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Techin’ In With Fletch - July 2014

Dan Fletcher Jun 6, 2014
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How Swede It Is

My name is Magnus Joelsson from Sweden. My car is a ’57 Chevy, which I drive 90 percent on the street and 10 percent race. The weight is around 3,870 pounds, and it has a 406 SBC, TH350 transmission, and a 4.56 rear. My best elapsed time is 11.50 seconds at 117 mph. I would like a little more power and to run low 11s. My engine specs are as follows: 400 block and crank, Eagle 5.7 rods, 12:1 compression, Crane Cams mechanical roller (duration at 0.50-inch intake is 260, exhaust 270), lift is 0.611-inch intake, exhaust 0.615, Dart iron heads (200 cc with 2.08/1.60 valves), Edelbrock Victor Jr. intake, Holley 850 carb, and 13/4-inch tube headers with 3-inch collectors.

I have some ideas myself, like better aluminum heads and 17/8-inch headers. Can you recommend what is best to do with my engine to gain some more power? I’m looking forward to your answer.

Magnus Joelsson
Via email

Honestly, I’d have to say 11.50s at almost 3,900 pounds in a street car is pretty darn good. If it has good driveability characteristics as a daily cruiser, I’d be hard pressed to screw with much, but that’s just me. If you want to pick up a few tenths by adding some steam under the hood, that shouldn’t be too hard, just make it a bigger or more efficient air pump. More camshaft and cylinder head is generally a surefire way to accomplish your stated goal, and I’d definitely agree that the 13/4-inch headers are probably not the optimum choice for your setup. You don’t mention what you’ve done in the way of testing, but obviously, finding the optimum configuration in regards to timing, jetting, valve lash, etc. is most critical.

With that said, your mph exceeds the elapsed time by a bit (IMO), so you might want to work on other aspects of your setup instead of just throwing more power at it. I wish I knew a little more, like what the 60-foot time is, because I’m thinking there could be quite a bit of e.t. left on the table right there. The correct torque converter and rear tire could help substantially. A general, ballpark rule for the converter is that you’d like it to flash a couple hundred rpm above peak torque to produce the best e.t. card. In the Stock and Super Stock classes of the NHRA, we’ve found the radial slick to be a tenth of a second (or more) faster than the bias-ply. That might sound hard to believe, but it’s true.

Computer Woes: Fact or Fiction?

I have an ’06 Corvette with the 6.0 LS2 motor. I went to the local eighth-mile dragstrip this summer to see what times it would turn. It became the perfect bracket car; hot, cold, good air, bad air, it ran 8.50s. However, ’10-’12 6.0 Camaros were three- to five-tenths quicker than I was. I installed a cold-air system, a better MAF sensor, and a high-flow after-cat exhaust, and the car still ran 8.50s. Then I had the ECM re-flashed—more 8.50s. A local tuner said GM had anti-tamper computers in some cars and he could burn a new program for about $500. I’m afraid the ECM won’t be the only thing getting burned in this deal. The Camaros average 300 pounds heavier than my car, and 100 pounds is a tenth with everything else being equal, correct? Please help. I’m lost on this one. Thanks.

Richard Haas
Louisville, KY

I called my local expert on LS tuning, Mike Frumusa at New Era Performance in Rochester, New York. They have a plethora of experience with vehicles just like yours, so there’s no one I know who’s better suited to line you out. Check out the company’s website at Now, you obviously won’t be driving from Kentucky to Upstate New York for a tune, so he’s not just trying to drum up business, but Mike is adamant that the best and only way to deal with a car of your ilk is to have a proper tune done by a quality shop. Sorry to be the bearer of bad news, but apparently $500 is about the going rate. With that said, a nearly half-second quarter-mile e.t. reduction for $500 is a pretty good bang for the buck.

Mike felt a totally stock car like yours should, on average, be a 13.0 quarter-mile-type car. My math would calculate your Corvette’s 8.50 eighth-mile time to be in the 13.30s, so it does appear to be lacking. The “hundred pounds per tenth” is a general rule of thumb for a 3,000- to 3,500-pound car, but in the quarter, not the eighth. And while the Camaros are definitely heavier, we don’t know how they were prepped or run. The fans in your car don’t even come on till 220 degrees, and at 212, it starts pulling out timing. As for the changes you made, one could have cancelled the other. The cold-air system in effect leans the tune-up, but the different MAF could have changed that. Additionally, any power gain you may have seen could have been lost in the shift time, which is a torque-driven calculation made in the computer.

A simple transmission tune alone will yield two to three tenths, and 15 to 20 hp is a reasonable tune expectation with no real parts other than a low-temperature thermostat. Mike said the first hard parts he’d throw at it would be a set of good long-tube headers, which should get you around 25 hp, or almost another two tenths. As for a GM having an anti-tamper computer, not that I’m aware of. Mike said some tuners will “lock” the computer after they’ve done their thing, but GM didn’t.

Data logging is the only way for you to truly get the most out of your car. Find a competent, respected shop and let them spend the day on your car. Believe me, I’m a cheapskate, but you’ll be glad you did.

Chevelle Seat Swap

Three years ago, my wife gave me a ’65 Chevelle as a retirement present. It is a nice car that I enjoy working on and cruising. It currently has a ZZ4 350 in it. I have put a new interior in it, installed a beefed 200-4R transmission, and upgraded the brakes to 11-inch discs up front and 11-inch drums in the rear. I now want to upgrade the interior by replacing the front bench seat with bucket seats and a center console. As you know, original parts from a Chevelle are pretty expensive on the used market, so I picked up a set of bucket seats from a ’62 Pontiac Tempest for next to nothing. They appear to be dimensionally the same as ’64-’65 Chevelle seats. My plan is to use the Tempest frames with Chevelle spring assemblies, foam seat buns, and bucket seat upholstery. My question is: Will the Chevelle seat parts fit on the Tempest seat frames? Also, I see that there are brackets that are supposed to be used when changing a ’65 Chevelle from a bench seat to buckets. Where do these brackets go and how are they attached? Thanks for any advice you can provide.

Ben Lux
Huntington Beach, CA

I called my friends at Camaro Specialties in East Aurora, New York, for some guidance, as I was pretty confident they would work, but I sure don’t want to pass on bad intel. I spoke with the owner, “Camaro Bob,” because he knows everything Chevelle as well. You’re in good shape, as the ’62 Tempest frame will work with the Chevelle components. Regarding the brackets to be used in the bench-to-bucket conversion, you are correct. They weld to the floor, and the seat frames bolt directly to them.

Not that Super Chevy requires a personal description when submitting a question, but you didn’t mention your height. In addition to the adapting brackets you require, Camaro Specialties also offers an extended seat travel kit that provides added legroom for tall folks like me. They are priced at $49 and $79, respectively, and you can check out the company’s website at

Got a restoration question that’s been puzzling you? Send it to:
[ m ] Super Chevy, Fletch, 9036 Brittany Way, Tampa, FL 33619. [ e ] [ f ] 813-675-3557



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