The stock cylinder heads on my engine had to come off to fix the blown head gaskets. If you’re taking the heads off it is more than a good idea to inspect and clean them up while they are off the block. The last time those heads were off that engine was in 1983. And I might as well do it right. The second part of this question is to recognize the heads on an engine, especially these heads, are a limitation in the synergy of an engine. Air and fuel need to come in and exhaust needs to go out through the heads.
The stock heads were pretty basic and designed to help this engine offer 220-250 HP. The combustion chamber is 63.0, intake valve/Exhaust valve diameter was 1.78/1.45″. Interesting the 1967 289 HiPo specs were a combustion chamber of 54.5 and intake/exhaust diameter is 1.78/1.45″. Smaller combustion chamber giving higher compression, but the valves are the same size. The other issue with those stock heads is they needed to be cleaned up inside to make the air flow more smooth. The other difference between the hipo heads and non hipo heads were screw in rocker arm studs.
The engine builder and I discussed what to do about the heads on this build. I already knew the cost of a set of bare Edelbrock heads, $250 more than Dan wanted to clean up those stock heads. These heads already had bigger valves and better air flow. The other selling point is aluminum bleeds off heat much better than cast iron heads. This would help any detonation issues I might have. And two of these heads weigh less than one cast iron head. Plus they would look very cool on this engine. Potentially these heads alone could add 35 HP.
With the Edelbrock heads the intake valve would go from 1.78″ to 2.02″, a 35% increase. The exhaust valves were 1.45″ going to 1.60″, 11% increase. Plus the ports and air flow should be tremendously improved. And the Comp Cam chosen will also leave the valves open longer letting even more fuel and air into the cylinders. More fuel and air creates more horsepower.
These heads also have screw in studs for the rocker arms. The key difference between the stock Ford 289 4 barrel engine and the infamous Ford 298 HiPo engine were threaded studs. This allowed the engine to hit higher RPM’s.
Specs and info from Edelbrock
Edelbrock # 5024 Aluminum Heads for larger valves and better breathing.
Head Casting Number 6025P
Combustion Chamber Volume 60.0 cc
Intake Runner Volume 170.0 cc
Intake and Exhaust ports 2.02″
The Edelbrock #5024 E-Street cylinder heads are designed for Ford 289-351 W V8 applications. The Edelbrock E-Street cylinder heads offer American made quality and affordable performance. E-Street cylinder heads feature as-cast ports and are designed for entry-level street performance applications operating in the idle-to-5500 rpm range. The modern combustion chamber designs improve the combustion process and larger than stock intake and exhaust ports move more air through your engine for improve efficiency. For use on pre-pollution controlled vehicles only.
- Head Casting Number 6025P
- Rocker arm studs & guide plates are not included with bare versions of E-Street cylinder heads.
- Ideal for operating in the idle to 5500 rpm range
- Use with hydraulic flat tappet camshafts, .550″ maximum lift – not compatible with hydraulic roller camshafts
- 289-302 with 7/16″ head bolts require #9680 head bolt kit
- 2.02″ heads require additional piston to valve clearance
- Recommended spark plugs are Champion RC12YC or equivalent 14mm x 3/4″ reach with flat gasket seat.
- Requires hardened pushrods. 289-302 c.i.d. with 7/16″ head bolts requires #9680 head bolt bushing kit.
|Edelbrock||Stock 1968 4 bbl heads||Stock 66 2 bbl heads||1993 GT-40 heads|
|Combustion Chamber Volume||60.0 cc||53.5 cc||54. cc||60-63 cc|
|Deck Height||9.5 in|
|Deck Thickness||0.625 in|
|Guide Plates Included||No|
|Intake Runner Volume||170.0 cc|
|Push Rod Diameter||0.312 in|
|Valve Angle||20 deg|
|Intake/Exhaust valves size||2.02″/1.60″||1.78/1.45″||1.84″/1.54″|
|Intake/Exhaust Ports||1.94 x 1.04″ / 1.24 X 1.0″|