One of ? L89 Nova for sale at Russo and Steele

[Charley Lillard]

But the end result was about the same compression ratio. I'm just pointing out that GM could have done something like what we have here.

[Rixls6]

But why would GM put 842's on a 70 Chevelle with the L89 option, yet use the 074 for a Nova???

[kwhizz]

[ QUOTE ]
But the end result was about the same compression ratio. I'm just pointing out that GM could have done something like what we have here.

[/ QUOTE ]

11.0 to 1 with 842's and 9.5 with the 074's....and a possibility of the Domes on the Stock L-78 Pistons hitting the Combustion Chamber in the Exhaust valve area....the Closed Chamber had a straight sidewall next to the exhaust valve which shrouded it......the open has a much larger chamber, but to unshroud the valve, they open up that area, but tapered it and that's where possible contact would occur.........I'll see if I can find that 3 page Wiki-article later and post it..........Bottom line......GM "Never" made a piston for a 396 or 402 block to work with the 074 head...........I think Dave didn't do enough research about the head situation before deciding they were Factory installed on this size engine.....the 074's were only used on larger displacement engines where GM made pistons for that application.....

Been down this road.....when I was building the Gold Nova into a L-89 clone....the first set of heads I bought were 074's because I didn't know any better.....The Engine builder then informed me about the compression issue and Piston un-availability.......Sold them and bought the 842's from a member here......Got an education...Again.....The Heads are the "Value" to this car as he states.....Yet.....Everthing seems to indicate that some just installed them at some time in the cars past....
Look .......Don't want to be a "Jerk" here.....But, Dave is presenting the car as "Factory"......Yet, for all the knowledge that is here about knowing the smallest detail about the correct color of brake line clips, etc...A pass is given to a Engine combination that was "Never" a RPO is Amazing to me...........It just go's to show the "Respect" that everyone has for Brian's opinion....but...If Dave provided the "Documentation" and Brian and Klutt accepted that as Gosphel.....Well??...
Again........It's up to Dave to do a "Verified" Documented History of the car to prove it's pedigree to a potential new owner......The Heads are the Problem.....I know that the car had Issues and doubts in Judging at a couple of shows......?????? Wonder Why??

Ken

[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....

[Pulnaway]

He ( the owner ) has already given the date codes for both heads.
1/12/70 and 1/16/70.

[Kim_Howie]

I would like to know the casting # inside the piston??

[427.060]

It would be nice to know if he bought the heads he asked Chuck about. If he did, what were the casting dates?
James

[kwhizz]

[ QUOTE ]
[ 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....

[/ QUOTE ]


The Dates are not the Issue as the 074's started production....I believe in late 68 for use on 427 L-88's and ZL1's.......So...It is possible for the dates to match

Ken

[BUIZILLA]

I spent about 7 years researching this already... with that said, I'd say the heads were installed somewhere along the way, the piston/head combo ain't friendly with stock GM head gaskets... I can't esplain the P-Plate though Lucy..

[L78steve]

[ QUOTE ]
I spent about 7 years researching this already... with that said, I'd say the heads were installed somewhere along the way, the piston/head combo ain't friendly with stock GM head gaskets... I can't explain the P-Plate though Lucy..

[/ QUOTE ]Instead of looking at the heads which could have been changed early on perhaps in error under warranty the POP and the block stamp should be examined carefully.