Engine Newbie Deciding On A Cam

Some guidelines to help...

Far too many people put a dab of this and a dollop of that, and then wonder why the car doesn't run worth beans. Then they think off the shelf computer chips will fix their mismatched parts problem. It won't You have to have a plan for what kind of performance you want: Hot street. Street/Strip, Pure strip, Autocross or Road course. Each one requires a different strategy and a different set of components.. Mismatch the components and you’ll have a car that falls flat on its face when you demand performance.

Everyone thinks HP! HP! HP! and thinks that peak HP is what they need. Peak HP is great for a drag strip car when it has the proper gears and tires to get the car up into the high RPM range where it develops that high peak HP near the finish line. On a street car, that strategy will have Honda Accords outrunning you, because you will never get the engine RPMs high enough without running over everything in your path.

Here’s the strategy: Always remember that there are some tradeoffs in any engine combination. Most of us don’t have enough money to “have it all” as if it was possible by some masterful combination of parts and tuning.

The following recommendations are for 5 Speed Manual transmission cars without NO2 or pressurized induction, stock short block.

1.) Hot street: Broad flat torque curve, high velocity airflow in the intake and heads for best throttle response. Gears suitable for reasonable gas mileage and long road trips without excessive engine RPMs. Stand on the gas pedal from a rolling start to squeeze into that gap in traffic in front of you, and it jumps quick and hard to get you there. Max RPM’s are 5200-5500 RPM for best power. Lopey cams may sound cool, but run poorly in a low RPM street environment.
Use stock cam, stock, GT40 or mildly ported stock heads, Cobra or Explorer/GT40 intake, advanced timing, stock 19 lb injectors, stock fuel pump. Use some good 1.6 or 1.7 ratio roller rockers for extra punch. Use a King Cobra clutch, with stock iron or steel billet flywheel. MAF cars can use a 65 MM TB from the Explorer intake manifold and a 70MM MAF from a 94-95 Mustang. Drive train: 3:55 gears with soft tread compound tires. Use some Ford Racing unequal length headers, stock 2 1/4” cat pipe and some mufflers that don’t drone or get too much attention from the law enforcement or neighbors. The stock computer will handle all this with no problems and doesn’t need any help in 90% of the cases. No skinny or grossly undersize tires for the front: remember you still have to stop quickly in traffic. Make sure all the rubber bushings in the front and rear suspensions are in first class shape. Leave the emissions equipment intact and working. Removing or disabling it won’t get you any more HP or performance. Do not convert to carb or remove A/C: either one will reduce the resale value. Carb conversions cannot be titled for street use or get tags in some places. They definitely won’t pass smog inspections.

Street/strip: A little more slope to the torque curve with a gently sloping peak. Use slightly larger port volumes on intake and heads for more peak HP. Uses 3.55 or 3.73 gears to get the RPM’s up into a higher range quicker. Be prepared to sacrifice some low RPM throttle response in exchange for high RPM power. This by necessity will be a Mass Air or Mass Air conversion on 86-88 5.0 Mustangs, since stock speed density will not run well with the changes in engine airflow. Don’t get too crazy on any one engine part since you still have to drive the car on the street, and a mismatch can make street driving miserable.
Use stock or mild aftermarket cam, Ported GT 40, or 165-180 CC port volume aftermarket aluminum heads. Use a Trick Flow, Edelbrock Performer or equal intake manifold. Take a 73 MM aftermarket MAF calibrated for 24 lb injectors, and 24 lb injectors, 155 LPH fuel pump, Kirban adjustable fuel pressure regulator. Be prepared to shell out some $$$ for a custom burned chip using data gathered from a dyno run. Mass market chips will not get the job done. Use some Ford Racing unequal length headers, aftermarket 2 1/2” cat pipe and some mufflers that don’t drone or get too much attention from the law enforcement or neighbors. Drivetrain: expect the stock T5 to fail, so save your money for a super duty 5 speed trans. Tremec 3550, TKO 500 & TKO 600 are the best choices. Different gears in a stock T5 case work for some, but there is only so much power you can pass through a T5 in race mode before it breaks, even with stronger gears. Next are the Chassis mods: full length subframe connectors, different springs, different shocks, aftermarket lower and upper control arms with rubber or urethane bushings. Buy all the parts from someplace like Maximum Motorsports, Griggs or Steeda as a kit so that you know that all the parts fit and don’t argue with each other. Carry spare tires and wheels for the drag strip: skinnys for the front and drag radials for the rear. No skinnys for street driving! Over 85% of the breaking power is generated by the front tires, so skinnys won’t do the job in a panic stop situation. Disconnect the front anti-roll bar at the strip; reconnect it before you drive home. Leave the emissions equipment intact and working. Removing or disabling it won’t get you any more HP or performance. Do not convert to carb or remove A/C: either one will reduce the resale value. Carb conversions cannot be titled for street use or get tags in some places. They definitely won’t pass smog inspections.

Strip only: High RPM, High flow heads (185-215 CC port volume), wild cam, high flow intake manifold, 70 MM or larger TB, 80 MM or lager MAF, strip everything out of the car that doesn’t make it go faster. Carbs are OK if that’s what you want, but remember that as the temp/humidity/ barometric pressure/altitude changes, you have to re-jet and readjust the carb. EFI eliminates most of that with its built in compensation or you can tune of the fly with a high end Motes or Tweecer system combined with a wide band air/fuel ratio meter. Use custom headers, dumps and minimal mufflers. How fast you can go on 5 liters is a function of the skill level of the driver/mechanic and the size of your wallet.

TRAILER the car to the race track since it won’t be legal to drive it on the street. Drag slicks in the rear, skinnys up front, use 3.73 or bigger gears (4.xx) in the rear axle. Since you won’t be driving on long trips, the big gears with work with the high RPM power curve to get the best results. Drivetrain: TKO 500 & TKO 600 are the best choices. Different gears in a stock T5 case work for some, but there is only so much power you can pass through a T5 in race mode before it breaks, even with stronger gears. Next are the Chassis mods: full length subframe connectors, different springs, different shocks, aftermarket lower and upper control arms with rubber or urethane bushings. Buy all the parts from someplace like Maximum Motorsports, Griggs or Steeda as a kit so that you know that all the parts fit and don’t argue with each other. Remove the front sway bar, put an airbag in the rear spring of the side that spins the tire the most. Plan on a roll cage if you are truly serious about going fast: most strips will require it once you get to a certain ET range.

Autocross is a combination of Hot street engine and street strip chassis prep. The engine must accelerate quickly from low RPM and needs a broad, flat torque curve. Next are the Chassis mods: full length subframe connectors, different springs, different shocks, aftermarket lower and upper control arms with rubber or urethane bushings. Buy all the parts from someplace like Maximum Motorsports, Griggs or Steeda as a kit so that you know that all the parts fit and don’t argue with each other. Most of the time you’ll never hit third gear, so some 3.73 or bigger gears (4.xx) may help a lot. You’ll have to spend some more money on brakes since it kills brakes quickly. Rear disks, larger rotors up front, stainless steel brake lines, different brake pads. A 87-88 T Bird Turbo Coupe or SN 95 rear axle will be your best bet. Autocross will severely strain 1st & 2nd gears, so your T5 may take a premature dump. Save your money for a super duty 5 speed trans. Tremec 3550, TKO 500 & TKO 600 are the best choices.

All out road race is the most difficult of all: an engine that will run at high rpm hour after hour and never fail, yet pull hard out of the hairpin turns that will require a lot of torque at lower RPMs. In my opinion, guys that can successfully build a winning road race engine are the cream of the crop. Top this off with a chassis built for strip only duty, but with changes to the settings of springs, tires, roll bars brakes and shocks. It’s a whole other world of racing.
You’ll have to spend lots more money on brakes since it kills brakes quickly. Rear disks, larger rotors up front, stainless steel brake lines, different brake pads. Air ducting to cool the brake rotors will be a must. The brake rotors of cars on a high speed road course glow red after several hard laps of racing. Drivetrain: TKO 500 & TKO 600, and T56 close ratio are the best transmission choices.

I'm pretty sure 185's will not work without notching the pistons, something i have done with other heads and wouldn't do again.
If that is the case, the TW's are the better option.

For the cam, the extra $100 you spend for a custom will be worth it. Nobody grinds cams local, they almost all call comp with their own specs and have it done.

You will need 24lb injectors, and lose the C&L for a pro m or pmas calibrated for the 24's.

The gt40 intake (one of my favorites), is a tad undersized for maximum power with those heads, but it should make for a pretty nice daily driver, provided the cam (this is why i say go custom) specs match your rpm operating range.

Hey Aaron,

Interesting user name you have there

Sounds like you have a decent 5.0 and have a solid motor build about to happen. What chassis modifications do you have to support the (soon to be) increased HP and TQ? Subframes and torque box reinforcements are a must if not already done. What about gears?

Have a pic of your Notch?

Sounds like a sick ride!

As far as the AFR 185s go and piston to valve clearance i'm not knowledgeable about that. Trick Flow twisted wedge heads (the 170cc) are some of the most popular head choices around this site for a stock bottom 302 and you can't go wrong with them. With a custom grind it's going to be all about your combo, gear choice and how you want the car to drive on the street.

Looks pretty clean to me.

Do you have a MAF that's calibrated for the 24# injectors? A MAF that's programmed for 19# injectors will not run right if your using a different size injector.

Are you from Sandy Eggo?

Partially a good guess. I'm born and raised in SD and lived there for 35 years. What part of SD you live in?

Good looking car, nice starting point compared to most people that join the fox game these days.

4.10 to 3.73 isn't much of a change, i probably wouldn't bother.

Welcome Aaron, sounds like you have a solid foundation.

the AFR heads will need the pistons notched as they are inline heads, unless you get a custom cam ground with a shorter duration. If you can get teh TFS 170's with the better springs grab them, as they will outflow the AFR's and not have the same PTV issues as the valves are offset.

For a cam, I would recommend spending the extra $50 or so and contact Ed Curtis at FTI or Buddy Rawls. They are expert cam grinders that will make you a cam which is suited to your exact specs. There are a few OTS cams that will make power as well. It all depends on the heads you go with. Then what your use is for the car, powerband, N/A or power adder, gears, etc.

Everyone has their own favorite cam so I'm not going to throw out any here. It really depends on what you want to do with the car. I agree on swapping out the C&L for a Pro M mass air. I would go right to 30lb injectors and you will have room to 400hp. Don't forget to upgrade the intank fuel pump as well to at least a 155 lph. You may want to invest in an ajustable FPR as well to help tune the car- i like the old school Kirban unit.

master_bayshin said:

I grew up in north county, Encinitas to be exact. I actually live in la now but my dad lives in del mar so I do visit now and again. What about you?

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Formerly Clairemont / La Jolla Shores as well as other parts of SD. I miss my home town from time to time as well as surfing Del Mar at 15 St. and taking my Boxers to Dogs beach. There was nothing better than driving from Pacific Beach to Carlsbad on the PCH on the weekends with Encinitas being my favorite to stop for a drink and walk around.

Anyways,

master_bayshin said:

Btw, my roof collapses a little every time I detail it, and I have to bang on the headliner to pop it back out. Anything I can do about that?

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I'd remove the head liner and inspect your roof supports. Probably at some point in history somebody sat or stood on top of your car and thought it was funny until they collapsed the roof.