Chevy High Performance Question and Answers - Performance Q&A

Kevin McClelland Jul 26, 2010 0 Comment(s)
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Price Of Late-Model Performance
I always get this question from one of my performance colleagues in the industry: Why do I always write about early small-blocks and TH350 transmissions? He believes that the '60s through '90s are dead and gone and all we should be writing about is LS-based engines with electronic everything. I keep telling him that I answer the questions sent to me, and he keeps scratching his head!

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This week I dove headlong into late-model performance by getting a screaming deal on a brand-new GM Performance Parts '07 6.2L L92 Gen IV small-block crate engine, completely dressed with the front accessory drives, exhaust manifold, truck EFI manifold with electronic throttle body, and ignition coils and wiring. I purchased this engine to modify and install in our '80 Malibu wagon race car to step it up in bracket mode and hopefully run 10.90 Super Street. With the proper camshaft, an Edelbrock Victor Jr. manifold, an 850 Holley, an MSD 6LS ignition controller, and good headers, the engine should make around 580 hp on pump gas. This will get us down to about 10.70s at 124 mph in our 3,300-pound wagon.

This all sounds great doesn't it? Sure, until I researched the rest of the components I'll need to dress the engine and do the swap! Every time I wrote down another part and ran the price through my friendly mail-order performance store, I was coming up with $300 here and $400 there. I plan on making the engine mounts myself, and if I have to I will make the headers myself. However, when you look for a pan, manifold, ignition, SFI damper, electric water pump, LS2 starter, camshaft, and adjustable valvetrain, it all starts to add up.

One of the reasons we continue to hang on to our original small-blocks is the availability of inexpensive parts out there. We pick up parts from one of our friends, swap meets, manufacturers selling off the older stock at ripping deals. As long as money is tight out there, we're going to have our early small-blocks for years to come.

I'm very excited about this engine swap and the minimal changes to get a completely stock engine to make this kind of power. I love the looks on people's faces when they peer under the hoods of our cars, wondering how they can run so fast with so little modifications. I'm sure hoping this will be another one. I guess I better put in a little overtime to pay for the swap!

Semi Legal
Q My 18-year-old son drives a '55 Chevy Pro Street Car with a 540 big-block with a 4L80E trans. We do some bracket racing, and it has run 11.10 at 126 mph. Well, going through Tech, they have you rev the engine up to 3,000 rpm, then idle, then shut the electrical cutoff switch-but it didn't shut the car off. I run a one-wire, 100-amp alternator with the one wire going into the car to positive distribution block and the battery mounted in the trunk. When we race, I run a wire to the switch from alternator and disconnect the wire into the car's distribution block. The car will then shut off. With it set up this way, it won't charge the battery or keep systems running, right? Would different wiring or going to a 140-amp alternator help?
Nick Loesch
Hastings, MN

A You have found the problem fitting within the letter of the law in the NHRA rulebook. The only way to prevent the engine from running on is to isolate the alternator from the power feeds to your accessories. You've done this by running the alternator power wire to the battery side of the battery shutoff switch. By the rules, when you shut off the main battery shutoff switch, it is to kill all power in the car. The heavy-gauge wire running up the car to the alternator is still hot. Even though the engine dies when you cut off the switch, with it wired this way the alternator is charging the battery when the engine is running. The alternator is always connected to the battery.

When I wire in a remote mounted battery and shutoff switch, I will run a fine-stranded 6- to 8-gauge wire from the battery to the charging lug on the back of the alternator. For protection, I will run an 8- to 10-gauge fusible link at the battery. This smaller-gauge fusible link will melt if the main feed wire to the alternator gets to ground. This will prevent fires and problems in case of an accident.

This is the best I've come up with for the "All Kill" shutdown rule with the battery shutoff switches. This will keep the tech man happy and protect your car in case of mishap. Enjoy racing your very cool '55!

Give Me A Break-In
Q I have a fresh 355ci I assembled myself and it has not been started yet. I've heard two schools of thought concerning engine break-in, (not counting cam and lifters): The old school is to run it mildly for 1,000 miles so you don't glaze the rings, then you can go nuts. The newer theory is to break it in the way you intend to run it. What do you say? Also, at what mileage would you change the break-in oil: 500, 1,000?
Michael Roshon
Pataskala, OH

A Drive it like you stole it! Seriously, components and machine work have come a long way over the years. Back in the day, you needed everything to get real happy with each other before pouring the coals to it. Modern piston rings have been lapped at the factory to speed in break-in. Also, honing techniques and equipment have advanced greatly.

A break-in procedure we've used for years is to find a slight grade or hill in your area and run the car or truck up the grade at first with light throttle loads until you reach the top. Then turn around and, using the engine compression to limit the speed of the vehicle, return to the bottom. What this does is puts load on the rings as you go up the hill and creates heat as they break in. When you then come back down the hill, the engine braking creates high vacuum in the combustion space, drawing oil up to the rings, cooling them down. Next, run up the hill, progressively running the engine harder. Do this several times, stopping after three or four runs and letting the engine cool down. On your final track up the hill, run the engine under about 75 percent throttle. After you have taken the time to break the engine in this way, then change the oil and filter. We like to change the oil after break-in, long before 500 miles. This will get any debris out of the engine that has been shaken loose from the early running and any contaminants from everything getting happy with each other.

Once you have a fresh filter and oil in the engine, run the engine as hard as you wish, within reason. You probably can't run the thing wide open for five miles; however, this should give you a very good idea if everything is OK. We'd certainly have no problem running it right down a dragstrip.

For break-in, make sure you use petroleum-based oil and a high-shear additive like Lucas Engine Break-In Oil Additive, TB Zinc Plus (PN 10063, available at most auto parts stores). This additive replenishes the zinc and phosphorus that have been reduced in our current motor oils. You can also use this as an oil additive to protect flat-tappet camshafts. Source: lucasoil.com

Still Going To Burn
Q I am 17 years old and a senior in high school. I recently bought an '06 Monte Carlo SS with a 5.3L V-8 that has displacement on demand and is front-wheel drive. This car had 86,000 miles on it and now has 90,000. Since I bought the Monte it has used oil, about 1 quart per 600 miles. The dealer I bought the car from was in touch with GM and they thought it might be a lifter problem. The dealer replaced the lifters and GM covered half the bill, but it still cost me over $1,000 to repair. The problem now is the engine is still using oil at the same rate. What do you think the problem could be? Thanks. Connor Hiebner Via email

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A We turned to our good friend Ken Casey at Burt Chevy, and he checked all the technical service bulletins related to your car. The only thing reported for your car is a couple of oil leaks at the rear main cover and at the oil pressure sensor. There is nothing about excessive oil consumption like yours. He did state that there has been an issue with roller tappets in the 5.3L truck engines and the dealer may have done you a favor having you replace them.

Back to your oil issue, I'm assuming you don't have the leaks listed above and that you've done accurate consumption measurements. Your engine should be sealed up and have no problem going for 3,000 miles on an oil change without needing to add oil. Not knowing the history on the vehicle before you purchased it, we can only make a few guesses. Luckily, there is no oil path to the intake manifold like on the Gen I and Gen II small-blocks. This leaves the rings and the valveguides/seals as the leak path. If the engine was ever overheated badly in its past, it could have either cooked the valve seals or reduced the tension on the piston rings. Both are very tough to identify. A good technician should be able to see deposits on the spark plug if the intake valve seal is the leak path. When the piston rings are the leak path, the oil comes up around the head of the piston. If it is severe, the oil will make it up to the plug, but in your case the plug lights the mixture burning down to the oil.

We would push back on your dealership and have them help you with diagnosis of the rings or valve seals. These engines have come so far over the years that they run incredibly dry. Oil consumption issues have become things of the past. Hope these few tips will help. Good luck.

Easy Answer
Q Will a 305ci Chevy drop into my '56 Chevrolet Bel Air and work to replace the 265ci stock engine? Will it attach to the three-speed Powerglide transmission already there? Sure would like an answer. Thanks.
John Saunders
Coxs Cove, NL, Canada

A Yes, the 305 will drop right into your '56. You state that the car is equipped with a three-speed Powerglide. The original Powerglide is a two-forward-speed transmis-sion, and in the '56 was a cast-iron case transmission. The starter bolts directly to the bellhousing and all early (pre-'62) flexplates are 14.125-inch, 168-tooth design. Not knowing what year 305 you have, you will need to make sure that you have the correct flexplate. The engine mounts will bolt to the front face of the engine block. The rear engine mounts come off the side of the cast-iron bellhousing of the Powerglide.

Swap all the accessories off the front of your 265 and bolt them directly onto the 305. This should be one of the most painless swaps to perform. Do your homework before tearing the car apart. Make the list of parts you will need and have everything ready for the changeover. Have fun!

Stock Tails
Q I run a '70 Nova D/SA, 350/396 combo. The Q-jet I have the best luck with has the little booster box on the backside of the divider plate in the secondaries. Do you see any advantage in adding this booster to the left side of the secondaries and have this on both sides? I know this was only on big-block cars and I understand why, but not all big-blocks had this. I run a stock, low-rise intake and I'm looking for a little edge. Thanks for your time.
Kendal Jones
Via email

A If you've been racing in Stock for any length of time, you know the only way to find anything in Stock is testing. We've tried things that people swear will give you e.t. and picked up nothing. Then we test things that people say did nothing for them, and we find a couple of hundredths. The small box on the rear of the divider plate helps with fuel distribution on the lower plane of your dual-plane manifold. Will the dual box divider plate help in your application? We've heard that it can; however, testing is the only answer. We've said it before, it's tough to find very small gains like these because track and weather conditions vary from run to run. You'll need to make many runs with the change to see if there's a trend in your e.t.'s.

The dual box divider plate you're looking for came in the later ('77-and-up) big-block pickup trucks. We're currently running the bracket engine and trans in our wagon. We have a new camshaft, intake manifold, and a handful of carburetor tricks to try before the West Coast Sports Nationals. We hope we can find a couple of tenths from these changes, since NHRA took three tenths away from us in index. But that's another story. Good luck with your stocker.

Tune Ports Forever
Q First, I love this magazine, I have checked out several others, but none compare to CHP. My question is about the Tuned Port Injection 350 in an '87 IROC. I purchased one, but the injection is missing. I'd like to run the tuned port in this car, but I don't have any experience with it. The car has what's left of a 305 in it right now, but I'd like to go with the 350 and try to get around 400 hp out of it and hear the cam. It is currently an auto trans, but I am going to go with a five- or six-speed when I'm done. I have been looking for books or any info on the Tuned Port Injection systems and always seem to come up short. Thank you, and please keep up the great work.
Chris Hicks
New Castle, IN

A You need to check in with our good friend Myron Cottrell at Tune Port Induction Specialties. Myron started hopping up the TPI-equipped small-blocks the very first year they came out, in 1985. He has now moved on to the LT1s and LT4s, and currently the LS family of engines. He and his team still have a passion for the TPI engines.

Back in the day, Myron put together Insider Hints Handbook, PN 900-024, a complete book of hop-up tricks for the TPI engines. This tuning manual gives you all the little modifications that add up to modest power gains. Then you can take the engine anywhere you wish with the complete line: intake components, camshaft packages, cylinder head porting, and computer calibrations to support all of your upgrades. Check with Myron at 952.448.6021. Tell him Kevin says hi!
Source: tpis.com

Synthetic Leak, Part Two
Q This is in response to Bob Kay's problem with a persistent oil leak on his 305 (Apr. '10 PQA). One thing you didn't mention is crankcase pressure. In all my years of turning wrenches, almost all persistent leaks are due to excess crankcase pressure. No matter how well you have an engine sealed up, and no matter how many times you do it, with all the best sealants, seals, and gaskets, excess crankcase pressure will always rule. I've found over the years (GM and Ford dealers) that if the engine's PCV system is functioning properly and the engine is new, even normal crankcase pressure can-and sometimes will-push oil out through gaskets and seals during hard pulls. As much as I hate to do it (I think they are ugly), in addition to the PCV system, for these persistent leaks my remedy is to put a breather or two on each valve cover. It's a simple and cheap (though ugly) fix. Except for a couple of blocks that were porous, this has fixed all my persistent oil leak complaints from customers over the years-and for two BBCs of mine.
Barry Dukes
Baltimore, (Snow bound) MD

A Sometimes you can't see the forest for the trees! We're always looking for the cause of the problems and sometimes overlook the common-sense answers. You're right, you cannot beat excessive crankcase pressure, especially if the engine is breathing out the standard, Bow Tie filter in the air cleaner housing. This is on the early cars, and on most of the late-model EFI cars they are breathing through a straw. Most of the crankcase vents are going through a 3/8-inch tube to the inlet ducting or throttle body.

Going with extra breathers on the valve covers won't make the smog police too happy on late-model cars. The crankcase must be sealed with all oil and combustion vapor going back into the induction system. However, it's a great tool to diagnose oil leak problems. It's much easier to add a breather than drop the oil pan for the fourth time! Thanks for the great tip, and keep bending those wrenches.

Dual 4 Pots
Q I recently built a 383 stroker motor with a 9.4:1 compression ratio. It consists of the following: a 3.750-inch stroke cast-steel crank with 5.700-inch CNC forged I-beam rods, forged flat-top pistons, and AFR 195cc heads. Up top, I'm running an RPM Air-Gap manifold with a Holley 750-cfm vacuum secondary carb. The camshaft is a Comp hydraulic roller with a lift of 0.502/0.520-inch on the intake/exhaust. At 0.050-inch tappet lift it has duration of 224/236. This combination on an engine dyno turns out 491 hp at 6,000 rpm and 489 lb-ft of torque at 4,600 rpm. I would really like to use a dual-carb setup just for something different, plus they look way cool-does it run off just one carb at cruise or is it working off both? Edelbrock offers a kit with 600-cfm carbs. I just wonder if this would be too much carburetion for this engine combination? Thanks in advance for your help, Great mag!
Lon Ketchum
Via email

A Dual quads would be way cool on your 383. Edelbrock offers two kits for small-block Chevys. The original C-26 Dual Quad manifold is still around after some four decades! Several years ago, Edelbrock stepped up to support the vintage market by producing an RPM Air-Gap Dual Quad version, which features the distinctive Air-Gap design to give you cool, dense intake charges, and larger and taller runners for great airflow. The RPM Dual Quad is 1 5/8-inch taller at the carb flange over the C-26, which could cause hood clearance issues. This manifold and dual quad setup will not perform as well as the single four-barrel RPM Air-Gap, but I don't think that's what you're about. With the new RPM design you should see minimal power losses.

Edelbrock offers a complete RPM Dual Quad manifold and carburetor kit under PN 2025. This package features their Thunder Series AVS 500-cfm carbs, progressive throttle linkage, fuel lines, and intake gaskets. These 500-cfm carburetors will be perfect for your application. The secondaries on these carbs feature an air valve that tailors the airflow to the demand of the engine. The high-tech progressive linkage offered can be set up for either progressive or 1:1 ratios. In the progressive mode, the rear carburetor is for slow-speed driving (up to 20 degrees of throttle opening). Past that point, it brings in the front carb as well, until you reach wide-open throttle. If you're looking for a more aggressive throttle response you can set the linkage to 1:1, which opens the carbs in unison.

Check with Edelbrock for more information. Have fun. Your 383 will have some real authority with dual quads atop it. Source: edelbrock.com

Technical questions for Kevin McClelland can be sent to him at chevyhi@sorc.com

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