Lifter preload pushrod length help!!!
03-10-2018, 04:22 PM
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Lifter preload pushrod length help!!! Hi guys. I've searched the forum and have read several articles on this but having a hard time trying to figure this out. I have an LQ4 we built to put in my 2001 trans am. Block has been decked .007 pistons alall stick out .005. using ported 243 heads that haven't been decked. .040 felpro mls head gasket and abhowards ASA cam. Used 7.4 pushrods and getting a little noise kinda like the sewing machine deal. Pulled valve covers and did the EO/IC method and to get to 22 ft lbs we are having to go 2-3/4 turns. I have a length checker ordered and will check with it, but does this mean I need a shorter or longer pushrod? Any help and suggestions are appreciated. Thanks in advance guys. Great site by the way.
03-11-2018, 09:02 AM
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Yeah. Johnson says to use .020 to .040 on there lifters. Not running car anymore. I'm gonna wait on checker for sure. I'm thinking probably gonna need 7.350. Howards ASA has standard base circle. This sound right on length? Ordered a ZZPerformance length checker. Updated ones are .050 per turn now.
03-12-2018, 01:42 PM
#6
I'm running 7.350" BTR pushrods on my stock 5.3 block, cleaned heads with MLS gaskets and Morel 5315s. You can easily convert a stock pushrod to a length checker btw. Either way your going to want to keep the preload down on the johnsons and morels. Only lifter that likes a bit of preload as high as .120 is the LS7 style stock replacements.
03-12-2018, 02:04 PM
#7
Harbor Freight sell an 8" digital caliper made by Pittsburgh for $30 which will measure accurately enough to check you pushrod length without counting turns. I used tape to keep the adjustable pushrod from turning between pulling it from the motor and measuring.
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03-12-2018, 03:04 PM
#8
yup thats what I use. but you need to specify that they are overall length with a caliper vs the normal pushrod length. Since manufactures measure them with a special tool which sizes them on the ball and not end to end. Caliper length is longer than "measured manufacture length".
03-12-2018, 03:44 PM
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Thanks for the help. Great info!! I actually emailed frost and he gave great advice about a few issues I was having. Got my ecu tuned by him and well its awesome!! Still gotta get abdyno tune and use wideband to be 100 percent but if anyone is wondering his tunes rock!!! I'll update on my findings when we figure out what length we need.
03-12-2018, 04:02 PM
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Thanks for the help. Great info!! I called frost who gave great info on some issues I was having. Got my tune by him and btw it rocks!!! I still have to get it dyno tuned with wideband but for now it kicks a$$. Got another question. They say ideal preload on ls7 lifter is .080, or between .060 and .100. is there any issues if you run these on the light side. Like say .040 to .050? Thoughts?
03-12-2018, 08:38 PM
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Interesting. I know this has been discussed a million times so I'm not gonna dwell on it but I always thought a noisey lifter was because it was too tight or to much preload, or collapsed. I realize the ls7 has more travel than usual but I would think a little cushiio and extra travel would be better. I'm no expert by any means though. Just thinking out loud. LOL!! Thanks for all the help and insight. I'll keep you posted as to what we come up with.
03-14-2018, 06:22 PM
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Ok guys. Checker came in today. Checked 2 intake and 2 exhaust on each side. Put checker in and torqued rocker to 22 ft lbs. Have to come out 8.5 turns to have zero lash. At .050 per turn and checker being 6.800 that comes up to 7.225. and .075 for preload and I come up with 7.300. That doesn't seem correct to me. As stated before, .040 head gasket,block decked .007 and heads not milled, what gives?? HELP!!!!!
03-14-2018, 06:27 PM
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At 2.75 turns and 80 preload per turn (dont count the last 1/4 turn) you are 2.5 x 80 so you are at 200 preload with that measurement. So if that was a 7.4 pushrod and you want to run say 75 preload youll need to drop to a 7.400 - .125 = 7.275.
03-14-2018, 07:54 PM
#17
Why on earth are you torquing the bolts to 22ftlbs? Anything over basic hand snug is just bolt stretch. Crank it down normal tight with a socket wrench and don’t both tq’in it. Just a waste of time. As stated on my build it was a know. Stock block, never opened and I put on cleaned up stock heads... .005” and required 7.350 pushrods and I’m on the High side for the 5315s.
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03-14-2018, 08:15 PM
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Ok. Thanks. I just assumed that you were supposed to torque it just like it would be when you're done and then adjust checker to what ever took out lash and then add desired preload. Either way I just thought for being only a combined .018 off factory height that 7.300 seamed to short. I originally was guessing I was gonna need 7.350. car hasn't been ran for a week. Would that contribute to it? Lifters bled off?