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Setting Valve Lash

ksurfer2

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The cam in my 512 is a lunati that specifies lash of .026 intake and .028 exhaust. I spoke with tech support at Lunati and they confirmed that this is hot lash. knowing how much fun it is to work on a hot engine is there a fixed amount of adjustment from the recommended lash for setting on a cold motor (aluminum head, iron block)? If not, given the time it takes to lash all the valves, the engine temp will change. Is it best to set half the valves, restart the engine to let it heat back up and then set the other half?
 
My cam calls for the same lash and using alum heads aand iron block, I always set them to .022" cold. Never a problem. RUFFCUT
 
Aluminum on iron I'd start with .004 less than spec'd hot lash, when the engine is dead cold, then after running it and getting it good and hot just spot check a couple and see what they are, as quickly as possible after shutdown. If they're where you want them, great. If not, do another cold lash and add/subtract the difference, and you should be golden. Even trying to do only half at a time isn't as accurate because things start cooling and contracting quickly.
FWIW I ended up at .006 less cold...but I'd rather start with too little than too much.
 
I'd set all your valves after overnight cold soak. Warm the engine with a good drive or pass. Pull one valve cover, measure all 8 and write them down. Now recheck them cold the next day. Do the math between hot and this check. You'll know where you need to be cold. No reason to ever do them hot again. I'd set them .020" cold. Thatll get you close.
Doug
 
I’m kinda in the same boat with an old lunati cam and can’t for the life of me find the card.. it was a small block 318 with solid cam.. runs very good but I’ve never adjusted the lash..
 
The cam in my 512 is a lunati that specifies lash of .026 intake and .028 exhaust. I spoke with tech support at Lunati and they confirmed that this is hot lash. knowing how much fun it is to work on a hot engine is there a fixed amount of adjustment from the recommended lash for setting on a cold motor (aluminum head, iron block)? If not, given the time it takes to lash all the valves, the engine temp will change. Is it best to set half the valves, restart the engine to let it heat back up and then set the other half?
I'd do it exactly how Doug suggested.
 
.006 difference between hot and cold is where mine ended up at.
 
Our cam requires .024 inlet, 0.25 exh. on a solid roller. Cold check was .018/.019, mega block/ -13's.
 
My SFT cam calls for .020 hot. I set them at .014 cold. Ron
 
Follow the manufacturers recommendation or just pick which guys opinion that you like the best ?? Your choice. I always take the time to do as the maker of the part recommends, no issues later if there is a problem...
 
Ive set lash every 20-25 passes for over the last 8 years. 700 passes on the current motor. Setting cold is very repeatable. Seldom do more than 2 valves change by more than .001". If your specs are hot they can easily be converted to cold as mentioned in my earlier post. Hot is subjective. Most of you dont have an oil temperature gauge. It makes a difference regardless of water temp. The exhaust lash will tighten up by the time you make it to the other side of the motor. And that's being fast at it. Takes 15 minutes total. Loose lash is a recipe for damage, especially on solid roller. The actual hot spec means squat if it's close to spec. Once it's close you can experiment for best performance if you are so inclined. If not err to the tight side and run it. Solid flat tappet is not a picky as solid roller. Does it work? Same roller tappets, close to 500 passes with no noticable wear. 310 on the seat, 820 open.
Doug
 
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