The Next Level
Getting serious by going inside for more power
Frank Bohanan - November 21, 2013 10:00 AM
1 The first step was to remove the existing components. To be replaced were the stock iron cylinder heads, camshaft, and complete valvetrain. We kept the basic 5.0L short block as is, for the most part.
2 Cleaning all of the gasket surfaces is essential to ensuring a proper seal. The head gasket in particular requires a very smooth and clean surface, especially if newer multi-layer steel (MLS) gaskets are to be used.
3 It’s always a good idea to chase the threads of any bolt holes. Little bits of gasket material inevitably find their way into the holes or old sealant or threadlocker, which should also be removed before the bolts go in.
4 An inspection of the original iron heads shows there may have been a problem with one of the exhaust valves. This was also the cylinder with the lowest compression reading. Besides the odd color, the valve also was recessed a bit.
5 The cleaner you get the block’s deck surface, the better the head gaskets will seal. Be sure not to nick or gouge the surface of the block and by all means, DON’T use a scotch-brite wheel. It’s quicker, but that abrasive gets EVERYWHERE!
6 The Dart heads have a more efficient combustion chamber shape, the valve sizes are significantly larger and a multi-angle valve job is used, significantly increasing flow.
7 Our Dart Pro1 195s slightly raise the exhaust port to improve flow. Ours are raised 0.135-inch so there wasn’t any clearance issue in our case. These heads also have an extra thick deck surface to minimize warping and improve sealing.
8 The Dart heads have a much deeper spark plug thread. This requires the use of a longer reach spark plug to avoid misfire and get the best combustion.
9 We are switching over to a stud-type rocker arm mount (versus the OEM 5.0L pedestals) and needed to install the studs and guide plates. These were included, though not mounted. Always use threadlocker on the studs.
10 A long bolt will provide greater leverage as you insert the new cam further into the engine, thus helping to avoid nicking the cam bearings. Of course, both the cam and the bearings should be liberally coated with a suitable, tacky assembly lube.
11 We went with a new billet steel timing set from COMP Cams. The cam was installed “straight up” with the timing marks/dots in line.
12 When torqueing down the cylinder heads, you must first coat the bolts (or studs) with an appropriate lubricant (or a suitable thread sealant for any which pass through into the water jacket). Never install them dry unless there are specific instructions to do so.
13 After ensuring the pushrods are the correct length, you’ll need to set the lifter preload if you’re using hydraulic lifters (or the lash if you’re not).
14 You need to seal the timing cover bolts and seals properly to ensure there will be no leaks. Judicious use of RTV sealant is your friend.
15 The valley area should be cleaned to remove any dirt or debris. Any lifter retainers can be installed and pour some clean oil over the lifters.
16 These COMP Cams Ultra Pro Magnum steel rocker arms are super strong for a more stable valvetrain, even at very high rpms. Don’t forget to feed the rockers, valve stem and tip a little oil.
17 A common technique to minimize coolant and oil leaks is to use high temp RTV instead of normal end seals. It’s also a good idea to spread a thin layer of the sealant around the coolant passages on the head as well. The intake gaskets will be held in place both by the RTV and the tabs protruding from the head gaskets.
18 5.0L EFI engines have low profile valve covers to clear the intake manifold. When you upgrade to roller rockers, it’s often necessary to modify or remove their inner oil baffle. Modification is preferred, as these baffles do help prevent oil consumption.
19 Most aftermarket intake manifolds follow the OEM two-piece design with split upper and lower halves. This requires a unique gasket between the halves. There are quite a few connections on the underside of a 5.0L intake upper. Replace faulty hoses and cap off any fittings not used.
20 We installed a MagnaFlow Direct Fit catalytic converter-equipped crosspipe (PN 37338, CARB EO D-193-84). Compared to the restrictive OEM H-pipe, this unit has larger 2½-inch mandrel bent tubing along with less restrictive converters.
For Your Information:
Comp Cams, (800) 999-0853, www.compcams.com
DART Machinery, (248) 362-1188, www.dartheads.com
Fast Specialties, (855) 218-9248, www.fastspecialties.com
MagnaFlow, (800) 824-8664, www.magnaflow.com
Performance Associates, (909) 391-4440, www.pahorsepower.com
Mustangs are a great way to get into the automotive hobby.
They’re plentiful, very affordable, and easy to upgrade. Their insurance rates have even gotten more realistic since the value of the cars has gotten so low.
We’ve had our 5.0L Fox Mustang for a while and have done all of the usual stuff to it. We already had an upgraded intake manifold (extrude honed Edelbrock Performer EFI), Ford Racing 65mm throttle body/EGR spacer, Pro-M 77mm MAFS, and Hedman shorty headers, which would all be reused. The car is now much more fun to drive and is probably making somewhere around 215 rwhp (versus about 185 or so for the average ’87 and later 5.0L) but we still want more. For that, we need to get into the engine. Since we’re talking about a street performance car, we’ll stick with the more cost-effective “bang for the buck” stuff like better cylinder heads, a new cam with valvetrain upgrades, and an even better (but still truly street legal) exhaust.
Fortunately, the stock 5.0L is pretty stout. The block is good for up to 450 horsepower or so and the internals can handle about the same so long as you keep the revs below 6,500 rpm. A good tip, however, is to stick with a ’92 or earlier engine if you plan on going to such levels since Ford switched over to different pistons (hypereutectic) in ’93. These aren’t as strong as the forged pistons in the earlier engines. Also, with any engine, you need to make sure the short block you intend to use is healthy or else you’re just throwing money away.
We were fortunate to have a healthy short block in our second owner ’91 GT. There were no signs of oil burning and the compression checked out fine for each cylinder. One was a bit lower than the rest but still within the allowable range. We’ll check that cylinder more carefully when we get the heads off. Since we already had most of the usual inlet and exhaust modifications, we decided to go a little bit more aggressive in terms of the camshaft profile and the cylinder heads. We also decided to do a full valvetrain upgrade as well as doing all we could to further upgrade the exhaust while still remaining street legal in California.
We can’t show every step, not only because we don’t have the space, but because every car will be different. If you’re stepping up to this level of modification for your ride, you should have no trouble filling in the blanks for your particular situation. Our upgrades resulted in a 50-plus rwhp increase along with a smaller increase in torque. Overall driveability is significantly improved, especially in terms of throttle response.
As you would expect from a 25 percent increase in power, the acceleration was noticeably better as well. A slightly smoother idle and a small increase in fuel economy were completely unexpected. Best of all, as we make further upgrades such as a power adder, etc., the OEM heads and camshaft won’t be there to restrict the potential gain!