If you can get Cleveland heads for $50-$75 a pair, it could be worth it. The last Ebay auction I saw, the heads started at $250 or so. That makes it much less attractive.
Do check out
http://www.pricemotorsport.com/ if you have any interest at all in Cleveland engines. They have adapter plates to mate an EFI intake manifold to Cleveland heads or Cleveland heads and block.
The heads will need to have hardened valve seats installed to be used with unleaded fuel. That adds $275-$400 to the cost. Then you need adapters to mate your EFI manifold to the Cleveland heads - see
http://www.pricemotorsport.com/ for the adapters. The 2V adapters are $255, the 4v adapters are $267. If you use the 4V heads, you need a set of port stuffers to reduce the port volume in increase the flow velocity - that adds $112 plus maybe $150 worth of machine work to install the stuffers. Then you need to modify the heads and block to make the water passages line up. New push rods and gaskets are needed too.
Totals: ( I’m sure that I have missed some things)
2 V Heads
$75 heads
$350 machine work
$225 manifold adapters
$650
If you paid $350 for the heads, that works out to $1000, and a good set of used Trick Flows or AFRs could be had for that price
4V heads
$75 heads
$350 machine work valve seats
$267 manifold adapters
$112 port stuffers
$150 port stuffer machine work
$924
If you paid $350 for the heads, that works out to $1274, which is in the price range for a new set of AFR's
If you have to change the pistons, this isn't a bargain. If you can run the 2V heads and stock pistons (don't know if this is possible), it could be a cheap upgrade.
Cylinder head selection advice:
Dollar for dollar, Trick Flow heads flow better "as cast" than almost any other head. The only heads that flow better are the CNC machined AFR heads, which will carry a $200-$400 price premium above the Trick Flows and almost all the other heads.
The gotcha on the Trick Flow is that they require stud mount rocker arms, and require you to have a push rod gauge and special length push rods. Trick Flow or Summit can supply all these extra parts, but be aware of the extra costs involved. The extra labor and different valve adjustment procedure for Trick Flow heads must also be figured into the equation.
The Edelbrock E-STREET heads use a stud mounted rocker like the Trick Flow and may be subject to some of the same requirements for push rod setup and length. They probably won't flow as good as cast as the Trick Flow heads and the extra wrestling with the push rod and rocker arms is a minus. Check out the Edelbrock site: (
http://www.edelbrock.com/automotive_new/mc/cylheads/ford/sb_estreet.shtml ) the E street heads are not setup for any emissions provisions and will not work with hydraulic roller lifter cams used in 1986 and later 5.0 HO engines. For these reasons I would avoid using them in an 86 or later 5.0 Mustang.
AFR, and some Edelbrock and the other cylinder head manufacturers use pedestal mount rocker arms, and standard length push rods unless you have milled the block or heads. The installation is a little simpler but with the exception of AFR, the flow numbers are lower than Trick Flow.
If you buy used heads, plan on having them serviced at a reputable automotive machine shop. They will check the valves, guides and springs and do a valve job on the heads. You will also want to have the heads checked for cracks and stripped bolt holes. In many cases this brings the cost of having the heads serviced makes them equal in cost to a new, still in the factory box set of heads. If the seller tells you "all that stuff has been done" make him show you the receipt and then visit the machine shop where the work was done.
.Since you have a street driven car, keep the intake port volume low - 165-175 CC. This will give better around town low speed performance and faster acceleration in a stock bodied car. Avoid heads with big port volumes and cams with wild timing for a street driven car. The numbers may sound exciting, but you will have to rev the engine above the point you would normally do for day to day street driving. Bottom line: the car may have to be up past 4000 RPM before it starts to pull good. That translates into you will run into the car in front of you before you get into the power range of the engine. High number rear end gears are a necessity for cars that don't start to develop power until the engine revs past the 4000 RPM mark
All in all your best, least problematic approach is a kit with heads, intake manifold and cam. The manufacturer will have matched the components together to get the performance specs you are looking for.
. that's a good way to make a bad exhaust port even worse.
