These are decent heads and quite popular, they only bolt to the classic 1955-1986 intake pattern.
You will need to purchase valves that are .1 inch longer than stock GM. As typical with aftermarket aluminum heads the entire spring assembly is positioned that much higher from the head gasket surface. This also requires push rods that are .1 inch longer than normally stock.
The valve spring assemble from bottom to top require a spring seat as the steel spring will eat the softer aluminum without a spring seat, guide/stem seal, spring itself, spring retainer, and locks.
- The spring seat can be a cup or a locator:
- The cup which is shaped like a shallow saucer with a central ID hole and a raised OD edge. Sizing these The ID hole needs to fit over the guide boss OD. The cup OD rim needs to fit the spring OD and within that of the pad’s machined edges.
- The locator has a collar that has to have an ID that fits over the guide OD and fits inside the spring ID this can be tricking to a non player with nested springs but works well with beehives. The base as with the spring cup needs to fit inside the machined spring pad OD. Additionally the collar needs to be low enough to not interfere with seal installation.
All of this spring seat measuring and selecting is probably the biggest headache of doing bare head stuffing yourself. You will find that the fits of the spring seat are in close enough to get the job done not in precise fits as you think of as machine part clearances.
- Guide seals need to fit the guide boss and stem diameters while providing for lift clearance to the underside of the retainer. Unless you’re running lifts over well .5 inch this usually isn’t a problem.
- Springs need to be decently matched to the cam, here I’m not talking roller or flat tappet but rather if your chosen cam requires special springs by the manufacturer. Generally short of all out competition cams I like beehives. They do more work across a broader range of lobe and lifter designs with less pressure. You have to keep in mind that beehives are really designed for metric valves so when matching them to the 11/32nd standard SBC valve stem you need a retainer that bridges this metric spring to US like the Comp 767-16. It’s done a lot.
- Your retainer choices are going to match your performance level and spring size and type.
- Locks need to match retainer and valve stem, here again this depends on how you use the engine more than less standard lock uses a 7 degree angle where super duty racing parts use 10 degrees. This in addition to previously mentioned constraints is going to affect the retainer choice.
So pretty much going on your own with bare heads this is the rocket science you need to get into. Follow this link and order up their free paper catalog it is a gold mine of information that is hard to come by otherwise.
www.competitionproducts.com
Bogie