One of ? L89 Nova for sale at Russo and Steele

[Rixls6]

18 1970 big block Chevelles got the aluminum heads.

[69SSZL1]

What casting are those Alum Chevelle heads? I just checked my Colvin book for '70-75 and don't come up with any alum heads for that time except the '71 074 castings. All 70 and up had tapered seat spark plugs, so I was wrong, even the 842 castings would be incorrect.

[Kim_Howie]

I just wanted to know about one, not 18 of them. O K I didn't know about them.

[markjohnson]

The '71 LS-6 Corvettes are something I was also gonna bring up. I'm pretty sure Tonawanda just slapped the 118cc Open Chamber Aluminum heads onto a standard 11.00-1 closed chamber piston motor. This is gonna knock the compression ratio down to 9 or 10.00-1. I'm also pretty sure that the Crate LS-6 's that were produced for several decades as 10.2-1 Compression engines were done so by putting Cast Iron Open Chamber heads onto a closed-chamber piston short block.

[RPO LS7]

[ QUOTE ]
The '71 LS-6 Corvettes are something I was also gonna bring up. I'm pretty sure Tonawanda just slapped the 118cc Open Chamber Aluminum heads onto a standard 11.00-1 closed chamber piston motor.

[/ QUOTE ]
6262976

[70 Forest Green Zee]

This has been a very interesting thread, I've read every post from the first to the last. First off let me say I have a great deal of respect for Brian Henderson for the quality of work that he and his crew does, and his second to none knowledge of Chevy Novas. Here's my question and what I'm having a problem with: Brian was standing right there when the engine in question was disassembled so he obviously knows both what heads were on the engine when it was disassembled, and what pistons were in the engine during dis-assembly. These two components are basically what will determine the cars authenticity. Brian, you can end this right now by stating what were the heads and date codes during dis assembly, and what pistons were present at the time this engine was disassembled.

[kwhizz]

Dave............Still waiting for an explanation on the 1970 Head/ Piston combination for the 074 heads on a 396 block..........GM Piston Part#'......

[kwhizz]

After doing some research on the Piston/Head combo's.....Putting 074 heads on a L78 short block would yield approx 9.5 to 1 compression.....doesn't make any sense why the factory would do that in a High Performance application......there was also concerns about the posibility of the closed chamber piston dome hitting the 074 head in the exhaust valve area, even though the chamber was larger ..... Some hit....some didn't......so.....Why would GM put High Performance Aluminum Heads and lower the compression ratio by 1.5 points........Seems more likely that the heads were added at some time in the cars early life by someone who didnt know the difference..



Ken

[Charley Lillard]

Isn't that what they did with the 71 LS6 ?

[iluv69s]

[ QUOTE ]
Brian, you can end this right now by stating what were the heads and date codes during dis assembly, and what pistons were present at the time this engine was disassembled.

[/ QUOTE ]

...inquiring minds want to know....