May 2012 Chevy High Performance Q&A

Richard’s at it Again

Kevin McClelland Mar 22, 2012 0 Comment(s)

The Richard that I’m referring to is Richard Maskin, president of Dart Machinery. Dick and I have been good friends since 1980 and we had the good fortune of running into each other at a local event last week. I hadn’t seen Dick in many years since he was Jeg Coughlin’s crew chief of his Pro Stock car. I think the last time we spoke at Pomona, I told him of a project I was working on with Flowmaster and Don Hardy of Hardy Race Car fame. We were building big-block Chevys to run in the irrigation fields of Northern Texas; these engines ran 24/7 for months at a time on natural gas. Don needed more torque at 1,800 rpm to pump more water and use less fuel in the process. We built a special set of custom headers and single exhaust system, this in combination with a very short camshaft gained about 50 lb-ft of torque at 1,800 rpm.

1204chp 01 O  April 2012 Chevy High Performance Qa Editor 1/2

Well, fast-forward to my conversation with Dick. He’s now working with Hardy on the same issue of building big torque at slow engine speeds. They are using the Gen VII 8.1L big-blocks as a foundation. Many readers have asked me over the years how to hop up the 8.1L big-blocks, and I’ve basically had to pass on these questions until now. Dart has released a bolt-on Gen VII cast-iron cylinder head that is brand new, featuring symmetrical intake ports displacing 308cc and a small kidney-shaped 108cc combustion chamber. Dart has stuffed a traditional 2.19/1.88 valve package in these heads and sold under PN 15400170. These heads are a direct bolt-on and match up to the factory EFI inlet manifold with much greater flow potential.

Now for the hot rodder in all of us, you can pick up an 8.1-liter out of the wrecking yard, swap out these heads, and bolt-on Dart’s new aluminum dual-plane intake manifold on top. The manifold not only lets you bolt on a standard flange model 4150 Holley carburetor, but also enables you to slide in a standard tall deck distributor to spark your Gen VII big-block. Up until now you were stuck with the restrictive EFI truck manifold, which would make a ton of torque, but you still had to deal with the late-model electronics to fire the plugs. These components will give you a very affordable foundation to have a 496-inch street performance big-block.

Why Dart did these cylinder heads was to build large displacement engines to re-power emission-constrained diesel yard trucks around the country. He has a 10.5L Gen VII big-block based on their Big M block, Gen VII cylinder heads, and the four-barrel manifold. When running one of these engines on Hardy’s water pumps and Gen Sets they are producing 221 hp at 1,800 rpm. This doesn’t sound like much, but at 1,800 rpm that’s 645 lb-ft of torque!

Dick has been at this performance game for much longer than I have known him and has single-handedly given affordable big horsepower to the masses through Dart Machinery. We’re all the better for knowing him. Thanks, Dick!

Old Guy Performance

I have read your column for a long time and enjoy learning from it. I’m from the old school (68 years old) and still enjoy building good motors.

I have a ’52 Chevy car and a fair motor, but now I need some help. The motor is the following: 350 Chevy bored 0.030-inch over with 10.5 pistons, Dart Iron Eagle heads with 64cc chambers 2.02/1.60-inch valves, and Crane 1.5:1 roller rocker arms. The cam is an Edelbrock Performer RPM, with duration at 0.050-inch lift of 234/244 degrees. The camshaft produces max lift of 0.488/0.510 inch. The intake manifold is an Edelbrock Performer RPM, and the carburetor is an old Holley 3310 780-cfm with an electric choke. The fire comes from a new MSD ignition. I have a TH350 tranny behind the motor. The headers are Sanderson 2-inch, and have a 21/2-inch Flowmaster exhaust. The rearend is from an ’89 S-10 truck with 3.73:1 gears.

When I start the car it has to be up to temperature or it will not accept the gas, and it still has a flat spot. I have 58 jets in the primaries and 64 jets in the secondaries of the 3310 Holley. What do I need to do with the carb? I have the floats set at the bottom of the sight hole with the engine running.

Also, do you think the S-10 rearend will hold up behind this engine, being it is for street driving? I have 12 inches of rubber under the fender skirts, which is why I went to a shorter rearend.

From reading your Q&A, I think I’m around 400 hp. Would you put your pen to it for me, please? I know you get tired of the same old questions, but I don’t know how to figure it. Thanks.

Jim Palmour
Tennessee Ridge, TN

We old guys have to stick together. Keep building those old-school engines, as they power around many a nice street car.

We believe you’re very close with your estimate of 400 ponies. With the Dart heads, 10.5:1 squeeze, RPM intake, and RPM camshaft we’d give you around another 20 horses. At this point, it really doesn’t matter if you’re happy with the performance of your engine. Sometimes we have to laugh a little about how wrapped up people on the Internet get talking about horsepower.

The remedy for your flat spot is to add more fuel. The factory calibration for the early 3310 vacuum-secondary Holley is a 72 jet on the primary side and 76 jets on the secondary. We’re surprised you don’t have a surging problem even when the engine is warm and cruising down the road. And you’ll love this: increasing the jet to the factory settings will probably pick you up 20-30 hp at wide-open throttle! Then you will be making the estimated ponies listed above. To find any of the original calibration specifications, check out the Holley website and look under Tech Help, then Numerical Listings.

Your S-10 rear will be just fine for street rod applications. If you try to go out and drag-race the car, you may run into some complications. The early S-10 rearends were equipped with a 71/2-inch ring gear. You can upgrade this case with the 75/8-inch gears, and the 28-spline axles and carrier. Down the road, if you wish to really step on it, you could look into a complete rearend from the ’95-and-up S-10. Some of these trucks came equipped with the larger 8.5/8.625-inch ring gear. These were the strongest 10-bolts GM built. Unfortunately, there isn’t an easy way to spec one out from model years and options. The best way is to check out the differential itself. The easiest way we know of identifying an 8.5 10-bolt is by the two casting ears at the bottom of the case by the rearend cover. The 8.5s have two ears that are parallel with the ground and squared off. The 7.5s have a semicircle machined into these two casting ears. They are easy to spot by just looking under any late 10-bolt-equipped vehicle.

Ahoy, Matey

I’ve been a reader and subscriber for many years and have worked on Chevy engines in cars, trucks, boats, and even generator sets. My current engine project is for my Sea Ray boat. It has a ’78 Chevy four-bolt main engine with a COMP Cams 252 flat-tappet cam. I’ve become disturbed over the years with the loss of zinc from modern oils and the cam going flat. To enhance the issue, the boat will sometimes sit there for weeks without being run. I’ve come across a Vortec 350 complete with the roller cam I would like to build. The price was right (free), although it has a lightly spun No. 2 main bearing that will clean up with an oversize bearing. Since it needs line bore anyway, I figured a set of Milodon splayed caps would be a good upgrade. I’ll feel better running at 4,000 rpm for a couple hours with the extra beef on the bottom end. I’m not looking for a powerhouse as I am limited to about 300 hp, due to the driveline limits. I’d like a clean-burning engine, and the Vortec heads are advertised to create a swirl (vortex) in the combustion chamber. I was looking at an 0.030 overbore and the use of Keith Black 12cc D-dish pistons. The pistons would yield roughly a 9:1 compression (in the ballpark of what I want). How would this affect the air/fuel flow in the chamber? Will they enhance or disturb the vortex? Thanks for the great magazine.

Al Hauser
Superior, WI

The Vortec truck engine will be a great base engine to build for your maritime adventure. Making 300 hp out of this package will be very easy. Let’s check out a couple of parts you’ll be needing.

The Milodon four-bolt caps will be a great upgrade to the standard two-bolt bottom end. While you’re there, make sure you continue with main studs to round out the package. The three center four-bolt Milodon caps are sold under PN 11150 for the 4.490-inch narrow register, and PN 11160 for the 6.200-inch-wide register. Check out the registration width of your Vortec and order the appropriate caps. Also, we’d go with the Milodon replacement two-bolt front main. In a marine application with continuous operation at torque peak, the front main can take a beating. The front main cap is sold under PN 11153. Last but not least, pick up a set of Milodon’s main studs, PN 81125. This will give you the most bulletproof bottom end for crankshaft stability in a production block.

The Vortec heads were a major improvement over other factory production iron heads. These heads were modeled after the LT1 aluminum heads that came out in 1992. When the engineers went back to the drawing board to build the LT1 engine for the Impala with iron heads, they applied everything they’d learned and then some. The iron LT1s were a stepping stone to the Vortec truck heads. The iron Vortecs are the best production Gen I small-block head ever produced. Yes, it does create a good deal of mixture motion, but most of the gains come from good old-fashioned airflow increase. The intake valve area and bowl of the port introduce the fuel and air into the combustion space in a very efficient manner that keeps the mixture well homogenized. The kidney-shaped combustion chamber promotes good mixture motion in the combustion chamber when the piston comes to top dead center. The KB D-shaped dished piston retains a good deal of quench area on the top side of the piston. This will match nicely with the deck of the Vortec head.

Now that you have a roller camshaft case, let’s pick the right camshaft. With the boat’s outdrive limitations for power potential and the need for good idle quality to be able to shift the outdrive, we’d keep it mild. You mentioned 4,000 rpm as an engine speed your boat sees for periods. Building great torque at this speed should be a focus. The factory Mercury Marine small-block hydraulic roller PN 144097395 is a nice little camshaft, and GM uses this camshaft in its RamJet 350 and the HT383 crate engines. The RamJet 350 produces 350 hp at peak, and more importantly, 400 lb-ft of torque from 3,500 to 4,500 rpm! This will give your boat very nice acceleration and keep it on plane with no drama. The camshaft specs out at 196/206 degrees of duration at 0.050-inch tappet lift, 0.431/0.451-inch max lift with 1.5 ratio rockers, and is ground on a tight 109 separation angle. This gives the engine outstanding throttle response and great midrange torque. To get the full performance from this package make sure that you use 1.6 ratio rockers. This will boost the max lift up to 0.460/0.481 inch. This is right where the stock Vortecs start running out of airflow.

This should give you many years of reliable engine performance in your marine application. With the hydraulic roller camshaft you will never have to worry about our new inferior oils and dry starts. Start with a mild 32 degrees of total spark advance and tune from there. Remember, you always want to get back to the dock!

Sources: gmperformanceparts.com, milodon.com

Tuning In The 21St Century, Part 2

At the ripe old age of 72 and having been involved in this addicting sport of drag racing for nearly 54 years, I must say yours is one of the best tech columns to come my way. Your article in the Jan. ’10 issue on tuning with AFR systems hit home, as I am in the process of setting one up in our ’78 Malibu bracket car. You are absolutely right; trying to get the proper jetting by using the mph on any given day of testing is virtually impossible due to wind and weather changes in our part of the country. I went with the Innovate Motorsports LC-1 Digital Air/Fuel Ratio Sensor Controller and a DB Digital Air/Fuel Gauge setup. The sensor is installed in the left header collector. I also have a Moroso Crankcase Evacuation System installed into both headers. Will this affect the readings, or is it necessary to plug the left side where the sensor is installed? It will be a few more months before we get to try this, but I’m encouraged by your results, and if all goes well, we’ll be doing the same in my other son’s Camaro. Keep the excellent tech articles coming.

Ralph Talbot, Talbot Racing
Windsor, ON, Canada

Very nice combination. The full-frame A- and G-bodies are great building blocks. Between having a solid foundation to build from and the aftermarket making all the components we need, they are great race cars.

Every track we have here on the West Coast has the same conditions you’re dealing with. Wind and atmospheric conditions change so fast that you never get a real handle on tuning. The O2 sensors are a tremendous help in these types of conditions. Also, watching the fuel curve of your carburetor throughout the rpm range can give you clues of consistency issues. Just this last week we installed another sensor in our good friend Greg Ventura’s ’66 Nova Super Street car. The fuel curve was very nice up to 7,000 rpm, but from 7,000 to 8,000 in high gear, the AFR climbed over 1 ratio. This took the engine right up to 14:1, much too lean. We haven’t put our finger on the cause yet, but it could be either the fuel delivery system or the way the carb is sealed to the hoodscoop. At least we have a tool now to know when we’ve touched the right part.

You have a great question about the Vac-u-Pan system. If the crankcase vent is before the O2 sensor, there’s a chance you are introducing free oxygen in front of the O2 sensor. In addition, if you have slip-fit collectors you must ensure that they are not allowing air to make its way into the exhaust stream ahead of the sensor. The Vac-u-Pan system is a good crankcase vent system, but it really doesn’t draw much vacuum on the crankcase. You can plug the header collector and run a filter breather on the left side valve cover while using the O2 sensor. Once you are finished tuning you should remove the sensor to prevent lead fouling. They will last around 10 hours of running before the sensor starts dying. After you have the car dialed in, get the sensor out of there and only use it if you run into issues with the performance of the car, or you’ve changed the combination.

Thanks for the kind words about the column. If we all keep helping each other out maybe we all will get a little smarter. Every time we think we’re getting a little sharper one of our cars will put us right back in our place!

Charging Problem

I’m having some trouble with my charging system. I have a ’69 Camaro with a 383 and 700-R4. The battery (Duralast Gold) is in the trunk. Both the positive and the negative battery cables are four-gauge. The negative cable is grounded to the frame at the rear bumpstop bracket. The positive cable goes to a battery disconnect switch, and then to the starter. The alternator (Powermaster 100-amp, internally regulated, one-wire, 25/8-inch pulley) is connected to the starter with a four-gauge wire. There is also a four-gauge wire from the starter to a junction block on the radiator support. The junction is where almost everything else is connected (electric fan, front wiring harness, MSD box). The engine block is grounded to the frame, again, with a four-gauge wire.

When I drive (cruising around), the voltage is at 14 V. I don’t seem to have any problems while driving. At idle or low rpm (at stopxlights or in traffic), it slowly drops below 11-12 V, as low as 9-10 V. When the volts drop, I give it some throttle, and the volts come back up but drop again unless I keep my foot on the throttle. When the fan (Flex-a-lite Black Magic, 15-inch, 3,300-cfm, puller) comes on, it draws a lot of voltage. I don’t drive much at night, since I don’t want to draw more by turning on the lights and find myself with a dead battery on the side of the road.

I didn’t seem to have any problems before the battery went in the trunk, but I would like to keep it in that location. I’ve been told that maybe I should try switching all the four-gauge wiring to 0/1-gauge, or maybe a smaller diameter alternator pulley.

The battery, starter, and alternator are all new within the last year or so. I think I’ve done everything short of rewiring the whole car. I want to add a stereo system and fuel injection, but without the proper amount of voltage, I’m sure they won’t work correctly. What do you suggest? Thanks for your help.

Rick Umipig
Renton, WA

We’ve covered battery relocation questions several times, but you have the answer in your letter and we want to see you out driving your Camaro. First of all, anytime we relocate the battery to the trunk we use 0/1-gauge welding cable. Welding cable is a very fine-stranded copper conductor. The current actually travels across the top of each strand of the cable. With the fine-stranded wire, you get two benefits: outstanding current-carrying capacity, and flexibility to get into difficult locations.

You said you have your ground cable running from the battery to the rear bumpstop bracket. This may be a great ground for the unibody, but there is no ground path to the front subframe that the engine is grounded to by your four-gauge cable. Your problem is likely that there is no ground from the main body to the front subframe. The subframe is mounted to the unibody by four rubber isolators that will prevent the engine from having a ground path to the battery. Another clue is that everything worked just fine until you relocated the battery. The Powermaster alternator didn’t have an issue keeping up with all your power accessories until the relocation. Again, we like to see a ground cable running from the battery directly to the rear of the transmission case, to eliminate any ground path issues with battery relocation. Don’t remove your current ground going to the unibody, just add one to the engine or trans.

Running one cable should take care of your problem. Since you have the car finished in four-gauge, try adding a four-gauge ground up the car to your powerplant. It’s worth a try to see if your gremlins go away. Good luck, and let us know how it turns out.

Little Leaks

I have a set of AFR 180 aluminum heads for my ’66 Nova. After bending a rod and thinking is was my fault, I rebuilt the engine with a new rod and piston. I noticed that after a few weeks there was antifreeze underneath the car. Thinking I had a cracked block, I took the block to a friend, an engine builder. He could not find a crack in the block. He checked the brand-new heads and found one leaked through the intake port. I sent them back to Air Flow after marking the head where the leak was located. Their testing could not re-create the leak. The owner had the heads coated inside the water jackets. This will be the third time I have put the engine together and I am afraid these may leak a month or a year down the road. Should I put the engine together and trust this sealer or should I just get a new set of heads? Thank you for your advice.

Gerry Clark
Via email

Sand casting is an art. Anyone who has been involved with pouring cylinder heads or intake manifolds knows it is virtually impossible to pour a perfect part. Air Flow Research goes to great lengths to re-create perfect parts every time.

We have a few questions: What pressure did your machinist apply to the water jackets to create the leak in the inlet port, and did AFR use the same pressure? Usually, when doing a pressure test you will use what would be considered maximum operating pressure. This would be what the radiator cap relief is at plus some headroom. You wouldn’t want to put more than 30 psi of pressure in the water jackets.

We’ve had good experiences and not-so-good experiences with water jacket sealers. Usually, a latex-type sealer is used, which is a thick liquid poured into the water jackets. Plates are installed on the deck surface, covering the water ports on the intake flange. The cylinder head is rotated around to ensure that the sealer has reached all surfaces of the water jacket. Then air pressure is applied to the water jackets to impregnate the sealer into whatever porosity is in the water jackets. After the air pressure has forced in the sealer, the plates are removed and the excess sealer is drained. Then the head is baked in an oven to cure the sealer.

As we have said, we’ve had good and bad experiences with this type of sealer. We’ve had it work perfectly in an inlet port like yours. Then we had another set of heads that were leaking in the rocker arm area. The sealer worked for the first couple of rebuilds (this was our 700hp dyno engine). After the heads were removed and installed several times, the persistent leaks began to reappear. We blamed it on the re-torquing of the cylinder heads and opening up new porous openings in the casting.

You’ll need to make the call. New heads would surely take care of the problem. However, for your application, your repaired cylinder head may be just fine. Hope this gives you a little peace of mind.

Fire In The Hole

My ’95 Chevy Camaro Z28 has a 383 stroker, a racing 4L60E transmission, a six-point rollcage, and true dual exhaust. The problem is that the engine will not fire most of the time until the third hit of the key; when I go to start it, if it doesn’t fire the first time I let go of the key. I don’t just sit there and crank on the engine so I don’t burn up the starter. The engine is turning over; it just won’t fire. It has been doing this for about three years now. I can hear the fuel pump kick on every time. Sometimes it will fire up on the first or the second turn of the key, but usually it’s the third turn. I have replaced the carbon can, the check valve for the carbon can, the TPS sensor, and the fuel pressure regulator. I think that’s about it. When I first built the engine it would fire up right away, just barely had to touch the key and it would fire. However, it still had the stock injectors and stock fuel pressure regulator. I’m just wondering if that could be the problem. I have sprayed starting fluid into the throttle body. It would fire up, then burn all the starting fluid off and die. Then I would go to start the car again and it would fire and run fine. So I do know it is a fuel problem. But I would think if it was a fuel pump it would have gone out by now or the problem would get worse. But it’s not. The problem is staying the same. Please help!

Betty Mead
Via email

The first thing you need to do is install a fuel pressure test gauge on the test port on the fuel rail. This will give you insight into what is happening with your fuel pressure. As you stated, you can hear the pump cycle when you turn on the key. But is the pump running when you crank the engine? Also, when the pump cycles with the key in the run position, does the fuel rail hold fuel pressure? If it doesn’t hold pressure right after the pump shuts off, the check valve is bad in the pump. If that is the case, and the pump isn’t firing off when the engine cranks, it’s not going to start.

One thing that bothers us is that you said that it would fire right off with starting fluid; however, the engine stalled after the starting fluid had burned up. The fuel pump should have been running once it fired on the starting fluid. An oil pressure switch controls the fuel pump relay. This switch closes at 4 psi of oil pressure. Your fuel pump should have been singing when it was running on the starting fluid. The only way you’re going to track this down is with a fuel pressure gauge. Get some help from one of your friends so one can be behind the wheel while the other watches the gauge. Always be safe.

What is the correct way to vent a Chevy big-block? Are two push-in breathers, one on each valve cover, enough? Is using a PCV on one and a breather on the other valve cover better? Do you have other ideas on this? What happens if the engine is not properly vented? This is not a smog engine; it’s a race-only car. I enjoy reading your column every month—keep up the great work.

George Baresich
Riverside, CA

Dual push-in breathers will vent a big-block just fine. If you’re using this as a racing application, we wouldn’t use a PCV valve. With larger camshafts with low vacuum, a PCV valve can cause idle stability issues that will cause you to chase your tail. You’ll think it’s a carburetor or timing issue, and it’s just that the valve won’t seat and it’s constantly causing a vacuum leak through the crankcase out the other breather.

As a reader brought to our attention not too long ago, inadequate ventilation can cause oil leaks from many places on our engines. You may think that the engine is sealed up, but if the ring seal isn’t happy, the crankcase will build pressure at full-throttle very quickly. This can push oil out of seals and gaskets that you think should be sealed up well. Happy racing!

Kickin’ It Sideways

I have a ’72 Chevelle with a big-block Chevy 469ci (0.070-inch overbore, making approximately 550 hp and 580 lb-ft at the crank). My problem is it goes sideways when I hit Second gear. It heads for the ditch and does not want to straighten out. The drivetrain and suspension consist of the following: solid motor mounts, an Art Carr 200-R4 transmission with super servo, a 12-bolt posi with 373:1 gears, Hotchkis 1-inch lowering springs with Bilstein shocks all around, a Hotchkis hollow-tube front sway bar, Hotchkis lower rear trailing arms, Air Lift airbags with 10 pounds in the right side and 5 in the left, an NOS rear sway bar, pinion angle set to -2 degrees, and Mickey Thompson drag radials 275/60R15. The front tires are 215/75R15. I have purchased the adjustable upper rear trailing arms but have not installed them yet. I hope I listed enough information. Any help would be appreciated.

Mike Ruffing
Westland, MI

OK, first the obvious: You’re doing this on the street?! There is road crown, and with you mentioning that it’s tossing you into the ditch we’ll assume the car is turning right. The road crown is going to pitch the car to the right, as will the torque applied to the left rear tire. When you apply large amounts of torque to the rear suspension and the rotation of the engine and driveshaft imparts a twisting force that plants the left rear tire. When you’re at speed, the car doesn’t weight-transfer to the right rear to compensate for this added load to the left rear tire. This is another reason that it’s tossing you in the ditch. You can add more air pressure to the right rear airbag to artificially load the right rear tire to compensate. We run only one bag in our Malibu wagon and it’s in the right with 30 psi of air to launch the car somewhat straight. We’re right on the edge of needing to add a rear antiroll bar to keep the car square on the launch.

Finally, get off the street if you’re going to do WOT Second gearshifts. We don’t want to see you getting hurt or hurting someone else. The rest of your package sounds like it should take the power you’re working with. Keep the upper bars equal length. We’ve tried putting preload in the upper bars in our wagon with no success. Stick with the preload in the airbag. Be safe, please! CHP

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

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