E-mail your tech questions to us at carcraft@primedia.com (include the words "What's Your Problem?" in the subject line) or fax them to 323/782-2223. All correspondence must be signed with the sender's real name (not a nickname or a screen name) and include the sender's hometown and state or province. While mail cannot be answered personally, Car Craft will publish as many letters and replies as space permits. Photos are welcome, but no materials will be returned.
FE Follow-Up
In the Dec. '04 issue we answered a question regarding some disappointing power figures for an upgraded 390 Ford FE engine. We offered advice on checking the ignition advance curve, because the '63 engine had been fitted with a mid-'70s truck distributor, and then talked about verifying the compression ratio, as Edelbrock aluminum heads had been installed. One aspect of this combination we completely overlooked was the intake manifold. In describing the engine combination, the writer mentioned that it was running an old Edelbrock Street Master manifold, and since some of us were too young to recall these '70s smog-era pieces (which are no longer produced), the assumption was made that it was a garden-variety dual-plane design. In fact, some Edelbrock personnel informed us that it was a single-plane with exceedingly small runner cross-sections intended to boost torque for RV-type applications. We're told this intake is all done by 4,500 rpm, so it's entirely possible that the 390 is being choked now that it has significantly increased airflow capacity thanks to the new Edelbrock aluminum heads. Edelbrock goes on to recommend that an upgrade to even the base Performer dual-plane would probably have a significant effect on the 390's output. Edelbrock also offers a Performer RPM for the FE Ford, but the tech staff felt the regular Performer would suit this particular engine well.
Tuning by Rebuilding
My brother-in-law has a '68Camaro that he purchased a couple months ago. He called me this morning to tell me he had taken the car to Union Grove, the local quarter-mile, for open race day. Last fall he bought his wife an '04 Cobra convertible, which she dearly loves and drives in nice weather. They, along with their son, ran the two cars with some embarrassment for dad. It seems sonny drove the Cobra to a 14.2 his first time with severe axle hop. Dad took a shot and eased off the line to a 13.6 at 104 mph. Well the Camaro ran a big 15.8, smokin' out the tailpipes, much to his wife and son's embarrassment. My brother-in-law was devastated and now wants to rebuild the engine. I asked how bad it smoked and all his wife would say was that it was the only car doing that all day and it looked awful. Shouldn't a car like that run low 13s all day long? He's determined to do a major rebuild, which I believe he should but with care.Tom KinneyLake Villa, IL
Before your man rips into that engine, he should take steps to determine its actual condition. It's a good bet that the smoke coming from the Camaro wasn't necessarily an indication that it's time for a rebuild, but rather an indication of a bad tune-up or some other less serious problem. These days, 35-plus years after they were built, first-gen Camaros that are in nice shape (as your brother-in-law's appears to be from your photo) are that way because they've either been meticulously cared for or restored; the days of good-looking but worn-out original '67-'69 Camaros has pretty much passed. For that reason, it seems unlikely that an example as clean as your brother-in-law's would have an engine that was so wiped out that the ring seal would be wasted, unless the problem is that the engine was poorly built during its last rebuild. Of course, there is the chance that a rebuild is in order, but the point here is that you should determine to some degree of certainty whether or not a rebuild is required before tearing it down.
You didn't specify what color the smoke was, but it's a good bet that it was the result of an overly rich carburetor. Some may also have been from carbon buildup if the car hasn't been hammered on for a while, but it's extremely common for older, modified cars to run rich, either because the carburetor wasn't properly calibrated or because it has a problem, like a leaky needle-and-seat or blown power valve (on Holleys).
Your bro should find a genuinely knowledgeable tuner-and I don't mean a guy who bolts big wings to Hondas; someone who remembers what a carburetor is and that timing isn't always adjusted with a laptop. Such a person could diagnose the smoke and also get the engine dialed in properly. You'd be amazed at how much power can be lost on an older car with mechanical controls. The car might start, run, and drive acceptably, but if the carb isn't producing the right air/fuel mixture and if the ignition timing isn't advancing optimally, you'll be giving up lots of performance potential. Lots of guys who have musclecars for cruising never give any thought to wide-open-throttle performance, assuming that if the car idles well, it will run good wide open, which is absolutely not so. The trick is finding a gearhead-type mechanic with proper experience in accurately diagnosing and tuning old-school mechanically controlled components like carburetors (particularly Holleys) and distributors. Many wrench men today are only familiar with late-model computer-controlled drivetrains. Plus, the guys who are only concerned with maintenance and repair are also the guys who will be telling you to get a new engine with 8.5:1 compression, an RV cam, and whatever carburetor came stock.
If you determine that the smoke you're seeing is from oil consumption, start by checking out the crankcase ventilation system. We've seen lots of Mickey Mouse PCV set-ups using aftermarket breathers and air cleaners (on cars where the original stuff was discarded) that wind up dumping oil into the intake tract. If the problem does prove to be oil smoke and it's not from faulty crankcase ventilation, the cylinder heads are the most likely culprits. Big-block Chevys were notorious for leaky valveguides back in the day.
By the way, the late-model supercharged Cobra is no joke; we've seen them run 12s in stock form. With a blower pulley swap and an aftermarket after-cat exhaust upgrade, 425 hp at the wheels seems to be about the norm, which is more than enough to walk away from lots of classic musclecars at the track.
Trans Am Transplant
I am going to put a 350/TH350C in my '82 Trans Am. I have the torque-arm adapter, but I was wondering if there is anything else you know of that I will need for the swap. The 350 is out of a '79 van, as is the TH350C. It's a GM crate engine that the guy I bought it from referred to as a "target motor." What does that mean? My '82 T/A had a 305/TH200 combo with a carburetor, and I'd like to stick with the carb-I don't like fuel injection or sensors.John DoeVia e-mail
That 350 should bolt right in place of your original 305, and you can even retain the stock intake and carb if you so desire, though the computer-controlled Q-Jet will need some recalibrating to properly feed the 350-without that you'll be lean. The junkyard route would entail locating a feedback (computer-type) Q-Jet from an original 350 application, like a pickup or police package Impala/Caprice. The computer will also have to be recalibrated for the bigger engine, though you may be able to source Hypertech, as it still stocks all PROM chip applications ever listed in the catalog. The TH350C you list uses a lock-up torque converter (the "C" indicates computer-controlled), just like the TH200 originally installed, and your ECM should operate the converter just as it did with the stock trans. Ditching the TH200 is a wise idea, as this lightweight could barely handle the torque of the wimpy stock 305. The TH350 has the same overall length and driveshaft spline as the TH200 three-speed, so it should bolt right in after the torque-arm adapter has been mounted.
The "target motor" the seller referred to is actually a Target Master-the old brand name for GM's replacement engines that has stuck in the minds of many consumers. But for the past 15 years or so, these service replacement engines have been marketed under the Goodwrench name.
Lame Mustang
I have an '86 Mustang 5.0 EFI with a manual trans, which has been converted to mass-air sensing from speed density. I put the motor together with all brand-new parts, including the block, 20,000 miles ago. It has never run right since then. The idle quality is poor, there is surging at light-throttle cruising, it stalls when coming to a stop, and it's extremely soggy at low rpm. The short-block is essentially stock, with forged flat-tops that are 0.010 inch in the hole, factory crank, and so on. The fun begins with a Ford Racing B-303 cam, 1.7:1 roller rockers, Edelbrock Performer heads with the 2.02 intake valves, Trick Flow Track Heat intake, Ford Racing 65mm throttle-body and EGR spacer, C&L 73mm mass-air meter, and 24 lb/hr injectors running 27-psi fuel pressure. I just tore it apart and resealed everything thinking I had several vacuum leaks. The only mechanical changes I made included a 180-degree thermostat (from a 160), new air charge, O2, and water-temp sensors, and the Edelbrock timing chain was adjusted from straight up to advanced. I am also now running BBK headers with 151/48 primaries.
There is virtually no change in performance, but the idle has evened out somewhat, though it still stalls when coming to a stop with the clutch pressed and it is soggy like a warm bowl of cereal at low rpm (below 4,000). Is there a problem with this combination? It seems like it runs really rich. Would a chip help (I am wondering about total ignition advance)? I am particularly concerned with the throttle-body, since I'm not sure the TPS is accurate. I have measured it, and it is within specs (0.98 volt), however I know the throttle-stop screw underneath has been moved, and if I recall, it is not supposed to be adjusted at all. Oh yeah, I am also running the stock 3.08s out back.Marc McPhersonEllensburg WA
For the most part, your combination is a fairly common gathering of components, so it should be a strong performer as well as a decent driver. The most questionable item in your list of specs is the fuel pressure-why are you only running 27 psi when the factory spec is 40? Most Mustang tweakers run a little over 40 psi to gain a little extra fuel, so cutting fuel pressure back seems odd. You listed 24-lb/hr injectors and a C&L 73mm mass-air meter, and hopefully you're aware that the two must be calibrated together. The C&L 73mm unit is a housing that takes the factory electronics from the original mass airflow (MAF) sensor, and then uses a "sample tube" inside the housing to calibrate the larger meter to the stock Ford EEC-IV engine management. The sample tube must be matched to the injectors being used, and C&L offers the tubes in several sizes to mate with the popular 5.0 injector sizes, from the stock 19-pounders up. If your meter has the sample tube for the stock 19 lb/hr injectors and you're cutting fuel pressure to compensate for the larger 24-lb/hr injectors, you need to get the proper sample tube and put the fuel pressure back where it should be, at around 40 psi. Fuel injectors require a specific amount of fuel pressure to operate properly, otherwise the stream of fuel sprayed may not atomize sufficiently.
Next, you say your idle quality is poor, and that the engine stalls when coming to a stop. While it is true that the idle speed of these engines is not to be adjusted with the throttle stop, as you would on a carburetor, an adjustment does need to be made.
The standard procedure is to disconnect the idle air control (IAC) valve located on the side of the throttle-body, and then adjust the throttle plate so the engine will just barely idle. In your case, it's likely the engine won't hold an idle without the IAC connected because the throttle plate is closed all the way-this may be the root of your stalling problem. The IAC can compensate for a completely closed throttle plate, but there can be a lag in the time it takes for this to occur.In addition to this, your engine management is constantly trying to cope with the B303, which causes more erratic idle vacuum and intake pulses than the factory programming is calibrated for.
If you can get your engine to idle without the IAC connected, you should be able to eliminate the stalling problem once it's plugged back in. If you still have rough idle issues, check out the engine idle-speed plate offered by Windsor-Fox. It's a small aluminum plate that fits between the IAC and the throttle-body, containing an additional air passage that can be metered with two set screws. Windsor-Fox claims that idle quality with aftermarket camshafts can be smoothed out a bit with this unit.
As far as the "sogginess" you report at low rpm, some of this is to be expected. Though the 5.0 Mustang is known as a strong performer, it's still a fairly small engine. The factory combination makes a surprising amount of torque for an engine of this size, though you may have noticed the factory redline set at about 4,800 rpm-pretty low for a short-stroke V-8. Fortifying the engine's breathing capabilities allows it to make more power in the upper rpm range, but usually at the expense of low-end grunt-the classic hot rodding compromise. The bigger ports reduce low-rpm airflow velocity, and adding the big cam only compounds the situation. Most 'Stang-bangers gladly make the trade-off, but then they also ditch the factory economy-minded rearend gearing, and this is probably where your real problem is.
The optional stock 3.08 gears, though better than the standard 2.73s, are still a bit long-legged. Try a set of 3.73s and the lack of low-end shove should seem less cumbersome, plus your quarter-mile times will improve significantly.
