Jeff Pimental, via CarCraft.com: I was reading your column in the August issue on the air/fuel ratios of E85. Could you tell me what ratio to use if we mixed E85 with 50 percent 110-octane leaded race fuel? This would give us 2 grams of lead without hardened seats and octane to support 11:1 compression easily. By what percentage would we have to increase the volume of fuel through the carb?
The Innovate air/fuel ratio meter will read as either air/fuel ratio or in lambda. The beauty of lambda readings is that max power is always around 0.85 lambda, while the stoichiometric air/fuel ratio is always 1 for gasoline, ethanol, or methanol. Plus, if you talk in lambda, everybody will think you're an engineer. Just don't wear the pocket protector.>>>
Jeff Smith: I called on my friend Klaus Allmendinger, the resident engineer at Innovate Motorsports, the company that builds that trick air/fuel ratio meter we use for tuning. Here's his approach. The stoichiometric (abbreviated stoich) air/fuel (A/F) ratio for gasoline is 14.7:1, while the stoich ratio for 100 percent ethanol is 7.87:1. The lambda reading for stoich air/fuel ratios for both these fuels is 1.0. Keep in mind that stoich is a chemically correct A/F for least combined emissions, but not for best power. A best power A/F for gasoline is 12.5:1 while the 100 percent ethanol number is 9:1. As you can see from the different A/F ratios, ethanol requires a greater volume of fuel for max power. This is because of ethanol's reduced Btu heat content when combusted.
When looking at increasing jet size, what we're really concerned with is jet area. To use a simplified example, let's say you have a jet combination in a Holley carburetor of 85 jets in all four corners. Holley conveniently publishes the hole diameter for all its jets in its catalog. The drill diameter for a Holley 85 jet is 0.100 inch. According to Klaus, dividing the stoich ratios of gasoline by pure ethanol (14.7 / 9 = 1.63) is the jet-area factor. But because jet area changes with the square of the jet diameter, we have to take the square root of 1.63, which equals 1.278, or 27.8 percent. Hang on, we have to now go a little deeper.
If all we wanted to do was determine how much jet area to increase if we ran straight ethanol, we would take our 85 jet diameter of 0.100 inch and increase it by 27.8 percent, which would make it a 0.1278-inch-diameter jet. The Holley jet chart shows that the closest is a 100 jet. So far we're on track here, and it all makes sense because we've seen in previous testing that we need to increase fuel flow by roughly 25 to 30 percent when converting from gasoline to E85. This change to a 100 Holley jet will put you in the ballpar, but probably would require fine tuning to dial in the optimal jetting.
Now you've added a twist because you want to mix E85 and gasoline together. First off, mixing 50/50 E85 and gasoline is not truly a 50/50 solution of ethanol and gasoline because there is 15 percent gasoline mixed with the E85. To produce a true 50/50 ratio, you will have to mix 5.88 gallons of E85 with 4.12 gallons of race gasoline to make 10 gallons of that 50/50 brew. This makes the math much simpler in Klaus' next equation. Plus, mixing 105-octane E85 with 110-octane race gas in the 5.88 + 4.22 ratio will produce roughly an octane rating of 108. To come up with an air/fuel ratio, Klaus suggests using a simple equation that will produce an air/fuel ratio you can shoot for with this mixture. Basically, we're multiplying the stoich A/F ratio of gasoline times the amount of fuel mixed, then doing the same with E85, and then adding those two together. With a true 50/50 mix, it looks like this: (0.50 x 14.7) + (0.50 x 9) = stoich A/F for this mixture of fuel. Doing the math gives us 7.35 + 4.5 = 11.85 stoich A/F. Warning: This is the stoichiometric ratio-NOT the maximum power air/fuel ratio. When you mix the fuel is when you would apply the jetting conversion calculated above. The ideal max-power A/F ratio will be roughly 10.:1. We shoot for a max-power A/F ratio using Innovate's meter in the lambda scale. Ken Duttweiler has been beating this into us for the last couple of years, since we started working with E85. His point is that max power occurs with a lambda reading (regardless of fuel used) of around 0.85-or 15 percent richer than 1.0 (lambda) with fuels like gasoline, methanol, or alcohol, or any mixture of the above since the number is the same. So with a calculated A/F for the 50/50 fuel mix of 11.85:1 (1.0 lambda), multiply by 0.85 (best power in lambda), and we come up with a 10.0:1 A/F ratio as what you should target. Interestingly, the baseline test for this thought process is simply to take the gasoline stoich A/F of 14.7 and multiply times 0.85 (lambda), and you get 12.49:1 A/F. Amazing how all this ties together, isn't it?
If we haven't totally confused you, I think this is a great way to approach what you want to do, and working through this will help you with other mixture calculations that you might want to try such as E75 or E90. I'd like to thank Klaus Allmendinger and Innovate Motorsports for enduring several rounds of my questions about this issue. If this subject intrigues you, Innovate Motorsports has a great forum full of interesting questions, and Klaus is a frequent contributor who can produce laser-beam answers.
Innovate Motorsports; Irvine, CA; 949/502-8400; innovatemotorsports.com
Oldsguy, via CarCraft.com tech forum: I have an '84 Olds Cutlass with a 403ci with pocket-ported heads, an Edelbrock RPM intake, and an RPM camshaft. The cam is 2 degrees retarded from the spec card, so I advanced it 4 degrees. This combo in a street car with open headers ran an 8.19 in the eighth-mile with a Q-jet and a 1-inch spacer. After that I began having trouble with the idle. I had a new Holley 830 for another car that is not done yet, so I put it on with a new 50cc rear accelerator pump and cams to eliminate a flat spot on the launch. I lost 0.30 second and can't seem to get it back. I replaced the front power valve with a plug and raised the jets the recommended amount from 78 to 85-still no help. I had to put on some collectors with short 3-inch turndowns because it burned my shifter cable. This cost more time, and now we are at 8.7s. I put on an NX Hitman with 150hp jets to get back to 8.20s. I spent over $1,000 to get the same time again. The plugs are black, so I'm thinking I should lean out the air/fuel mix, replace the 1-inch spacer, remove the collectors, leaving the shield in, or just burn the whole car and start over since I bent the butterflies. As you can see, I need help. It seems every way I go costs more money. I am still having a good time, but it would be better to get back to the 8.19s without the nitrous. Then the real fun can begin.
Quadrajets have an undeserved reputation as a Quadra-bog. Secondary hesitations can be largely eliminated by adjusting the secondary air-valve door spring to delay the opening until there is sufficient air velocity to pull fuel out of the secondary metering circuit.>>>
Jeff Smith: Wow, there's a lot going on here. My first recommendation is to go back to the original combination with the Q-jet and the way the car was set up and evaluate the e.t., speed, and 60-foot times. When a car slows down, it can be from multiple factors. Let's first look at what happened when you removed the Q-jet and went with the big 830-cfm Holley carb. Right away, you experienced a hesitation that you addressed with a larger 50cc rear accelerator pump. That may not have been totally the carburetor's fault. I have a buddy who used to run a small-block Chevy bracket car and discovered that his mild engine didn't like uncovering all four barrels of a large Holley carburetor on the starting line. His car actually would 60-foot quicker with a same-size vacuum-secondary Holley, because there was higher velocity through the primaries alone for the first few feet off the line until the secondaries started to open. Your 403ci Olds sounds like a relatively mild engine. Did you know that your original Q-jet is rated between 750 and 800 cfm? The Q-jet uses huge mechanical secondaries but tempers this with a velocity-sensitive air-valve door. The door opens only when a sufficient volume of air is traveling through the primaries. Once there is sufficient velocity, the air begins to push on the door, whose opening point is controlled by a small, adjustable spring. Loosening the spring tension allows the door to open sooner. This is very similar in operation to a vacuum-secondary Holley carb.
This is the engine that is in the GeeTO Tiger drag race GTO in the Wangers collection. The 467ci Pontiac is blessed with a stout cam, Edelbrock aluminum heads, and an Edelbrock Victor single-plane intake.>>>
Now with the big Holley and its mechanical secondary, it kills the velocity when you dump all four throttle blades open on the starting line, especially if the torque converter has a low-stall rpm. The hesitation you experienced with the out-of-the-box Holley carb is likely due to very low air velocity through the carb at low rpm. Your solution was to cover up that lean sag with a giant accelerator-pump squirt. The problem with adding the 50cc pump is that the engine probably didn't need that much accelerator-pump volume. When you add the larger capacity, the greater volume of fuel extends the duration of the acceleration enrichment. The duration of the accelerator-pump squirt is determined by the size of the discharge nozzle. It's possible that you could remove the larger rear pump and have just added the more aggressive cam you mentioned and that might have Band-Aided the problem, but it is still not corrected. You lost 0.30 second with all this most likely because the air/fuel ratio went dead rich for the first 60 feet and that's what hurt your e.t.
You also mentioned that you plugged the power valve on the front (primary side) and added jet. This made the air/fuel ratio go richer right off idle, because the power valve is designed to remain closed until the manifold vacuum drops below its rated level, where the engine demands more fuel. This allows the primary circuit to run at a leaner air/fuel ratio at part-throttle where it's happier-somewhere around 13.5:1 to 14:1. The most common power valve is rated at 6.5 inches of manifold vacuum, which means the fuel is not added to the primary main metering circuit until load (throttle opening) achieves 6.5 inches of manifold vacuum level or lower. By plugging the power valve, you're now running around at part-throttle with a much richer air/fuel ratio in the primaries. That's why the spark plugs are black.
Next, you said you added a collector to the headers, so we're assuming you're running this engine at the track uncorked. Collector extensions are an excellent way to add torque at low speeds, but they really work best with camshafts with lots of overlap. Your combination is already advanced 2 degrees, and the Edelbrock RPM cam is not that radical at 224/234 degrees of duration with 0.050-inch tappet lift and 0.496/0.520-inch valve lift. However, the collector extensions should still help torque. You say that the car slowed down, but again it could be because the air/fuel ratio was dead rich. Perhaps with the collector extensions, the air/fuel ratio needed to be leaner. There's also the question of atmospheric conditions. It sounds like these changes occurred over several trips to the track. If the air was getting progressively warmer each time you drove at the track, it would also affect your times. It's not unusual for the warmer air with higher humidity and lower pressure to slow a car down by 0.30 second. If you did not keep track of the conditions, this is a huge variable. Plus, warmer air temperature combined with lower pressure and more humidity require you to lean the engine out, but it appears that you went richer instead. It's not surprising that the car slowed down.
Black And White
The photo in This Guy's Garage shows the GeeTO Tiger in black and gold-but wait, this one has white paint. Are there two cars? No. Back in 1966, there were two cars, one white and gold, the other black and gold. For the re-creation, this car is half and half.>>>
Here is my suggestion. First, figure out what happened to the Q-jet that caused the idle problems. It might be something as simple as a little dirt in one of the idle-mixture circuits that a disassembly, cleaning, and shot of compressed air and new gaskets will probably fix. Then see if the car returns to its previous performance. If it does, you know that the Holley was probably too rich. If you want to try to make the Holley work, put the power valve back in, put the stock accelerator pump back in, and try leaning the carb out, especially on the primary side, to see if that cleans up the launch. If it still bogs, then the carb is just too big for your combination, which is why the Q-jet worked so well. If you're into the Holley stuff, borrow a vacuum-secondary carb that you know works well and see if that improves the 60-foot times.
We'd suggest not attempting to run the nitrous until you get the normally aspirated combination completely dialed in. This means doing at minimum a jetting and timing exercise of making one change at a time and evaluating performance based on trap speed only. Do not use e.t. as the gauge, because if you make more power, it might spin the tires and slow the car down from an e.t. standpoint, but the trap speed will always increase. If you do this exercise you will have a good baseline from which to judge how well the nitrous performs. Nitrous is not supposed to be a crutch for poor tuning. Plus, those bad tuning techniques will only get you into more trouble with nitrous. Ask us how we know.
Riding on Air
Dave Hyatt, via CarCraft.com: I am working on a '70 442 convertible and need to choose which direction to go on the suspension. I want to play a bit in the winding roads and would like to get rid of the wallow associated with its size and 455-loaded nose. The car won't see more than a couple of thousand miles of service a year, but I'd like it to be comfortable enough to jump in and tally a few hundred miles at a sitting without rattling every bone in my ever-aging body. It seems everybody is pushing the poly bushings to firm things up, but my painter thinks it will be too harsh for the occasional Sunday cruise. I would like to bring the stance down a hair and I know that will help. I've been hearing about Air Ride's setup. How would it compare in performance and cost? Would it need a compressor and onboard tank taking up space in the trunk? Should I tubular this up front and out back? Right now, the car is sporting '70s technology and needs some love. I'd like to do it now while the body is off rather than dig it out after the body goes back on.
Jeff Smith: The Air Ride Technologies suspension parts are high-quality pieces, but we should take a look at what you want to achieve. Merely exchanging the coil springs in all four corners of your '70 442 for airbags will allow you to raise and lower the ride height of the car at will. Yes, it will require an onboard air tank and compressor as well as some support equipment and controls located in the interior within arm's reach of the driver seat. Air Ride sells a very basic system that will do the job at an affordable price, but this does very little to affect handling other than vary the ride height. Also, keep in mind that the first thing to be done before setting front-end alignment is to establish a ride height. Any change affects camber, caster, and toe-in. So if you choose to modify it, select the position where the car will spend its time on the road and align the front end at that height.
Air Ride offers several levels of suspension components that revolve around the basic air spring.>>>
If you choose to modify the suspension to improve handling, there are several ways to go about it. We'll offer some suggestions progressing from the least to the most expensive. Especially with a big-block A-body like your Cutlass, the car tends to push, or understeer, in the corners. This condition is created by a very soft front spring rate, road-weary shocks, and a small front sway bar. Normally, stiffening the front on a car that already understeers is not the way to go. But with these early cars, the soft package allows the body to roll excessively, which creates a major positive camber gain in the front suspension that rolls the tops of the tires outboard, reducing traction by leveraging the inside edge of the tire off the ground. By increasing the front sway bar diameter along with polyurethane sway bar and end-link bushings, body roll and positive camber gain are reduced. Global West sells a solid 111/44-inch front bar (PN SB-709), while Hotchkis offers a tubular 131/48-inch front bar (PN 1916F).
In addition, we'd suggest increasing the front spring rate, assuming you don't convert to air springs. Both Global and Hotchkis offer spring upgrades. Don't be concerned that this will ruin your ride quality. What will affect the ride quality is shock-absorber valving. Be aware that budget shocks are often very stiff. Recently we went for a ride in a buddy's Chevelle outfitted with Bilstein shocks, and we were impressed with its handling and ride quality. Don't tell anybody we said this, but the Hotchkis HPS 1000 shocks look suspiciously like Bilsteins. The Hotchkis HPS 1000 shock part numbers for your car are 70010012 for the fronts and 71010009 for the rear. These are designed to be used with the Hotchkis springs. Our recommendation for bushings is somewhat pricey, but I've been driving on Global West Del-A-Lum bushings in my Chevelles since 1981, and not only do these bushings ride nicely, but they last forever and do not deflect or squeak.
Getting back to the Air Ride springs approach, you may have seen magazine stories trumpeting how '70s-vintage A-bodies like yours can pull over 1 g on the skidpad. This requires a serious investment in tubular upper and lower control arms to change the front suspension geometry as well as tubular upper and lower rear arms to prevent lateral movement of the rear axle. The Global West and Hotchis tubular upper control arms that are so popular with everyone right now are designed to modify the stock camber curve created by the front-suspension geometry, so you can see these parts are much more than just a fashion statement. Air Ride is offering this same design of control arms to be used in conjunction with air springs to create what it calls the Street Challenge System, which is Air Ride's premiere system. This entire front- and rear-suspension system also costs over $6,000, but it offers advantages of both adjustable ride height and vastly improved handling. To be fair, it is also possible to rack up an honest $4,000-plus in conventional coil-spring handling components, so none of this is cheap.
Our recommendation would be to first ensure that all your ball joints and control-arm suspension bushings are in good shape. If they are not, fix them first. Then add a good set of shocks and a larger front sway bar and bushings, and seriously consider better tires and wheels. You didn't mention that area, but the quickest and easiest way to improve handling would be at least a 16x8-inch wheel package on all four corners with 255/50VR16 performance tires. We don't have the room to get into tires, but BFGoodrich, Firestone, Yokohama, Kumho, and a long list of others make performance street radials that will radically improve handling and braking, and contribute greatly to an overall positive driving experience.
The Chevy Spectrum
Among the Wangers collection that we couldn't show you without a 180-degree lens is this unlikely pair of Chevys. It doesn't get much more diverse than a drag-inspired Pro Street '65 Chevelle parked next to a Can-Am road racer. One thing they both have in common is big-block Chevy engines. From there, the comparison gets a little complicated.>>>
Air Ride Technologies; Jasper, IN; 812/482-2932; ridetech.com
Global West Suspension Components; San Bernardino, CA; 909/890-0759; globalwest.net
Hotchkis Performance; Santa Fe Springs, CA; 562/907-7757; hotchkisperformance.com
Gary DeMichelle, Lompoc, CA: I sent a set of small-block Chevy 305 TPI cast 416 heads out for a valve job. After torquing them down and putting the intake on, I went to put the rockers on and give them a preliminary adjustment. I found that once I set the preload on the No. 5 intake, the rocker would slide off the valve tip and want to slightly ride on the 90-degree edge of the tip. I tried other rockers, then looked at the stud and the pushrod. It turned out the pushrod guide in the head would not let the pushrod align the rocker directly over the valve as designed. Just looking at the pushrod in relation to the rest of the valvetrain, I could see it was out of alignment. This was a good running engine with 100,500 miles on it.
We thought this lump on the floor was made of cement, but it was actually formed by years of tiny drops of paint applied by the guys who work at Santini Paint and Body Werkes. Pete Santini plans to harvest it eventually and polish it into a sphere.>>>
Since this was just an experimental engine for my car, I finished the assembly and fired the motor up on a stand just to see what would happen. It made a clacking loose rocker noise and started to mushroom the valve tip. This was definitely not a problem previously. When I called the machine shop, they assured me that I got the same set of heads back that I delivered to them.
Since, again, this was an experiment, I ground out the pushrod guide enough to align the rocker properly and made my own pushrod guideplate that bolted to the rocker stud. It has worked great for approximately 400 miles but looks like a bad accident waiting to happen. I do have a roller cam motor that I hope to have more success with.
Do you have any information on the Trick Flow 23-degree heads, PN 30300002? Also, do you feel it necessary to go to the larger-diameter springs on a 305 TPI if using a roller cam with 0.431/0.451-inch lift and 196/206 degrees of duration? I am going to try and squeeze this cam into my motor with the 416 heads.
Jeff Smith: The photograph you included with your e-mail, Gary, illustrates nicely how you solved this problem. Your approach was absolutely correct. There should not be a lot of side pressure on your homemade guideplate, and it looks pretty beefy, but it would still be worth checking from time to time. Also, did you use a hardened pushrod? And this brings up the question of material for your homemade guideplate. Excessive wear may be an issue here. My guess is you did not want to pull the intake and cylinder head in order to install screw-in studs and guideplates, which is understandable.
This is a common problem with many small- and big-block engines. Especially when you get into aftermarket cylinder heads, some manufacturers are moving the position of the intake and exhaust valves in order to improve flow. When this happens, the position of the valve in relation to the rocker stud has now changed. This means that when you bolt on a typical guideplate, it may not position the rocker arm directly over the valve as it should. Until recently, small-block Chevy engine builders were forced to cut the guideplate down the center to allow independent positioning of both rockers and then weld the plate back together. Isky has come up with an adjustable small-block Chevy guideplate that has overlapping slots to allow lateral positioning of the pushrods. Then you just lock the plates down with the rocker studs (PN 200-AGP for 51/416-inch pushrods, 300-AGP for 31/48-inch pushrods; both are $55.99 at Summit Racing). The plates can also be welded for a more permanent solution. We've had to deal with this misalignment situation as well on small-block Fords and big-block Chevys. Dart recently introduced an adjustable guideplate for the Rat motor that is incredibly simple and effective. A small nut and bolt can be loosened, and then the spacing can be adjusted to line up the rockers with the valves. Dart sells this under PN 27001230-4 for a set of four for $33.69 from Summit Racing. The only thing we've noticed is that these adjustable guideplates occasionally hit the cylinder head on some aftermarket heads, which might require some grinding on the head to make them fit, but it's still a great idea.
Check out the redline tires and oversized Cragar S/S wheels. Looks like a Hot Wheels Charger, no?>>>
As for your question concerning valvesprings, the camshaft you refer to is a GM hydraulic roller cam used in HT383 crate engines with iron Vortec heads and a 1.250-inch-outside-diameter valvespring. The cam makes great torque and will extend the rpm a little bit for a 350ci engine. If you wanted to stick with a GM spring, the PN 10134358 spring is rated at 110 pounds of load at a 1.70-inch installed height, which would generate roughly 260 pounds of force at max intake lift, slightly more on the exhaust. This is more than enough spring to control that cam. You can buy the spring at any GM dealership, but we priced it through Scoggin-Dickey at $3.75 each or $60 for a set of 16. Just make sure you have plenty of retainer-to-seal clearance, but there should be enough room because of the limited lift. One thing to consider when adding stiffer springs to older iron heads is that the additional spring load may just begin pulling the studs out of the heads. Most production iron heads use press-in studs that pull out rather easily with stiffer springs. The best solution is to machine the heads for screw-in studs and guideplates. But be careful. By the time you've added quality screw-in studs and guideplates, rebuilt the guides, and added new springs, you've got almost as much invested in these old iron heads as a new set of aluminum heads would cost. So we recommend doing your homework first and then deciding.
The Trick Flow Specialties head you mention is TFS's classic 23-degree aluminum small-block Chevy head, which works very well and is an excellent alternative to putting money into stock iron heads ($1,130.95 from Summit Racing). This is the entry-level head with a high-velocity 175cc intake-port volume and 1.94/1.50 valves. It's a good choice since the larger 2.02-inch intake valve won't fit the small 305 bore. We'd go with a little more cam than that factory HT 383 grind. One thing in your favor is that you can reuse the stock factory hydraulic roller lifters, so all you should need is the cam. Crane builds a hydraulic roller called the Zcam that's slightly longer in duration at 214/222 degrees at 0.050-inch tappet lift (276/284 degrees advertised duration) with the big incentive being the added lift of 0.488/0.509 inch on the intake and exhaust (PN 109821, $295.95 from Summit Racing). This added lift with the TFS heads would really wake up that little 305, but it will increase the peak-torque rpm point, which may not be your goal. If you stick with the iron 461 heads, your original cam choice will probably be better, only because the iron heads may not be able to accommodate the extra lift without additional machine work.
This is Gary's solution to his rocker-arm location problem: creating a guideplate without
Always check for lift capacity when changing cams. Generally, more lift with stock-type he
Hemi Crank Fact
Only the 426 Hemi came with an eight-bolt flywheel/flexplate flange. All others used six-bolts. The Hemi crank material was also superior and featured nitride-hardened journals for increased reliability under extreme duress.>>>
Crane Cams; Daytona Beach, FL; 386/258-6174; cranecams.com
Summit Racing; Akron, OH; 800/230-3030; summitracing.com
Trick Flow Specialties (TFS); Tallmadge, OH; 330/630-1555; trickflow.com
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