas. One of my concerns is the vacuum system. I have a T running off the back of the carb to a PCV valve on the driver-side valve cover and the other line running under the intake to an elbow running off the other valve cover. There isn't much room for a breather because of the coil packs on the valve covers.
Jeff Smith: You mention the engine is a "dog" and it's slow on acceleration. The Holley carb you mention is a 750-cfm, 4160-style Holley. The specs on this carb use a 72 primary jet with a 65 power valve, while the secondary uses a metering plate with a drilled secondary "jet" orifice that is equivalent to a 75 jet with no provision for a secondary power valve. The accelerator pump squirter is 0.025 inch with a plain (no color) secondary diaphragm spring. Since you are using this carb on a rather large-plenum single-plane intake manifold, it's possible you'll need a bit more jet in the primary. You mentioned a 70 jet but stock is a 72. We'd suggest upping that to a 74 primary jet to compensate for the reduced signal resulting from the big-plenum intake manifold and the rather slow-responding, straight-leg boosters. If the engine had a dual-plane intake, this additional jetting might not be necessary. We'd also try adding a slightly larger 30cc accelerator pump squirter and see if that helps.
It does sound like the problem is the secondary opening. You didn't mention what lighter spring you are now using, but here are some things to consider. First, let's make sure the diaphragm is actually functional. Vacuum leaks are common with secondary diaphragms that have been disassembled. A quick test is to remove the diaphragm housing from the carb and push the plunger in to collapse the spring. Then hold your finger over the outlet hole. This hole should have a small cork seal that seals it to the carb main body. If you hold your finger over the hole and release the fully collapsed diaphragm, it should stay in place. If the diaphragm spring slowly pushes the plunger out, you have a vacuum leak in the diaphragm, and it will not open under wide-open throttle. Generally, the leak is around the diaphragm. Usually, one of the little cover screws snags the thin rubber diaphragm and tears it. This will cause a leak. Or, the diaphragm is not seated flat in the housing and there's a leak.
The best way to fix this is to lay the diaphragm flat on the lower portion of the two-piece housing and use two fingers to firmly hold the plunger in place. Then install the cover with the spring (start with a purple spring-that's one step lighter than the plain spring). Carefully compress the spring while holding the diaphragm plunger in place. Then start all the cover screws by hand with the cover as flat as possible. If you feel a snag, back the screw out and reposition the diaphragm until all the screws are finger tight on the cover. Then tighten all the screws while you continue to hold the plunger up into the cover. Only release the plunger after all the screws are fully secured. Then test your work to ensure the diaphragm is sealed. You might also try removing the little steel ball that Holley includes in the vacuum circuit. Sometimes the secondary will open more quickly when the ball is removed.
Another thing to keep in mind is that this 5.3L is basically a 326ci engine-it's not very big. Plus, you have a heavy car with a 2.73 gear. Because your engine is so small, it won't have a lot of torque to begin with, even in First gear.
The other variable is the ignition. You mentioned chips, so it sounds like you have the Edelbrock system (PN 7118) that uses different chips to establish a timing curve. This system dials it in so you should be close. If the engine runs OK (doesn't surge or buck or sneeze through the carburetor) in acceleration but is just slow, I think the problem is more related to a leaking vacuum diaphragm. Fix the leak, fatten the carb up a little, and it will probably make this a much more lively combination.
You also mentioned breather-system problems. This is becoming an issue with the Gen III engines. It may stem from the rather small crankcase area built into these engines as compared with the older Gen I small-blocks with much more area. Blow-by can become difficult to manage at higher engine speeds because of this lack of crankcase volume. GM even bored holes in the main web bulkheads on the LS6 engine in an attempt to reduce the crankcase pressure fluctuations. Look for a place where you can increase the external vent area to atmosphere. It may require several stages of oil separators to accomplish this task. We know of one carbureted LS1 that used a breather plumbed right off the floor of the lifter valley. At higher engine speeds, it threw oil right out of the breather, so this is a problem with the Gen III engines.
A typical positive crankcase ventilation (PCV) system connects engine vacuum from the carburetor or manifold to a PCV valve that meters a given amount of crankcase fumes into the carb to be burned at idle or part-throttle. For this to work, you must have a vent to atmosphere on the other side of the engine. Stock engines pull filtered air from the air cleaner, while many car crafters merely install a filtered breather on the opposite valve cover from the PCV valve. Given your engine is a smaller 5.3L, it should be fine with the PCV valve system just described.
Clelia, via CarCraft.com: I'm 16 and my first Mustang is out of commission because of a power-steering problem. My dad and I have replaced the steering high-pressure hose three times now. Within 100 miles of installation, a fine split appears in the S-curve entering the control valve. We have observed tension on this S-curve as the hose does not travel properly during turns, particularly when turning to the right.
As the hose leaves the power-steering pump, we have formed a loop where the hose seems too long to fit otherwise. It travels through the inboard side (engine) of the hold-down clamp and then to the control valve on the steering linkage.
Our two ideas are improper placement and/or looping of the hose in the engine compartment or binding through the hold-down clamp in the engine compartment
Jeff Smith: We took a look at the power-steering setup in our own '67 Mustang, Clelia, and found something interesting. Our car had a heavy steel clamp that looks like a factory postproduction retrofit or perhaps an aftermarket piece that secures the steel tubing end of the high-pressure power-steering hose in place (see accompanying photo). It appears that if left unsupported, the steel line will vibrate, which eventually could create the stress crack you mentioned. An Adel clamp or some type of rubber-cushioned clamp that would secure the line without crimping or abrading the tubing would be the best solution. It's a simple fix, and it should only take an extra five minutes to mount the clamp. Then you can go back to driving and enjoying your Mustang rather than working on it!
Clark Dexter, East Islip, NY: My daily driver is a '98 Yukon. I've racked up 168,000 miles and am now thinking about a fresh engine. I was going to do a 383, but my transmission guy insisted the 4L60E won't live behind the torque of a bigger engine. I am going to use an Eagle kit in the short-block and was wondering if there is any advantage to building a 6-inch-rod 350. Also, I'll probably use E-Tec heads and shorty headers. Can you guys recommend a cam? I will be running the stock EFI.
Jeff Smith: First thing we'd do is run a compression check and see exactly where the engine's at for cranking compression. This will tell you what kind of cylinder leakage you have compared with the factory specs. Assuming the stock cranking pressure is 175 psi, consider anything less than 160 psi, or 20 percent, suspect. The beauty of late-model engines is that with EFI, overdrive transmissions, and today's superior lubricants, it's entirely possible an engine with more than 150,000 miles could still be in decent shape.
As for the 6-inch-rod question, there is little benefit to spending the extra money for a longer rod in this application. Perhaps if this were a high-rpm engine, where piston speed was a concern, the longer rod might help durability. There is no horsepower advantage to be gained from a longer rod. That statement will generate many letters with differing opinions, but the reality is there are a ton of places to spend your money that will have a far more positive effect on power. Rod length is not one of them. The only advantage might be to reduce piston compression height, which will reduce piston weight, but we're really splitting hairs here.
But let's get to the meat of this issue. We wanted all the details on the '98 Tahoe 350 engine, so we called our pal Ken Casey at Burt Chevrolet in Englewood, Colorado, and discovered some interesting information. Unless you're a real animal with the throttle or haul 10,000-pound trailers all day, we think your 4L60E trans can handle the torque of a 383, and we have the perfect solution. According to Casey, GM Performance Parts has just released a brand-new version of the now-famous HT 383 complete engine that is a direct bolt-in for your vehicle. The long-block comes with the same camshaft as the HT 383 short-block that's available but also comes with the iron Vortec heads that will bolt up to your existing port fuel-injection-induction system. In addition, the new HT 383 long-block comes with a water pump, flexplate, balancer, and brand-new distributor and plug wires. All you do is add your existing intake and fuel-delivery system, oil and spark plugs, and you're done!
The part number for this package is 17800393, and the Burt Chevrolet price is $4,295. Keep in mind this is a brand-new motor from Chevrolet that has a very good warranty. Plus, according to Casey, this engine package does not require a recalibration of the factory fuel curve. This is mainly because the '98 5.7 port fuel-injected engines used a mass airflow sensor (MAF) that reads the increased airflow and will automatically compensate (within a reasonable range) for the additional airflow with the stock injectors. Based on our experience with TBI 5.7 engines, it would be a good idea to check your existing fuel pressure to ensure it is on the good side of the factory specs. A new fuel filter would also help this situation. This will ensure the fuel injectors have sufficient fuel pressure.
Based on this information, you have a second alternative. You could opt for the HT 383 short-block, or what GM calls a partial engine. This comes without a camshaft or chain but does come with a balancer and flexplate (PN 12499106). GM's list price is $4,415, but call Burt for its price. You could add the HT 383 stock hydraulic roller camshaft (PN 14097395) and all the other parts, but you might also end up right back at the price for the complete engine very quickly even without buying new heads. Then you could sell your original 350 Vortec engine to some young car crafter for a couple hundred dollars, and he'd have the basis for a budget 383 configured for a one-piece rear main seal and roller cam and be on his way to a great street engine. That way, everybody wins.
We'd also go for a much better exhaust system downstream of your dual-cat system to help engine breathing. After-cat systems tend to be underrated, but most systems will reduce backpressure even after the catalytic converters, which will improve not only top-end power but will also be noticeable in terms of part-throttle torque.
We also have some ideas on a bunch of inexpensive upgrades for your 700-R4 or 4L60E transmission to make it more durable using GM components. GM has come up with a series of better parts that create what it's now calling the 4L65E, including a stronger sun-shell housing with a bearing instead of a bushing that solves a nagging cracking problem. The combination of an upgraded 4L60E with your 383 should be very durable. That's what we would do.
To Clear Or Not To Clear
Greg Nuhfer via CarCraft.com: I own a '70 Chevelle SS convertible. I purchased the car in 1988 for a song (by today's standards). Even then I didn't think the car was worth the $3,800 I shelled out for it! It was a true convertible. Only a small piece of material was sticking to the rusty roof frame, and a 2x4 supported the front seat from falling into the back seat. I think the previous owner must have been a sumo wrestler. The car showed signs of having been hit hard front and rear. Long story short, I emptied my wallet and drove this pig home.
That was the first time I bought the car. I spent years scouring junkyards, purchasing N.O.S. parts from every GM parts store I could, and receiving countless items from Santa. I assembled the car piece by beautiful piece. I had it painted Porsche Guards Red with factory black stripes. That's when I got the famous "me or the car" ultimatum.
We split everything. She got the inside of the house and I got the outside (Rodney Dangerfield), but still I wasn't selling my car. She had it appraised at just over $30,000. Now, $15,000 later, I still own the car! That was four years ago. Recovering from the financial setback of divorce, I have still never had clearcoat sprayed on the car. Micro-finishing the paint helped, but up close, it's not up to my satisfaction. Am I too late to have this done, or do I start over with strip and paint? I will frame-off in probably 5 to 10 years. To clear or not to clear, that is the question. I drive the car every nice weekend I can. I'm willing to disassemble the car to do a clearcoat. If so, what prep to the paint should be done before clear? The car has always been garaged since it was painted and shines like a new dime except it has no depth.
Jeff Smith: We included your story, Greg, because we have a feeling there are quite a few car crafters out there who can appreciate your being true to your machine, even if it did cost you more than you bargained for.
We called our buddy Pete Santini at Santini USA Paint & Body to get the skinny on your paint issue. According to Santini, as long as the car was originally painted with a single-stage urethane, you can still hit it with clear, but Santini had a few suggestions that will create even better results. Single-stage refers to a single coat of color applied with no second stage of clear to cover the color. Santini says since the prep work to apply clear is quite extensive (including sanding, masking, and spraying), why not go ahead and lay on an additional layer of paint to really make the final product better? For the price of a gallon of paint and clear, you can have the equivalent of a new paint job. You mentioned the paint was applied several years ago, which means it has probably been subjected to dirt, silicone overspray, bird droppings, acid rain, grease, muck, and all other kinds of nasty things that have a bad habit of nesting deep in the paint.
All these volunteers must be removed from the paint before you take any steps to enhance the finish. First, Santini suggests cleaning the surface with wax and grease remover over all the painted surfaces. Next, step up to an inexpensive aggressive cleaner like a Comet or Ajax cleanser. This may rough up the paint, which will actually help adhesion. Now you can go over the paint with 600- or 800-grit wet and dry sandpaper to again help with adhesion. This is just to rough up the paint. Several companies such as Bulldog, DuPont, and House of Kolor offer adhesive clear sealers that are adhesion promoters, which means they increase the chance that the paint will stick to the parent surface. Santini says these materials price out around $30 per quart, which should be enough to cover your car. Consider this as cheap insurance that the new paint will stick to the old paint.
Now you can actually lay down a new coat of red as part of a two-stage paint process with the final coat being a layer or two of clear. If you read our story on how to color-sand a new or existing paint job that has been cleared ("How To Make Good Paint Great," July '06), you know the key to an excellent paint job is lots of coats of clear that give you the thickness to sand the clear to a mirror-like finish. With the clearcoat applied, you should wait the prescribed time before attempting to rub the paint out, but once that is done, you should have a paint job that will at least remind you why you put so much time, money, and effort into this car. The result will be its own reward.
GM Performance Parts
Goodmark Installation Center
5200 S. Broadway