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#1
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solid roller valve lash
Did a search for this topic and found a good thread back from Jan. 2019. So I called lunati about my cam which according to the cam card calls for .020/.022 lash I/E. I assumed incorrectly that their #s were for cold. The tech said they were for hot setting and he suggested since I have aluminum heads to set the I/E at .012/.014 cold and then check hot to see how much increase. He gave a range of .007-.010 increase when hot for the aluminum heads. This seems to square pretty much with the #s I was seeing from the past thread although a little on the high side.
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69 Bird w/1970 400 block(409 cubes), #64 heads, hyd. roller, Q-jet by Jeff E., original interior, ps, pdb, th350, and 3.73 gears. Pump gas, street driven muscle. 3800 lbs. race weight. Best, 11.39 @118, my son's car. 79 T/A w/463, Scat crank, Eagle rods, Icon pistons, Lunati solid roller, 262/270, KRE 325 heads, Northwind intake, QF950 carb, full interior, ps, pdb, th350, and 3.73 gears. Pump gas, 3650 lbs. race weight. 10.68 @ 126 so far... no tuning yet. |
#2
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That cold setting works, I have on average seen the hot lash grow by .009”.
This however was with the Added X cooling lines under the intake on a drag motor. On the street depending on your cooling system and or on a hot day you might see more growth in lash.
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I do stuff for reasons. |
#3
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I lash my 400 with eddy heads at 0.014" both sides cold. Mine grows around 0.006" between hot/cold -- street driven.
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'71 Holden HQ Monaro - 3850lbs race weight, 400c/i - 11.4 @ 120 '66 Pontiac GTO - 389, 4 speed street cruiser |
#4
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I figure .006 on mine , ia2 block and high ports
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Illinois Outlaw Gassers 6.27@107 9.97@131 |
#5
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Interesting Tidbit about aluminum engines and valve lash. Extreme example of lash growth. Current Top Fuel and Funny Car engines are lashed at 0.00" cold. They just take the adjuster down until zero is reached and stop. When the engine is run, the heat creates the lash they use. After a pass, engine hot, the lash will be around .020". If you ever wondered why these cars seem to miss pretty badly the first 2-3 minutes of a warm-up, it's partly due to valve leakage from zero lash until they warm up.
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The Following User Says Thank You to mgarblik For This Useful Post: | ||
#6
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We find about .006 growth with iron blocks and aluminum heads. About .014 with aluminum block and aluminum heads. I recall a friend trying to run solid roller lifters with a hydraulic roller cam and he had aluminum heads and aluminum block. He had to preload the valves about an 1/8 turn to get .004 lash hot.
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#7
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Ours also IA2 block and Aluminum heads. .006 growth. Set at .010- .011 cold. Requires .016 hot.
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68 Firebird. IA2 block, 505 cu in, SD Performance E-head, Solid roller 3600 weight. Reid TH400 4:11 gear. 29" slick. Best so far 9.95@134 mph. 1.43 60 ft. 76 Trans am, TKX .81 o/d, 3.73 Moser rearend, 468 with KRE D-ports, Doug headers, 3" Exh. |
#8
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I did mine on an engine run in stand. Immediately after reaching full temp, I adjusted the valve last as per Comp Cams cam card (Intake .020 hot / Exhaust .022 hot). Let engine set and checked the lash the next day.
Intake .011 cold / Exhaust .013 cold. I asked a good friend that worked for Crane Cams as a Tech advisor, and he stated that it sounds about right to him. |
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