i may attempt to rebuild the heads on my car, however i lack all knowledge on how heads work and what parts there are on them. they are 305 lg4 heads. can someone give me a crash course and maybe some blown apart diagrams of the parts involved.

 

There isn't much you can do for a "rebuild" outside of a machine shop. In the "old days", before hardened valves & seats, you'd hear things like grinding stones and guide knurling & reaming, but not today.

The parts involved are intake and exhaust valves, valve springs, spring retainers, retainer keepers, valve guides, and valve stem seals. The factory also used "exhaust valve rotators", but there are only not-so-kind words that go along with them. One non-moving player is the rocker arm studs.

Rebuilding involves disassembly and checking parts for wear. The spring has to be compressed with the retainer so the keepers can be removed from the valve stem. Then the spring is released and all the parts can be removed from the head. That is repeated 16 times for the two heads.

A common wear point on small block Chevy heads is the guides. They can be knurled and reamed back to size, or reamed out and replaced. Replacement is usually recommended, and bronze guides are popular.

Then the valves and seats are "ground", which is really a cutting operation with hardened parts. This restores the sealing surfaces.

Another weak design in SBC heads is the stem seal. Positive sealing types are often substituted for the o-rings the factory uses. The best ones require the top of the guide to be machined so it fits snuggly over the guide and the stem for a good seal.

New valves springs are a good idea. A set from Comp Cams or Crane, and not reusing the exhaust rotators, will greatly improve the RPM capability of the engine. This is a must if you upgrade the cam to a higher reving piece.

Finally, the factory uses press-in rocker studs. They are prone to pull out, even more so with higher lift cam and higher pressure valve springs. Having them replaced with screw-in type, or at least pinned in place, is a good idea while the heads are apart.

 

machine shop and poor 16 year old does not go in the same sentence. how much no average to machine my heads so i have a little less blow by. also, tomorrow im doing a leak down test, what is the chance that the engine is shot and the heads are not the culperate, and it is really the rings? i hope i can get a couple more miles out of the engine till i can afford a 350.