Perhaps this was part of the vacuum leak I have been chasing to include a corner intake bolt loose
Could be especially if you decked the block and milled the heads plus when those processes are done and not modded for an adjustable valvetrain they sell shim kits for the pedestal mount rockers to finetune proper Valvetrain geometry..Sometimes at full pump-up the valve just hangs off the seat very so minutely it will cause running issues that seem like vacuum leaks...
A vacuum gauge while running will tell you important info plus also doing a cylinder leakdown test using a cylinder leakdown tester tool on each cylinder while priming the oilpump to fully pump the lifters up will tell you if the valves arent totally sealing too...
A similar thing happened in my 1978 Hurts Olds w/350 rocket engine after refurbing he heads because of burnt valves/valveseats..... A .025" thick pedestal shim on each pedestal fixed the issue to keep my 10.5:1 compression ratio.
I found out on my 410w I had to retorque the intake bolts a few times and on the third time I even torqued the bolts to 28ftlbs and so far so good.....Another thing I found is I needed to use sealant on the bolt threads and shoulders because the holes arent blind..
Sometimes the conventional thickness off the shelf FelPro intake gaskets dont seal right after sending heads to a machine shop and thicker intake gaskets are needed and if you used racing gaskets like Edelbrock #7227 Intake gaskets those types arent recommended for street use...
A really good machine shop will recommend torque specs for the headbolts also tell you or even supply proper brand and thickkness headgaskets also intake gaskets to use after doing the headwork to keep the engine as close to AERA specs as possible.............
Before I put the intake gaskets and seal down the intake I put a super bright light inside the lifter galley then I tighten down the intake without gaskets and turn out the lights to make the garage pitch dark then I peek down the runners with an inspection camera attached to my cellphone and look inside the runners to see how good or how bad the intake seals to the heads without gaskets and also note the gap thicknesses on the china rails too and also to note I never use the rubbber or caulk china rail gaskets either,,,,I use The Right Stuff gasket maker.........
Nothing is too straight forwards when you modify stock parts........Unless the valveseats are replaced and recut to A.E.R.A specs and proper thickness headgaskets are properly spec'd and used to make up for block decking and head milling also to mention when the valves and valveseats are recut the valves in essence raise up and that makes the pushrods looser also to add that the actual geometry and shape of the Lunati Rockers doesnt exactly mirror stock stamped steel rocker arms......
Even the lifter body heights changes the A.E.R.A number sometimes pretty substantial to where different length pushrods &/or pedestal shims are also needed...
These lifters came in the same boxes...Upon disassembly and cleaning them before installation I noticed this....
Look at the differences in heights.........When I put the lifter in to see how much difference in rocker nut adjustment and there was a .065" max difference with one that was .013" larger in rocker nut adjustment heights so I sent them back...
Good Luck
