I'm building a 1962 327 motor. Found correctly dated (December, 1961) 461X heads and the "870" block on EBay. However, the engine had been disassembled and the pistons discarded when I bought it. I'm now starting to have it machined. The machinist wants to know what pistons I want. He has opinions, and I'd like to be informed. Will probably need .030" over. But I won't know that until the machine shop starts measuring and honing. Haven't decided whether forged or hypereutectic. Would like to hit over 9.5 to 1 and keep under 10.5 to 1 so I can run on pump premium.

1. Recommendations on forged vs. hypereutectic? Don't know how fast I'll spin the motor because I haven't decided on the cam.

2. How do I measure deck height?

3. What's the volume on stock 1962 461X heads? (1.94/1.50 valves)

(I've already got the good Scott Marzahl group purchase rods.)

 

Are you trying to build a 300 HP engine? 340 HP? Or something else?

Has the block been decked?

Don't let the machinist cut any metal, but ask him to measure the deck height - crankshaft C/L to top of deck. Better shops have the tools to do this, and they should measure at each cylinder along the deck length to determine if the decks are parallel to the crankshaft axis.

The maximum CR the engine can handle is a function of inlet valve closing point, so if you haven't chosen a cam, you don't have a plan that will allow you to determine other engine parameters. If you don't have a plan you better set the tools aside and develop one if you want a good outcome.

You would probably be better served to have started this thread on the C1/2 forum, but whatever...

Duke

 

With an old cast iron block & heads like these, the first thing you want to do is have the machine shop check out the block to see what, if any, previous machine work has been done. It's not uncommon to see blocks overbored to 0.060", decked, or even aligned bored with four bolt caps. Same thing applies for the heads. Screw-in studs and angle-milled heads aren't uncommon modifications. It's best to start out knowing what has been done rather than start buying parts that may not fit. Unless you intend to use a lead substitute, you may want to consider hardened valve seats for your heads.

I'm guessing that you want a period correct engine for your vintage Corvette. If so, then the type of transmission and rear end ratio are going to greatly influence what type of cam/compression ratio you will end up using as will the type of driving you anticipate. For a street driven car you want as much low end torque as possible while a racer is more concerned about upper RPM HP. Please post this additional information if you can.

To answer your questions:

1. If you're building a street engine (< 5800 RPM), hypereutetic pistons are a good way to go. If you plan on a dual purpose street/strip engine (> 6000 RPM), plan on forged pistons to counteract any detonation encountered.

2. Answered by SWCDuke. Measure first before cutting!

3. Nominal 64cc. Only way to know is cc the heads after all head work has been done especially if cutting new seats.