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Car Craft Mag
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El Segundo, CA 90245
One Piece or Two?
Chris Schwarz; Dunlap, IL: I have a question about swapping a one-piece or a two-piece rear main seal Chevy small-block engine. I have a ’98 Chevy K1500 truck with the stock Vortec 350, which is getting tired. I also currently have a pretty mild 383 built from a ’70s-era block in my’85 Monte Carlo that I built while I was in college. The 383 is a two-bolt main running a cast Scat crank, Speed-Pro hypereutectic pistons, a mild Crane cam, and cast-iron Vortec heads. I have a good job now and can afford to build something stupidly fun for the Monte Carlo but don’t think modifying the 383 would be worth it. It runs perfectly fine and would work well in my truck. What parts would I have to change to put the 383 in the truck? I assume I would need a new flywheel (the truck has the NV3500 manual transmission). Also, what needs to be done to put the truck’s fuel injection and accessory-drive system on the 383?
This is what you get with the FAST EZ-EFI conversion system for a multi-point fuel-injecti
Jeff Smith: As you’ve anticipated, the swap is relatively easy in terms of physically adapting the engine to the truck, and even the serpentine accessory drive will cross over, but I think the conversion of the TBI would be disappointing. Let’s hit the easy things first. Yes, you will need a new flywheel because the Vortec small-block is a one-piece, rear-main-seal engine, while your ’70s-vintage 383 is based on the earlier two-piece, rear-main-seal version of the small-block Chevy. I will assume that because the Scat crank is cast, it is externally balanced. This means you will need a 400-style externally balanced flywheel. Since you will be bolting this engine into a truck, we’re going to also assume that the truck’s five-speed will not work well for a performance application. This means you’re not going to abuse the truck with lots of high rpm. If that’s true, then you could get away with a non-SFI–style flywheel, which will be less expensive, though I would recommend at least nodular (rather than cast) iron. Better still is a steel flywheel, but it doesn’t have to be SFI. Cost is directly related to better materials, with the cast iron being the cheapest, then nodular iron, then steel, and finally an SFI-spec’d steel flywheel.
This is the MSD 6-AL2 digital box. Combine it with the Pro-Data+ software, and you can def
The accessory drive should bolt right on as long as the heads on your 383 have the accessory boltholes. That serpentine system bolts directly to the block and the heads and does not connect to the water pump, which is nice when it comes to swapping water pumps. This leaves us with the TBI injection. This system will be too small for a 383, unless you don’t mind that the engine won’t make 300 hp. Frankly, the TBI is undersized even for a 350ci engine. Even if the 383 has a stock cam and heads, the TBI throttle-body will be a cork at around 480 cfm. There are ways to marginally improve the airflow, but doing so would only aggravate the even more constricted fuel delivery, since with only two small injectors, fuel pressure is limited to 15 psi. From an emission standpoint, you’re not supposed to change things, but Illinois is thankfully less overbearing than California. You could use a Tuned Port Injection (TPI) setup if you’re only going to spin the engine to around 4,500 rpm. The TPI would deliver some fantastic torque—just not horsepower. If this sounds plausible, you could easily adapt FAST’s EZ-EFI to the TPI package. The universal EZ-EFI adapt kit (PN 302000, $891.95, Summit Racing) is affordable, but you will need 28-lb/hr-or-larger injectors for the 383 to flow enough fuel to make 375 hp. Another suggestion is the super affordable MegaSquirt. If you are willing and/or capable of soldering together your own mother board, you could assemble a complete system for around $400, and there are tons of people on the Internet with MegaSquirt experience. The least expensive approach would be to control just the fuel and use a separate ignition like an HEI distributor. There are more complex MegaSquirt systems that also control the ignition, much like a GM system, using a GM HEI small-cap distributor. This isn’t an emissions-legal EFI package, but functionally, it is very close. This could cost almost the same as the EZ-EFI system if you dial up the most complex MegaSquirt. But if you can accomplish the DIY thing and solder up your own system, you can keep the cost down to around $400–$500. That’s about as cheap as you can get and still call it EFI.
Fuel Air Spark Technology (FAST)
Rattle and Hum
Wayne Tullis; Coquitlam, British Columbia, Canada: I am having issues with detonation in my '71 Nova. I have built a 383 stroker with 10.71:1 compression made up of:
- Forged flat-top pistons with 4cc valve reliefs
- Ported Edelbrock 64cc Performer RPM heads
- 4.030-inch bore and 3.75-inch stroke
- 0.020-inch deck height and 0.041-inch head gasket
- Comp 274 XE with 230/236 degrees duration at .050, 110 lobe separation and 0.490-inch lift
- Comp 1.6:1 roller rockers
- Edelbrock RPM Air Gap Intake
- Holley 750 DP, 81 primary and 84 secondary
- MSD distributor and coil with 18 initial and 34 degrees total at 3,000 rpm
- 94-octane Chevron RON+MON/2 (Canada)
- Five-speed manual and 3.73:1 gears.
The car doesn't overheat and pulls very strong. When I put the engine under load at low rpm, I get detonation. At high rpm, I don't notice it. I have had it on a dyno, and we could not tune out detonation unless we backed the timing way down, which created a loss of power. Air/fuel mixture is good. I have checked the cranking compression and have 205 psi. I have retarded the cam 4 degrees to bleed off a little cylinder pressure. This helped but did not solve the problem. I am thinking of running a 284 XE cam to bleed off a little more cylinder pressure and running a thinner 0.019-inch-thick head gasket to get my quench more in line. If you would suggest the 284 or other cam, would it be with 1.5:1 or the existing 1.6:1 rockers? Is the 205 psi higher than what I can safely use with my fuel or is it another issue? Thank you in advance for any help you can provide.
Jeff Smith: It's interesting how many different questions all seem to eventually lead back to a few common issues. You have also made this a little easier by including excellent information on how your engine was assembled. It is this information and your own suggestion that offers clues as to why your engine detonates. In the engine description, you mention that in the current configuration the pistons are 0.020 inch below the deck height, and you are using a 0.041-inch-thick head gasket. This puts the piston-to-head clearance (also called the quench) at 0.061 inch. This is the distance between the top of the piston and the cylinder head, with the piston at top dead center (TDC). As the distance increases, the compression decreases. The downside is that this additional clearance reduces the quench. The idea behind quench is to squeeze a portion of the air/fuel mixture between the piston and the head so as the piston nears TDC, it pushes the air/fuel mixture into the far portion of the chamber. This increased activity more thoroughly mixes the air/fuel mixture. This generally improves combustion performance and can often result in additional power while simultaneously reducing an engine's sensitivity to both ignition timing and detonation. All of these are positives. We can't overlook the fact that decreasing the piston-to-head clearance (improving quench) also increases the static compression ratio, which might seem counterintuitive, but in most cases, improving or tightening the quench generally improves performance. Your idea to reduce the head-gasket thickness from 0.041- to 0.019-inch thickness is good, as it will improve the quench. But this will raise your compression ratio to 11.29:1, which is a healthy gain of over half a ratio. While this may be a step in the right direction, it is still a pretty serious static compression, and your cranking pressure will increase.
Before you go to this effort, it might be a good idea to try another idea. You mentioned that you are currently using 18 degrees of initial timing with 34 degrees of total timing. One trick that might help is to reduce the initial timing to 16 degrees, and then add two more degrees of mechanical advance. This will create the same 34 degrees of total timing, but it might help with the low-speed detonation problem. Another trick might be to slightly slow the rate of mechanical advance. You didn't mention when the engine rattles, but let's assume it occurs at around 3,000 rpm. Most quick curves have the timing fully advanced by 2,500 rpm. If you slow the rate of advance down by using heavier springs on the mechanical advance, it may delay the onset of detonation at the lower engine speeds. Here's why this might work: All engines create maximum cylinder pressure at or near peak torque. Peak torque is primarily determined (though there are dozens of contributing factors) by cam timing. As you increase cam duration, the engine's peak torque moves up in rpm. That's why going to that larger 282 cam you suggested would also work. The longer duration will raise the rpm point at which peak torque occurs. But before you do this, there are a couple of other less-labor-intensive and less-expensive methods to try. If peak torque occurs around 3,800 rpm, it's possible that delaying maximum timing until after that point might resolve the detonation issue. You can simulate this by just pulling initial timing back by 2 degrees. If that works, you can try delaying total advance. You didn't mention whether the MSD distributor is equipped with vacuum advance. If the engine rattles at part-throttle, it could also be that there is too much vacuum advance at that point. The quick test for that is to disconnect the vacuum advance and see if it still rattles. If not, then you might be able to restrict the vacuum advance to keep the engine out of detonation.
If the previous ideas don't solve the detonation, there's another possibility. MSD offers a digitally programmable MSD 6AL-2 CD ignition box (PN 6530; $359.95, Summit Racing), which offers the opportunity to use MSD's Pro-Data+ software to create a custom digital ignition curve. Here's a quick overview. You lock out the distributor mechanical advance and use the software to create a digital version. The reason you would want to do this is because the digital version offers a way to create a non-linear curve. Start the procedure by digitally duplicating your 18 degrees of initial timing and your mechanical advance curve. Then test to see at what rpm the engine begins to rattle. Let's assume that the detonation begins at 4,000 rpm and is gone by 4,500. All you have to do is pull the timing back by roughly 4 degrees between 4,000 and 4,500. The rpm band between 4,000 and 4,500 is the only place where you have to retard the timing.
In essence, you have built a timing curve that is a dedicated version of what a detonation sensor would produce. You might even experiment with larger amounts of timing retard, as often an engine will experience trace detonation that you cannot hear but yet can still affect power. The beauty of the digital curve is that it is very easy to modify the curve in as little as one-tenth degree steps in 100-rpm increments, if necessary. Of course, there are other ways to accomplish this same task, with items such as add-on detonation ignition retards from a company called J&S Electronics, which we've previously mentioned in this column. There's also water injection from companies such as Snow Performance, which makes a kit specifically for normally aspirated carbureted engines that can be triggered by using a manifold absolute pressure (MAP) sensor and/or rpm to trim cylinder pressures and prevent detonation (PN 20020MC; $550, Snow Performance).
Autotronic Controls Corp. (MSD)
Robert Stiles; Greendale, IN: I am building an engine for a local demolition derby. It is well known that derby cars are in reverse most of the time to save the radiator. I would like to have my engine turn counter-clockwise (backward) so I can utilize all three gears in my tranny as reverse, and reverse as a low gear to drive forward. Is this possible?
Jeff Smith: Wouldn't it just be easier to relocate the radiator to a safer location than to convert the engine to reverse rotation? Maybe it's not legal per the rules. Are there rules in demo derby? But your question piqued my interest in what it would take to reverse the rotation of the engine. Let's use a small-block Chevy as our example. At first, it seems all you would have to do is to have a cam company grind a reverse-rotation camshaft. But then that would reverse the rotation of the distributor gear, which might change gear wear. It would also mean the standard mechanical and vacuum advance would not work, so you'd have to convert to electronic ignition control. Next, the oil pump will not pump if turned in reverse, which means you'd have to convert to an externally driven oil pump with the requisite plumbing. At least the water pump would be easy since serpentine belt engines all use a reverse-rotation water pump. But if you ran this pump with a serpentine belt, the pump would be running in the “correct” rotation and would be running backward. So you would need to convert that pump to run with a non-reverse beltdrive. Finally, a stock starter motor would spin the engine in the wrong rotation, so you would need a reverse-rotation starter motor. You can't move the starter to the other side of block because it would hit the oil-filter boss. Next, the trans is also going to spin in reverse, which might mean that the pump may not make pressure. I'm probably missing a couple items here, but as you can see, this isn't really a good idea mainly because you'd probably have $3,000 or more invested in a demolition-derby engine, and I doubt winnings would pay you back. I think you'd be better off to just put the radiator on the roof of the car with an electric fan.
Smokey Yunick built a reverse-rotation Offy engine for the '59 Indy 500. The reasoning behind his approach was that by reversing the engine's rotation, the torque reaction in the chassis would push the right-rear tire into the pavement in the middle of the corner as engine torque increased on corner exit. According to Smokey's book, the car was a rocket coming off the corners because he could apply power off the corner sooner than the other cars. I stumbled across a reverse-rotation small-block Chevy that he built, which has now taken up residence at the Speedway Motors museum in Omaha, Nebraska.
Kyle Lutz; Houston, TX: I purchased my first Chevelle more than two years ago. It's been a frame-on restoration. I've read several of your articles over the years and have learned a lot. A while back, you did a piece on building a budget 400 (“How to Build a 400ci SBC Torque Monster for $2,500!” May '11). I'm not sure I can do all of the upgrades that you did but was wondering where I would get the most added horsepower for the least amount of money. The car already has a 400 in it with dual exhaust.
Have you thought about doing a comparison between Edelbrock's EFI conversion and the EZ EFI? I'd like to upgrade to an EFI system, but I am not sure which one would be the most reliable. Any suggestions? You can check out the progression of my car on my website at www.my71chevy.com. Thanks for your input and for writing such a quality magazine.
Jeff Smith: What is it about simple questions that seem easy but can quickly get very complicated? The question of the best-bang-for-your-buck upgrade really depends on a host of variables, but we'll take a shot at it. I dialed up your website and it appears the 400 engine has an Edelbrock intake and cast-iron manifolds. We'll assume for a moment that it's a stock short-block with a stock cam and heads. Our experience with that production 400 showed us that in an effort to pull decent emissions out of these big '70s motors, GM lowered the pistons in the cylinders between 0.060 and 0.080 inch! The stock compression on our 400 with 76cc chambers was a miserable 7.8:1. If you were trying to kill the efficiency of an engine, that's the way to do it. No wonder everybody spit on these engines back in the day. We put 64cc Vortec heads on our original version of the 400 in a marginal attempt to improve the compression, but that only brought the static compression up to around 8.4:1, which isn't even close to what it should be. But with a limited budget, that would the best call. With the stock cam, stock Vortec heads will also help power. As we mentioned in the story, you will need to modify the heads if a cam swap is in the works. As you saw with our engine, it was less than impressive even with the cam and Vortec heads, making barely 400 hp, but at least the torque was decent at 458 lb-ft.
Since your engine is equipped with cast-iron exhaust manifolds, headers and/or an exhaust system are the first things I would suggest changing. Improving on the existing dual exhaust (which is probably a compression-bent 21⁄4-inch system), to a true 2 1⁄2-inch mandrel-bent system will help that 400, even with the iron manifolds. I have personal experience with Flowmaster's American Thunder series of exhaust systems on Chevelles, and they fit very well. This is an entire 21⁄2-inch system with H-pipes, a pair of Super 40 mufflers, tailpipes, hangers, and clamps. You will still need to adapt the lead pipes to exhaust flanges, but that can be handled by a muffler shop. The system is PN 17119 and sells through Summit Racing for $349.95. This is by far the best bang-for-the-buck thing you can do for your car—even if the engine can't really take full advantage of what the system offers. Another company that builds excellent systems designed specifically for a GM A-body is Torque Technologies. They offer several options for both 2-1⁄2 and 3.0-inch systems. They charge a little more (the 21⁄2-inch system is $349, plus mufflers), but you have a choice of several different mufflers. Check 'em out. Because your Chevelle offers the room, you might even consider a 3-inch exhaust system or perhaps a 3-inch system to the muffler and then 21⁄2-inch tailpipes. Torque Technologies offers a system like this complete with either an H- or X-pipe.
The Eastwood Internal Exhaust Coating spray paint uses a 24-inch-long spray tube to allow
For headers, the best route would be a set of 1 5⁄8-inch long-tube headers. Shorter headers will fit better, but the long-tube headers increase torque and are just a better idea for overall power. They are more of a hassle to install, but well worth the effort. Some might consider 15⁄8-inch primary tube headers too small—and if you were going drag racing with a healthy 400 small-block, they'd be correct. But the smaller-tube headers won't be a restriction for this mild 400 and will help build even more torque. Hedman makes a 15⁄8-inch header that uses a ball-and-socket sealing flange for the collector that does not require a gasket, but these are a bit more money (PN 68291; $369.95, Summit Racing). This is a painted—not coated—header. I've used these Hedman headers before, and I like the ball-and-socket collector seal because it's easy to connect, and there's no gasket to blow out. I'd suggest carefully removing the paint on these headers using a Scotch-Brite pad and lacquer thinner, and then repainting them with the far superior VHT hi-temp Flameproof Coating (PN SP102; black, $9.95 Summit Racing). Basically, the paint on the headers is there just to protect them in the box and will burn off with the first exposure to exhaust heat. The VHT paint won't last forever, but might last a season, and the headers can be removed and repainted occasionally to maintain appearances. VHT even has a curing procedure: After the paint fully dries for 24 hours, idle the engine for 10 minutes, then cool for 10 minutes. Idle it for another 20 minutes, then let it cool for 20 minutes. Then run the engine normally for 30 minutes, and the paint should be fully cured. A fan blowing cool air across the headers during the first procedure will help to improve the paint's durability. Further, consider painting inside the headers. Most enthusiasts don't realize that the inside of a header corrodes, too. Eastwood sells a spray coating that comes with a 24-inch-long flexible tube that directs the paint down the header pipe. Since primary pipe lengths are usually around 32–34 inches, you can come in from both ends and coat the entire inside of each header tube. I don't have any experience with this paint, but it can't hurt and might keep the corrosion down on the inside of new pipes which would maximize your investment. The Eastwood paint is PN 13795 and sells for $19.99 per 11-ounce can.
As for your question about the Edelbrock versus the FAST EZ-EFI systems, I think a better question would be to address the four systems that operate in a similar manner with self-tuning capability: Edelbrock E-Street, the MSD Atomic EFI, the Holley Avenger EFI, and the one that started it all—the FAST EZ-EFI. These systems all employ a throttle-body mounting four large injectors, which means you don't have to plumb a manifold for injectors. All use the basic speed-density style of fuel injection that does not require a mass airflow sensor (MAF), and all use a wide-band oxygen sensor as the feedback mechanism for the self-learning capability. The MSD and FAST systems do not control spark, which means ignition will require a normal distributor. The Holley system offers an additional wire harness that can be purchased separately (for around $100) that can upgrade the Avenger to electronically control the spark using a GM small-cap HEI distributor. The Edelbrock also allows a similar situation, so these two at least have a small advantage if you are interested in digital ignition control. All four EFI systems require a high-pressure fuel-delivery system that operates generally around 43 psi. The FAST, Holley, and Edelbrock systems use a return system that requires a separate line back to the fuel tank. The MSD Atomic is simpler since it does not need a return line. It would require a full-blown story to get into all the details of all four of these systems (a good idea, don't you think?) but suffice it to say that all four are priced around $2,000 for a basic system with lots of options. For example, Holley offers two different throttle-bodies (700 or 900 cfm) with three different injector sizes (65, 75, and 85 lbs/hr) that offer greater peak horsepower potential up to around 600 hp. Most of the others also offer peak power up to around those same levels. An additional point for the Edelbrock system is a cool, 7-inch, touch-screen color tablet that offers built-in gauges for display as well as control over cooling fans. Most of the kits offer minor tuning control, while others are upgradable, like the Holley, and gives the user even more control over spark and fuel. Also, keep in mind that the EZ-EFI, MSD, and Holley kits include a fuel pump, while the Edelbrock does not. So you can see that depending upon how your car is currently configured, you have lots of options. The MSD basic kit is PN 2910 ($1,990, Summit Racing), the Edelbrock E-Street is PN 3600 (approx. $1,995.95), the Holley 700-cfm Avenger kit is PN 550-400 ($2,054.18, Summit Racing), and the FAST EZ-EFI TBI system is PN 30226 ($1,783.95, Summit Racing).
Autotronic Controls Corp. (MSD)
Fuel Air Spark Technology (FAST)
Holley Performance Products