Y-BlocksForever Forum / Y-BlocksForever! Forums 2006 / Aftermarket Cylinder Heads

½” Head bolt capability

Ted — Fri, 04 Jan 2008 07:35:57 GMT

Heads need to be able to use ½” head bolts. Stock factory heads can be drilled without hitting water so that ½” head bolts can be used. Likewise should be the same with any aftermarket replacement heads. One idea is for the head bolt holes to be ½” except for a shoulder at the top to accommodate a 7/16” head bolt. If using a ½” head bolt, then the shoulder is simply drilled out. This feature is already on a variety of the SBF aftermarket heads so the heads can be used on either 302’s or 351W’s.

Valve lengths

Ted — Thu, 03 Jan 2008 08:17:25 GMT

Longer that stock length valves would be nice. This allows some additional flexibility in port design and when using higher lift camshafts. Drawback is that the supports in the heads for the rocker stands will have to be higher to maintain proper rocker arm geometry. This then makes the valve cover rail higher and in turn and the valve cover sits higher. Is this a problem for those of you with a power brake booster?

Raising the rockers would also dictate longer pushrods. Instruction sheet could include a recommended length for a starting point but this is something that might be varied depending upon the brand of rocker, deck or head milling, etc

Feel free to add thoughts.

Overall look of the head

Ted — Thu, 03 Jan 2008 08:20:17 GMT

Appears to be two trains of thought here. One where the head is cast similar to the originals with casting lines and roughness. The other where the heads are actually smooth on the exterior finish and potentially can be emblazoned with the manufacturers logo on the ends. Smooth works okay for myself. What’s the general concensus here?

Prerequisites in a replacement head design

Ted — Thu, 03 Jan 2008 08:22:24 GMT

Some thoughts on some of the standard design features to keep a replacement head marketable to the masses would be:

Must accept current Y-Block intake manifolds and gaskets.

Must accept current Y-Block exhaust manifolds, headers, gaskets.

Must accept current Y-Block valve covers and gaskets.

Must accept current Y-Block rocker arm assemblies.

If spark plug location is revised, must be able able to use with current exhaust systems.

14mm spark plugs. Lots of these available in the various heat ranges.

Available ready to run with valves, springs, retainers, etc.

If aluminum, then heli-coils in the rocker stand, intake, and exhaust bolt hole threads.

Open for discussion. If necessary, just start a new thread for the topic you have in mind or add to this thread any additional standard features.

Instruction sheet for new head installation

Ted — Thu, 03 Jan 2008 08:12:09 GMT

Definitely needs an instruction sheet. How many times have you purchased something only to question what the manufacturer wanted because no literature was included? Some items to include on an instruction sheet would include:

Head gasket recommendation.

Torque specs and tightening sequence.

Spark plug recommendation with the heat range.

Pushrod length if different than stock.

Head bolt recommendation with part numbers.

Any warnings – ie. “DO NOT USE ORIGINAL EQUIPMENT HEAD BOLTS!!!”, “USE ANTI-SEIZE ON SPARK PLUG THREADS BEFORE INSTALLING”, etc.

Feel free to make corrections or additions. This is just a start.

Thicker decks

Ted — Fri, 04 Jan 2008 07:36:49 GMT

Thicker decks for serious milling and potentially some additional rigidity for head gasket sealing.

Head installation accessories

Ted — Thu, 03 Jan 2008 08:13:45 GMT

Installing a new pair of heads will require at the very least a pair of head gaskets, an intake manifold gasket set, valve cover gaskets, and exhaust gaskets. Other items could include pushrods and head bolts. Thoughts are split between including the accessory kit with the heads or having it available as a separate item. Including the items with the heads does eliminate someone trying to use their 1955 vintage head bolts with the new heads but does add significantly to the initial cost of a pair of heads. Having the kit available separately gives some flexibility to the end user in being able to use some of their own parts or different brand preferences while also keeping the initial cost of a pair of heads less.

Feel free to add thoughts to this.

Aluminum or iron for the head material?

Ted — Fri, 04 Jan 2008 07:39:24 GMT

There are options in head materials. Aluminum is lighter but has more heat going straight to the water jacket and subsequently not being turned into energy (horsepower). But improved air flow as well as a compression increase can compensate for this. On the other hand, iron heads would be good too especially if the flow numbers are increased and even if the combustion chambers stay at the stock 69cc ‘G’ size.

I’m assuming that the head manufacturer will have final say in the material being used but will be nice if the heads are designed around the material. I’d personally hate to see another fiasco like the Edelbrocks for the Fe where there’s a drop in performance using the aluminum head over the factory cast irons only because there was not an accompanying increase in air flow and compression ratio to go along with production of them in aluminum. Referring to out of the box and unported of course.