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Performance Q&A

Hi-Tech Engine Swap

Kevin McClelland Mar 1, 2008
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What was your first engine swap? Did you rop a small-block in place of a six-cylinder? Or was that a big-block into a small-block Camaro's engine bay? Any of those swaps are very straightforward, even back in the '70s. No, what I'm talking about is when you started with nothing but a sheet of cardboard, scissors, scrap steel, and a stick welder!

My very first engine swap was dropping a 396 into my good friend Ron Kober's '55 Chevy. We were in our senior year of high school (back when dinosaurs roamed the planet) and he bought a pearl-white, glass-tilt-frontend, early-Oldsrearend, small-block-powered '55. My dad and I were running his injected big-block Fiat race car at the time, and Ron and I scored all the used parts from the Fiat. We built a handgrenade 396 from an Impala and used a Hurst front mount for the engine, along with a set of Horsepower Engineering in-frame headers. That car was a blast with its 4.88:1 gears and Muncie four-speed. I'm truly amazed that either of us is still here to talk about it.

Now for the real swap. While attending Los Angles Trade Tech, I was working for Norm Sappenfield at NCP Motors. This was a shop in L.A. that had been in the business since the early '50s. Norm was famous for working on the "stars' cars" from Hollywood and building some very odd creations. His personal car was a '70 Maserati Ghibli with an aluminumheaded L-88 crate engine and a TH400 that he had swapped into it. This car was an absolute blast to drive, and it could spin the wheels all day long. One afternoon, there was a '52 XK-120 Jaguar in the shop for a small-block Chevy engine swap. He looked to me and said, "There is your next job." I had never done anything like that! I credit Norm with giving me the vision that anything can be built. Needless to say, I'll never forget my first real swap.

Today, there are many very popular engine swaps out there. With the availability of the LS engine family and the six-speed trannies attached to them, they are finding their way into many engine bays. The first one that comes to mind is the Gen III small-blocks going into Mazda RX-7s. They are showing up at dragstrips all over the country. These cars are cheap and very easy to come by with blown rotary engines. Drop in a 400hp LS6, a six-speed, and a mild camshaft, and you're knocking on the 10s! If you search YouTube for LS1 swaps, you will find some outstanding, well-documented engine conversions. The common theme of these videos is the cars being thrown out of dragstrips for running too fast without a rollbar.

Step back and look around for a lightweight donor car. Many willing hot rods are laying around, just looking for some serious horsepower. Remember, anything can be done, but we never said it would be easy.

Why More Flow?
QMy question runs to the airflow requirements of your typical 23-degree 350ci small-block Chevy. In summary, a 350 that peaks at 6,500 rpm and operates at 100 percent volumetric efficiency would need airflow of approximately 658 cfm (which, by the way, is the same amount calculated on various Web sites dedicated to determining carburetor sizing requirements). Therefore, each cylinder requires approximately 83 cfm.

However, when reviewing the flow capabilities of several high-performance 23 degree small-block cylinder heads of 180cc intake port size, I noticed that, on average, the intake port flowed at least 100 cfm at 0.200 inch lift and as much as 250 cfm at 0.600 inch lift. I realize it's not appropriate to focus on peak numbers, but the flow rates at the lowest lift seem to be more than adequate to service the engine. If this is the case, why does the quest for cylinder heads that flow more air go on, and how does the engine benefit from it?Frank LanutoVia e-mail

ALet's see if I can do this one justice. When it comes down to testing cylinder heads on a flow bench, you are flowing in one direction at a constant depression against the restriction of the port. This gives you an average airflow in cubic feet per minute (cfm). When an engine is running, the intake system has very chaotic flow. Let's take a middle-of-the-road racing camshaft duration and say the valve is open 300 degrees of crankshaft rotation. Each intake cycle, you must first get the air column moving, ram the cylinder full, and come to a complete stop when the valve closes, then reverse the direction of the flow in the port and inlet manifold runner. This happens every cycle that the engine rotates. As you know, it takes 720 degrees of crankshaft rotation to complete the four-stroke cycle. Also, the piston is constantly moving down the bore on the intake stroke, at different speeds based on location in the bore, and doesn't have a constant suction (or depression) on the inlet system. With all this being said, the port is at peak flow for a very limited amount of time in this 720 degrees. This is why we're constantly looking for more airflow out of cylinder head designs. Also, you don't want to make the ports arger just for the sake of airflow. Youwant the smallest port that flows the most air. You need small (proper size for the displacement) ports to keep the velocity high. This proper-sized port will always run the best and accelerate the engine the fastest.

On street-performance engines, it's very rare to see 100 percent volumetric efficiency on the engine dyno. This is measured airflow at the carburetor. Yes, if it was average flow by the minute, we could easily fill up the cubic-inch displacement of the engine. Don't we all wish it was that easy?

Overseas Education
Q I hate to ask such a rudimentary question of a guy who writes such technically filled answers, but we've all got to start somewhere, right?

I want to educate myself on basic and advanced engine and drivetrain perfor - mance, so I've started to read your magazine every month, but I'm finding that I'm missing some fundamental knowledge that will help me understand what the writers are talking about. For example, what are the differences between a 427 and a 383 block, between H-beam and I-beam rods, dual-plane and single-plane intakes? How do you decide on a rearend? What cam and what rocker ratio to run? I realize these might be easy to most of your readers, but again, I'm just back into building cars.

I know all these answers don't exist in one book, but can you suggest a few to get me moving in the right direction? I've got lots of time on my hands now and don't want it to go to waste. I'm serving as a staff officer in Baghdad, and once I return, I'll transition into life as a civilian which will afford me much more time to continue my engine education and future buildups. I plan to find a car or truck (early '60s/late '70s) somewhere in the neighborhood of 30-50 percent complete and finish it. Thanks for your time.William Richardson CPT, ENBaghdad, Iraq

A It's great that you wish to use your downtime for absorption of Bow Tie knowledge! Some of the questions you have are far from rudimentary. Design answers are somewhat straightforward; however, the camshaft selection, gearing, and powerbands can elude the most seasoned veteran.

If you're looking for basic education, we'd recommend starting with the standard small-block Gen I Chevy. More has been printed on this engine over the 52 years of its life than on any other engine. The fundamentals will carry over to any dead dinosaur- eating internal combustion engine. That said, we'd start with How to Hot Rod a Small Block Chevy, originally printed by HP Books but now owned by Penguin Group. Then, from SA Design is the must-read Smokey Yunick's Power Secrets. Smokey tarted working with the small-block for GM back in '55. If it's been done, he did it at some time. Other good reads are The Step by Step Guide to Engine Blueprinting, High Performance Chevy Small Block Cam/ Valve Trains, and Small Block Chevy Performance 1955-1996.

This will give you a good foundation and answer many of your questions. Also, don't hesitate to contact your manufacturer of choice for the components in questions. They have great technical service lines and can help eliminate some of the confusion.


Steering Gear
Q I'm swapping a big-block into a '78 Chevy Nova. What Chevy is a good donor for a manual steering gearbox? And what is the total mechanical advance built into the GM Performance HEI that JEG's sells under PN 809-93440806? Great job helping us readers out! Thanks.Tee ShartownTucson, AZ

A There are many manual donor cars out there. However, I just went through the same process with my '80 Malibu wagon, converting it to manual gear. All the manual boxes I found were either too worn to use or the gear, worm/sector was rusted from moisture getting into the boxes. An easy donor is an early- to mid-'90s S-10 truck manual steering gear, if you wish to look for used units.

I picked up one of the new boxes on the market from my pal Ken Casey at Burt Chevy for my Malibu wagon. It was a 525 Saginaw manual box and fits all '60s and '70s GM cars originally equipped with a 605- or 800-series Saginaw power box. The 525 manual box's very slow 20:1 ratio makes it quite easy to turn, but it keeps your arms in exercise! Both Summit and JEG's also sell the Flaming Riverreproduction pieces, which are quite affordable if you compare how much you're going to pay in core charges before finding a good one.


It's An Emergency!
Q I've put a set of rear disc brakes from an '86 Camaro into my '70 Camaro. Does someone make emergency brake cables for this conversion or offer individual parts so I can fabricate them myself?
Sonny LindamoodVia e-mail

A Check out Lokar Performance Products' universal E-brake cable system. Several universal sys tems are offered, based on the clevises and brackets you have on your disc brakes. Also, for the rest of you guys, Lokar offers cable kits if you're using '84-87 or '88-and-up Vette, Baer Brakes, Wilwood, or Stainless Steel Brakes rear disc kits...and also parts for those F-word brake systems if you decided to go that way.


Hot Rod Chevette
Q I want to slightly modify my '83 Chevette with a large-journal 350 into a 327 with a 307 crank. I'd like to go with a set of 6-inch rods (to help deal with piston side loading) and pistons to give me about 10:1 compression with a set of fast-burn aluminum Vortec heads with 62cc combustion chambers. I'd also like to go with a Lunati Voodoo cam (219/227 degrees duration at 0.050 inch tappet lift, 0.468/0.489 inch max lift), round out the cylinder heads with a set of beehive springs and some roller rocker arms, and op it all off with a Weiand X-celerator intake and a 770 Street Avenger carb. I'm going to back up the 327 with a fivespeed overdrive from a Camaro, 3.23:1 rear gears, and P215/50R15 rear tires. This is going to be a 2,400- to 2,800- pound (or lighter) daily driver. Does this sound like a good, streetable package? I don't really want to have to balance the rotating assembly, so do you have any recommendations for rods and pistons that are as light as the 307 units? I've heard the Fitch fuel catalyst allows you to have a higher CR with a lower octane. Is this true, and if so, will the 10:1 CR work well on the street with 87-octane and a lead foot? Thanks for any help. If I can get it all together in a couple of months, I'll send you some pictures of my little 327 Vette. John BlaggVia e-mail

A Let's start with the Fitch fuel catalyst. Until your letter, I hadn't heard of this unit. I read what Fitch has to offer on the Internet, and while there are testimonials from magazines, customers, and state agencies, my personal experience with such devices hasn't been good. However, like I said, I've never seen or tested this unit. It's got some great claims, and if you get half of what it boasts, it's worth the money. If any of you readers have any experience with one of these units, I'd love to hear your impartial views.

Next, you'll need to balance your rotating assembly. With the 6-inch rods, it'll be tough to match the weight of a standard 5.7-inch rod. With the extra steel and the change in reciprocal weight, you could end up with a shaker. Spend the money and enjoy the smooth engine operation.

I think the rest of your plan is very solid. The engine isn't too wild, and with the lightweight Chevette, the T-5 five-speed overdrive should live with few troubles, if any. Reinforce the body structure to accommodate the added torque of your little Mouse; that thing will want to twist and shout.


Monkey Bars
QI am looking for a 12-point rollcage for a '94 Chevy S-10 pickup. I've searched endlessly on the Internet and at local speed shops and parts houses, and the best I could find is an eight-point roll bar from Summit Racing. Do you know where I could get one, or do they just not make one? Or do I have to have one custom made? I'm putting a small-block 427 in my pickup, and the 12-point would really help strengthen the frame.Joe BushUnadilla, NY

A Finding a custom-made 'cage kit for everything on the road is really tough. That eight-point rollbar kit is by Competition Engineering and features a 13/4-inch-tubing main hoop (PN C3134A) and strut kit (PN C3001) that rounds out the bar. This is your side bars, rear bars, and X-brace. You could have Competition Engineering custom-bend you up the associated Halo bar for the front windshield. The uprights and firewall bars are straightforward and would all be made in 13/4-inch tubing that is a minimum 0.134-inch wall thickness to meet NHRA certification requirements.

I've been very happy with Applied Racing Tech nology, which sells a 12- point 'cage kit under PN 19713, made of 15/8x0.134-inch-thick mild steel tubing. The kit includes a Funny Car 'cage, a roof diagonal brace, a Kidney bar, and Door X-bars. Vehicles aren't listed by application in the catalog, but the company has bent up a 'cage for just about every application out there. If there's no data in-house, you just need to supply the proper dimensions so the perfect-fitting 'cage for your S-10 can be bent up for you.

Good luck with your monkey bars. I hope you never need to use them.


Break-In Debate
Q I just finished assembling a 396 small-block Chevy. It's a one-piece rear main seal block bored 0.030 inch over, 3.875-inch stroke, with a 6.0-inch rod. It has AFR 210 race heads (66 cc) making 11:1 compression. I'm running a Comp solid roller cam that specs out at 268/274 duration at 0.050 inch lift and 0.676/0.653 max lift. It's topped off with an Edelbrock Victor Jr. intake and a HP 750 Holley. The fire is lit with an MSD Pro Billet distributor and a 6AL ignition, and the spent gases go through 17/8-inch Hooker Super Comp headers.

The machine shop that did the shortblock assembly (so I didn't do all the work) said to start it and run it for 20 minutes. However, talking to people at the track, some say run it for 5 minutes with 30- weight oil then change it-this gets all the assembly lube and any dirt you may have in it out-then run it with the new oil for 20 minutes. Everything I've read says once you start it, don't turn it off unless you have to. What do I do?
Rich JohnsonSt. George, UT

A The proper break-in procedure for a sliding contact (flat-tappet) camshaft and lifters is to run the engine for 20 minutes above 2,000 rpm, varying engine speed between 2,000 and 2,500 rpm. This is required to splash enough oil up to the tappet and camshaft surface to prevent undue wear during the mating process of break-in. There isn't enough leak age between the lifter body and the block to adequately lubricate the tappet face. Also, when assembling the engine, you must use an extreme-pressure lube on the camshaft lobes and tappet face. Finally, use a high-quality racing oil, engine oil, or GM Engine Oil Supple ment PN 1052367 to fortify the oil with extreme-pressure additives to make it through break-in. This is the most critical period for the long life of your engine.

Next, we move on to any engine that has a roller follower for the camshaft action. It doesn't matter if it is a mechanical or hydraulic roller tappet; neither requires a break-in period. When you fire an engine with either of these camshafts, you may bring the engine to an idle right after firing.

With any engine, I run the vehicle until the engine is fully up to operating temperature and may even take the car around for the first testdrive before draining out the break-in/ start-up oil. Never put the engine under full load with start-up oil. Yes, you will wash down any debris that wasn't caught in cleaning and all the assembly lubrication. The filter will catch anything that will cause a problem. Drain the oil when it's at full operating temperature to ensure that you get the most of the start-up oil out. Then add a fresh batch of your choice of quality engine oil. I hope this clears up engine start-up procedure based on camshaft selection.

I Blew It Up!
Q I've seen quite a few articles on the 400s lately in your magazine. I happen to have a 406 in my '89 fullsize Blazer (lifted and such with 36s). My engine is a '76 400 small-block bored 0.030 inch over. Not sure of the cam specs, stock/ mild. I have my 350 '89 TBI setup and heads (steam holes drilled), intake, and harness. I don't have a chip or different injectors on it; it's all stock. I've had quite a few people tell me I'm going to blow engine up because it's running lean. They also say it will never work with the setup I have. Of course they've never seen my truck, and they're all "expert engine builders." The engine was originally built and stuck in my buddy's van three years ago and I put it in my Blazer two years ago.

Can you put a stock 350 TBI setup on a stock 400/406 and have it perform without reprogramming the computer? For the dollar-conscious, would that be reasonable low-buck build? I tow my boat to the lake (120 miles away) and average 16 mpg driving 65-70 mph. I thought this was OK, but with all these people on an online forum telling me I'm going to toast the engine, I thought I'd get an expert opinion. Also, if I did want to upgrade my setup, what would be some good choices? I'd like to keep it a reasonable street engine and keep the TBI. Thanks for any input.ShawnVia e-mail

A How does it work on yours, but everyone else's melts down? All the people telling you "You're gonna blow it up" are not wrong. Why doesn't your engine burn up? That's a really tough question. Let's take a look at some of the facts.

Going from 350 to 400 cid is an increase in displacement of about 14 percent. Working nothing else into the equation, you should be flowing 14 percent more air with the larger displacement. To properly fuel the engine, you should also need approximately 4 percent more fuel. The fuel injection system on your Blazer is what is called a speed density system. The factory creates an airflow model on the engine dyno called the volumetric effi ciency table. This is programmed into the computer and based on the displacement of the engine, it fuels the engine to a pre programmed air/fuel ratio. The computer has the ability to learn when the O2 sensor sees air/fuel ratios that are out of the boundary of the calibration. Can the O2 move the fuel 14 percent? No, it shouldn't have the room to move the fueling that far; however, your truck has lived a lucky life, and you have more than two years on it, towing and everything.

We would contact GMCOPO's Tom Woodside; he worked with GM when developing the HT502 TBI engine package for GMPP. He has tremendous experience working with GM TBI systems both on small- and big-blocks. He can adjust the displacement in your calibration to your new 406 cid. This will give the computer the room to go either leaner or richer based on operating condition.

Based on the fact that you've been knocking down very good mileage numbers, and that you're happy with your current performance, we wouldn't make big changes. Upgraded exhaust and air-intake system, and getting the calibration right would be our recommendations.


Don't Get Cranky
Q I purchased a CVR Protorque mini starter, PN 5323OS, for an '84 Camaro with 355ci small-block. My problem is how to wire it. There is no terminal for the start wire from the ignition, only a positive from the battery and a ground. Do I need a remote starter solenoid? Thanks.Dave CaslerVia e-mail

A It took some digging, but I found your starter. Sold by CVR Automotive, it's a Nippondenso Gear Reduction unit that produces 1.9 hp, weighs 10 pounds, and has a 4:1 gear reduction, which is very similar to what was used in the late-'80s Corvettes.

As for the wiring, the photos I found showed a positive battery terminal with a 13mm nut, and next to it is a blade spade con nector to attach your start wire from the ignition switch.


Z-Car Runner
Q I've never written for advice before. I have always just worked through problems and often spent more money han necessary. After reading your responses to others' questions, I'm confident you won't find mine stupid. I appreciate that!

My 240Z has a small-block Chevy, a Corvette rearend with a 3.75:1 gearset, and a Richmond six-speed with a 0.62 final drive ratio. The car weighs approximately 2,300 pounds. The engine in it now is stock -and very tired. I plan to replace it shortly, but there are so many choices out there. I hope you can advise me on which route to take. The car will not be used for drag racing, but is being built to be a Corvette killer and have a little fun with the tuner crowd. It will see periodic highway use and, of course, cost is a consideration, but $5-9K for an engine is within my budget. I have every thing but the long-block. Dealing with a unibody, I am a little concerned about torque. I'm willing to install a 'cage, but that affects comfort. Also, I am connecting the frame this winter, so that much will be done, but the 'cage is something I would like to avoid.

Do I go for the torque-monster 383-434 (and subsequent 'cage), or do I stay with a shorter stroke and get something that will rev quick (302-350)? If you were building a car for this purpose with my budget, what would you do to maximize your fun?
Alan HaleMemphis, TN

A I think if all of us had stopped for a minute and asked a few questions, we'd all be a little be wealthier. I know I would be. Also, this is a great question with many points to work out. I just hope I don't throw too big of a wrench into your plans.

I have a very large soft spot in my heart for small-block-powered Z-cars. Back in the day, when I had McClelland Automotive, I took care of a customer's '71 Scarab Z-car. These were built by Scarab Automobiles in San Jose, California, which produced approximately 250 finished cars that were upgraded with blueprinted 327s, T-10 four-speeds, Koni struts and shocks, heavier antiroll bars, Teflon bush ings, and stiffer front springs. You could order the cars in total stealth mode with no body kit-or with full-blown spoilers and air dams to personalize your Z. This was in the early '80s, and I'll never forget driving that car. A bunch of my buddies have small-block-powered drag race Z-cars. They run mid to low 10s with very mild small-block 350s. Lightweight is a wonderful thing.

What would we do to maximize the fun? We'd drop the Gen I small-block for an LS2 all-aluminum small-block. You'd be shedding several pounds over the Gen I small-block. Also, if you look around the junkyards online and find a '05 LS2 from a Corvette or GTO, swap in a GMPP Hot cam or similar, a set of headers, and your driveline, you would have one very quick Z-car. This will give you a very streetable 500 hp at the crank and 400 ponies to the ground. Many have been built, and the components are now becoming readily available. Check with Johns Cars for engine mounts. Then go to Jags that Run for a set of 13/4x3-inch four-tube headers and air-intake system. Everything else is straight forward. You should have no problem attaching your Richmond six-speed to the back of the LS2 with the proper flywheel. Centerforce can help with that. The bell housing bolt pattern is no problem; you just have to make up for the crankshaft flange being 0.400 inch shorter from the bellhousing face.

I know you said you have everything except the long-block for your small-block, but you'll barely touch your budget with this swap. This will give you a great, balanced street sleeper. You will get the torque you're looking for with the high-winding performance of a little small-block.


New-World 30-30
Q Several years ago, I pulled an old '68 Z/28 drag racer out of the garage, where it had been for 15 years. It was dissembled by the previous owner, but the car and engine parts were complete. I reassembled it all and got it running last summer. After 45 minutes, a cam lobe went down. I'm now rebuilding the engine (and planning on using an oil break-in additive in addition to the cam lube.)

Which cam should I go with? The engine is a 0.030-inch-over 302, about 11:1 compression, with a full race port on the original 2.02 heads. The intake stock. The original 12-bolt rearend has 4.11:1 gears. This car will be driven on the street. It's not going to be a racer except for the occasional quarter-mile outing. I'd like to go with a camshaft employs some modern technology, I don't want to lose the sound of the 30-30 cam.

I'm considering the Comp Cams Nostalgia Plus PN 12-673-4 solid lifter. has the characteristics of the original Z/28 cam but more power throughout powerband. What do you think?
Rich SutliffeVia e-mail

A Camshaft technology has come light-years since the 30-30 Duntov camshaft made its way to the streets back in '64. For its time, it was one rowdy camshaft. I've lashed many a valve with that stick pushing them.

Most camshaft manufacturers have released a blueprint line of camshafts to fill the restoration market. Some have taken it a step further by freshening up the old 30-30 with new technology. Yes, that camshaft will run much better than the original cam. But with your engine combination, you may want to take it a step further. Since you have fully ported heads, you could take advantage of some increased lift. The Nostalgia Plus comes in at 247/254 degrees duration at 0.050 inch tappet lift, peak lift of 0.504/0.498 before lash, ground on 112 centers. If you went with one of Comp's Xtreme Energy mechanicals, you could benefit from another 0.040 inch of max lift. The XS 282S comes in at 244/252 at 0.050 inch, 0.520/0.540 inch max lift, ground on 110 centers. With less duration and more lift, the Xtreme Energy camshaft has even more lift rate and should have equal overlap even with the tighter centers.

Either camshaft should run very well in your 302. And as for rpm range, the sky is the limit. If you want to tweak out the last bit of horsepower-and look the part-get an Edelbrock RPM PN 7101 and grind off all the markings to make it look stock. They sure run a lot better than the original factory dual-plane.


If you have technical questions for Kevin McClelland, send him an e-mail at

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