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Before we bought our 2005 Corvette in 2012, I had a 1969 SS396 Chevelle with the L78 engine and 11-1 compression. First, I blocked the heat riser open. Getting heat away from the incoming air charge was the big thing. I added the sheet metal heat shield that snaps in between the heads. I blocked off the intake heat crossover passage in the intake. I also installed the GM aluminum heat shield that goes under the carb base and used two thick base gaskets for extra insulation. These engines run the 4346 780 Holley carb but the same rules apply to other carbs. I ran #73 jets on the primary side which are one size richer than what came in 1966. I toyed a lot with the advance curve with different weights and springs until things worked right. No numbers for that part of the mods. I drove the car that way from 1998 until 2012 with no problems.

<blockquote data-quote="Keith Tedford" data-source="post: 242014" data-attributes="member: 1228"><p>Before we bought our 2005 Corvette in 2012, I had a 1969&nbsp; SS396 Chevelle with the L78 engine and 11-1 compression.&nbsp; First, I blocked the heat riser open.&nbsp; Getting heat away from the incoming air charge was the big thing.&nbsp; I added the sheet metal heat shield that snaps in between the heads.&nbsp; I blocked off the intake heat crossover passage in the intake.&nbsp; I also installed the GM aluminum heat shield that goes under the carb base and used two thick base gaskets for extra insulation.&nbsp; These engines run the 4346 780 Holley carb but the same rules apply to other carbs.&nbsp; I ran #73 jets on the primary side which are one size richer than what came in 1966.&nbsp; I toyed a lot with the advance curve with different weights and springs until things worked right.&nbsp; No numbers for that part of the mods.&nbsp; I drove the car that way from 1998 until 2012 with no problems.</p></blockquote><p></p>

[QUOTE="Keith Tedford, post: 242014, member: 1228"] Before we bought our 2005 Corvette in 2012, I had a 1969 SS396 Chevelle with the L78 engine and 11-1 compression. First, I blocked the heat riser open. Getting heat away from the incoming air charge was the big thing. I added the sheet metal heat shield that snaps in between the heads. I blocked off the intake heat crossover passage in the intake. I also installed the GM aluminum heat shield that goes under the carb base and used two thick base gaskets for extra insulation. These engines run the 4346 780 Holley carb but the same rules apply to other carbs. I ran #73 jets on the primary side which are one size richer than what came in 1966. I toyed a lot with the advance curve with different weights and springs until things worked right. No numbers for that part of the mods. I drove the car that way from 1998 until 2012 with no problems. [/QUOTE]

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