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November 2011 Chevy High Performance Q&A

Kevin McClelland Sep 22, 2011
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This past weekend I had the honor of guest-judging the Hot Rodders of Tomorrow engine-building competition. This competition was held at the sixth annual Rev’ved Up 4 Kids Charity Car Show at Vic Edelbrock’s Garage in Torrance, California. The car show began in 2006 under the leadership of Vic’s daughter, Christi, and benefits The Center for Learning Unlimited, which combines a unique transdisciplinary approach to helping gifted kids with Autism, Asperger’s syndrome, bipolar disorder, ADD, and ADHD. This outstanding car show was attended by thousands of people and more than 400 cars participated. A very cool car show for a very important cause. Thanks, Vic, for the hospitality.

The Hot Rodders of Tomorrow is a high school auto shop competition, held in eight divisions all around the country throughout the year. The final build-off is held at the SEMA show each year with over $1 million in scholarships going out to the students. The student teams take identically prepared 350 Chevys dressed with Edelbrock carburetors, air cleaners, manifolds, aluminum cylinder heads, and valve covers. The ignition duties are handled by MSD, all the hardware is ARP; the bottom end is capped with a Moroso oil pan and finished off with a K&N oil filter. The five-person high school teams must dissemble the engine down to the crankshaft and camshaft, then completely reassemble the engine under five watchful judges and the ticking clock. This year, there were 13 teams in competition, and five teams went head-to-head in three rounds. This year’s winner was Loara High School Team 1 from Anaheim, California, with a world-record time of 22 minutes and 34 seconds! They accomplished this feat with no errors. Unbelievable. Not a lifter or rocker out of place or adjustment. Not a washer out of place or fastener out of torque spec. This was done with all handtools, as no power tools were allowed. It was one of the most impressive displays of teamwork by high school students I’ve seen in a long time.

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Not only was the winning team impressive, but the enthusiasm of all the participating students was moving. Some of the teams were challenged by the daunting task. For those teams, we, as judges, were there to give them guidance, tips, and techniques to make the competition a learning experience for everyone; I hope to be invited to judge again next year by the good folks at Edlelbrock. It was truly a pleasure helping young people, the gearheads of tomorrow, who are so passionate about engine building. Until next year, I’ll keep finding ways to pay it forward, expanding the minds of young people. For more information on these two great programs, please check them out at and

We love letters, especially technical questions. Submit your tech questions to Kevin McClelland at Regular shout-outs and good tidings are also always welcome.

Big Mutha

I’m in the process of building a 496 big-block Chevy for the street. The only strip time this engine will see is when I’m on a highway onramp. I am using a production block, aluminum heads, and EZ-EFI up top. I’d like to use a hydraulic roller cam but am unsure of the best one to use. I’ve been looking into the Thumpr series from COMP Cams because I love the sound, but I’m a little hesitant on whether it would be my best option. Any advice?

Mac D.

You didn’t give us anything to go on except that you wanted a nasty idle, and that you’re going to stand on the throttle getting on the freeway. We only wish selecting a camshaft grind was that easy. Is your 496 going in a lightweight street car or a 4x4 with 40-inch gumbo mudder tires? Are you running a manual transmission or a stock-stall automatic? From your questions, we can tell that you have a clue about what you need. Please, guys and gals, give me enough info to help you!

The 496 cid of your engine will help with a larger size camshaft. The EZ-EFI is also going to help by constantly learning the correct fuel curve needed by your engine and feeding it properly. The Thumpr camshaft series even surprised COMP Cams with the power they produce. These camshafts were first designed to satisfy the masses out there who wanted an aggressive idle to give their cars and truck personality. What COMP didn’t figure is that these camshafts made really good power on the dyno, to the point that they rivaled the best grinds out there for street use. If you equip your car with the proper converter, gears, and brakes, you can have one badass street car with your engine combination. As always, we’re going to stay conservative with the selection and not go “bottom of the page”. COMP offers three grinds in the hydraulic rollers for the big-block: the Thumpr, the Mutha Thumpr, and finally the Big Mutha Thumpr. Again, if you equip the car with the right parts, we’d recommend going with the Mutha Thumpr grind (PN 291THR7) that specs out at 235/249 degrees duration at 0.050-inch tappet lift, 0.558-/0.542-inch max lift, and ground on a tight 107-separation angle. With the right aluminum cylinder heads and 10:1 compression ratio, you will be pushing the limits of the EZ-EFI’s 600hp headroom! Sounds like fun to us!


Stripped gears

I rebuilt a 350 small-block a while back for an early Chevy pickup. I put in a COMP flat-tappet hydraulic cam and used an Edelbrock RPM manifold and an MSD distributor. Recently, it stopped running while driving down the road. The problem turned out to be the distributor gear: The teeth wore off. I have talked to both COMP Cams and MSD about this. COMP said that with a flat-tappet cam and a double roller chaindrive, I shouldn’t have that much trouble with cam movement. MSD said it might be an alignment problem. Is there some measurement I can take that would help me solve this issue? Thank you for any help you can give, and I enjoy the magazine.

Dale Heck
Via email

Usually our Chevy engines don’t have issues with distributor gear wear when using standard cast-iron camshafts. We see issues when we run billet steel shafts and have to run special gears. We agree with the tech at COMP Cams. The camshaft lobes are ground with taper into them to force the camshaft to the rear of the block when it’s running. If you didn’t have any issues with the engine except for the gear wear, we doubt it’s an alignment issue. If the camshaft was offset too far forward or rearward to tear up the distributor gear, you’d have had lifters running into adjacent cylinder lobes. When this happens, everything gets really ugly!

Other issues that can accelerate distributor gear wear are using a high-volume/pressure oil pump with heavyweight engine oil. We’ve seen where people use high-volume pumps when not necessary and 20W-50 weight oil and have wear. This usually happens when they run the engine too hard before it has come up to operating temperature and the oil isn’t close to temp.

To check for the proper alignment, climb up into the engine bay and, with the distributor out of the engine, look down the distributor hole in the manifold with a flashlight. The gear of the camshaft should be somewhat in the center of the distributor hole, down in the block. It can be slightly forward or rearward without causing an issue. If you’re running the above high-volume pump with thick oil, try lowering the viscosity of your oil.

Finally, you can help by adding some lubricant directly to the distributor and camshaft gears. These gears run in a mist of oil from the windage of the crankshaft and the oil thrown off the rod bearings. These two gears are in the very back of the block and are somewhat shielded from a good amount of splash lubrication. Most of the oil comes from directly above, in the clearance between the block and the distributor body. The distributor body has a radial groove that connects the oil galley passage from the rear of the block and down the lifter galley. If your MSD distributor has a nice, snug fit, there can be very little oil leaking past the housing. With your distributor in place, timed properly, put a mark on the distributor body pointing to the driver side of your truck, 90 degrees to the camshaft centerline. This line will be directly over the cam and distributor gear meshing area. From this mark, transfer a new mark to the end of the distributor, right above the distributor gear up to the oil transfer slot. With this mark you would want to use either a small triangle file or a high-speed die grinder with a small cutter, and make a very small slot. You would be amazed at how much oil will flow through a 0.020-inch slot under 60 psi of pressure. This slot will give a direct spray of oil on the two gears while they are at work. This will cool and lubricate these gears and cure most wear issues.

We’ve got it easy with our Chevy engines. Again, we usually don’t see any wear issues with our design. Now, Ford engines are another story. You put a high-volume pump in a small-block Ford and they will eat distributor gears. It’s not pretty.

Big-Block Camaro fun

I have an ’80 Z28 with a 350 ci. It was the 18th car off the assembly line back in 1979. I was wondering if you could fit a 454 big-block in it. Would I have header issues with the fenders, and will the trans fit? Do I need to change the crossmember? Any info would help!

Al Castillo
Rio Rancho, NM

The second-gen Camaros were released in 1970, and this platform wasn’t built until 1982 with very few changes to the actual chassis; they simply hung new sheetmetal and bumpers onto these cars. Yes, a big-block engine will fit into the engine bay of your Camaro, and headers are on the market that will allow it to fit right in. Have you thought about putting a more relevant engine into your Camaro? An LS-based small-block will also bolt in with mounts and headers. These engines are slightly lighter than your original small-block, and with the proper parts will run and handle like a dream. The added 200-plus pounds that a big-block places squarely on the front tires really changes the characteristics of your Camaro. If you’re looking to cook the hides, then this is where you want a big-block!

We assume you have a 454 around looking for a home. The big-block will actually bolt right into the chassis where your small-block lives with the same transmission, mounts, and crossmember. You will need to use a standard 4-quart passenger car oil pan, or a Milodon street/strip oil pan. Milodon offers a 7-quart pan that is 81/2 inches deep and is now notched for easy oil filter removal with close-fitting headers. The Mark IV (’65-89) big-block pan is PN 30951, and the Gen V/VI (’90-and-up) is PN 30956. We’ve used these pans in plenty of big-block swaps; the additional 3 quarts of oil are really important. If you truly knew how much oil is in a standard 4-quart pan at high rpm, you would not run your engine there!

You can go many directions for headers. Hedman offers full-length (PN 65105) or shorty (PN 66617) headers for this application. The shorty headers are 13/4-inch primary pipes with 3-inch collectors and will accommodate both power steering and air conditioning. The long-tube headers feature 2-inch primary pipes and 3-inch collectors. They will fit with P/S, but not with A/C.

Between these choices of headers and oil pans, your big-block install is just a credit card and mouse click away! Keeping a transmission behind your big-block, keeping it cool, and keeping tires on the beast is the next question. You didn’t state if you had a rare Saginaw four-speed model or if you have the more pedestrian TH-350 automatic version. Yet, you will either need to rebuild and modify to contain the torque your big-block will produce. Just remember, you can bolt anything together. Making it live is in the project planning. Good luck and have fun!


Life goes on

I haven’t had any project cars in about 15 years; I have been busy with life, raising kids, and working. I was just wondering what would the effect be if I were to change the rocker arm ratios from 1.5:1 to 1.6:1 on a stock small-block Chevy? I don’t know what year the engine is but I’m pretty sure that it is pre-’80s and it has the dipstick on the driver side.

Also, I rebuilt a 350 out of a ‘69 Camaro about 15 years ago. It was never installed in a car and I tore it down to check it out. It looks clean and in good shape. Problem is, I forgot what cam I put in it and I have lost the paperwork for it. I am pretty sure it is a 0.480-inch lift cam. Is there a way to figure out what I have? Lastly, it had a three-speed manual trans on it. I want to put it in my ’83 Z28, which has a four-speed auto. Are there any balance issues or problems involved in that?

Tim Ferris
Mason, MI

At some point in our life our car projects get put on hold. We’re glad that you’re at a point in your life to pick up your car hobby where you left off 15 years ago. For the rocker swap, if the small-block in question is completely stock you will have enough additional valvespring to accommodate 0.030-inch max lift. This is what you usually pick up on average with stock-type camshafts lift. Along with the increased lift, you will see a couple of degrees of duration at the valve based on the increased rocker ratio. Increasing the rocker ratio is an easy way to pick up some power gains.

Identifying the camshaft in your small-block can be as easy as removing the camshaft plug in the rear of the block. Most aftermarket cams have the part number or some type of identification number stamped into the face of the rear journal. If you’re lucky enough to find ID numbers, you should be able to search on the Internet and find the specs. If there aren’t any markings on the camshaft, you could profile it with a degree wheel and a dial indicator. This isn’t that tough if you have the equipment. You can check on the COMP Cams, Crane Cams, or Lunati’s websites for profiling instructions. You can find duration at any tappet lift, separation angle, max lift, and camshaft installation point. It’s very straightforward with the proper instructions and, again, the tools to do so.

The ’69 350 small-block is what is called neutral balanced. This means that all balancing is done with the crankshaft and rotating assembly. An externally balanced engine means that either or both the harmonic damper and flywheel have balance weights designed into them to complete the balanced rotating assembly. You can install your ’69 engine with an ’85-and-earlier, 350-cid-or-smaller displacement flexplate and have no worries on balancing. All these engines are neutral balanced.


Delicate touch

I have a question on color sanding. Can you color-sand a car that is three to four years old to remove any small defects, then repolish it with 3M materials as in your article (“Color Sanding To Perfection”, Aug. ’10 issue)?

Tom Bowder
Medford WI

If you have never ventured into the world of color sanding and the process of polishing the paint to a high luster, it’s not for the faint of heart. You can easily sand through edges of your paintjob, right down to the primer--or worse yet--to the metal. Then as you’re using the buffing pad and cutting compound, you can burn the paint and it’s all over. Now, we’re not saying that you shouldn’t take on this process. The reward at the end is worth every hour you’re going to put into it. Just make sure you’re ready to follow through before you start.

As for cutting the paint after it’s three to four years old, it’s not a problem. Really, the paint has had plenty of time to completely dry and get all the solvents out of the material, and it’s shrunk to its final size. One of the issues with color sanding and buffing out the paint after it’s painted is waiting enough time for the paint to cure. We’ve seen shrinkage issues where the paint was beautiful several months after the job, then after a summer in the sun the paint presents with very fine sanding imperfections that were in the base primer and have come to the surface.

The 3M products and the techniques listed in the story will have your ride looking better than when it was first shot. If you have some buddies with paint and body experience you may want to bribe them with barbecue and adult beverages.

Hidden Wipers

I’ve got a ’67 Camaro that I’m planning on shaving the firewall completely, but I don’t want to lose the windshield wipers. Is there a kit available to relocate the wiper motor to under the driver-side front fender where the “X” is on the firewall? Thanks.

Tony Ramos
Via email

Clearing off the firewall of your engine bay is a clean option. We’ve done it to several builds when installing Vintage Air into our early iron. It wasn’t a completely shaved wall, but getting rid of the factory suitcase for ’60s A/C was nice.

Many retrofit electric wiper conversions are on the market for street rods. These are to replace the original vacuum-powered wipers that stopped every time you stood on the throttle, or were climbing a grade, which lowered the engine vacuum. Not too convenient when it’s pouring rain. They use compact little electric wiper motors and that, in conjunction with your factory wiper arm off your stock motor, will keep the ratio the same. We’ve never seen a kit to place the wiper motor where you mention under the driver-side fender. Great idea! We could see some manufacturer picking up your idea and running with it.

We’re impressed by the selection and features of the systems offered by Classic Motor World for three-speed operation, intermittent operation, and support windshield washer pumps. Putting together a system using these components would be a great improvement over the stock ’67 wiper system. The electric wiper motors are small enough to fit into the location you referenced. Check them out online and let us know how it all works out.




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