Given we had not one but three impressive small blocks to test (actually four counting the low-compression LT-1), we fully expected there to be a few issues and true to form, this dyno session was not without its incidents. The first issue occurred when we brought the finished 461 heads to the airflow bench. What we thought was a set of untouched, factory castings with a fresh valve job was actually a ported set. With no replacement set of 461s at our disposal, we opted to run the 327 with the same set of 186s used on the 302. Given the similarities in airflow between a set of 461s and 186s, this was an accurate representation of the true power of the 327.
Next up was the intake manifold, The author purchased the required intake via E-bay but the intake was actually for a 1963 L76 and not the later (and higher HP) 1965 L76. The difference was that the 1963 version was equipped with a Carter carburetor and not the more desirable (and available for our dyno session) Holley carb.
With time running out, we opted to run all three small blocks with the 1970 LT-1 Z/28 intake. Correct for the LT-1 and as-near spot on (in terms of performance) for the DZ302, the intake was actually slightly better than the original manifold for the L76. We'll run a back-to-back test on the two intakes to clear up this issue and provide the results for the interested parties, but know that the L76 might be up slightly from where it would be with the stock manifold.
Naturally the stock exhaust manifolds would kill some of the power compared to the long-tube headers, but the factory tested them with open headers in the late-'60s and early-'70s (SAE gross) so we were comfortable with this (especially since all of the test engines were run in the same configuration.
When we test the stock L76 intake, maybe we'll toss on a set of stock manifolds just to see what the headers were worth. Let's hit the dyno and find out which combo is king.
*461 heads eliminated for test due to obvious porting; 327 was run with 186 heads.