Last month, we tossed a cam, an intake, and an NOS Cheater nitrous kit at a Goodwrench 350 crate engine from Scoggin-Dickey and made 524 hp with a 200hp shot (“Saturday Night Special,” May ’12). On the normally aspirated side of the ledger, Mr. Goodwrench managed to squeak out 330 hp and 350 lb-ft of torque. These numbers were OK, but we had greater expectations. The goal this month was to bolt the motor in our ’66 Orange Peel Chevelle, run a normally aspirated 12-second pass, possibly squeeze an 11, and not break anything. But before we dropped the 350 into the engine compartment, the original short-block needed enhancing.
While we successfully mixed nitrous with cast pistons, we know all it takes is one minor detonation demerit or tuning miscue for the results to be catastrophic. We’ve grenaded our share of cast-piston engines in the past, so we elected to serve up a set of very affordable Federal-Mogul flat-tops for less than $300, which also bumped compression. We added further insurance with a set of ARP rod bolts, which required rebuilding the big end of the stock powdered-metal rods. That was ably handled by our friends at Jim Grubbs Motorsports. We reused the main bearings because they were virtually new and added a new set of rod bearings with clearances hovering around 0.0025 inch. New Sealed Power rings were also cheap, and for the record, we checked the top and second ring-end gaps, since we planned to hit this package with nitrous. We needn’t have worried about the top ring-end gap, as it measured 0.032 inch, with the second rings slightly tighter. The top ring-end gap on a normally aspirated performance gasoline engine would be closer to 0.018 inch. If we’d used file-fit rings that would have allowed us to custom-set the gaps, we would have chosen a spec more like 0.026 inch for the top rings and 0.030 for the second rings.
While our budget small-block won't win any billet-beauty contests, it's still plenty stout
The Scoggin-Dickey-modified Vortec heads came with better valvesprings and increased clear
In addition to the Summit flat-tappet hydraulic cam from last month, we added forged Seale
After bolting the pieces together, we measured the deck height on all eight holes and were rewarded with eight different heights. It became apparent that the block becomes taller at the rear, adding 0.010 inch of deck height compared with those on the front cylinders. The cure would be to mill the block square to the crankshaft, but we elected to skip this step to minimize expenses. With a Fel-Pro composition head gasket, the front cylinders came in at 9.66:1 compression ratio while the back cylinders measured 9.51:1.
Because our Summit camshaft pushes the lift well over 0.450 inch, we wanted to use the iron Vortec heads but knew that in stock conditions, lift exceeding 0.450 tends to kill the valve-stem seals. Scoggin-Dickey came to the rescue with a modified set of heads that include taller, Z28 valve- springs and enough clearance to handle up to 0.525 inch of valve lift. So if we add a set of 1.6:1 roller rockers at a later time, we will still have plenty of clearance. The price increase for these modded heads is about $170 more for the pair over the stock L-31 Vortec heads, but it’s easily worth the investment. We reused the HEI ignition, the wires, the carb, and the air cleaner from last month’s dyno test, so we were ready to drop the small-block into our Orange Peel Chevelle.
|Camshaft, Summit PN 1105||Dur. 0.050||Valve Lift||Lobe-Separation Angle |
We had a few details to attend to before we could get to the track. The previous engine in the car had been our Lester Scruggs LS 404 ci, which required a resistor in the charging signal wire to the alternator. That tripped us up for several hours before we realized the oversight. After we achieved charging-system success, the next snafu was that our 63-amp alternator was unable to maintain system voltage with the electric fans, the fuel pump, and the headlights all working with the engine idling. We let this slide, but it caused grief later, as you’ll see.
Kevin McMillan and Dave Blanchard at McMillan Speed and Fab reconfigured our exhaust to co
We used Comp's 10W-30 performance oil after the cam was fully broken in. The Comp oil has
In the absence of indoor plumbing in our home shop, these Gojo scrubbing wipes are a great
|Track||60-Foot||Elapsed Time eighth-mile||MPH eighth-mile||Elapsed Time quarter-mile||MPH quarter-mile|
|Irwindale (N20)||2||7.82||94.56||12.12 est.||114.50 est.
|Irwindale (N2O)||2||7.68||95.08||11.90 est.||115.00 est.
The above details ate up the day we had planned for the nitrous installation, so our first shot at the dragstrip had to be without the fast gas. After an hour drive to California Speedway in Fontana, California, we mounted our budget, 26x8x15 DOT Mickey Thompson ET Street tires and headed to the starting line. Our first attempt was going to be a soft launch by rolling in on the throttle and shifting at 5,800 rpm. The tires didn’t spin, but the car felt soft on the launch, which only added to our surprise when the Compulink timers spit out a 12.90-at-105.01-mph pass. The 60-foot time was indeed slow at 1.98, but we were genuinely surprised at the 12-second e.t. We then spent the next five runs trying to replicate the first one, as the car experienced a huge hesitation whenever we tried to nail the throttle on the starting line. A wide-ranging series of tuning efforts failed to produce significant improvements, and we settled for rolling in the throttle to produce our best pass of the day with a 12.86 at 105.64 mph.
After our first dragstrip session with a brand-new engine, it was obvious our hesitation problem was related to a serious lean condition caused when all four barrels of the Holley Street HP carburetor were simultaneously slammed open. It seemed we needed more fuel. We tried using the stock pink accelerator pump cams in the No. 1 position and increasing the secondary squirter size up to a 50, but even with these changes, we still had a major hesitation that would not go away. Our swap-meet carburetor had a major flaw (which is probably why it was cheap), so we switched to a 750-cfm vacuum-secondary carburetor that immediately eliminated the starting line bog. We were now ready to go back to the track.
Now that the car was able to generate a decent launch normally aspirated, we were ready to hit it with the nitrous. On the dyno, we had merely retarded the initial timing to compensate for the nitrous, but we needed something more sophisticated on the dragstrip. This called for an MSD 6AL-2 box. This digital CD controller/amplifier offers the luxury of digitally programming the ignition-advance and nitrous-retard functions via a laptop. This can be done with an add-on retard box and an MSD 6AL, but we liked the idea that for only a few more bucks, we could have a 6AL-2 digital control. The digital curve gives us the freedom to add more timing at low speed and then flatten or even lower the timing at higher rpm. The 6AL-2 offers burnout and launch rpm control, but our focus was on the single retard function that we would use when the nitrous is triggered.
Tuning the Chevelle at our first track test presented a bad starting line hesitation chall
We bolted the 10-pound blue bottle in the car and added an NOS 12-volt bottle heater. Bott
Manually retarding the timing every time we want to use the nitrous kills launch torque, s
When using the MSD digital control over the standard mechanical advance, the first thing to do is lock out the distributor’s advance curve and set the maximum advance with the initial- timing setting. The MSD box then retards the timing back from that setting to your maximum advance spec. For example, we set the initial timing at 40 degrees and then dialed in the curve with a total of 36 degrees for the normally aspirated runs. We used a GM large cap HEI originally used on EFI engines, which has no advance mechanism. Alternatively, we could have used any MSD distributor. The MSD units feature a simple relocation of the advance pin that locks out the advance. We used the factory distributor because it was cheap, and we adapted it to the MSD-6AL-2.
Because we were making more power now with the better heads, we decided to start with the 150hp nitrous tune-up (0.063 jets for both nitrous and fuel). We also opted for the most conservative NOS timing recommendation of 25 degrees.
Due to a minor trans leak that required a short stay at California Performance Transmission, we only had time to mount the MSD and the nitrous system, which we unfortunately wired into the car with a little too much haste. Worse yet, we did not have time to test it before going to the track. Can you guess what happened next?
We arrived at Fontana during Street Legal Drags day, along with a thousand other cars, just a few days before deadline. Our first baseline pass netted a slower normally aspirated run with a 13.13 at 103 mph, nearly three-tenths and 2 mph slower than our first test. We attributed this to warmer weather with less atmospheric pressure, because our 60-foot times were the same. After waiting in line for two hours, we rolled into the bleach box only to lose fire with a dead fuel pump. A quick diagnosis revealed a blown fuse in the Chevelle’s fuse box that we were using to power the nitrous arming switch. This also turned out to be the switched power source to the relay for our fuel pump. With a new fuse and the fuel flowing again, we decided not to be stupid and try the nitrous, because if the fuse blew during the run with the nitrous engaged, the fuel pump would quit and the fuel bowls would run dry and burn up the engine. Arrrgh. We couldn’t take the risk, so it was back to the shop for a complete electrical rehash of the nitrous and fuel-pump relay circuits.
At the expense of a completely blown deadline, we took the time to install the nitrous bottle heater. This demanded its own dedicated, 30-amp power circuit. This is when we realized that with the 20-amp bottle heater circuit added to the 40-amp draw from the electric fans, added to 12 from both nitrous solenoids, 10 from the fuel pump, 10 for headlights, and roughly 3 amps for the ignition, we were looking at a total load of 90 amps. And all we had to feed that drain was a 63-amp alternator. This required us to juggle amp loads in the staging lanes to avoid overloading our seriously underpowered alternator. It felt like that scene in the movie Apollo 13. Later, we researched a higher-output alternator and decided on a 140-amp CS130 Powermaster that will take the place of our weak-kneed 12Si alternator.
The MSD Pro software is easy to use and allows far more freedom to create the exact curve
Here's how the engine compartment looks with the nitrous solenoids and all the wiring hook
Nitrous is great fun when you get all the details working correctly. With timing retarded
By now we’d performed multiple changes to the Chevelle, adding a vacuum-secondary, 750-cfm Holley, the 150hp nitrous system, and the MSD Digital ignition box. We decided to go right to the nitrous for the final passes, which now had to be run at Irwindale’s eighth-mile track. Arming the nitrous, we launched the car on the engine and then triggered the nitrous about 30 feet out. We did this to allow the engine to gain some rpm before we hit the squeeze, which would prevent loading the engine with nitrous at a too-low rpm. We set the MSD 6AL-2 to retard the timing back to 24 degrees with the nitrous engaged. As expected, the small-block felt exactly like a 500hp motor, responding with an eighth-mile 7.82 at 94.56 mph, which equates to roughly a 12.12 at 114-mph quarter-mile pass. The tires spun hard, which is why the 60-foot times were slower. Though hard to do, on the next pass we waited longer to hit the button, improving the 60-foot time to a still-slow 1.94, but this produced a 7.68/95.08-mph pass that’s equal to an 11.90 at around 115 mph, which is almost exactly 1 second and 20 mph faster than our best normally aspirated pass. That’s cookin’ for a brown bag 350 small-block Chevy with stock iron heads. As a point of history, we learned the following Monday that Irwindale closed its doors forever, so the Orange Peel was among the last cars down the dragstrip. A moment of silence is probably in order.
Along the way, we learned that the hydraulic side of a typical nitrous system is relatively easy to control. Where we had problems was on the electrical side, partly because of our Chevelle’s terribly outdated wiring harness and partly due to our own haste. It’s also worth noting that our Chevelle only weighs 3,460 pounds with fuel and driver and has a very good California Performance Transmissions 200-4R trans, a decent Global West suspension system, and a set of dated Mickey Thompson ET Street tires that all contributed to helping this car pull down a budget 11-second pass. With some tuning and better traction, this combination is conservatively worth 11.60s at probably 120 mph. Even though the new generation of LS engines are certainly more horsepower efficient, it’s clear that the small-block Chevy isn’t ready for the museum just yet.
|Goodwrench 350 crate engine||10067353||Scoggin-Dickey||$1,499.99*|
|SD Vortec modified iron heads (pair)||SD8060A2||Scoggin-Dickey||779.9|
|Sealed Power forged pistons, standard||ZL2256F||Summit Racing||287.6|
|Sealed Power rings||ZE251K||Summit Racing||38.95|
|ARP rod bolts||134-6005||Summit Racing||69.16|
|F-M rod bearings||8-7100CH std||Summit Racing||56.95|
|Hedman headers||68,299||Summit Racing||169.95*|
|Edelbrock Performer RPM Vortec||7,116||Summit Racing||189.95|
|Fel-Pro gasket set||KS2600||Summit Racing||46.95|
|Fel-Pro Vortec intake gasket||1,255||Summit Racing||33.99|
|MSD programmable CD box||6,530||Summit Racing||359.95|
|NOS bottle heater||14164NOS||Summit Racing||149.95|
|Spectre dip stick||4,255||Summit Racing||6.95|
|Balance rotating assembly||N/A||JGM||200|
|Comp 10W-30 oil (5)||1,594||Summit Racing||39.75|
|N2O Bottle fill 10 pounds ||N/A||Local||50|
|Powermaster 140 amp CS 130 alternator||47,860||Summit Racing||161.95*|
|Total ||$2,435.05 |
|*Not included in total price.|
Automotive Racing Products (ARP); Oxnard, CA; 800/826-3045; ARP-Bolts.com
California Performance Transmissions; Huntington Beach, CA; 800/278-2277; CPTTransmission.com
Edelbrock; Torrance, CA; 310/781-2222; Edelbrock.com
GoJo Industries; Akron, OH; 800/321-9647; Gojo.com
Federal-Mogul; Southfield, MI; 248/354-7700; Federal-Mogul.com
Hedman Hedders; Whittier, CA; 562/921-0404; Hedman.com
Holley Performance Products; Bowling Green, KY; 270/781-9741; Holley.com
Jim Grubbs Motorsports (JGM); Valencia, CA; 661/257-0101
McMillan Speed & Fab; Oxnard, CA; 805/732-8293; SpeedAndFab.com
MSD Performance; El Paso, TX; 915/855-7123; MSDIgnition.com
Powermaster Electrical Systems; Chicago, IL; 630/957-4019; PowermasterMotorsports.com
Scoggin-Dickey Parts Center; Lubbock, TX; 800/456-0211; SDParts.com
Summit Racing; Akron, OH; 800/ 230-3030; SummitRacing.com